* [RFC PATCH 01/31] x86/topology: Export topo_lookup_cpuid() for resctrl use
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
@ 2026-08-02 16:02 ` Chen Yu
2026-08-02 16:02 ` [RFC PATCH 02/31] x86/resctrl: Require 64-bit x86 for resctrl support Chen Yu
` (29 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:02 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
Enhanced RDT (ERDT) enumerates its monitoring and control resources
through ACPI tables that identify each CPU by its x2APIC ID. To
associate this firmware-provided data with the kernel's per-CPU
structures, ERDT must translate those x2APIC IDs into logical CPU
numbers.
topo_lookup_cpuid() already performs this translation, but it is
static to topology.c and therefore not reachable from resctrl.
Export topo_lookup_cpuid() and add its declaration to asm/apic.h so
that ERDT can resolve x2APIC IDs from ACPI tables to logical CPU
numbers.
No functional change intended.
Tested-by: Hongyu Ning <hongyu.ning@linux.intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/include/asm/apic.h | 1 +
arch/x86/kernel/cpu/topology.c | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 9cd493d467d4..bb84651b14bd 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -54,6 +54,7 @@ static inline void x86_32_probe_apic(void) { }
#endif
extern u32 cpuid_to_apicid[];
+int topo_lookup_cpuid(u32 apic_id);
#define CPU_ACPIID_INVALID U32_MAX
diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c
index 4913b64ec592..bcee70fb9277 100644
--- a/arch/x86/kernel/cpu/topology.c
+++ b/arch/x86/kernel/cpu/topology.c
@@ -92,7 +92,7 @@ static inline u32 topo_apicid(u32 apicid, enum x86_topology_domains dom)
return apicid & (UINT_MAX << x86_topo_system.dom_shifts[dom - 1]);
}
-static int topo_lookup_cpuid(u32 apic_id)
+int topo_lookup_cpuid(u32 apic_id)
{
int i;
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 02/31] x86/resctrl: Require 64-bit x86 for resctrl support
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
2026-08-02 16:02 ` [RFC PATCH 01/31] x86/topology: Export topo_lookup_cpuid() for resctrl use Chen Yu
@ 2026-08-02 16:02 ` Chen Yu
2026-08-02 16:02 ` [RFC PATCH 03/31] x86/resctrl: Parse ACPI ERDT table and save CACD cpumask for RMDD domains Chen Yu
` (28 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:02 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
All known hardware that supports Intel RDT or AMD QoS is 64-bit. Future
enhancements like MMIO-based Enhanced RDT (ERDT) monitoring require
readq()/writeq() which are only available on 64-bit. There is also no
realistic use case for users to build a 32-bit kernel on a server and
enable resctrl.
Drop 32-bit support by changing the X86_CPU_RESCTRL dependency from X86
to X86_64.
Since X86_CPU_RESCTRL now implies X86_64, remove the redundant X86_64
dependency from X86_CPU_RESCTRL_INTEL_AET.
Tested-by: Hongyu Ning <hongyu.ning@linux.intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/Kconfig | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f3f7cb01d69d..97d210bd9bb5 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -515,7 +515,7 @@ config X86_MPPARSE
config X86_CPU_RESCTRL
bool "x86 CPU resource control support"
- depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
+ depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
depends on MISC_FILESYSTEMS
select ARCH_HAS_CPU_RESCTRL
select RESCTRL_FS
@@ -538,7 +538,7 @@ config X86_CPU_RESCTRL
config X86_CPU_RESCTRL_INTEL_AET
bool "Intel Application Energy Telemetry"
- depends on X86_64 && X86_CPU_RESCTRL && CPU_SUP_INTEL && INTEL_PMT_TELEMETRY=y && INTEL_TPMI=y
+ depends on X86_CPU_RESCTRL && CPU_SUP_INTEL && INTEL_PMT_TELEMETRY=y && INTEL_TPMI=y
help
Enable per-RMID telemetry events in resctrl.
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 03/31] x86/resctrl: Parse ACPI ERDT table and save CACD cpumask for RMDD domains
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
2026-08-02 16:02 ` [RFC PATCH 01/31] x86/topology: Export topo_lookup_cpuid() for resctrl use Chen Yu
2026-08-02 16:02 ` [RFC PATCH 02/31] x86/resctrl: Require 64-bit x86 for resctrl support Chen Yu
@ 2026-08-02 16:02 ` Chen Yu
2026-08-02 16:03 ` [RFC PATCH 04/31] x86/resctrl: Attach ACPI ERDT information to L3 mon domain on CPU online Chen Yu
` (27 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:02 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
From: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Parse the RMDD subtables within the ERDT ACPI table and their nested
CACD entries to construct per-domain CPU masks.
There is one ERDT table per platform. Each RMDD describes one resource
management domain (RMD), also known as an L3 domain, and carries MMIO
base information for later monitoring support.
For each RMDD, parse the associated CACD, map its x2APIC IDs to logical
CPUs, and save the resulting CPU mask. This mask associates each ERDT
domain with the CPUs that belong to it and is used later when attaching
ERDT data to resctrl monitoring domains.
Suggested-by: Tony Luck <tony.luck@intel.com>
Suggested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Tested-by: Hongyu Ning <hongyu.ning@linux.intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/Makefile | 1 +
arch/x86/kernel/cpu/resctrl/core.c | 14 +-
arch/x86/kernel/cpu/resctrl/erdt.c | 266 +++++++++++++++++++++++++
arch/x86/kernel/cpu/resctrl/internal.h | 31 +++
4 files changed, 311 insertions(+), 1 deletion(-)
create mode 100644 arch/x86/kernel/cpu/resctrl/erdt.c
diff --git a/arch/x86/kernel/cpu/resctrl/Makefile b/arch/x86/kernel/cpu/resctrl/Makefile
index 273ddfa30836..2216ee084832 100644
--- a/arch/x86/kernel/cpu/resctrl/Makefile
+++ b/arch/x86/kernel/cpu/resctrl/Makefile
@@ -2,6 +2,7 @@
obj-$(CONFIG_X86_CPU_RESCTRL) += core.o rdtgroup.o monitor.o
obj-$(CONFIG_X86_CPU_RESCTRL) += ctrlmondata.o
obj-$(CONFIG_X86_CPU_RESCTRL_INTEL_AET) += intel_aet.o
+obj-$(CONFIG_X86_CPU_RESCTRL) += erdt.o
obj-$(CONFIG_RESCTRL_FS_PSEUDO_LOCK) += pseudo_lock.o
# To allow define_trace.h's recursive include:
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 07c6ebb7fc43..e6f501c6782d 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -1147,6 +1147,7 @@ static __init void check_quirks(void)
static __init bool get_rdt_resources(void)
{
+ erdt_init();
rdt_alloc_capable = get_rdt_alloc_resources();
rdt_mon_capable = get_rdt_mon_resources();
@@ -1232,7 +1233,7 @@ void resctrl_cpu_detect(struct cpuinfo_x86 *c)
}
}
-static int __init resctrl_arch_late_init(void)
+static int __init __resctrl_arch_late_init(void)
{
struct rdt_resource *r;
int state, ret, i;
@@ -1275,6 +1276,15 @@ static int __init resctrl_arch_late_init(void)
return 0;
}
+static int __init resctrl_arch_late_init(void)
+{
+ int ret = __resctrl_arch_late_init();
+
+ if (ret)
+ erdt_exit();
+ return ret;
+}
+
late_initcall(resctrl_arch_late_init);
static void __exit resctrl_arch_exit(void)
@@ -1288,6 +1298,8 @@ static void __exit resctrl_arch_exit(void)
* removed here.
*/
resctrl_exit();
+
+ erdt_exit();
}
__exitcall(resctrl_arch_exit);
diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
new file mode 100644
index 000000000000..8998cae47090
--- /dev/null
+++ b/arch/x86/kernel/cpu/resctrl/erdt.c
@@ -0,0 +1,266 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Enhanced Resource Director Technology (ERDT)
+ *
+ * Copyright (C) 2026 Intel Corporation
+ *
+ */
+
+#define pr_fmt(fmt) "resctrl: " fmt
+
+#include <linux/acpi.h>
+#include <linux/overflow.h>
+#include <linux/resctrl.h>
+#include <linux/sizes.h>
+
+#include <asm/apic.h>
+
+#include "internal.h"
+
+static LIST_HEAD(domain_info_list);
+
+/* True when the ERDT ACPI table describes at least one domain with at least one CPU. */
+static bool erdt_enabled;
+
+#define ERDT_VALID_VERSION 1
+#define RMDD_FLAG_CPU_L3_DOMAIN BIT(0)
+
+/* Bitmask of valid sub-tables found in the first RMDD, used to ensure all RMDDs match. */
+static u32 valid_subtbl_mask;
+
+/* Domain ID of the first RMDD that established @valid_subtbl_mask, for diagnostics. */
+static u16 first_rmdd_domain_id;
+
+static int erdt_max_rmid;
+
+int erdt_get_max_rmid(void)
+{
+ return erdt_max_rmid;
+}
+
+static void __iomem *erdt_ioremap(phys_addr_t base, u32 num_pages, const char *desc)
+{
+ void __iomem *addr;
+ size_t size;
+
+ if (check_mul_overflow(num_pages, SZ_4K, &size))
+ return NULL;
+
+ addr = ioremap(base, size);
+ if (!addr)
+ pr_warn(FW_BUG "ERDT: Failed to map %s at phys addr %pa (size: %u pages)\n",
+ desc, &base, num_pages);
+
+ return addr;
+}
+
+static void erdt_iounmap_domain(struct erdt_domain_info *domain)
+{
+ for (int i = 0; i < ERDT_MMIO_NUM_TYPES; i++) {
+ if (domain->base[i]) {
+ iounmap(domain->base[i]);
+ domain->base[i] = NULL;
+ }
+ }
+}
+
+static void cleanup_one_domain(struct erdt_domain_info *d)
+{
+ erdt_iounmap_domain(d);
+ kfree(d);
+}
+
+/*
+ * Save CACD information for this RMDD:
+ * convert the X2APIC to CPU and save them in a mask.
+ */
+static __init int cacd_init(struct acpi_subtbl_hdr_16 *subtbl,
+ struct erdt_domain_info *domain_info)
+{
+ struct acpi_erdt_cacd *cacd = (struct acpi_erdt_cacd *)subtbl;
+ int num_ids, cpu;
+
+ if (cacd->header.length < struct_size(cacd, X2APICIDS, 1)) {
+ pr_warn(FW_BUG "Invalid x2apicid CACD table\n");
+ return -EIO;
+ }
+
+ num_ids = (cacd->header.length - sizeof(*cacd)) / sizeof(cacd->X2APICIDS[0]);
+
+ for (int i = 0; i < num_ids; i++) {
+ cpu = topo_lookup_cpuid(cacd->X2APICIDS[i]);
+ if (cpu < 0) {
+ pr_warn(FW_BUG "Unknown x2apicid 0x%x\n", cacd->X2APICIDS[i]);
+ return -EIO;
+ }
+
+ cpumask_set_cpu(cpu, &domain_info->cpu_mask);
+ }
+
+ return 0;
+}
+
+static inline struct acpi_subtbl_hdr_16 *rmdd_subtbl(struct acpi_erdt_rmdd *rmdd)
+{
+ return (void *)rmdd + sizeof(*rmdd);
+}
+
+static inline struct acpi_subtbl_hdr_16 *next_subtbl(struct acpi_subtbl_hdr_16 *subtbl)
+{
+ return (void *)subtbl + subtbl->length;
+}
+
+static inline bool subtbl_valid(void *end, struct acpi_subtbl_hdr_16 *subtbl)
+{
+ /* Ensure the header is within bounds before dereferencing it. */
+ if ((void *)subtbl + sizeof(*subtbl) > end)
+ return false;
+
+ /* A sub-table must be at least as large as its header. */
+ if (subtbl->length < sizeof(*subtbl))
+ return false;
+
+ /* The entire sub-table (including body) must fit within the parent. */
+ if ((void *)subtbl + subtbl->length > end)
+ return false;
+
+ return true;
+}
+
+static __init bool parse_rmdd_table(struct acpi_subtbl_hdr_16 *rmdd_hdr)
+{
+ struct erdt_domain_info *domain_info;
+ struct acpi_subtbl_hdr_16 *subtbl;
+ struct acpi_erdt_rmdd *rmdd;
+ u32 subtbl_mask = 0;
+
+ if (rmdd_hdr->length < sizeof(*rmdd)) {
+ pr_warn(FW_BUG "Invalid RMDD length %u bytes\n", rmdd_hdr->length);
+ return false;
+ }
+
+ rmdd = (struct acpi_erdt_rmdd *)rmdd_hdr;
+
+ /* Quietly ignore non-CPU-based L3 domains */
+ if (!(rmdd->flags & RMDD_FLAG_CPU_L3_DOMAIN))
+ return true;
+
+ domain_info = kzalloc_obj(*domain_info, GFP_KERNEL);
+ if (!domain_info)
+ return false;
+
+ domain_info->dom_id = -1;
+
+ domain_info->base[ERDT_MMIO_RMDD_CREG] =
+ erdt_ioremap(rmdd->creg_base, rmdd->creg_size, "RMDD ctrl base");
+ if (!domain_info->base[ERDT_MMIO_RMDD_CREG])
+ goto cleanup;
+
+ for (subtbl = rmdd_subtbl(rmdd);
+ subtbl_valid((void *)rmdd + rmdd->header.length, subtbl);
+ subtbl = next_subtbl(subtbl)) {
+ switch (subtbl->type) {
+ /* An RMDD table has one or more CACD sub-table(s) */
+ case ACPI_ERDT_TYPE_CACD:
+ if (cacd_init(subtbl, domain_info))
+ goto cleanup;
+
+ subtbl_mask |= BIT(ACPI_ERDT_TYPE_CACD);
+ break;
+ default:
+ break;
+ }
+ }
+
+ if (!subtbl_mask)
+ goto cleanup;
+
+ /*
+ * Require all RMDDs to support same set of sub-tables
+ */
+ if (!valid_subtbl_mask) {
+ valid_subtbl_mask = subtbl_mask;
+ first_rmdd_domain_id = rmdd->domain_id;
+ } else if (subtbl_mask != valid_subtbl_mask) {
+ pr_warn(FW_BUG "RMDD %u sub-table set does not match the first RMDD %u\n",
+ rmdd->domain_id, first_rmdd_domain_id);
+ goto cleanup;
+ }
+
+ if (!rmdd->max_rmid) {
+ pr_warn(FW_BUG "Unreasonable RMDD max_rmid %u\n", rmdd->max_rmid);
+ goto cleanup;
+ }
+ domain_info->max_rmid = rmdd->max_rmid;
+
+ if (!erdt_max_rmid)
+ erdt_max_rmid = rmdd->max_rmid;
+ else
+ erdt_max_rmid = min_t(int, erdt_max_rmid, rmdd->max_rmid);
+
+ list_add(&domain_info->entry, &domain_info_list);
+
+ return true;
+
+cleanup:
+ cleanup_one_domain(domain_info);
+ return false;
+}
+
+void erdt_exit(void)
+{
+ struct erdt_domain_info *d, *tmp;
+
+ list_for_each_entry_safe(d, tmp, &domain_info_list, entry) {
+ list_del(&d->entry);
+ cleanup_one_domain(d);
+ }
+ erdt_enabled = false;
+ valid_subtbl_mask = 0;
+ first_rmdd_domain_id = 0;
+}
+
+static __init int enumerate_erdt_table(struct acpi_table_header *table_hdr)
+{
+ struct acpi_table_erdt *erdt = (struct acpi_table_erdt *)table_hdr;
+ struct acpi_subtbl_hdr_16 *subtbl;
+ void *table_end;
+
+ if (erdt->header.revision != ERDT_VALID_VERSION) {
+ pr_info("Unsupported ERDT table revision %u (expected %u)\n",
+ erdt->header.revision, ERDT_VALID_VERSION);
+ return -EINVAL;
+ }
+
+ if (erdt->header.length < sizeof(*erdt)) {
+ pr_warn(FW_BUG "ERDT: Invalid table length %u bytes\n", erdt->header.length);
+ return -EINVAL;
+ }
+
+ subtbl = (void *)erdt + sizeof(struct acpi_table_erdt);
+ table_end = (void *)erdt + erdt->header.length;
+
+ while (subtbl_valid(table_end, subtbl)) {
+ if (subtbl->type == ACPI_ERDT_TYPE_RMDD &&
+ !parse_rmdd_table(subtbl))
+ goto cleanup;
+
+ subtbl = next_subtbl(subtbl);
+ }
+
+ if (list_empty(&domain_info_list))
+ goto cleanup;
+
+ erdt_enabled = true;
+
+ return 0;
+
+cleanup:
+ erdt_exit();
+ return -EINVAL;
+}
+
+int __init erdt_init(void)
+{
+ return acpi_table_parse(ACPI_SIG_ERDT, enumerate_erdt_table);
+}
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 04b9f438a7dd..95e971c934e6 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -21,6 +21,33 @@
#define RMID_VAL_UNAVAIL BIT_ULL(62)
+/*
+ * Index into erdt_domain_info::base[] for each MMIO region.
+ * @ERDT_MMIO_RMDD_CREG: RMDD control register base address
+ */
+enum erdt_mmio_type {
+ ERDT_MMIO_RMDD_CREG,
+ ERDT_MMIO_LAST = ERDT_MMIO_RMDD_CREG
+};
+
+#define ERDT_MMIO_NUM_TYPES (ERDT_MMIO_LAST + 1)
+
+/**
+ * struct erdt_domain_info - Per-domain ERDT information
+ * @base: Array of ioremapped MMIO region base addresses, indexed by ERDT_MMIO_* type
+ * @cpu_mask: CPUs belonging to this resource management domain
+ * @max_rmid: Maximum RMID supported by this domain
+ * @dom_id: L3 cache ID shared by all CPUs in this domain (-1 if unset)
+ * @entry: Links into the global domain_info_list
+ */
+struct erdt_domain_info {
+ void __iomem *base[ERDT_MMIO_NUM_TYPES];
+ struct cpumask cpu_mask;
+ u32 max_rmid;
+ int dom_id;
+ struct list_head entry;
+};
+
/*
* With the above fields in use 62 bits remain in MSR_IA32_QM_CTR for
* data to be returned. The counter width is discovered from the hardware
@@ -269,4 +296,8 @@ static inline void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resour
static inline bool intel_handle_aet_option(bool force_off, char *tok) { return false; }
#endif
+int erdt_get_max_rmid(void);
+int erdt_init(void);
+void erdt_exit(void);
+
#endif /* _ASM_X86_RESCTRL_INTERNAL_H */
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 04/31] x86/resctrl: Attach ACPI ERDT information to L3 mon domain on CPU online
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (2 preceding siblings ...)
2026-08-02 16:02 ` [RFC PATCH 03/31] x86/resctrl: Parse ACPI ERDT table and save CACD cpumask for RMDD domains Chen Yu
@ 2026-08-02 16:03 ` Chen Yu
2026-08-02 16:03 ` [RFC PATCH 05/31] x86/resctrl: Parse ACPI CMRC table Chen Yu
` (26 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:03 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
Reading LLC occupancy counters via MMIO requires the per-domain ERDT
information, parsed earlier from the ACPI ERDT table, to be reachable
from the resctrl L3 monitoring domain. Nothing links the two yet, so
the monitoring code cannot locate the MMIO registers of a domain.
ERDT and CPUID enumerate CPU-to-L3-domain membership independently:
CPUID leaf 4 describes the L3 cache topology, while the firmware CACD
sub-table lists the CPUs of each ERDT domain. Both views must agree on
a CPU's L3 domain for that CPU to be monitored safely.
When a CPU comes online, validate that firmware and CPUID agree on its
L3 domain before adding it to a resctrl monitoring domain. Exclude the
CPU from all monitoring domains on a mismatch because a topology
inconsistency between ERDT and CPUID indicates a firmware defect that
makes the CPU's domain placement unreliable for any resource. Otherwise
attach the matching ERDT domain information to the L3 monitoring domain
so that later code can read monitoring data via ERDT and its sub-tables.
Suggested-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Hongyu Ning <hongyu.ning@linux.intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/core.c | 11 ++++-
arch/x86/kernel/cpu/resctrl/erdt.c | 66 ++++++++++++++++++++++++++
arch/x86/kernel/cpu/resctrl/internal.h | 5 ++
3 files changed, 81 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index e6f501c6782d..4e2922ec1dda 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -705,6 +705,9 @@ static void domain_add_cpu_mon(int cpu, struct rdt_resource *r)
return;
}
+ if (!erdt_cpu_valid(cpu))
+ return;
+
hdr = resctrl_find_domain(&r->mon_domains, id, &add_pos);
if (hdr)
cpumask_set_cpu(cpu, &hdr->cpu_mask);
@@ -714,8 +717,14 @@ static void domain_add_cpu_mon(int cpu, struct rdt_resource *r)
/* Update the mbm_assign_mode state for the CPU if supported */
if (r->mon.mbm_cntr_assignable)
resctrl_arch_mbm_cntr_assign_set_one(r);
- if (!hdr)
+ if (!hdr) {
l3_mon_domain_setup(cpu, id, r, add_pos);
+ hdr = resctrl_find_domain(&r->mon_domains, id, NULL);
+ }
+
+ if (hdr)
+ erdt_l3_mon_domain_setup(cpu, hdr);
+
break;
case RDT_RESOURCE_PERF_PKG:
if (!hdr)
diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
index 8998cae47090..6257869d0db2 100644
--- a/arch/x86/kernel/cpu/resctrl/erdt.c
+++ b/arch/x86/kernel/cpu/resctrl/erdt.c
@@ -207,6 +207,72 @@ static __init bool parse_rmdd_table(struct acpi_subtbl_hdr_16 *rmdd_hdr)
return false;
}
+bool erdt_cpu_valid(int cpu)
+{
+ struct erdt_domain_info *d;
+ int dom_id;
+
+ if (!erdt_enabled)
+ return true;
+
+ dom_id = get_cpu_cacheinfo_id(cpu, RESCTRL_L3_CACHE);
+ if (dom_id < 0)
+ return true;
+
+ /*
+ * Find the erdt_domain_info that contains this CPU,
+ * check if all CPUs in erdt_domain_info's cpumask
+ * have the same id(L3 id).
+ *
+ * For example, erdt_domain_info reports:
+ * domain0: CPU0, CPU2, domain1: CPU1, CPU3
+ * rdt_domain_hdr reports:
+ * domain0: CPU0, CPU1, domain1: CPU2, CPU3
+ * As a result, CPU1, CPU2 should not be covered by resctrl.
+ */
+ list_for_each_entry(d, &domain_info_list, entry) {
+
+ if (cpumask_test_cpu(cpu, &d->cpu_mask)) {
+ if (d->dom_id == -1) {
+ d->dom_id = dom_id;
+ } else if (d->dom_id != dom_id) {
+ pr_warn(FW_BUG "CPU%d's id=%d not equal to CACD domain(%*pbl) id=%d, skip this CPU\n",
+ cpu, dom_id, cpumask_pr_args(&d->cpu_mask), d->dom_id);
+
+ return false;
+ }
+
+ return true;
+ }
+ }
+
+ pr_warn(FW_BUG "Cannot find CACD domain for CPU%d\n", cpu);
+ return false;
+}
+
+/*
+ * Associate ERDT table information with this domain.
+ */
+void erdt_l3_mon_domain_setup(int cpu, struct rdt_domain_hdr *hdr)
+{
+ struct rdt_hw_l3_mon_domain *hw_dom;
+ struct erdt_domain_info *d;
+
+ if (!erdt_enabled)
+ return;
+
+ hw_dom = resctrl_to_arch_mon_dom(container_of(hdr, struct rdt_l3_mon_domain, hdr));
+
+ list_for_each_entry(d, &domain_info_list, entry) {
+ if (cpumask_test_cpu(cpu, &d->cpu_mask)) {
+ /* Assign the ERDT information to hw_dom */
+ if (!hw_dom->d_info)
+ hw_dom->d_info = d;
+ return;
+ }
+ }
+}
+
void erdt_exit(void)
{
struct erdt_domain_info *d, *tmp;
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 95e971c934e6..d6e82eb570a3 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -132,14 +132,19 @@ struct rdt_hw_ctrl_domain {
* @arch_mbm_states: Per-event pointer to the MBM event's saved state.
* An MBM event's state is an array of struct arch_mbm_state
* indexed by RMID on x86.
+ * @d_info: ERDT table information of this domain
*
* Members of this structure are accessed via helpers that provide abstraction.
*/
struct rdt_hw_l3_mon_domain {
struct rdt_l3_mon_domain d_resctrl;
struct arch_mbm_state *arch_mbm_states[QOS_NUM_L3_MBM_EVENTS];
+ const struct erdt_domain_info *d_info;
};
+bool erdt_cpu_valid(int cpu);
+void erdt_l3_mon_domain_setup(int cpu, struct rdt_domain_hdr *hdr);
+
static inline struct rdt_hw_ctrl_domain *resctrl_to_arch_ctrl_dom(struct rdt_ctrl_domain *r)
{
return container_of(r, struct rdt_hw_ctrl_domain, d_resctrl);
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 05/31] x86/resctrl: Parse ACPI CMRC table
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (3 preceding siblings ...)
2026-08-02 16:03 ` [RFC PATCH 04/31] x86/resctrl: Attach ACPI ERDT information to L3 mon domain on CPU online Chen Yu
@ 2026-08-02 16:03 ` Chen Yu
2026-08-04 17:19 ` Luck, Tony
2026-08-02 16:03 ` [RFC PATCH 06/31] x86/resctrl: Refactor the monitor read function Chen Yu
` (25 subsequent siblings)
30 siblings, 1 reply; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:03 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
The CMRC (Cache Monitoring Registers for CPU Agents Description) sub-table of
ERDT describes the MMIO registers used to read cache monitoring counters (e.g.
LLC occupancy) for an RMD.
Parse each CMRC sub-table, ioremap its register window, and save a copy of the
CMRC table in the corresponding ERDT domain entry so that later monitoring code
can read the counters via MMIO.
Suggested-by: Tony Luck <tony.luck@intel.com>
Tested-by: Hongyu Ning <hongyu.ning@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/include/asm/resctrl.h | 2 +
arch/x86/kernel/cpu/resctrl/erdt.c | 57 ++++++++++++++++++++++++++
arch/x86/kernel/cpu/resctrl/internal.h | 6 ++-
3 files changed, 64 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/resctrl.h b/arch/x86/include/asm/resctrl.h
index 575f8408a9e7..e60c2aea7ebd 100644
--- a/arch/x86/include/asm/resctrl.h
+++ b/arch/x86/include/asm/resctrl.h
@@ -49,6 +49,8 @@ DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key);
DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);
+int erdt_get_scale(void);
+
static inline bool resctrl_arch_alloc_capable(void)
{
return rdt_alloc_capable;
diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
index 6257869d0db2..422618991927 100644
--- a/arch/x86/kernel/cpu/resctrl/erdt.c
+++ b/arch/x86/kernel/cpu/resctrl/erdt.c
@@ -23,6 +23,7 @@ static LIST_HEAD(domain_info_list);
static bool erdt_enabled;
#define ERDT_VALID_VERSION 1
+#define CMRC_SUPPORTED_INDEX_FN 1
#define RMDD_FLAG_CPU_L3_DOMAIN BIT(0)
/* Bitmask of valid sub-tables found in the first RMDD, used to ensure all RMDDs match. */
@@ -33,11 +34,19 @@ static u16 first_rmdd_domain_id;
static int erdt_max_rmid;
+/* Scale to bytes for the monitoring counters when ERDT is enabled. */
+static int erdt_scale;
+
int erdt_get_max_rmid(void)
{
return erdt_max_rmid;
}
+int erdt_get_scale(void)
+{
+ return erdt_scale;
+}
+
static void __iomem *erdt_ioremap(phys_addr_t base, u32 num_pages, const char *desc)
{
void __iomem *addr;
@@ -67,6 +76,7 @@ static void erdt_iounmap_domain(struct erdt_domain_info *domain)
static void cleanup_one_domain(struct erdt_domain_info *d)
{
erdt_iounmap_domain(d);
+ kfree(d->cmrc);
kfree(d);
}
@@ -100,6 +110,43 @@ static __init int cacd_init(struct acpi_subtbl_hdr_16 *subtbl,
return 0;
}
+static __init int cmrc_init(struct acpi_subtbl_hdr_16 *subtbl,
+ struct erdt_domain_info *domain_info)
+{
+ struct acpi_erdt_cmrc *cmrc = (struct acpi_erdt_cmrc *)subtbl;
+
+ if (cmrc->header.length < sizeof(*cmrc)) {
+ pr_warn(FW_BUG "Truncated CMRC subtable\n");
+ return -EIO;
+ }
+
+ if (cmrc->index_fn != CMRC_SUPPORTED_INDEX_FN) {
+ pr_info("Unsupported CMRC index function %u\n", cmrc->index_fn);
+ return -EIO;
+ }
+
+ if (!cmrc->clump_size) {
+ pr_warn(FW_BUG "CMRC clump_size is zero\n");
+ return -EIO;
+ }
+
+ domain_info->base[ERDT_MMIO_CMRC_BASE] =
+ erdt_ioremap(cmrc->cmt_reg_base, cmrc->cmt_reg_size, "CMRC base");
+ if (!domain_info->base[ERDT_MMIO_CMRC_BASE])
+ return -EIO;
+
+ domain_info->cmrc = kmemdup(cmrc, cmrc->header.length, GFP_KERNEL);
+ if (!domain_info->cmrc) {
+ iounmap(domain_info->base[ERDT_MMIO_CMRC_BASE]);
+ domain_info->base[ERDT_MMIO_CMRC_BASE] = NULL;
+ return -ENOMEM;
+ }
+
+ erdt_scale = max_t(int, erdt_scale, cmrc->up_scale);
+
+ return 0;
+}
+
static inline struct acpi_subtbl_hdr_16 *rmdd_subtbl(struct acpi_erdt_rmdd *rmdd)
{
return (void *)rmdd + sizeof(*rmdd);
@@ -166,6 +213,16 @@ static __init bool parse_rmdd_table(struct acpi_subtbl_hdr_16 *rmdd_hdr)
goto cleanup;
subtbl_mask |= BIT(ACPI_ERDT_TYPE_CACD);
+ break;
+ case ACPI_ERDT_TYPE_CMRC:
+ /*
+ * Only one CMRC is supported per domain as there is no
+ * method to distinguish different CMRCs within a domain.
+ */
+ if (!(subtbl_mask & BIT(ACPI_ERDT_TYPE_CMRC)) &&
+ !cmrc_init(subtbl, domain_info))
+ subtbl_mask |= BIT(ACPI_ERDT_TYPE_CMRC);
+
break;
default:
break;
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index d6e82eb570a3..4779f54b0c84 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -24,10 +24,12 @@
/*
* Index into erdt_domain_info::base[] for each MMIO region.
* @ERDT_MMIO_RMDD_CREG: RMDD control register base address
+ * @ERDT_MMIO_CMRC_BASE: CMRC monitoring register base address
*/
enum erdt_mmio_type {
ERDT_MMIO_RMDD_CREG,
- ERDT_MMIO_LAST = ERDT_MMIO_RMDD_CREG
+ ERDT_MMIO_CMRC_BASE,
+ ERDT_MMIO_LAST = ERDT_MMIO_CMRC_BASE
};
#define ERDT_MMIO_NUM_TYPES (ERDT_MMIO_LAST + 1)
@@ -35,6 +37,7 @@ enum erdt_mmio_type {
/**
* struct erdt_domain_info - Per-domain ERDT information
* @base: Array of ioremapped MMIO region base addresses, indexed by ERDT_MMIO_* type
+ * @cmrc: Copy of the ACPI CMRC sub-table for this domain
* @cpu_mask: CPUs belonging to this resource management domain
* @max_rmid: Maximum RMID supported by this domain
* @dom_id: L3 cache ID shared by all CPUs in this domain (-1 if unset)
@@ -42,6 +45,7 @@ enum erdt_mmio_type {
*/
struct erdt_domain_info {
void __iomem *base[ERDT_MMIO_NUM_TYPES];
+ struct acpi_erdt_cmrc *cmrc;
struct cpumask cpu_mask;
u32 max_rmid;
int dom_id;
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* Re: [RFC PATCH 05/31] x86/resctrl: Parse ACPI CMRC table
2026-08-02 16:03 ` [RFC PATCH 05/31] x86/resctrl: Parse ACPI CMRC table Chen Yu
@ 2026-08-04 17:19 ` Luck, Tony
2026-08-04 18:13 ` Luck, Tony
0 siblings, 1 reply; 37+ messages in thread
From: Luck, Tony @ 2026-08-04 17:19 UTC (permalink / raw)
To: Chen Yu
Cc: Reinette Chatre, Ben Horgan, James Morse, Dave Martin, Babu Moger,
Fenghua Yu, Borislav Petkov, Thomas Gleixner, Dave Hansen,
Peter Newman, chen.yu, x86, linux-kernel
On Mon, Aug 03, 2026 at 12:03:48AM +0800, Chen Yu wrote:
> The CMRC (Cache Monitoring Registers for CPU Agents Description) sub-table of
> ERDT describes the MMIO registers used to read cache monitoring counters (e.g.
> LLC occupancy) for an RMD.
>
> Parse each CMRC sub-table, ioremap its register window, and save a copy of the
> CMRC table in the corresponding ERDT domain entry so that later monitoring code
> can read the counters via MMIO.
>
> Suggested-by: Tony Luck <tony.luck@intel.com>
> Tested-by: Hongyu Ning <hongyu.ning@linux.intel.com>
> Reviewed-by: Thomas Gleixner <tglx@kernel.org>
> Signed-off-by: Chen Yu <yu.c.chen@intel.com>
See the "Ordering of commit tags" section in Documentation/process/maintainer-tip.rst
> ---
> arch/x86/include/asm/resctrl.h | 2 +
> arch/x86/kernel/cpu/resctrl/erdt.c | 57 ++++++++++++++++++++++++++
> arch/x86/kernel/cpu/resctrl/internal.h | 6 ++-
> 3 files changed, 64 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/resctrl.h b/arch/x86/include/asm/resctrl.h
> index 575f8408a9e7..e60c2aea7ebd 100644
> --- a/arch/x86/include/asm/resctrl.h
> +++ b/arch/x86/include/asm/resctrl.h
> @@ -49,6 +49,8 @@ DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
> DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key);
> DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);
>
> +int erdt_get_scale(void);
> +
> static inline bool resctrl_arch_alloc_capable(void)
> {
> return rdt_alloc_capable;
> diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
> index 6257869d0db2..422618991927 100644
> --- a/arch/x86/kernel/cpu/resctrl/erdt.c
> +++ b/arch/x86/kernel/cpu/resctrl/erdt.c
> @@ -23,6 +23,7 @@ static LIST_HEAD(domain_info_list);
> static bool erdt_enabled;
>
> #define ERDT_VALID_VERSION 1
> +#define CMRC_SUPPORTED_INDEX_FN 1
> #define RMDD_FLAG_CPU_L3_DOMAIN BIT(0)
>
> /* Bitmask of valid sub-tables found in the first RMDD, used to ensure all RMDDs match. */
> @@ -33,11 +34,19 @@ static u16 first_rmdd_domain_id;
>
> static int erdt_max_rmid;
>
> +/* Scale to bytes for the monitoring counters when ERDT is enabled. */
> +static int erdt_scale;
Single value for scale? See below.
> +
> int erdt_get_max_rmid(void)
> {
> return erdt_max_rmid;
> }
>
> +int erdt_get_scale(void)
> +{
> + return erdt_scale;
> +}
> +
> static void __iomem *erdt_ioremap(phys_addr_t base, u32 num_pages, const char *desc)
> {
> void __iomem *addr;
> @@ -67,6 +76,7 @@ static void erdt_iounmap_domain(struct erdt_domain_info *domain)
> static void cleanup_one_domain(struct erdt_domain_info *d)
> {
> erdt_iounmap_domain(d);
> + kfree(d->cmrc);
> kfree(d);
> }
>
> @@ -100,6 +110,43 @@ static __init int cacd_init(struct acpi_subtbl_hdr_16 *subtbl,
> return 0;
> }
>
> +static __init int cmrc_init(struct acpi_subtbl_hdr_16 *subtbl,
> + struct erdt_domain_info *domain_info)
> +{
> + struct acpi_erdt_cmrc *cmrc = (struct acpi_erdt_cmrc *)subtbl;
> +
> + if (cmrc->header.length < sizeof(*cmrc)) {
> + pr_warn(FW_BUG "Truncated CMRC subtable\n");
> + return -EIO;
> + }
> +
> + if (cmrc->index_fn != CMRC_SUPPORTED_INDEX_FN) {
> + pr_info("Unsupported CMRC index function %u\n", cmrc->index_fn);
> + return -EIO;
> + }
> +
> + if (!cmrc->clump_size) {
> + pr_warn(FW_BUG "CMRC clump_size is zero\n");
> + return -EIO;
> + }
> +
> + domain_info->base[ERDT_MMIO_CMRC_BASE] =
> + erdt_ioremap(cmrc->cmt_reg_base, cmrc->cmt_reg_size, "CMRC base");
> + if (!domain_info->base[ERDT_MMIO_CMRC_BASE])
> + return -EIO;
> +
> + domain_info->cmrc = kmemdup(cmrc, cmrc->header.length, GFP_KERNEL);
> + if (!domain_info->cmrc) {
> + iounmap(domain_info->base[ERDT_MMIO_CMRC_BASE]);
> + domain_info->base[ERDT_MMIO_CMRC_BASE] = NULL;
> + return -ENOMEM;
> + }
> +
> + erdt_scale = max_t(int, erdt_scale, cmrc->up_scale);
I'd expect that on a machine all CMRC tables would report the same
up_scale factor. But RDT architecture allows them to be different. Two
ways to handle this:
1) Check that they are all the same. Complain if they are different and
don't enable cache occupancy events.
2) Save the value for each domain and use that value to upscale when
reporting to user.
Picking the max value doesn't feel like a good answer.
> +
> + return 0;
> +}
-Tony
^ permalink raw reply [flat|nested] 37+ messages in thread* Re: [RFC PATCH 05/31] x86/resctrl: Parse ACPI CMRC table
2026-08-04 17:19 ` Luck, Tony
@ 2026-08-04 18:13 ` Luck, Tony
2026-08-05 4:59 ` Chen, Yu C
0 siblings, 1 reply; 37+ messages in thread
From: Luck, Tony @ 2026-08-04 18:13 UTC (permalink / raw)
To: Chen Yu
Cc: Reinette Chatre, Ben Horgan, James Morse, Dave Martin, Babu Moger,
Fenghua Yu, Borislav Petkov, Thomas Gleixner, Dave Hansen,
Peter Newman, chen.yu, x86, linux-kernel
On Tue, Aug 04, 2026 at 10:19:26AM -0700, Luck, Tony wrote:
> On Mon, Aug 03, 2026 at 12:03:48AM +0800, Chen Yu wrote:
> >
> > +/* Scale to bytes for the monitoring counters when ERDT is enabled. */
> > +static int erdt_scale;
>
> Single value for scale? See below.
Now I've read ahead to patch 9 and see how this is used to set
resctrl_rmid_realloc_threshold. Needs better comments here and
for above erdt_get_scale()
>
> > +
> > int erdt_get_max_rmid(void)
> > {
> > return erdt_max_rmid;
> > }
> >
> > +int erdt_get_scale(void)
> > +{
> > + return erdt_scale;
> > +}
> > +
> > + erdt_scale = max_t(int, erdt_scale, cmrc->up_scale);
>
> I'd expect that on a machine all CMRC tables would report the same
> up_scale factor. But RDT architecture allows them to be different. Two
> ways to handle this:
>
> 1) Check that they are all the same. Complain if they are different and
> don't enable cache occupancy events.
>
> 2) Save the value for each domain and use that value to upscale when
> reporting to user.
I see in patch 9 that you do use this option "2" with "cmrc->up_scale".
> Picking the max value doesn't feel like a good answer.
Given how this is actually used, seems like the best option.
>
> > +
> > + return 0;
> > +}
>
-Tony
^ permalink raw reply [flat|nested] 37+ messages in thread* Re: [RFC PATCH 05/31] x86/resctrl: Parse ACPI CMRC table
2026-08-04 18:13 ` Luck, Tony
@ 2026-08-05 4:59 ` Chen, Yu C
0 siblings, 0 replies; 37+ messages in thread
From: Chen, Yu C @ 2026-08-05 4:59 UTC (permalink / raw)
To: Luck, Tony
Cc: Reinette Chatre, Ben Horgan, James Morse, Dave Martin, Babu Moger,
Fenghua Yu, Borislav Petkov, Thomas Gleixner, Dave Hansen,
Peter Newman, chen.yu, x86, linux-kernel
Hi Tony,
On 8/5/2026 2:13 AM, Luck, Tony wrote:
> On Tue, Aug 04, 2026 at 10:19:26AM -0700, Luck, Tony wrote:
>> On Mon, Aug 03, 2026 at 12:03:48AM +0800, Chen Yu wrote:
>
>>>
>>> +/* Scale to bytes for the monitoring counters when ERDT is enabled. */
>>> +static int erdt_scale;
>>
>> Single value for scale? See below.
>
> Now I've read ahead to patch 9 and see how this is used to set
> resctrl_rmid_realloc_threshold. Needs better comments here and
> for above erdt_get_scale()
OK, will add comment here.
resctrl_rmid_realloc_threshold is a single global value,
and resctrl_arch_round_mon_val() takes no domain argument, so a
single scale has to be derived from the per-domain cmrc->up_scale.
max() was chosen because the rounding is a floor: a larger scale
yields a slightly lower threshold, i.e. an RMID has to drop to
a slightly lower occupancy before it is reused.
>>
>>> +
>>> int erdt_get_max_rmid(void)
>>> {
>>> return erdt_max_rmid;
>>> }
>>>
>>> +int erdt_get_scale(void)
>>> +{
>>> + return erdt_scale;
>>> +}
>>> +
>>> + erdt_scale = max_t(int, erdt_scale, cmrc->up_scale);
>>
>> I'd expect that on a machine all CMRC tables would report the same
>> up_scale factor. But RDT architecture allows them to be different. Two
>> ways to handle this:
>>
>> 1) Check that they are all the same. Complain if they are different and
>> don't enable cache occupancy events.
>>
>> 2) Save the value for each domain and use that value to upscale when
>> reporting to user.
>
> I see in patch 9 that you do use this option "2" with "cmrc->up_scale".
>
>> Picking the max value doesn't feel like a good answer.
>
> Given how this is actually used, seems like the best option.
OK, the erdt_mon_read() reads via the per domain cmrc->up_scale.
thanks,
Chenyu
>>
>>> +
>>> + return 0;
>>> +}
>>
> -Tony
^ permalink raw reply [flat|nested] 37+ messages in thread
* [RFC PATCH 06/31] x86/resctrl: Refactor the monitor read function
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (4 preceding siblings ...)
2026-08-02 16:03 ` [RFC PATCH 05/31] x86/resctrl: Parse ACPI CMRC table Chen Yu
@ 2026-08-02 16:03 ` Chen Yu
2026-08-02 16:04 ` [RFC PATCH 07/31] fs/resctrl: Do not invoke smp_processor_id() in preemptible context Chen Yu
` (24 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:03 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
Split the monitor read helper into an L3 read path and an AET
(Intel Application Energy Telemetry) read path. This makes the
two distinct monitoring sources easier to extend independently
and prepares the L3 path for ERDT-based MMIO reads.
No functional change.
Tested-by: Hongyu Ning <hongyu.ning@linux.intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/monitor.c | 27 +++++++++++++++++++--------
1 file changed, 19 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 794a6fb175e4..30ff6b0293ab 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -238,9 +238,9 @@ static u64 get_corrected_val(struct rdt_resource *r, struct rdt_l3_mon_domain *d
return chunks * hw_res->mon_scale;
}
-int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain_hdr *hdr,
- u32 unused, u32 rmid, enum resctrl_event_id eventid,
- void *arch_priv, u64 *val, void *ignored)
+static int arch_l3_read_event(struct rdt_domain_hdr *hdr, u32 rmid,
+ enum resctrl_event_id eventid, u64 *val,
+ struct rdt_resource *r)
{
struct rdt_hw_l3_mon_domain *hw_dom;
struct rdt_l3_mon_domain *d;
@@ -250,11 +250,6 @@ int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain_hdr *hdr,
int cpu;
int ret;
- resctrl_arch_rmid_read_context_check();
-
- if (r->rid == RDT_RESOURCE_PERF_PKG)
- return intel_aet_read_event(hdr->id, rmid, arch_priv, val);
-
if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, RDT_RESOURCE_L3))
return -EINVAL;
@@ -275,6 +270,22 @@ int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain_hdr *hdr,
return ret;
}
+int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain_hdr *hdr,
+ u32 unused, u32 rmid, enum resctrl_event_id eventid,
+ void *arch_priv, u64 *val, void *ignored)
+{
+ resctrl_arch_rmid_read_context_check();
+
+ switch (r->rid) {
+ case RDT_RESOURCE_L3:
+ return arch_l3_read_event(hdr, rmid, eventid, val, r);
+ case RDT_RESOURCE_PERF_PKG:
+ return intel_aet_read_event(hdr->id, rmid, arch_priv, val);
+ default:
+ return -EINVAL;
+ }
+}
+
static int __cntr_id_read(u32 cntr_id, u64 *val)
{
u64 msr_val;
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 07/31] fs/resctrl: Do not invoke smp_processor_id() in preemptible context
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (5 preceding siblings ...)
2026-08-02 16:03 ` [RFC PATCH 06/31] x86/resctrl: Refactor the monitor read function Chen Yu
@ 2026-08-02 16:04 ` Chen Yu
2026-08-02 16:04 ` [RFC PATCH 08/31] x86/resctrl: Introduce erdt_cpu_has() and erdt_support() Chen Yu
` (23 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:04 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
From: Tony Luck <tony.luck@intel.com>
LLC occupancy can be read on any CPU when the counter is accessed via
MMIO, so such an event is read from task context on whatever CPU the
caller happens to be running on rather than being bounced to a CPU in
the monitoring domain. mon_evt::any_cpu marks these CPU-agnostic events.
__l3_mon_event_count() calls smp_processor_id() to find the CPU to read
from. For an any_cpu event that lookup is unsafe:
the code runs in preemptible task context, so smp_processor_id() emits a
debug warning.
Skip the current-CPU lookup when an event's any_cpu flag is set, events with
this flag do not require execution on a specific CPU. For legacy MSR-based
access, update rmid_read::err if the reading of the event was dispatched to
a wrong CPU, according to the change at:
https://lore.kernel.org/lkml/6b3c66a49788828bd8c04a6911bd74c91ccd56f3.1782857711.git.reinette.chatre@intel.com/
Signed-off-by: Tony Luck <tony.luck@intel.com>
Tested-by: Hongyu Ning <hongyu.ning@linux.intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
fs/resctrl/monitor.c | 48 +++++++++++++++++++++++++++++++-------------
1 file changed, 34 insertions(+), 14 deletions(-)
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 8dfc54f8a1f2..89baed73bcd6 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -417,9 +417,37 @@ static void mbm_cntr_free(struct rdt_l3_mon_domain *d, int cntr_id)
memset(&d->cntr_cfg[cntr_id], 0, sizeof(*d->cntr_cfg));
}
+/**
+ * cpu_on_correct_domain() - Check if current CPU is in the correct
+ * domain for the event.
+ * @rr: The rmid_read structure containing event and domain information.
+ *
+ * Context: Preemptible process context when @rr->evt->any_cpu is set.
+ * Non-migratable process context (via smp_call_on_cpu()) or
+ * non-preemptible context (via smp_call_function_any()) when
+ * the event must be read on a specific CPU.
+ * Return: true if the current CPU can read this event, false otherwise.
+ */
+static bool cpu_on_correct_domain(struct rmid_read *rr)
+{
+ int cpu;
+
+ /* Any CPU is OK for this event */
+ if (rr->evt->any_cpu)
+ return true;
+
+ cpu = smp_processor_id();
+
+ /* Single domain. Must be on a CPU in that domain. */
+ if (rr->hdr)
+ return cpumask_test_cpu(cpu, &rr->hdr->cpu_mask);
+
+ /* Summing domains that share a cache, must be on a CPU for that cache. */
+ return cpumask_test_cpu(cpu, &rr->ci->shared_cpu_map);
+}
+
static int __l3_mon_event_count(struct rdtgroup *rdtgrp, struct rmid_read *rr)
{
- int cpu = smp_processor_id();
u32 closid = rdtgrp->closid;
u32 rmid = rdtgrp->mon.rmid;
struct rdt_l3_mon_domain *d;
@@ -452,11 +480,6 @@ static int __l3_mon_event_count(struct rdtgroup *rdtgrp, struct rmid_read *rr)
return 0;
}
- /* Reading a single domain, must be on a CPU in that domain. */
- if (!cpumask_test_cpu(cpu, &d->hdr.cpu_mask)) {
- rr->err = -EIO;
- return -EINVAL;
- }
if (rr->is_mbm_cntr)
rr->err = resctrl_arch_cntr_read(rr->r, d, closid, rmid, cntr_id,
rr->evt->evtid, &tval);
@@ -474,7 +497,6 @@ static int __l3_mon_event_count(struct rdtgroup *rdtgrp, struct rmid_read *rr)
static int __l3_mon_event_count_sum(struct rdtgroup *rdtgrp, struct rmid_read *rr)
{
- int cpu = smp_processor_id();
u32 closid = rdtgrp->closid;
u32 rmid = rdtgrp->mon.rmid;
struct rdt_l3_mon_domain *d;
@@ -492,12 +514,6 @@ static int __l3_mon_event_count_sum(struct rdtgroup *rdtgrp, struct rmid_read *r
return -EINVAL;
}
- /* Summing domains that share a cache, must be on a CPU for that cache. */
- if (!cpumask_test_cpu(cpu, &rr->ci->shared_cpu_map)) {
- rr->err = -EIO;
- return -EINVAL;
- }
-
/*
* Legacy files must report the sum of an event across all
* domains that share the same L3 cache instance.
@@ -528,7 +544,11 @@ static int __mon_event_count(struct rdtgroup *rdtgrp, struct rmid_read *rr)
{
switch (rr->r->rid) {
case RDT_RESOURCE_L3:
- WARN_ON_ONCE(rr->evt->any_cpu);
+ if (!cpu_on_correct_domain(rr)) {
+ rr->err = -EIO;
+ return -EINVAL;
+ }
+
if (rr->hdr)
return __l3_mon_event_count(rdtgrp, rr);
else
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 08/31] x86/resctrl: Introduce erdt_cpu_has() and erdt_support()
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (6 preceding siblings ...)
2026-08-02 16:04 ` [RFC PATCH 07/31] fs/resctrl: Do not invoke smp_processor_id() in preemptible context Chen Yu
@ 2026-08-02 16:04 ` Chen Yu
2026-08-02 16:05 ` [RFC PATCH 09/31] x86/resctrl: Add MMIO-based LLC occupancy monitoring support Chen Yu
` (22 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:04 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
Introduce erdt_cpu_has() to verify if a specific RDT feature is backed
by an ERDT table. erdt_cpu_has() is derived from rdt_cpu_has(), which
not only considers firmware (ERDT table and its sub-tables) support for
an event, but also considers userspace input like "rdt=!cmt".
Similar to rdt_cpu_has(), erdt_cpu_has() expects an x86 feature flag
as parameter.
Introduce erdt_support() as a helper called by erdt_cpu_has() to check
whether the ERDT firmware supports a given feature.
erdt_support() deliberately claims no feature yet and returns false. A
feature may only be reported as ERDT backed once the low level accessors
that read its monitoring data via MMIO exist, otherwise callers would
take the ERDT path and find no implementation behind it. Features are
added to erdt_support() as their MMIO implementations are introduced.
Tested-by: Hongyu Ning <hongyu.ning@linux.intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/include/asm/resctrl.h | 1 +
arch/x86/kernel/cpu/resctrl/core.c | 23 +++++++++++++++++++++++
arch/x86/kernel/cpu/resctrl/erdt.c | 5 +++++
arch/x86/kernel/cpu/resctrl/internal.h | 2 ++
4 files changed, 31 insertions(+)
diff --git a/arch/x86/include/asm/resctrl.h b/arch/x86/include/asm/resctrl.h
index e60c2aea7ebd..5491853113dd 100644
--- a/arch/x86/include/asm/resctrl.h
+++ b/arch/x86/include/asm/resctrl.h
@@ -49,6 +49,7 @@ DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key);
DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);
+bool erdt_cpu_has(int flag);
int erdt_get_scale(void);
static inline bool resctrl_arch_alloc_capable(void)
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 4e2922ec1dda..5a56966103f2 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -1021,6 +1021,29 @@ bool rdt_cpu_has(int flag)
return ret;
}
+bool erdt_cpu_has(int flag)
+{
+ struct rdt_options *o;
+ bool ret;
+
+ ret = erdt_support(flag);
+
+ if (!ret)
+ return ret;
+
+ for (o = rdt_options; o < &rdt_options[NUM_RDT_OPTIONS]; o++) {
+ if (flag == o->flag) {
+ if (o->force_off)
+ ret = false;
+ if (o->force_on)
+ ret = true;
+ break;
+ }
+ }
+
+ return ret;
+}
+
bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt)
{
if (!rdt_cpu_has(X86_FEATURE_BMEC))
diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
index 422618991927..167d2dfc368d 100644
--- a/arch/x86/kernel/cpu/resctrl/erdt.c
+++ b/arch/x86/kernel/cpu/resctrl/erdt.c
@@ -37,6 +37,11 @@ static int erdt_max_rmid;
/* Scale to bytes for the monitoring counters when ERDT is enabled. */
static int erdt_scale;
+bool erdt_support(int flag)
+{
+ return false;
+}
+
int erdt_get_max_rmid(void)
{
return erdt_max_rmid;
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 4779f54b0c84..ee1990302177 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -305,6 +305,8 @@ static inline void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resour
static inline bool intel_handle_aet_option(bool force_off, char *tok) { return false; }
#endif
+bool erdt_support(int flag);
+bool erdt_cpu_has(int flag);
int erdt_get_max_rmid(void);
int erdt_init(void);
void erdt_exit(void);
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 09/31] x86/resctrl: Add MMIO-based LLC occupancy monitoring support
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (7 preceding siblings ...)
2026-08-02 16:04 ` [RFC PATCH 08/31] x86/resctrl: Introduce erdt_cpu_has() and erdt_support() Chen Yu
@ 2026-08-02 16:05 ` Chen Yu
2026-08-02 16:05 ` [RFC PATCH 10/31] Revert "x86/resctrl: NOT_FOR_INCLUSION: Example support for multiple controls" Chen Yu
` (21 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:05 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
Add erdt_mon_read() to read LLC occupancy via MMIO and use it when
the platform supports ERDT. Register the L3 occupancy event with
ERDT enabled when available, falling back to the MSR-based path
otherwise.
Use the CMRC (Cache Monitoring Registers for CPU Agents Description)
ACPI sub-table to read LLC occupancy counters for each RMID via MMIO
when ERDT is enabled. This CMRC information is stored in the
rdt_hw_l3_mon_domain, which could be accessed directly.
Currently, the per-domain limbo handler is still in use. There is no need
to switch to a global limbo handler, because even after such a switch, the
worker thread would still have to iterate through all domains one by one.
The per-domain handler already accomplishes this using a worker thread rather
than costly IPIs, so there is no clear benefit to switching to a global handler.
Suggested-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Hongyu Ning <hongyu.ning@linux.intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/include/asm/resctrl.h | 8 +++-
arch/x86/kernel/cpu/resctrl/core.c | 5 ++-
arch/x86/kernel/cpu/resctrl/erdt.c | 59 ++++++++++++++++++++++++++
arch/x86/kernel/cpu/resctrl/internal.h | 7 ++-
arch/x86/kernel/cpu/resctrl/monitor.c | 9 +++-
5 files changed, 84 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/resctrl.h b/arch/x86/include/asm/resctrl.h
index 5491853113dd..0948f64856ef 100644
--- a/arch/x86/include/asm/resctrl.h
+++ b/arch/x86/include/asm/resctrl.h
@@ -132,7 +132,13 @@ static inline void __resctrl_sched_in(struct task_struct *tsk)
static inline unsigned int resctrl_arch_round_mon_val(unsigned int val)
{
- unsigned int scale = boot_cpu_data.x86_cache_occ_scale;
+ unsigned int scale = boot_cpu_data.x86_cache_occ_scale, escale;
+
+ if (erdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC)) {
+ escale = erdt_get_scale();
+ if (escale)
+ scale = escale;
+ }
/* h/w works in units of "boot_cpu_data.x86_cache_occ_scale" */
val /= scale;
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 5a56966103f2..07d669e6e11b 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -1131,7 +1131,10 @@ static __init bool get_rdt_mon_resources(void)
struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
bool ret = false;
- if (rdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC)) {
+ if (erdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC)) {
+ resctrl_enable_mon_event(QOS_L3_OCCUP_EVENT_ID, true, 0, NULL);
+ ret = true;
+ } else if (rdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC)) {
resctrl_enable_mon_event(QOS_L3_OCCUP_EVENT_ID, false, 0, NULL);
ret = true;
}
diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
index 167d2dfc368d..5f9377c80be6 100644
--- a/arch/x86/kernel/cpu/resctrl/erdt.c
+++ b/arch/x86/kernel/cpu/resctrl/erdt.c
@@ -26,6 +26,10 @@ static bool erdt_enabled;
#define CMRC_SUPPORTED_INDEX_FN 1
#define RMDD_FLAG_CPU_L3_DOMAIN BIT(0)
+/* Set in a monitoring counter when it holds no valid data to report. */
+#define UNAVAILABLE_COUNTER BIT_ULL(63)
+#define CMRC_FLAG_UNAVAILABLE_BIT BIT(0)
+
/* Bitmask of valid sub-tables found in the first RMDD, used to ensure all RMDDs match. */
static u32 valid_subtbl_mask;
@@ -39,6 +43,9 @@ static int erdt_scale;
bool erdt_support(int flag)
{
+ if (flag == X86_FEATURE_CQM_OCCUP_LLC)
+ return valid_subtbl_mask & BIT(ACPI_ERDT_TYPE_CMRC);
+
return false;
}
@@ -52,6 +59,58 @@ int erdt_get_scale(void)
return erdt_scale;
}
+static u32 cmrc_index_function_1(struct acpi_erdt_cmrc *cmrc, u32 rmid)
+{
+ /*
+ * MMIO_offset_for_RMID# =
+ * (RMID / ClumpSize) * Stride +
+ * (RMID % ClumpSize) * 8
+ */
+ return (rmid / cmrc->clump_size) * cmrc->clump_stride +
+ (rmid % cmrc->clump_size) * 8;
+}
+
+static int erdt_read_l3_occupancy(const struct erdt_domain_info *d, u32 rmid, u64 *val)
+{
+ struct acpi_erdt_cmrc *cmrc;
+ u64 l3_cmt_count;
+ u32 offset;
+
+ cmrc = d->cmrc;
+ if (!cmrc)
+ return -EIO;
+
+ offset = cmrc_index_function_1(cmrc, rmid);
+ /* Overflow of cmt_reg_size * SZ_4K already validated in erdt_ioremap(). */
+ if (offset + sizeof(u64) > (u32)cmrc->cmt_reg_size * SZ_4K)
+ return -EINVAL;
+
+ l3_cmt_count = readq(d->base[ERDT_MMIO_CMRC_BASE] + offset);
+ if ((cmrc->flags & CMRC_FLAG_UNAVAILABLE_BIT) &&
+ (l3_cmt_count & UNAVAILABLE_COUNTER))
+ return -EINVAL;
+
+ *val = l3_cmt_count * cmrc->up_scale;
+
+ return 0;
+}
+
+int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 rmid, u64 *val)
+{
+ struct rdt_hw_l3_mon_domain *hw_dom;
+ const struct erdt_domain_info *d;
+
+ hw_dom = resctrl_to_arch_mon_dom(container_of(hdr, struct rdt_l3_mon_domain, hdr));
+ d = hw_dom->d_info;
+ if (!d)
+ return -EIO;
+
+ if (evtid == QOS_L3_OCCUP_EVENT_ID)
+ return erdt_read_l3_occupancy(d, rmid, val);
+
+ return -EIO;
+}
+
static void __iomem *erdt_ioremap(phys_addr_t base, u32 num_pages, const char *desc)
{
void __iomem *addr;
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index ee1990302177..c175d8884516 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -175,7 +175,11 @@ struct rdt_perf_pkg_mon_domain {
* resctrl_arch_get_num_closid() to avoid confusion
* with struct rdt_resource_final's property of the same
* name, which has been corrected for features like CDP.
- * @mon_scale: cqm counter * mon_scale = occupancy in bytes
+ * @mon_scale: Scale factor applied to a raw counter value on the
+ * MSR-based read path: CMT occupancy counter * mon_scale =
+ * occupancy in bytes, and MBM chunk count * mon_scale = bytes
+ * transferred. ERDT reads occupancy via MMIO and applies its
+ * own firmware-provided scale instead.
* @mbm_width: Monitor width, to detect and correct for overflow.
* @cdp_enabled: CDP state of this resource
* @has_per_cpu_cache_cfg: True if QOS_CFG register for this cache resource
@@ -308,6 +312,7 @@ static inline bool intel_handle_aet_option(bool force_off, char *tok) { return f
bool erdt_support(int flag);
bool erdt_cpu_has(int flag);
int erdt_get_max_rmid(void);
+int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 rmid, u64 *val);
int erdt_init(void);
void erdt_exit(void);
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 30ff6b0293ab..0e011b1f7fd2 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -278,6 +278,10 @@ int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain_hdr *hdr,
switch (r->rid) {
case RDT_RESOURCE_L3:
+ if (eventid == QOS_L3_OCCUP_EVENT_ID &&
+ erdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC))
+ return erdt_mon_read(hdr, eventid, rmid, val);
+
return arch_l3_read_event(hdr, rmid, eventid, val, r);
case RDT_RESOURCE_PERF_PKG:
return intel_aet_read_event(hdr->id, rmid, arch_priv, val);
@@ -419,12 +423,15 @@ int __init rdt_get_l3_mon_config(struct rdt_resource *r)
struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
unsigned int threshold;
u32 eax, ebx, ecx, edx;
+ int max_rmid;
snc_nodes_per_l3_cache = snc_get_config();
+ max_rmid = erdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC) ?
+ erdt_get_max_rmid() : boot_cpu_data.x86_cache_max_rmid;
resctrl_rmid_realloc_limit = boot_cpu_data.x86_cache_size * 1024;
hw_res->mon_scale = boot_cpu_data.x86_cache_occ_scale / snc_nodes_per_l3_cache;
- r->mon.num_rmid = (boot_cpu_data.x86_cache_max_rmid + 1) / snc_nodes_per_l3_cache;
+ r->mon.num_rmid = (max_rmid + 1) / snc_nodes_per_l3_cache;
hw_res->mbm_width = MBM_CNTR_WIDTH_BASE;
if (mbm_offset > 0 && mbm_offset <= MBM_CNTR_WIDTH_OFFSET_MAX)
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 10/31] Revert "x86/resctrl: NOT_FOR_INCLUSION: Example support for multiple controls"
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (8 preceding siblings ...)
2026-08-02 16:05 ` [RFC PATCH 09/31] x86/resctrl: Add MMIO-based LLC occupancy monitoring support Chen Yu
@ 2026-08-02 16:05 ` Chen Yu
2026-08-02 16:05 ` [RFC PATCH 11/31] x86/resctrl: Rename struct resctrl_membw to struct resctrl_ctrl_scalar Chen Yu
` (20 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:05 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
This reverts commit 37557cac804539e802e887a320e85c7a916a0bb9.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/core.c | 115 ++++++-----------------------
1 file changed, 21 insertions(+), 94 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 07d669e6e11b..1357f3e5ebd3 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -53,8 +53,6 @@ bool rdt_alloc_capable;
static void mba_wrmsr_intel(struct msr_param *m);
static void cat_wrmsr(struct msr_param *m);
static void mba_wrmsr_amd(struct msr_param *m);
-static void update_temporary_max(struct msr_param *m);
-static void update_temporary_min(struct msr_param *m);
#define ctrl_init(id) LIST_HEAD_INIT(rdt_resources_all[id].r_resctrl.controls)
#define mon_domain_init(id) LIST_HEAD_INIT(rdt_resources_all[id].r_resctrl.mon_domains)
@@ -182,47 +180,10 @@ static inline void cache_alloc_hsw_probe(void)
rdt_alloc_capable = true;
}
-static __init bool __temporary_multiple_mba_intel_controls(struct rdt_resource *r,
- struct resctrl_hw_ctrl *hw_ctrl,
- u32 ecx, u32 max_delay,
- enum resctrl_ctrl_name name)
-{
- hw_ctrl->r_ctrl.scope = RESCTRL_L3_CACHE;
- hw_ctrl->r_ctrl.type = RESCTRL_CTRL_SCALAR;
- hw_ctrl->r_ctrl.name = RESCTRL_CTRL_NAME_DEF;
- INIT_LIST_HEAD(&hw_ctrl->r_ctrl.domains);
-
- hw_ctrl->r_ctrl.membw.max_bw = MAX_MBA_BW;
- hw_ctrl->r_ctrl.membw.min_bw = MAX_MBA_BW - max_delay;
- hw_ctrl->r_ctrl.membw.bw_gran = MAX_MBA_BW - max_delay;
-
- hw_ctrl->r_ctrl.membw.resolution = 100;
- hw_ctrl->r_ctrl.membw.tolerance = 5;
- hw_ctrl->r_ctrl.membw.scale = 1;
- hw_ctrl->r_ctrl.membw.unit = RESCTRL_CTRL_UNIT_ALL;
-
- hw_ctrl->r_ctrl.name = name;
-
- switch (name) {
- case RESCTRL_CTRL_NAME_DEF:
- hw_ctrl->msr_base = MSR_IA32_MBA_THRTL_BASE;
- hw_ctrl->msr_update = mba_wrmsr_intel;
- break;
- case RESCTRL_CTRL_NAME_MIN:
- hw_ctrl->msr_update = update_temporary_min;
- break;
- case RESCTRL_CTRL_NAME_MAX:
- hw_ctrl->msr_update = update_temporary_max;
- break;
- }
-
- return true;
-}
-
static __init bool __get_mem_config_intel(struct rdt_resource *r)
{
struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
- struct resctrl_hw_ctrl *hw_ctrl0, *hw_ctrl1, *hw_ctrl2;
+ struct resctrl_hw_ctrl *hw_ctrl;
union cpuid_0x10_3_eax eax;
union cpuid_0x10_x_edx edx;
u32 ebx, ecx, max_delay;
@@ -234,50 +195,34 @@ static __init bool __get_mem_config_intel(struct rdt_resource *r)
if (!(ecx & MBA_IS_LINEAR))
return false;
+ hw_ctrl = kzalloc_obj(*hw_ctrl);
+ if (!hw_ctrl)
+ return false;
+
+ hw_ctrl->r_ctrl.scope = RESCTRL_L3_CACHE;
+ hw_ctrl->r_ctrl.type = RESCTRL_CTRL_SCALAR;
+ hw_ctrl->r_ctrl.name = RESCTRL_CTRL_NAME_DEF;
+ INIT_LIST_HEAD(&hw_ctrl->r_ctrl.domains);
+
+ hw_ctrl->r_ctrl.membw.max_bw = MAX_MBA_BW;
+ hw_ctrl->r_ctrl.membw.min_bw = MAX_MBA_BW - max_delay;
+ hw_ctrl->r_ctrl.membw.bw_gran = MAX_MBA_BW - max_delay;
+
r->bw_delay_linear = true;
if (boot_cpu_has(X86_FEATURE_PER_THREAD_MBA))
r->bw_throttle_mode = THREAD_THROTTLE_PER_THREAD;
else
r->bw_throttle_mode = THREAD_THROTTLE_MAX;
- hw_ctrl0 = kzalloc_obj(*hw_ctrl0);
- if (!hw_ctrl0)
- return false;
-
- if (!__temporary_multiple_mba_intel_controls(r, hw_ctrl0, ecx, max_delay, RESCTRL_CTRL_NAME_DEF)) {
- kfree(hw_ctrl0);
- return false;
- }
-
- hw_ctrl1 = kzalloc_obj(*hw_ctrl1);
- if (!hw_ctrl1) {
- kfree(hw_ctrl0);
- return false;
- }
-
- if (!__temporary_multiple_mba_intel_controls(r, hw_ctrl1, ecx, max_delay, RESCTRL_CTRL_NAME_MIN)) {
- kfree(hw_ctrl0);
- kfree(hw_ctrl1);
- return false;
- }
-
- hw_ctrl2 = kzalloc_obj(*hw_ctrl2);
- if (!hw_ctrl2) {
- kfree(hw_ctrl0);
- kfree(hw_ctrl1);
- return false;
- }
+ hw_ctrl->r_ctrl.membw.resolution = 100;
+ hw_ctrl->r_ctrl.membw.tolerance = 5;
+ hw_ctrl->r_ctrl.membw.scale = 1;
+ hw_ctrl->r_ctrl.membw.unit = RESCTRL_CTRL_UNIT_ALL;
- if (!__temporary_multiple_mba_intel_controls(r, hw_ctrl2, ecx, max_delay, RESCTRL_CTRL_NAME_MAX)) {
- kfree(hw_ctrl0);
- kfree(hw_ctrl1);
- kfree(hw_ctrl2);
- return false;
- }
+ hw_ctrl->msr_base = MSR_IA32_MBA_THRTL_BASE;
+ hw_ctrl->msr_update = mba_wrmsr_intel;
+ list_add(&hw_ctrl->r_ctrl.entry, &r->controls);
- list_add(&hw_ctrl0->r_ctrl.entry, &r->controls);
- list_add(&hw_ctrl1->r_ctrl.entry, &r->controls);
- list_add(&hw_ctrl2->r_ctrl.entry, &r->controls);
r->alloc_capable = true;
return true;
@@ -434,24 +379,6 @@ static u32 delay_bw_map(unsigned long bw, struct rdt_resource *r)
return MAX_MBA_BW;
}
-static void update_temporary_max(struct msr_param *m)
-{
- struct rdt_hw_ctrl_domain *hw_dom = resctrl_to_arch_ctrl_dom(m->dom);
-
- /* Any control properties available via m->ctrl */
- pr_info("Updata temporary MAX control on domain %d with user value %i\n",
- m->dom->hdr.id, hw_dom->ctrl_val[m->low]);
-}
-
-static void update_temporary_min(struct msr_param *m)
-{
- struct rdt_hw_ctrl_domain *hw_dom = resctrl_to_arch_ctrl_dom(m->dom);
-
- /* Any control properties available via m->ctrl */
- pr_info("Updata temporary MIN control on domain %d with user value %i\n",
- m->dom->hdr.id, hw_dom->ctrl_val[m->low]);
-}
-
static void mba_wrmsr_intel(struct msr_param *m)
{
struct rdt_hw_ctrl_domain *hw_dom = resctrl_to_arch_ctrl_dom(m->dom);
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 11/31] x86/resctrl: Rename struct resctrl_membw to struct resctrl_ctrl_scalar
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (9 preceding siblings ...)
2026-08-02 16:05 ` [RFC PATCH 10/31] Revert "x86/resctrl: NOT_FOR_INCLUSION: Example support for multiple controls" Chen Yu
@ 2026-08-02 16:05 ` Chen Yu
2026-08-02 16:05 ` [RFC PATCH 12/31] x86/resctrl: Rename struct resctrl_cache to struct resctrl_ctrl_bitmap Chen Yu
` (19 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:05 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
Rename struct resctrl_membw to struct resctrl_ctrl_scalar to better
reflect its role as the property container for scalar-type controls.
Also rename the union member from 'membw' to 'scalar' for consistency.
This follows the design discussed in the generic schema RFC where
controls are classified by type (scalar vs bitmap) rather than by
the specific resource they manage (memory bandwidth).
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/core.c | 30 +++++++++++++++---------------
drivers/resctrl/mpam_resctrl.c | 6 +++---
fs/resctrl/ctrlmondata.c | 6 +++---
fs/resctrl/monitor.c | 8 ++++----
fs/resctrl/rdtgroup.c | 20 ++++++++++----------
include/linux/resctrl.h | 16 ++++++++--------
6 files changed, 43 insertions(+), 43 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 1357f3e5ebd3..9566ee43f206 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -204,9 +204,9 @@ static __init bool __get_mem_config_intel(struct rdt_resource *r)
hw_ctrl->r_ctrl.name = RESCTRL_CTRL_NAME_DEF;
INIT_LIST_HEAD(&hw_ctrl->r_ctrl.domains);
- hw_ctrl->r_ctrl.membw.max_bw = MAX_MBA_BW;
- hw_ctrl->r_ctrl.membw.min_bw = MAX_MBA_BW - max_delay;
- hw_ctrl->r_ctrl.membw.bw_gran = MAX_MBA_BW - max_delay;
+ hw_ctrl->r_ctrl.scalar.max_bw = MAX_MBA_BW;
+ hw_ctrl->r_ctrl.scalar.min_bw = MAX_MBA_BW - max_delay;
+ hw_ctrl->r_ctrl.scalar.bw_gran = MAX_MBA_BW - max_delay;
r->bw_delay_linear = true;
if (boot_cpu_has(X86_FEATURE_PER_THREAD_MBA))
@@ -214,10 +214,10 @@ static __init bool __get_mem_config_intel(struct rdt_resource *r)
else
r->bw_throttle_mode = THREAD_THROTTLE_MAX;
- hw_ctrl->r_ctrl.membw.resolution = 100;
- hw_ctrl->r_ctrl.membw.tolerance = 5;
- hw_ctrl->r_ctrl.membw.scale = 1;
- hw_ctrl->r_ctrl.membw.unit = RESCTRL_CTRL_UNIT_ALL;
+ hw_ctrl->r_ctrl.scalar.resolution = 100;
+ hw_ctrl->r_ctrl.scalar.tolerance = 5;
+ hw_ctrl->r_ctrl.scalar.scale = 1;
+ hw_ctrl->r_ctrl.scalar.unit = RESCTRL_CTRL_UNIT_ALL;
hw_ctrl->msr_base = MSR_IA32_MBA_THRTL_BASE;
hw_ctrl->msr_update = mba_wrmsr_intel;
@@ -246,7 +246,7 @@ static __init bool __rdt_get_mem_config_amd(struct rdt_resource *r)
if (!hw_ctrl)
return false;
- if (BITS_PER_TYPE(hw_ctrl->r_ctrl.membw.max_bw) <= eax) {
+ if (BITS_PER_TYPE(hw_ctrl->r_ctrl.scalar.max_bw) <= eax) {
pr_warn("Unable to support hardware's maximum bandwidth\n");
kfree(hw_ctrl);
return false;
@@ -257,7 +257,7 @@ static __init bool __rdt_get_mem_config_amd(struct rdt_resource *r)
hw_ctrl->r_ctrl.name = RESCTRL_CTRL_NAME_DEF;
INIT_LIST_HEAD(&hw_ctrl->r_ctrl.domains);
- hw_ctrl->r_ctrl.membw.max_bw = BIT(eax);
+ hw_ctrl->r_ctrl.scalar.max_bw = BIT(eax);
/* AMD does not use delay */
r->bw_delay_linear = false;
@@ -267,12 +267,12 @@ static __init bool __rdt_get_mem_config_amd(struct rdt_resource *r)
* the allocation like Intel does.
*/
r->bw_throttle_mode = THREAD_THROTTLE_UNDEFINED;
- hw_ctrl->r_ctrl.membw.min_bw = 0;
- hw_ctrl->r_ctrl.membw.bw_gran = 1;
- hw_ctrl->r_ctrl.membw.resolution = 8;
- hw_ctrl->r_ctrl.membw.tolerance = 0;
- hw_ctrl->r_ctrl.membw.scale = 1;
- hw_ctrl->r_ctrl.membw.unit = RESCTRL_CTRL_UNIT_GBPS;
+ hw_ctrl->r_ctrl.scalar.min_bw = 0;
+ hw_ctrl->r_ctrl.scalar.bw_gran = 1;
+ hw_ctrl->r_ctrl.scalar.resolution = 8;
+ hw_ctrl->r_ctrl.scalar.tolerance = 0;
+ hw_ctrl->r_ctrl.scalar.scale = 1;
+ hw_ctrl->r_ctrl.scalar.unit = RESCTRL_CTRL_UNIT_GBPS;
if (r->rid == RDT_RESOURCE_MBA) {
hw_ctrl->msr_base = MSR_IA32_MBA_BW_BASE;
diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c
index a9bfab03f0d5..b97c9b80d0ed 100644
--- a/drivers/resctrl/mpam_resctrl.c
+++ b/drivers/resctrl/mpam_resctrl.c
@@ -1043,9 +1043,9 @@ static int mpam_resctrl_control_init(struct mpam_resctrl_res *res)
r->bw_delay_linear = true;
r->bw_throttle_mode = THREAD_THROTTLE_UNDEFINED;
- mpam_ctrl->r_ctrl.membw.min_bw = get_mba_min(cprops);
- mpam_ctrl->r_ctrl.membw.max_bw = MAX_MBA_BW;
- mpam_ctrl->r_ctrl.membw.bw_gran = get_mba_granularity(cprops);
+ mpam_ctrl->r_ctrl.scalar.min_bw = get_mba_min(cprops);
+ mpam_ctrl->r_ctrl.scalar.max_bw = MAX_MBA_BW;
+ mpam_ctrl->r_ctrl.scalar.bw_gran = get_mba_granularity(cprops);
list_add(&mpam_ctrl->r_ctrl.entry, &r->controls);
r->name = "MB";
diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
index d95ab8ad36e2..fd1a9203d6e5 100644
--- a/fs/resctrl/ctrlmondata.c
+++ b/fs/resctrl/ctrlmondata.c
@@ -86,13 +86,13 @@ static bool bw_validate(char *buf, u32 *data, struct rdt_resource *r,
return true;
}
- if (bw < ctrl->membw.min_bw || bw > ctrl->membw.max_bw) {
+ if (bw < ctrl->scalar.min_bw || bw > ctrl->scalar.max_bw) {
rdt_last_cmd_printf("MB value %u out of range [%d,%d]\n",
- bw, ctrl->membw.min_bw, ctrl->membw.max_bw);
+ bw, ctrl->scalar.min_bw, ctrl->scalar.max_bw);
return false;
}
- *data = roundup(bw, (unsigned long)ctrl->membw.bw_gran);
+ *data = roundup(bw, (unsigned long)ctrl->scalar.bw_gran);
return true;
}
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 89baed73bcd6..63d48be41025 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -758,11 +758,11 @@ static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_l3_mon_domain *dom_m
* 40% would go past the limit by multiplying current bandwidth by
* "(30 + 10) / 30".
*/
- if (cur_msr_val > ctrl->membw.min_bw && user_bw < cur_bw) {
- new_msr_val = cur_msr_val - ctrl->membw.bw_gran;
+ if (cur_msr_val > ctrl->scalar.min_bw && user_bw < cur_bw) {
+ new_msr_val = cur_msr_val - ctrl->scalar.bw_gran;
} else if (cur_msr_val < MAX_MBA_BW &&
- (user_bw > (cur_bw * (cur_msr_val + ctrl->membw.min_bw) / cur_msr_val))) {
- new_msr_val = cur_msr_val + ctrl->membw.bw_gran;
+ (user_bw > (cur_bw * (cur_msr_val + ctrl->scalar.min_bw) / cur_msr_val))) {
+ new_msr_val = cur_msr_val + ctrl->scalar.bw_gran;
} else {
return;
}
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 5ccd09b16e0f..4392242e63da 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -1179,7 +1179,7 @@ static int rdt_min_bw_show(struct kernfs_open_file *of,
if (!ctrl || ctrl->type != RESCTRL_CTRL_SCALAR)
return 0;
- seq_printf(seq, "%u\n", ctrl->membw.min_bw);
+ seq_printf(seq, "%u\n", ctrl->scalar.min_bw);
return 0;
}
@@ -1222,7 +1222,7 @@ static int rdt_bw_gran_show(struct kernfs_open_file *of,
if (!ctrl || ctrl->type != RESCTRL_CTRL_SCALAR)
return 0;
- seq_printf(seq, "%u\n", ctrl->membw.bw_gran);
+ seq_printf(seq, "%u\n", ctrl->scalar.bw_gran);
return 0;
}
@@ -1622,7 +1622,7 @@ bool is_mba_sc(struct rdt_resource *r, struct resctrl_ctrl *ctrl)
return false;
}
- return ctrl->membw.mba_sc;
+ return ctrl->scalar.mba_sc;
}
/*
@@ -2256,7 +2256,7 @@ static int resctrl_ctrl_min_show(struct kernfs_open_file *of,
{
struct resctrl_ctrl *ctrl = rdt_kn_parent_priv(of->kn);
- seq_printf(seq, "%u\n", ctrl->membw.min_bw);
+ seq_printf(seq, "%u\n", ctrl->scalar.min_bw);
return 0;
}
@@ -2266,7 +2266,7 @@ static int resctrl_ctrl_max_show(struct kernfs_open_file *of,
{
struct resctrl_ctrl *ctrl = rdt_kn_parent_priv(of->kn);
- seq_printf(seq, "%u\n", ctrl->membw.max_bw);
+ seq_printf(seq, "%u\n", ctrl->scalar.max_bw);
return 0;
}
@@ -2276,7 +2276,7 @@ static int resctrl_ctrl_resolution_show(struct kernfs_open_file *of,
{
struct resctrl_ctrl *ctrl = rdt_kn_parent_priv(of->kn);
- seq_printf(seq, "%u\n", ctrl->membw.resolution);
+ seq_printf(seq, "%u\n", ctrl->scalar.resolution);
return 0;
}
@@ -2286,7 +2286,7 @@ static int resctrl_ctrl_tolerance_show(struct kernfs_open_file *of,
{
struct resctrl_ctrl *ctrl = rdt_kn_parent_priv(of->kn);
- seq_printf(seq, "%d\n", ctrl->membw.tolerance);
+ seq_printf(seq, "%d\n", ctrl->scalar.tolerance);
return 0;
}
@@ -2296,7 +2296,7 @@ static int resctrl_ctrl_scale_show(struct kernfs_open_file *of,
{
struct resctrl_ctrl *ctrl = rdt_kn_parent_priv(of->kn);
- seq_printf(seq, "%u\n", ctrl->membw.scale);
+ seq_printf(seq, "%u\n", ctrl->scalar.scale);
return 0;
}
@@ -2306,7 +2306,7 @@ static int resctrl_ctrl_unit_show(struct kernfs_open_file *of,
{
struct resctrl_ctrl *ctrl = rdt_kn_parent_priv(of->kn);
- switch (ctrl->membw.unit) {
+ switch (ctrl->scalar.unit) {
case RESCTRL_CTRL_UNIT_ALL:
seq_puts(seq, "all\n");
return 0;
@@ -2901,7 +2901,7 @@ static int set_mba_sc(bool mba_sc)
if (!supports_mba_mbps(ctrl) || mba_sc == is_mba_sc(r, ctrl))
return -EINVAL;
- ctrl->membw.mba_sc = mba_sc;
+ ctrl->scalar.mba_sc = mba_sc;
rdtgroup_default.mba_mbps_event = mba_mbps_default_event;
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 72fb7256270e..f54a889c6d99 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -258,10 +258,10 @@ enum resctrl_ctrl_unit {
};
/**
- * struct resctrl_membw - Memory bandwidth allocation related data
- * @min_bw: Minimum memory bandwidth percentage user can request
- * @max_bw: Maximum memory bandwidth value, used as the reset value
- * @bw_gran: Granularity at which the memory bandwidth is allocated
+ * struct resctrl_ctrl_scalar - Scalar control type properties
+ * @min_bw: Minimum scalar control value user can request
+ * @max_bw: Maximum scalar control value, used as the reset value
+ * @bw_gran: Granularity at which the scalar control is allocated
* @resolution: If the control is proportional (for example, a
* percentage) this is the number of divisions that
* resource can be divided into. Otherwise, since this
@@ -284,7 +284,7 @@ enum resctrl_ctrl_unit {
* the amount of resource allocated by this control is:
* C * scale / resolution * unit
*/
-struct resctrl_membw {
+struct resctrl_ctrl_scalar {
u32 min_bw;
u32 max_bw;
u32 bw_gran;
@@ -370,7 +370,7 @@ enum resctrl_ctrl_name {
* For example, with resource name "MB" and control name "MAX" the
* schema entry will be "MB_MAX".
* @cache: Cache allocation control properties.
- * @membw: Bandwidth control properties.
+ * @scalar: Scalar control properties.
*/
struct resctrl_ctrl {
struct list_head entry;
@@ -380,7 +380,7 @@ struct resctrl_ctrl {
enum resctrl_ctrl_name name;
union {
struct resctrl_cache cache;
- struct resctrl_membw membw;
+ struct resctrl_ctrl_scalar scalar;
};
};
@@ -483,7 +483,7 @@ static inline u32 resctrl_get_default_ctrlval(struct resctrl_ctrl *ctrl)
case RESCTRL_CTRL_BITMAP:
return BIT_MASK(ctrl->cache.cbm_len) - 1;
case RESCTRL_CTRL_SCALAR:
- return ctrl->membw.max_bw;
+ return ctrl->scalar.max_bw;
}
return WARN_ON_ONCE(1);
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 12/31] x86/resctrl: Rename struct resctrl_cache to struct resctrl_ctrl_bitmap
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (10 preceding siblings ...)
2026-08-02 16:05 ` [RFC PATCH 11/31] x86/resctrl: Rename struct resctrl_membw to struct resctrl_ctrl_scalar Chen Yu
@ 2026-08-02 16:05 ` Chen Yu
2026-08-02 16:05 ` [RFC PATCH 13/31] x86/resctrl: Add per-control and per-resource flags Chen Yu
` (18 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:05 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
Rename struct resctrl_cache to struct resctrl_ctrl_bitmap to better
reflect its role as the property container for bitmap-type controls.
Also rename the union member from 'cache' to 'bitmap' for consistency.
This follows the design discussed in the generic schema RFC where
controls are classified by type (scalar vs bitmap) rather than by
the specific resource they manage (cache allocation).
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/core.c | 20 +++++++++---------
drivers/resctrl/mpam_resctrl.c | 8 +++----
fs/resctrl/ctrlmondata.c | 12 +++++------
fs/resctrl/pseudo_lock.c | 2 +-
fs/resctrl/rdtgroup.c | 34 +++++++++++++++---------------
include/linux/resctrl.h | 10 ++++-----
6 files changed, 43 insertions(+), 43 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 9566ee43f206..896906f86da2 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -167,10 +167,10 @@ static inline void cache_alloc_hsw_probe(void)
hw_ctrl->r_ctrl.type = RESCTRL_CTRL_BITMAP;
hw_ctrl->r_ctrl.name = RESCTRL_CTRL_NAME_DEF;
INIT_LIST_HEAD(&hw_ctrl->r_ctrl.domains);
- hw_ctrl->r_ctrl.cache.cbm_len = 20;
- hw_ctrl->r_ctrl.cache.shareable_bits = 0xc0000;
- hw_ctrl->r_ctrl.cache.min_cbm_bits = 2;
- hw_ctrl->r_ctrl.cache.arch_has_sparse_bitmasks = false;
+ hw_ctrl->r_ctrl.bitmap.cbm_len = 20;
+ hw_ctrl->r_ctrl.bitmap.shareable_bits = 0xc0000;
+ hw_ctrl->r_ctrl.bitmap.min_cbm_bits = 2;
+ hw_ctrl->r_ctrl.bitmap.arch_has_sparse_bitmasks = false;
list_add(&hw_ctrl->r_ctrl.entry, &r->controls);
hw_res->num_closid = 4;
@@ -308,16 +308,16 @@ static void rdt_get_cache_alloc_cfg(int idx, struct rdt_resource *r)
hw_ctrl->r_ctrl.name = RESCTRL_CTRL_NAME_DEF;
INIT_LIST_HEAD(&hw_ctrl->r_ctrl.domains);
- hw_ctrl->r_ctrl.cache.cbm_len = eax.split.cbm_len + 1;
+ hw_ctrl->r_ctrl.bitmap.cbm_len = eax.split.cbm_len + 1;
default_ctrl = BIT_MASK(eax.split.cbm_len + 1) - 1;
- hw_ctrl->r_ctrl.cache.shareable_bits = ebx & default_ctrl;
+ hw_ctrl->r_ctrl.bitmap.shareable_bits = ebx & default_ctrl;
if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) {
- hw_ctrl->r_ctrl.cache.arch_has_sparse_bitmasks = ecx.split.noncont;
- hw_ctrl->r_ctrl.cache.min_cbm_bits = 1;
+ hw_ctrl->r_ctrl.bitmap.arch_has_sparse_bitmasks = ecx.split.noncont;
+ hw_ctrl->r_ctrl.bitmap.min_cbm_bits = 1;
} else if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
- hw_ctrl->r_ctrl.cache.arch_has_sparse_bitmasks = true;
- hw_ctrl->r_ctrl.cache.min_cbm_bits = 0;
+ hw_ctrl->r_ctrl.bitmap.arch_has_sparse_bitmasks = true;
+ hw_ctrl->r_ctrl.bitmap.min_cbm_bits = 0;
} else {
return;
}
diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c
index b97c9b80d0ed..be3bd3d38ef1 100644
--- a/drivers/resctrl/mpam_resctrl.c
+++ b/drivers/resctrl/mpam_resctrl.c
@@ -1009,11 +1009,11 @@ static int mpam_resctrl_control_init(struct mpam_resctrl_res *res)
mpam_ctrl->r_ctrl.name = RESCTRL_CTRL_NAME_DEF;
INIT_LIST_HEAD_RCU(&mpam_ctrl->r_ctrl.domains);
- mpam_ctrl->r_ctrl.cache.arch_has_sparse_bitmasks = true;
+ mpam_ctrl->r_ctrl.bitmap.arch_has_sparse_bitmasks = true;
- mpam_ctrl->r_ctrl.cache.cbm_len = class->props.cpbm_wd;
+ mpam_ctrl->r_ctrl.bitmap.cbm_len = class->props.cpbm_wd;
/* mpam_devices will reject empty bitmaps */
- mpam_ctrl->r_ctrl.cache.min_cbm_bits = 1;
+ mpam_ctrl->r_ctrl.bitmap.min_cbm_bits = 1;
if (r->rid == RDT_RESOURCE_L2) {
r->name = "L2";
@@ -1031,7 +1031,7 @@ static int mpam_resctrl_control_init(struct mpam_resctrl_res *res)
* we have configured the SMMU and GIC not to do this 'all the
* bits' is the correct answer here.
*/
- mpam_ctrl->r_ctrl.cache.shareable_bits = resctrl_get_default_ctrlval(&mpam_ctrl->r_ctrl);
+ mpam_ctrl->r_ctrl.bitmap.shareable_bits = resctrl_get_default_ctrlval(&mpam_ctrl->r_ctrl);
list_add(&mpam_ctrl->r_ctrl.entry, &r->controls);
r->alloc_capable = true;
break;
diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
index fd1a9203d6e5..74fa1215e8b2 100644
--- a/fs/resctrl/ctrlmondata.c
+++ b/fs/resctrl/ctrlmondata.c
@@ -136,8 +136,8 @@ static int parse_bw(struct rdt_parse_data *data, struct rdt_resource_final *f,
*/
static bool cbm_validate(char *buf, u32 *data, struct resctrl_ctrl *ctrl)
{
- u32 supported_bits = BIT_MASK(ctrl->cache.cbm_len) - 1;
- unsigned int cbm_len = ctrl->cache.cbm_len;
+ u32 supported_bits = BIT_MASK(ctrl->bitmap.cbm_len) - 1;
+ unsigned int cbm_len = ctrl->bitmap.cbm_len;
unsigned long first_bit, zero_bit, val;
int ret;
@@ -147,7 +147,7 @@ static bool cbm_validate(char *buf, u32 *data, struct resctrl_ctrl *ctrl)
return false;
}
- if ((ctrl->cache.min_cbm_bits > 0 && val == 0) || val > supported_bits) {
+ if ((ctrl->bitmap.min_cbm_bits > 0 && val == 0) || val > supported_bits) {
rdt_last_cmd_puts("Mask out of range\n");
return false;
}
@@ -156,15 +156,15 @@ static bool cbm_validate(char *buf, u32 *data, struct resctrl_ctrl *ctrl)
zero_bit = find_next_zero_bit(&val, cbm_len, first_bit);
/* Are non-contiguous bitmasks allowed? */
- if (!ctrl->cache.arch_has_sparse_bitmasks &&
+ if (!ctrl->bitmap.arch_has_sparse_bitmasks &&
(find_next_bit(&val, cbm_len, zero_bit) < cbm_len)) {
rdt_last_cmd_printf("The mask %lx has non-consecutive 1-bits\n", val);
return false;
}
- if ((zero_bit - first_bit) < ctrl->cache.min_cbm_bits) {
+ if ((zero_bit - first_bit) < ctrl->bitmap.min_cbm_bits) {
rdt_last_cmd_printf("Need at least %d bits in the mask\n",
- ctrl->cache.min_cbm_bits);
+ ctrl->bitmap.min_cbm_bits);
return false;
}
diff --git a/fs/resctrl/pseudo_lock.c b/fs/resctrl/pseudo_lock.c
index f2bf6a6b40a4..cece32880a23 100644
--- a/fs/resctrl/pseudo_lock.c
+++ b/fs/resctrl/pseudo_lock.c
@@ -639,7 +639,7 @@ bool rdtgroup_cbm_overlaps_pseudo_locked(struct rdt_ctrl_domain *d, unsigned lon
return false;
}
- cbm_len = ctrl->cache.cbm_len;
+ cbm_len = ctrl->bitmap.cbm_len;
cbm_b = d->plr->cbm;
if (bitmap_intersects(&cbm, &cbm_b, cbm_len))
return true;
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 4392242e63da..cb85108b4a1b 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -1030,7 +1030,7 @@ static int rdt_min_cbm_bits_show(struct kernfs_open_file *of,
if (!ctrl)
return 0;
- seq_printf(seq, "%u\n", ctrl->cache.min_cbm_bits);
+ seq_printf(seq, "%u\n", ctrl->bitmap.min_cbm_bits);
return 0;
}
@@ -1045,7 +1045,7 @@ static int rdt_shareable_bits_show(struct kernfs_open_file *of,
if (!ctrl)
return 0;
- seq_printf(seq, "%x\n", ctrl->cache.shareable_bits);
+ seq_printf(seq, "%x\n", ctrl->bitmap.shareable_bits);
return 0;
}
@@ -1091,7 +1091,7 @@ static int rdt_bit_usage_show(struct kernfs_open_file *of,
list_for_each_entry(dom, &ctrl->domains, hdr.list) {
if (sep)
seq_putc(seq, ';');
- hw_shareable = ctrl->cache.shareable_bits;
+ hw_shareable = ctrl->bitmap.shareable_bits;
sw_shareable = 0;
exclusive = 0;
seq_printf(seq, "%d=", dom->hdr.id);
@@ -1141,7 +1141,7 @@ static int rdt_bit_usage_show(struct kernfs_open_file *of,
hw_shareable |= ctrl_val;
}
- for (i = ctrl->cache.cbm_len - 1; i >= 0; i--) {
+ for (i = ctrl->bitmap.cbm_len - 1; i >= 0; i--) {
pseudo_locked = dom->plr ? dom->plr->cbm : 0;
hwb = test_bit(i, &hw_shareable);
swb = test_bit(i, &sw_shareable);
@@ -1337,7 +1337,7 @@ static int rdt_has_sparse_bitmasks_show(struct kernfs_open_file *of,
if (!ctrl)
return 0;
- seq_printf(seq, "%u\n", ctrl->cache.arch_has_sparse_bitmasks);
+ seq_printf(seq, "%u\n", ctrl->bitmap.arch_has_sparse_bitmasks);
return 0;
}
@@ -1375,8 +1375,8 @@ static bool __rdtgroup_cbm_overlaps(struct rdt_resource *r, struct rdt_ctrl_doma
/* Check for any overlap with regions used by hardware directly */
if (!exclusive) {
- ctrl_b = ctrl->cache.shareable_bits;
- if (bitmap_intersects(&cbm, &ctrl_b, ctrl->cache.cbm_len))
+ ctrl_b = ctrl->bitmap.shareable_bits;
+ if (bitmap_intersects(&cbm, &ctrl_b, ctrl->bitmap.cbm_len))
return true;
}
@@ -1386,7 +1386,7 @@ static bool __rdtgroup_cbm_overlaps(struct rdt_resource *r, struct rdt_ctrl_doma
mode = rdtgroup_mode_by_closid(i);
if (closid_allocated(i) && i != closid &&
mode != RDT_MODE_PSEUDO_LOCKSETUP) {
- if (bitmap_intersects(&cbm, &ctrl_b, ctrl->cache.cbm_len)) {
+ if (bitmap_intersects(&cbm, &ctrl_b, ctrl->bitmap.cbm_len)) {
if (exclusive) {
if (mode == RDT_MODE_EXCLUSIVE)
return true;
@@ -1591,10 +1591,10 @@ unsigned int rdtgroup_cbm_to_size(struct rdt_resource *r, struct resctrl_ctrl *c
if (WARN_ON_ONCE(ctrl->scope != RESCTRL_L2_CACHE && ctrl->scope != RESCTRL_L3_CACHE))
return size;
- num_b = bitmap_weight(&cbm, ctrl->cache.cbm_len);
+ num_b = bitmap_weight(&cbm, ctrl->bitmap.cbm_len);
ci = get_cpu_cacheinfo_level(cpumask_any(&d->hdr.cpu_mask), ctrl->scope);
if (ci)
- size = ci->size / ctrl->cache.cbm_len * num_b;
+ size = ci->size / ctrl->bitmap.cbm_len * num_b;
return size;
}
@@ -3883,11 +3883,11 @@ static int mkdir_mondata_all(struct kernfs_node *parent_kn,
static u32 cbm_ensure_valid(u32 _val, struct rdt_resource *r,
struct resctrl_ctrl *ctrl)
{
- unsigned int cbm_len = ctrl->cache.cbm_len;
+ unsigned int cbm_len = ctrl->bitmap.cbm_len;
unsigned long first_bit, zero_bit;
unsigned long val;
- if (!_val || ctrl->cache.arch_has_sparse_bitmasks)
+ if (!_val || ctrl->bitmap.arch_has_sparse_bitmasks)
return _val;
val = _val;
@@ -3920,8 +3920,8 @@ static int __init_one_rdt_domain(struct rdt_ctrl_domain *d, struct rdt_resource_
cfg = &d->staged_config[t];
cfg->have_new_ctrl = false;
- cfg->new_ctrl = ctrl->cache.shareable_bits;
- used_b = ctrl->cache.shareable_bits;
+ cfg->new_ctrl = ctrl->bitmap.shareable_bits;
+ used_b = ctrl->bitmap.shareable_bits;
for (i = 0; i < closids_supported(); i++) {
if (closid_allocated(i) && i != closid) {
mode = rdtgroup_mode_by_closid(i);
@@ -3951,8 +3951,8 @@ static int __init_one_rdt_domain(struct rdt_ctrl_domain *d, struct rdt_resource_
}
if (d->plr && d->plr->cbm > 0)
used_b |= d->plr->cbm;
- unused_b = used_b ^ (BIT_MASK(ctrl->cache.cbm_len) - 1);
- unused_b &= BIT_MASK(ctrl->cache.cbm_len) - 1;
+ unused_b = used_b ^ (BIT_MASK(ctrl->bitmap.cbm_len) - 1);
+ unused_b &= BIT_MASK(ctrl->bitmap.cbm_len) - 1;
cfg->new_ctrl |= unused_b;
/*
* Force the initial CBM to be valid, user can
@@ -3964,7 +3964,7 @@ static int __init_one_rdt_domain(struct rdt_ctrl_domain *d, struct rdt_resource_
* bitmap_weight() does not access out-of-bound memory.
*/
tmp_cbm = cfg->new_ctrl;
- if (bitmap_weight(&tmp_cbm, ctrl->cache.cbm_len) < ctrl->cache.min_cbm_bits) {
+ if (bitmap_weight(&tmp_cbm, ctrl->bitmap.cbm_len) < ctrl->bitmap.min_cbm_bits) {
rdt_last_cmd_printf("No space on %s:%d\n", f->name, d->hdr.id);
return -ENOSPC;
}
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index f54a889c6d99..c23c2f8bf2d1 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -211,7 +211,7 @@ struct rdt_l3_mon_domain {
};
/**
- * struct resctrl_cache - Cache allocation related data
+ * struct resctrl_ctrl_bitmap - Bitmap control type properties
* @cbm_len: Length of the cache bit mask
* @min_cbm_bits: Minimum number of consecutive bits to be set.
* The value 0 means the architecture can support
@@ -220,7 +220,7 @@ struct rdt_l3_mon_domain {
* executing entities
* @arch_has_sparse_bitmasks: True if a bitmask like f00f is valid.
*/
-struct resctrl_cache {
+struct resctrl_ctrl_bitmap {
unsigned int cbm_len;
unsigned int min_cbm_bits;
unsigned int shareable_bits;
@@ -369,7 +369,7 @@ enum resctrl_ctrl_name {
* Specifically, "rdt_resource_final::name"_"resctrl_ctrl::name".
* For example, with resource name "MB" and control name "MAX" the
* schema entry will be "MB_MAX".
- * @cache: Cache allocation control properties.
+ * @bitmap: Bitmap control properties.
* @scalar: Scalar control properties.
*/
struct resctrl_ctrl {
@@ -379,7 +379,7 @@ struct resctrl_ctrl {
enum resctrl_ctrl_type type;
enum resctrl_ctrl_name name;
union {
- struct resctrl_cache cache;
+ struct resctrl_ctrl_bitmap bitmap;
struct resctrl_ctrl_scalar scalar;
};
};
@@ -481,7 +481,7 @@ static inline u32 resctrl_get_default_ctrlval(struct resctrl_ctrl *ctrl)
{
switch (ctrl->type) {
case RESCTRL_CTRL_BITMAP:
- return BIT_MASK(ctrl->cache.cbm_len) - 1;
+ return BIT_MASK(ctrl->bitmap.cbm_len) - 1;
case RESCTRL_CTRL_SCALAR:
return ctrl->scalar.max_bw;
}
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 13/31] x86/resctrl: Add per-control and per-resource flags
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (11 preceding siblings ...)
2026-08-02 16:05 ` [RFC PATCH 12/31] x86/resctrl: Rename struct resctrl_cache to struct resctrl_ctrl_bitmap Chen Yu
@ 2026-08-02 16:05 ` Chen Yu
2026-08-02 16:06 ` [RFC PATCH 14/31] x86/resctrl: Add emulation controller list to resctrl_ctrl Chen Yu
` (17 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:05 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
Introduce a 'flags' field in both struct rdt_resource and struct
resctrl_ctrl to expose control properties via the resource_schemata
info directory. Define two flags:
RESCTRL_CTRL_FLAG_LINEAR - scalar control uses linear delay
RESCTRL_CTRL_FLAG_SPARSE_BITMASKS - bitmap control supports sparse masks
The resource-level flags (rdt_resource::flags) serve as the source of
truth for properties shared by all controls of a resource. Each control
duplicates these flags into its own resctrl_ctrl::flags field for
per-control visibility in the info/<resource>/resource_schemata/<ctrl>/
directory.
The existing fields (bw_delay_linear, arch_has_sparse_bitmasks) are
preserved for backward compatibility with the legacy info directory
files (delay_linear, sparse_masks).
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/core.c | 12 ++++++++++++
drivers/resctrl/mpam_resctrl.c | 4 ++++
include/linux/resctrl.h | 11 +++++++++++
3 files changed, 27 insertions(+)
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 896906f86da2..f0e30f22576c 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -171,6 +171,8 @@ static inline void cache_alloc_hsw_probe(void)
hw_ctrl->r_ctrl.bitmap.shareable_bits = 0xc0000;
hw_ctrl->r_ctrl.bitmap.min_cbm_bits = 2;
hw_ctrl->r_ctrl.bitmap.arch_has_sparse_bitmasks = false;
+ r->flags = 0;
+ hw_ctrl->r_ctrl.flags = 0;
list_add(&hw_ctrl->r_ctrl.entry, &r->controls);
hw_res->num_closid = 4;
@@ -209,6 +211,8 @@ static __init bool __get_mem_config_intel(struct rdt_resource *r)
hw_ctrl->r_ctrl.scalar.bw_gran = MAX_MBA_BW - max_delay;
r->bw_delay_linear = true;
+ r->flags = RESCTRL_CTRL_FLAG_LINEAR;
+ hw_ctrl->r_ctrl.flags = RESCTRL_CTRL_FLAG_LINEAR;
if (boot_cpu_has(X86_FEATURE_PER_THREAD_MBA))
r->bw_throttle_mode = THREAD_THROTTLE_PER_THREAD;
else
@@ -261,6 +265,8 @@ static __init bool __rdt_get_mem_config_amd(struct rdt_resource *r)
/* AMD does not use delay */
r->bw_delay_linear = false;
+ r->flags = 0;
+ hw_ctrl->r_ctrl.flags = 0;
/*
* AMD does not use memory delay throttle model to control
@@ -313,10 +319,16 @@ static void rdt_get_cache_alloc_cfg(int idx, struct rdt_resource *r)
hw_ctrl->r_ctrl.bitmap.shareable_bits = ebx & default_ctrl;
if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) {
hw_ctrl->r_ctrl.bitmap.arch_has_sparse_bitmasks = ecx.split.noncont;
+ if (ecx.split.noncont) {
+ r->flags = RESCTRL_CTRL_FLAG_SPARSE_BITMASKS;
+ hw_ctrl->r_ctrl.flags = RESCTRL_CTRL_FLAG_SPARSE_BITMASKS;
+ }
hw_ctrl->r_ctrl.bitmap.min_cbm_bits = 1;
} else if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
hw_ctrl->r_ctrl.bitmap.arch_has_sparse_bitmasks = true;
+ r->flags = RESCTRL_CTRL_FLAG_SPARSE_BITMASKS;
+ hw_ctrl->r_ctrl.flags = RESCTRL_CTRL_FLAG_SPARSE_BITMASKS;
hw_ctrl->r_ctrl.bitmap.min_cbm_bits = 0;
} else {
return;
diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c
index be3bd3d38ef1..d675f1c948c4 100644
--- a/drivers/resctrl/mpam_resctrl.c
+++ b/drivers/resctrl/mpam_resctrl.c
@@ -1010,6 +1010,8 @@ static int mpam_resctrl_control_init(struct mpam_resctrl_res *res)
INIT_LIST_HEAD_RCU(&mpam_ctrl->r_ctrl.domains);
mpam_ctrl->r_ctrl.bitmap.arch_has_sparse_bitmasks = true;
+ r->flags = RESCTRL_CTRL_FLAG_SPARSE_BITMASKS;
+ mpam_ctrl->r_ctrl.flags = RESCTRL_CTRL_FLAG_SPARSE_BITMASKS;
mpam_ctrl->r_ctrl.bitmap.cbm_len = class->props.cpbm_wd;
/* mpam_devices will reject empty bitmaps */
@@ -1042,6 +1044,8 @@ static int mpam_resctrl_control_init(struct mpam_resctrl_res *res)
INIT_LIST_HEAD_RCU(&mpam_ctrl->r_ctrl.domains);
r->bw_delay_linear = true;
+ r->flags = RESCTRL_CTRL_FLAG_LINEAR;
+ mpam_ctrl->r_ctrl.flags = RESCTRL_CTRL_FLAG_LINEAR;
r->bw_throttle_mode = THREAD_THROTTLE_UNDEFINED;
mpam_ctrl->r_ctrl.scalar.min_bw = get_mba_min(cprops);
mpam_ctrl->r_ctrl.scalar.max_bw = MAX_MBA_BW;
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index c23c2f8bf2d1..b2af0664cce7 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -356,6 +356,10 @@ enum resctrl_ctrl_name {
RESCTRL_CTRL_NAME_LAST = RESCTRL_CTRL_NAME_MAX
};
+/* Flags for rdt_resource::flags and resctrl_ctrl::flags */
+#define RESCTRL_CTRL_FLAG_LINEAR BIT(0)
+#define RESCTRL_CTRL_FLAG_SPARSE_BITMASKS BIT(1)
+
/**
* struct resctrl_ctrl - A resource control
* @entry: List entry of rdt_resource::controls
@@ -369,6 +373,9 @@ enum resctrl_ctrl_name {
* Specifically, "rdt_resource_final::name"_"resctrl_ctrl::name".
* For example, with resource name "MB" and control name "MAX" the
* schema entry will be "MB_MAX".
+ * @flags: Optional flags describing properties of the control.
+ * Duplicated from resource-level properties for per-control
+ * visibility via the resource_schemata info directory.
* @bitmap: Bitmap control properties.
* @scalar: Scalar control properties.
*/
@@ -378,6 +385,7 @@ struct resctrl_ctrl {
struct list_head domains;
enum resctrl_ctrl_type type;
enum resctrl_ctrl_name name;
+ unsigned long flags;
union {
struct resctrl_ctrl_bitmap bitmap;
struct resctrl_ctrl_scalar scalar;
@@ -399,6 +407,8 @@ struct resctrl_ctrl {
* different memory bandwidths
* @cache_io_alloc_capable:True if portion of the cache can be configured
* for I/O traffic.
+ * @flags: Resource-level flags (RESCTRL_CTRL_FLAG_*). Duplicated
+ * into each control's flags field for per-control visibility.
* @controls: List of controls of an alloc_capable resource
*/
struct rdt_resource {
@@ -413,6 +423,7 @@ struct rdt_resource {
bool bw_delay_linear;
enum membw_throttle_mode bw_throttle_mode;
bool cache_io_alloc_capable;
+ unsigned long flags;
struct list_head controls;
};
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 14/31] x86/resctrl: Add emulation controller list to resctrl_ctrl
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (12 preceding siblings ...)
2026-08-02 16:05 ` [RFC PATCH 13/31] x86/resctrl: Add per-control and per-resource flags Chen Yu
@ 2026-08-02 16:06 ` Chen Yu
2026-08-02 16:06 ` [RFC PATCH 15/31] x86/resctrl: Parse ACPI MMRC table Chen Yu
` (16 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:06 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
There is a requirement to emulate Controller A using a set of other
controllers. The purpose is to either supply hierarchy information in
the schema info directory or emulate legacy controllers via the new
controllers for backward compatibility.
A legacy controller can be emulated by more than one controller. For
example, on region aware platforms the legacy MBA control is emulated by
the MAX control of every available memory region. Track the emulating
controllers on a list anchored at resctrl_ctrl::emul, linked via
resctrl_ctrl::emul_entry.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/core.c | 4 ++++
include/linux/resctrl.h | 4 ++++
2 files changed, 8 insertions(+)
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index f0e30f22576c..a7322f0ebaea 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -167,6 +167,7 @@ static inline void cache_alloc_hsw_probe(void)
hw_ctrl->r_ctrl.type = RESCTRL_CTRL_BITMAP;
hw_ctrl->r_ctrl.name = RESCTRL_CTRL_NAME_DEF;
INIT_LIST_HEAD(&hw_ctrl->r_ctrl.domains);
+ INIT_LIST_HEAD(&hw_ctrl->r_ctrl.emul);
hw_ctrl->r_ctrl.bitmap.cbm_len = 20;
hw_ctrl->r_ctrl.bitmap.shareable_bits = 0xc0000;
hw_ctrl->r_ctrl.bitmap.min_cbm_bits = 2;
@@ -205,6 +206,7 @@ static __init bool __get_mem_config_intel(struct rdt_resource *r)
hw_ctrl->r_ctrl.type = RESCTRL_CTRL_SCALAR;
hw_ctrl->r_ctrl.name = RESCTRL_CTRL_NAME_DEF;
INIT_LIST_HEAD(&hw_ctrl->r_ctrl.domains);
+ INIT_LIST_HEAD(&hw_ctrl->r_ctrl.emul);
hw_ctrl->r_ctrl.scalar.max_bw = MAX_MBA_BW;
hw_ctrl->r_ctrl.scalar.min_bw = MAX_MBA_BW - max_delay;
@@ -260,6 +262,7 @@ static __init bool __rdt_get_mem_config_amd(struct rdt_resource *r)
hw_ctrl->r_ctrl.type = RESCTRL_CTRL_SCALAR;
hw_ctrl->r_ctrl.name = RESCTRL_CTRL_NAME_DEF;
INIT_LIST_HEAD(&hw_ctrl->r_ctrl.domains);
+ INIT_LIST_HEAD(&hw_ctrl->r_ctrl.emul);
hw_ctrl->r_ctrl.scalar.max_bw = BIT(eax);
@@ -313,6 +316,7 @@ static void rdt_get_cache_alloc_cfg(int idx, struct rdt_resource *r)
hw_ctrl->r_ctrl.type = RESCTRL_CTRL_BITMAP;
hw_ctrl->r_ctrl.name = RESCTRL_CTRL_NAME_DEF;
INIT_LIST_HEAD(&hw_ctrl->r_ctrl.domains);
+ INIT_LIST_HEAD(&hw_ctrl->r_ctrl.emul);
hw_ctrl->r_ctrl.bitmap.cbm_len = eax.split.cbm_len + 1;
default_ctrl = BIT_MASK(eax.split.cbm_len + 1) - 1;
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index b2af0664cce7..e8da30a71e13 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -378,6 +378,8 @@ enum resctrl_ctrl_name {
* visibility via the resource_schemata info directory.
* @bitmap: Bitmap control properties.
* @scalar: Scalar control properties.
+ * @emul: List of controls that emulate the current control.
+ * @emul_entry: List entry of the emulated control's resctrl_ctrl::emul.
*/
struct resctrl_ctrl {
struct list_head entry;
@@ -390,6 +392,8 @@ struct resctrl_ctrl {
struct resctrl_ctrl_bitmap bitmap;
struct resctrl_ctrl_scalar scalar;
};
+ struct list_head emul;
+ struct list_head emul_entry;
};
/**
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 15/31] x86/resctrl: Parse ACPI MMRC table
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (13 preceding siblings ...)
2026-08-02 16:06 ` [RFC PATCH 14/31] x86/resctrl: Add emulation controller list to resctrl_ctrl Chen Yu
@ 2026-08-02 16:06 ` Chen Yu
2026-08-02 16:06 ` [RFC PATCH 16/31] x86/resctrl: Replace "msr" in monitoring data identifiers Chen Yu
` (15 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:06 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
The MMRC table is used to provide Memory Bandwidth Monitor Register
information. Its register addresses are mapped, and the MMRC pointer
is saved in the corresponding domain information entry.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/erdt.c | 51 ++++++++++++++++++++++++++
arch/x86/kernel/cpu/resctrl/internal.h | 6 ++-
2 files changed, 56 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
index 5f9377c80be6..a14de9eb8b88 100644
--- a/arch/x86/kernel/cpu/resctrl/erdt.c
+++ b/arch/x86/kernel/cpu/resctrl/erdt.c
@@ -24,6 +24,7 @@ static bool erdt_enabled;
#define ERDT_VALID_VERSION 1
#define CMRC_SUPPORTED_INDEX_FN 1
+#define MMRC_SUPPORTED_INDEX_FN 1
#define RMDD_FLAG_CPU_L3_DOMAIN BIT(0)
/* Set in a monitoring counter when it holds no valid data to report. */
@@ -141,6 +142,7 @@ static void cleanup_one_domain(struct erdt_domain_info *d)
{
erdt_iounmap_domain(d);
kfree(d->cmrc);
+ kfree(d->mmrc);
kfree(d);
}
@@ -211,6 +213,49 @@ static __init int cmrc_init(struct acpi_subtbl_hdr_16 *subtbl,
return 0;
}
+static __init int mmrc_init(struct acpi_subtbl_hdr_16 *subtbl,
+ struct erdt_domain_info *domain_info)
+{
+ struct acpi_erdt_mmrc *mmrc = (struct acpi_erdt_mmrc *)subtbl;
+
+ if (subtbl->length < sizeof(*mmrc)) {
+ pr_warn(FW_BUG "Truncated MMRC subtable\n");
+ return -EIO;
+ }
+
+ if (mmrc->index_fn != MMRC_SUPPORTED_INDEX_FN) {
+ pr_info("Unsupported MMRC index function %d\n", mmrc->index_fn);
+ return -EIO;
+ }
+
+ /*
+ * The correction factor list is a trailing flexible array, so it is
+ * not covered by the sizeof(*mmrc) check above. Firmware could claim
+ * more entries than the sub-table actually carries, so only trust the
+ * length the sub-table can back.
+ */
+ if (subtbl->length < struct_size(mmrc, corr_factor_list,
+ mmrc->corr_factor_list_len)) {
+ pr_warn(FW_BUG "MMRC correction factor list of %u entries exceeds sub-table\n",
+ mmrc->corr_factor_list_len);
+ return -EIO;
+ }
+
+ domain_info->base[ERDT_MMIO_MMRC_BASE] =
+ erdt_ioremap(mmrc->reg_base, mmrc->reg_size, "MMRC base");
+ if (!domain_info->base[ERDT_MMIO_MMRC_BASE])
+ return -EIO;
+
+ domain_info->mmrc = kmemdup(mmrc, subtbl->length, GFP_KERNEL);
+ if (!domain_info->mmrc) {
+ iounmap(domain_info->base[ERDT_MMIO_MMRC_BASE]);
+ domain_info->base[ERDT_MMIO_MMRC_BASE] = NULL;
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
static inline struct acpi_subtbl_hdr_16 *rmdd_subtbl(struct acpi_erdt_rmdd *rmdd)
{
return (void *)rmdd + sizeof(*rmdd);
@@ -287,6 +332,12 @@ static __init bool parse_rmdd_table(struct acpi_subtbl_hdr_16 *rmdd_hdr)
!cmrc_init(subtbl, domain_info))
subtbl_mask |= BIT(ACPI_ERDT_TYPE_CMRC);
+ break;
+ case ACPI_ERDT_TYPE_MMRC:
+ if (!(subtbl_mask & BIT(ACPI_ERDT_TYPE_MMRC)) &&
+ !mmrc_init(subtbl, domain_info))
+ subtbl_mask |= BIT(ACPI_ERDT_TYPE_MMRC);
+
break;
default:
break;
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index c175d8884516..4bbe0c80c9e6 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -25,11 +25,13 @@
* Index into erdt_domain_info::base[] for each MMIO region.
* @ERDT_MMIO_RMDD_CREG: RMDD control register base address
* @ERDT_MMIO_CMRC_BASE: CMRC monitoring register base address
+ * @ERDT_MMIO_MMRC_BASE: MMRC monitoring register base address
*/
enum erdt_mmio_type {
ERDT_MMIO_RMDD_CREG,
ERDT_MMIO_CMRC_BASE,
- ERDT_MMIO_LAST = ERDT_MMIO_CMRC_BASE
+ ERDT_MMIO_MMRC_BASE,
+ ERDT_MMIO_LAST = ERDT_MMIO_MMRC_BASE
};
#define ERDT_MMIO_NUM_TYPES (ERDT_MMIO_LAST + 1)
@@ -38,6 +40,7 @@ enum erdt_mmio_type {
* struct erdt_domain_info - Per-domain ERDT information
* @base: Array of ioremapped MMIO region base addresses, indexed by ERDT_MMIO_* type
* @cmrc: Copy of the ACPI CMRC sub-table for this domain
+ * @mmrc: Copy of the ACPI MMRC sub-table for this domain
* @cpu_mask: CPUs belonging to this resource management domain
* @max_rmid: Maximum RMID supported by this domain
* @dom_id: L3 cache ID shared by all CPUs in this domain (-1 if unset)
@@ -46,6 +49,7 @@ enum erdt_mmio_type {
struct erdt_domain_info {
void __iomem *base[ERDT_MMIO_NUM_TYPES];
struct acpi_erdt_cmrc *cmrc;
+ struct acpi_erdt_mmrc *mmrc;
struct cpumask cpu_mask;
u32 max_rmid;
int dom_id;
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 16/31] x86/resctrl: Replace "msr" in monitoring data identifiers
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (14 preceding siblings ...)
2026-08-02 16:06 ` [RFC PATCH 15/31] x86/resctrl: Parse ACPI MMRC table Chen Yu
@ 2026-08-02 16:06 ` Chen Yu
2026-08-02 16:06 ` [RFC PATCH 17/31] x86/resctrl: Introduce region aware MBM event definitions Chen Yu
` (14 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:06 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
Monitoring counter values are currently obtained via MSR and many
identifiers involved in processing these values contain "msr"
as part of their names, for example "prev_msr" and "msr_val".
The ERDT ACPI table describes MMIO registers for monitoring data
access. Rename "msr"-based identifiers to be interface-agnostic
to support their upcoming use for MMIO-read values.
No functional change.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/internal.h | 8 +++----
arch/x86/kernel/cpu/resctrl/monitor.c | 30 +++++++++++++-------------
2 files changed, 19 insertions(+), 19 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 4bbe0c80c9e6..c337c4336789 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -66,13 +66,13 @@ struct erdt_domain_info {
/**
* struct arch_mbm_state - values used to compute resctrl_arch_rmid_read()s
* return value.
- * @chunks: Total data moved (multiply by rdt_group.mon_scale to get bytes)
- * @prev_msr: Value of IA32_QM_CTR last time it was read for the RMID used to
- * find this struct.
+ * @chunks: Total data moved (multiply by rdt_group.mon_scale to get bytes)
+ * @prev_mon_val: Previous monitor counter value for the RMID used to
+ * find this struct.
*/
struct arch_mbm_state {
u64 chunks;
- u64 prev_msr;
+ u64 prev_mon_val;
};
/* Setting bit 0 in L3_QOS_EXT_CFG enables the ABMC feature. */
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 0e011b1f7fd2..ac5353fd0efd 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -186,7 +186,7 @@ void resctrl_arch_reset_rmid(struct rdt_resource *r, struct rdt_l3_mon_domain *d
prmid = logical_rmid_to_physical_rmid(cpu, rmid);
/* Record any initial, non-zero count value. */
- __rmid_read_phys(prmid, eventid, &am->prev_msr);
+ __rmid_read_phys(prmid, eventid, &am->prev_mon_val);
}
}
@@ -209,16 +209,16 @@ void resctrl_arch_reset_rmid_all(struct rdt_resource *r, struct rdt_l3_mon_domai
}
}
-static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr, unsigned int width)
+static u64 mbm_overflow_count(u64 prev_val, u64 cur_val, unsigned int width)
{
u64 shift = 64 - width, chunks;
- chunks = (cur_msr << shift) - (prev_msr << shift);
+ chunks = (cur_val << shift) - (prev_val << shift);
return chunks >> shift;
}
static u64 get_corrected_val(struct rdt_resource *r, struct rdt_l3_mon_domain *d,
- u32 rmid, enum resctrl_event_id eventid, u64 msr_val)
+ u32 rmid, enum resctrl_event_id eventid, u64 mon_val)
{
struct rdt_hw_l3_mon_domain *hw_dom = resctrl_to_arch_mon_dom(d);
struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
@@ -227,12 +227,12 @@ static u64 get_corrected_val(struct rdt_resource *r, struct rdt_l3_mon_domain *d
am = get_arch_mbm_state(hw_dom, rmid, eventid);
if (am) {
- am->chunks += mbm_overflow_count(am->prev_msr, msr_val,
+ am->chunks += mbm_overflow_count(am->prev_mon_val, mon_val,
hw_res->mbm_width);
chunks = get_corrected_mbm_count(rmid, am->chunks);
- am->prev_msr = msr_val;
+ am->prev_mon_val = mon_val;
} else {
- chunks = msr_val;
+ chunks = mon_val;
}
return chunks * hw_res->mon_scale;
@@ -245,7 +245,7 @@ static int arch_l3_read_event(struct rdt_domain_hdr *hdr, u32 rmid,
struct rdt_hw_l3_mon_domain *hw_dom;
struct rdt_l3_mon_domain *d;
struct arch_mbm_state *am;
- u64 msr_val;
+ u64 mon_val;
u32 prmid;
int cpu;
int ret;
@@ -257,14 +257,14 @@ static int arch_l3_read_event(struct rdt_domain_hdr *hdr, u32 rmid,
hw_dom = resctrl_to_arch_mon_dom(d);
cpu = cpumask_any(&hdr->cpu_mask);
prmid = logical_rmid_to_physical_rmid(cpu, rmid);
- ret = __rmid_read_phys(prmid, eventid, &msr_val);
+ ret = __rmid_read_phys(prmid, eventid, &mon_val);
if (!ret) {
- *val = get_corrected_val(r, d, rmid, eventid, msr_val);
+ *val = get_corrected_val(r, d, rmid, eventid, mon_val);
} else if (ret == -EINVAL) {
am = get_arch_mbm_state(hw_dom, rmid, eventid);
if (am)
- am->prev_msr = 0;
+ am->prev_mon_val = 0;
}
return ret;
@@ -339,7 +339,7 @@ void resctrl_arch_reset_cntr(struct rdt_resource *r, struct rdt_l3_mon_domain *d
memset(am, 0, sizeof(*am));
/* Record any initial, non-zero count value. */
- __cntr_id_read(cntr_id, &am->prev_msr);
+ __cntr_id_read(cntr_id, &am->prev_mon_val);
}
}
@@ -347,14 +347,14 @@ int resctrl_arch_cntr_read(struct rdt_resource *r, struct rdt_l3_mon_domain *d,
u32 unused, u32 rmid, int cntr_id,
enum resctrl_event_id eventid, u64 *val)
{
- u64 msr_val;
+ u64 mon_val;
int ret;
- ret = __cntr_id_read(cntr_id, &msr_val);
+ ret = __cntr_id_read(cntr_id, &mon_val);
if (ret)
return ret;
- *val = get_corrected_val(r, d, rmid, eventid, msr_val);
+ *val = get_corrected_val(r, d, rmid, eventid, mon_val);
return 0;
}
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 17/31] x86/resctrl: Introduce region aware MBM event definitions
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (15 preceding siblings ...)
2026-08-02 16:06 ` [RFC PATCH 16/31] x86/resctrl: Replace "msr" in monitoring data identifiers Chen Yu
@ 2026-08-02 16:06 ` Chen Yu
2026-08-02 16:06 ` [RFC PATCH 18/31] x86/resctrl: Introduce memory region based MBM read callback on MMIO space Chen Yu
` (13 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:06 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
Region-Aware RDT supports per-region MBM. Per the specification,
there are a maximum of 4 memory regions currently: DDR, CXL link,
UPI link, and Persistent Memory (including both local and remote
regions).
Based on this information, introduce 4 region-based MBM events
accordingly.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
fs/resctrl/monitor.c | 13 +++++++++++++
fs/resctrl/rdtgroup.c | 15 ++++++++++++++-
include/linux/resctrl.h | 8 ++++++--
include/linux/resctrl_types.h | 14 +++++++++++++-
4 files changed, 46 insertions(+), 4 deletions(-)
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 63d48be41025..aadac544576b 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -802,6 +802,17 @@ static void mbm_update_one_event(struct rdt_resource *r, struct rdt_l3_mon_domai
resctrl_arch_mon_ctx_free(rr.r, evtid, rr.arch_mon_ctx);
}
+static void rmbm_update(struct rdt_resource *r, struct rdt_l3_mon_domain *d,
+ struct rdtgroup *rdtgrp)
+{
+ enum resctrl_event_id evt;
+
+ for_each_rmbm_event_id(evt) {
+ if (resctrl_is_mon_event_enabled(evt))
+ mbm_update_one_event(r, d, rdtgrp, evt);
+ }
+}
+
static void mbm_update(struct rdt_resource *r, struct rdt_l3_mon_domain *d,
struct rdtgroup *rdtgrp)
{
@@ -814,6 +825,8 @@ static void mbm_update(struct rdt_resource *r, struct rdt_l3_mon_domain *d,
if (resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID))
mbm_update_one_event(r, d, rdtgrp, QOS_L3_MBM_LOCAL_EVENT_ID);
+
+ rmbm_update(r, d, rdtgrp);
}
/*
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index cb85108b4a1b..c1aac0dcd332 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -126,10 +126,23 @@ void rdt_staged_configs_clear(void)
}
}
+static bool resctrl_is_rmbm_enabled(void)
+{
+ enum resctrl_event_id evt;
+
+ for_each_rmbm_event_id(evt) {
+ if (resctrl_is_mon_event_enabled(evt))
+ return true;
+ }
+
+ return false;
+}
+
static bool resctrl_is_mbm_enabled(void)
{
return (resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID) ||
- resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID));
+ resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID) ||
+ resctrl_is_rmbm_enabled());
}
/*
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index e8da30a71e13..7bbda28baccf 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -519,7 +519,7 @@ bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt);
static inline bool resctrl_is_mbm_event(enum resctrl_event_id eventid)
{
return (eventid >= QOS_L3_MBM_TOTAL_EVENT_ID &&
- eventid <= QOS_L3_MBM_LOCAL_EVENT_ID);
+ eventid <= QOS_L3_MBM_R3_EVENT_ID);
}
u32 resctrl_get_mon_evt_cfg(enum resctrl_event_id eventid);
@@ -527,7 +527,11 @@ u32 resctrl_get_mon_evt_cfg(enum resctrl_event_id eventid);
/* Iterate over all memory bandwidth events */
#define for_each_mbm_event_id(eventid) \
for (eventid = QOS_L3_MBM_TOTAL_EVENT_ID; \
- eventid <= QOS_L3_MBM_LOCAL_EVENT_ID; eventid++)
+ eventid <= QOS_L3_MBM_R3_EVENT_ID; eventid++)
+
+#define for_each_rmbm_event_id(eventid) \
+ for (eventid = QOS_L3_MBM_R0_EVENT_ID; \
+ eventid <= QOS_L3_MBM_R3_EVENT_ID; eventid++)
/* Iterate over memory bandwidth arrays in domain structures */
#define for_each_mbm_idx(idx) \
diff --git a/include/linux/resctrl_types.h b/include/linux/resctrl_types.h
index a5f56faa18d2..41dc1dff8c16 100644
--- a/include/linux/resctrl_types.h
+++ b/include/linux/resctrl_types.h
@@ -50,6 +50,18 @@ enum resctrl_event_id {
QOS_L3_MBM_TOTAL_EVENT_ID = 0x02,
QOS_L3_MBM_LOCAL_EVENT_ID = 0x03,
+ /*
+ * Region based MBM events.
+ * at most 4 regions for now, these
+ * 4 regions could be mapped to
+ * different memory regions, including
+ * local and remote regions.
+ */
+ QOS_L3_MBM_R0_EVENT_ID,
+ QOS_L3_MBM_R1_EVENT_ID,
+ QOS_L3_MBM_R2_EVENT_ID,
+ QOS_L3_MBM_R3_EVENT_ID,
+
/* Intel Telemetry Events */
PMT_EVENT_ENERGY,
PMT_EVENT_ACTIVITY,
@@ -65,7 +77,7 @@ enum resctrl_event_id {
QOS_NUM_EVENTS,
};
-#define QOS_NUM_L3_MBM_EVENTS (QOS_L3_MBM_LOCAL_EVENT_ID - QOS_L3_MBM_TOTAL_EVENT_ID + 1)
+#define QOS_NUM_L3_MBM_EVENTS (QOS_L3_MBM_R3_EVENT_ID - QOS_L3_MBM_TOTAL_EVENT_ID + 1)
#define MBM_STATE_IDX(evt) ((evt) - QOS_L3_MBM_TOTAL_EVENT_ID)
#endif /* __LINUX_RESCTRL_TYPES_H */
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 18/31] x86/resctrl: Introduce memory region based MBM read callback on MMIO space
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (16 preceding siblings ...)
2026-08-02 16:06 ` [RFC PATCH 17/31] x86/resctrl: Introduce region aware MBM event definitions Chen Yu
@ 2026-08-02 16:06 ` Chen Yu
2026-08-02 16:06 ` [RFC PATCH 19/31] x86/resctrl: Enable the region based events by adding them into the event Chen Yu
` (12 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:06 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
Enhance erdt_mon_read() to support region-based memory bandwidth reads,
and implement the low-level MMIO-based region-aware
erdt_read_region_mbm() to deal with region-aware MBM.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/erdt.c | 102 +++++++++++++++++++++++++
arch/x86/kernel/cpu/resctrl/internal.h | 4 +
arch/x86/kernel/cpu/resctrl/monitor.c | 8 +-
include/linux/resctrl_types.h | 5 ++
4 files changed, 115 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
index a14de9eb8b88..35217f48b3d9 100644
--- a/arch/x86/kernel/cpu/resctrl/erdt.c
+++ b/arch/x86/kernel/cpu/resctrl/erdt.c
@@ -30,6 +30,8 @@ static bool erdt_enabled;
/* Set in a monitoring counter when it holds no valid data to report. */
#define UNAVAILABLE_COUNTER BIT_ULL(63)
#define CMRC_FLAG_UNAVAILABLE_BIT BIT(0)
+#define MMRC_FLAG_UNAVAILABLE_BIT BIT(0)
+#define FIXPOINT_LOW_BITS 16
/* Bitmask of valid sub-tables found in the first RMDD, used to ensure all RMDDs match. */
static u32 valid_subtbl_mask;
@@ -96,6 +98,103 @@ static int erdt_read_l3_occupancy(const struct erdt_domain_info *d, u32 rmid, u6
return 0;
}
+static void __iomem *mmrc_index_function_1(const struct erdt_domain_info *d,
+ struct acpi_erdt_mmrc *mmrc,
+ int rmid, int region_idx)
+{
+ u64 blk_rmid, blk_offset;
+ void __iomem *vaddr;
+
+ /*
+ * Block_to_locate_RMID# = floor((RMID# % 32) / 8) x 4 x 4096B;
+ * Offset_within_this_Block = (floor(((RMID#/32)x8)+RMID#%8) x
+ * 8B)+(Region# x 2048B);
+ * MMIO_ADDRESS_for_RMID#_Region# =
+ * MBM Register Block Base Address + Block_to_locate_RMID# +
+ * Offset_within_this_Block;
+ */
+ blk_rmid = ((rmid % 32) / 8) * 4 * 4096;
+ blk_offset = ((rmid / 32) * 8 + (rmid % 8)) * 8 + region_idx * 2048;
+ vaddr = d->base[ERDT_MMIO_MMRC_BASE] + blk_rmid + blk_offset;
+
+ return vaddr;
+}
+
+static u64 apply_correction_factor(u64 val, u32 factor)
+{
+ if (!factor)
+ return val;
+
+ return ((val * factor) >> FIXPOINT_LOW_BITS);
+}
+
+static int erdt_read_region_mbm(struct rdt_domain_hdr *hdr,
+ const struct erdt_domain_info *d, int rmid,
+ int eventid, u64 *val)
+{
+ int region_idx = eventid - QOS_L3_MBM_R0_EVENT_ID;
+ int corr_factor_len, corr_factor = 0;
+ struct rdt_hw_l3_mon_domain *hw_dom;
+ u64 mbm_rmid_count = 0, chunks = 0;
+ struct acpi_erdt_mmrc *mmrc = NULL;
+ struct rdt_l3_mon_domain *mon_dom;
+ struct arch_mbm_state *am;
+ void __iomem *vaddr;
+
+ mmrc = d->mmrc;
+ if (!mmrc)
+ return -EIO;
+
+ if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, RDT_RESOURCE_L3))
+ return -EIO;
+
+ mon_dom = container_of(hdr, struct rdt_l3_mon_domain, hdr);
+ hw_dom = resctrl_to_arch_mon_dom(mon_dom);
+
+ vaddr = mmrc_index_function_1(d, mmrc, rmid, region_idx);
+ mbm_rmid_count = readq(vaddr);
+
+ /*
+ * Bit 63 only reports whether the data is unavailable on domains that
+ * advertise support for it. Where it is not supported the bit is part
+ * of the counter and must not be interpreted as a status flag.
+ */
+ if ((mmrc->flags & MMRC_FLAG_UNAVAILABLE_BIT) &&
+ (mbm_rmid_count & UNAVAILABLE_COUNTER))
+ return -EINVAL;
+
+ corr_factor_len = mmrc->corr_factor_list_len;
+ if (corr_factor_len) {
+ /*
+ * 0: Do not apply a correction factor to
+ * the MBM values.
+ * 1: Apply a single correction factor.
+ * Max RMID+1: Apply the indicated indexed
+ * correction factor to the corresponding
+ * RMID value for MBM counter.
+ */
+ if (corr_factor_len == 1)
+ corr_factor = mmrc->corr_factor_list[0];
+ else if (rmid < corr_factor_len)
+ corr_factor = mmrc->corr_factor_list[rmid];
+ else
+ return -EINVAL;
+ }
+
+ am = get_arch_mbm_state(hw_dom, rmid, eventid);
+ if (am) {
+ am->chunks += mbm_overflow_count(am->prev_mon_val, mbm_rmid_count,
+ mmrc->counter_width);
+
+ chunks = apply_correction_factor(am->chunks, corr_factor);
+ am->prev_mon_val = mbm_rmid_count;
+ }
+
+ *val = chunks * mmrc->up_scale;
+
+ return 0;
+}
+
int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 rmid, u64 *val)
{
struct rdt_hw_l3_mon_domain *hw_dom;
@@ -109,6 +208,9 @@ int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 r
if (evtid == QOS_L3_OCCUP_EVENT_ID)
return erdt_read_l3_occupancy(d, rmid, val);
+ if (rmbm_event(evtid))
+ return erdt_read_region_mbm(hdr, d, rmid, evtid, val);
+
return -EIO;
}
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index c337c4336789..b665b19b6f8b 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -320,4 +320,8 @@ int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 r
int erdt_init(void);
void erdt_exit(void);
+u64 mbm_overflow_count(u64 prev_val, u64 cur_val, unsigned int width);
+struct arch_mbm_state *get_arch_mbm_state(struct rdt_hw_l3_mon_domain *hw_dom,
+ u32 rmid,
+ enum resctrl_event_id eventid);
#endif /* _ASM_X86_RESCTRL_INTERNAL_H */
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index ac5353fd0efd..c60d3d55a96c 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -157,9 +157,9 @@ static int __rmid_read_phys(u32 prmid, enum resctrl_event_id eventid, u64 *val)
return 0;
}
-static struct arch_mbm_state *get_arch_mbm_state(struct rdt_hw_l3_mon_domain *hw_dom,
- u32 rmid,
- enum resctrl_event_id eventid)
+struct arch_mbm_state *get_arch_mbm_state(struct rdt_hw_l3_mon_domain *hw_dom,
+ u32 rmid,
+ enum resctrl_event_id eventid)
{
struct arch_mbm_state *state;
@@ -209,7 +209,7 @@ void resctrl_arch_reset_rmid_all(struct rdt_resource *r, struct rdt_l3_mon_domai
}
}
-static u64 mbm_overflow_count(u64 prev_val, u64 cur_val, unsigned int width)
+u64 mbm_overflow_count(u64 prev_val, u64 cur_val, unsigned int width)
{
u64 shift = 64 - width, chunks;
diff --git a/include/linux/resctrl_types.h b/include/linux/resctrl_types.h
index 41dc1dff8c16..ee8fc7df22f9 100644
--- a/include/linux/resctrl_types.h
+++ b/include/linux/resctrl_types.h
@@ -77,6 +77,11 @@ enum resctrl_event_id {
QOS_NUM_EVENTS,
};
+static inline bool rmbm_event(unsigned int e)
+{
+ return (e >= QOS_L3_MBM_R0_EVENT_ID) && (e <= QOS_L3_MBM_R3_EVENT_ID);
+}
+
#define QOS_NUM_L3_MBM_EVENTS (QOS_L3_MBM_R3_EVENT_ID - QOS_L3_MBM_TOTAL_EVENT_ID + 1)
#define MBM_STATE_IDX(evt) ((evt) - QOS_L3_MBM_TOTAL_EVENT_ID)
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 19/31] x86/resctrl: Enable the region based events by adding them into the event
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (17 preceding siblings ...)
2026-08-02 16:06 ` [RFC PATCH 18/31] x86/resctrl: Introduce memory region based MBM read callback on MMIO space Chen Yu
@ 2026-08-02 16:06 ` Chen Yu
2026-08-02 16:06 ` [RFC PATCH 20/31] x86/resctrl: Rename msr_update to hw_update Chen Yu
` (11 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:06 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
The following MBM events will be displayed under each domain:
[root@ mon_data]# tree
.
├── mon_L3_00
│ ├── llc_occupancy
│ ├── mbm_region0_bytes
│ └── mbm_region1_bytes
├── mon_L3_01
│ ├── llc_occupancy
│ ├── mbm_region0_bytes
│ └── mbm_region1_bytes
├── mon_L3_02
│ ├── llc_occupancy
│ ├── mbm_region0_bytes
│ └── mbm_region1_bytes
└── mon_L3_03
├── llc_occupancy
├── mbm_region0_bytes
└── mbm_region1_bytes
Note, the actual maximum number of available memory regions
is provided by the MRRM table. Suppose the maximum number of
available memory regions exposed by MRRM is 2; then each domain
can access at most 2 regions.
Region-aware MBM counters live in MMIO rather than in the QM_CTR MSR, so
resctrl_arch_reset_rmid() must read the initial counter value through
erdt_mon_read() instead of __rmid_read_phys(). Add a "first" parameter to
tell erdt_read_region_mbm() which kind of read this is: when set, only
record the raw counter value in am->prev_mon_val so that later reads can
compute a delta from it, without accumulating that absolute value into
am->chunks as if it had been consumed.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/core.c | 8 +++++
arch/x86/kernel/cpu/resctrl/erdt.c | 48 +++++++++++++++++++++++---
arch/x86/kernel/cpu/resctrl/internal.h | 4 ++-
arch/x86/kernel/cpu/resctrl/monitor.c | 14 ++++++--
fs/resctrl/monitor.c | 4 +++
include/linux/resctrl_types.h | 2 ++
6 files changed, 71 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index a7322f0ebaea..1827e3ea5fee 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -1081,6 +1081,13 @@ static __init bool get_rdt_mon_resources(void)
resctrl_enable_mon_event(QOS_L3_OCCUP_EVENT_ID, false, 0, NULL);
ret = true;
}
+
+ if (erdt_enable_mon()) {
+ ret = true;
+
+ goto done;
+ }
+
if (rdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL)) {
resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID, false, 0, NULL);
ret = true;
@@ -1092,6 +1099,7 @@ static __init bool get_rdt_mon_resources(void)
if (rdt_cpu_has(X86_FEATURE_ABMC))
ret = true;
+done:
if (!ret)
return false;
diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
index 35217f48b3d9..d16cd6af6648 100644
--- a/arch/x86/kernel/cpu/resctrl/erdt.c
+++ b/arch/x86/kernel/cpu/resctrl/erdt.c
@@ -49,9 +49,30 @@ bool erdt_support(int flag)
if (flag == X86_FEATURE_CQM_OCCUP_LLC)
return valid_subtbl_mask & BIT(ACPI_ERDT_TYPE_CMRC);
+ if (flag == X86_FEATURE_CQM_MBM_TOTAL)
+ return valid_subtbl_mask & BIT(ACPI_ERDT_TYPE_MMRC);
+
return false;
}
+bool erdt_enable_mon(void)
+{
+ int i, max_regions;
+
+ if (!erdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL))
+ return false;
+
+ max_regions = acpi_mrrm_max_mem_region();
+ for_each_rmbm_event_id(i) {
+ if (!max_regions--)
+ break;
+
+ resctrl_enable_mon_event(i, true, 0, NULL);
+ }
+
+ return true;
+}
+
int erdt_get_max_rmid(void)
{
return erdt_max_rmid;
@@ -130,9 +151,9 @@ static u64 apply_correction_factor(u64 val, u32 factor)
static int erdt_read_region_mbm(struct rdt_domain_hdr *hdr,
const struct erdt_domain_info *d, int rmid,
- int eventid, u64 *val)
+ int eventid, u64 *val, bool first)
{
- int region_idx = eventid - QOS_L3_MBM_R0_EVENT_ID;
+ int region_idx = RMBM_STATE_IDX(eventid);
int corr_factor_len, corr_factor = 0;
struct rdt_hw_l3_mon_domain *hw_dom;
u64 mbm_rmid_count = 0, chunks = 0;
@@ -163,6 +184,23 @@ static int erdt_read_region_mbm(struct rdt_domain_hdr *hdr,
(mbm_rmid_count & UNAVAILABLE_COUNTER))
return -EINVAL;
+ am = get_arch_mbm_state(hw_dom, rmid, eventid);
+
+ /*
+ * The first read only records the initial, non-zero count value so
+ * that later reads can compute a delta from it. Nothing is reported
+ * to the caller, and the software state must not accumulate the
+ * absolute counter value as if it had been consumed.
+ */
+ if (first) {
+ if (am)
+ am->prev_mon_val = mbm_rmid_count;
+
+ *val = 0;
+
+ return 0;
+ }
+
corr_factor_len = mmrc->corr_factor_list_len;
if (corr_factor_len) {
/*
@@ -181,7 +219,6 @@ static int erdt_read_region_mbm(struct rdt_domain_hdr *hdr,
return -EINVAL;
}
- am = get_arch_mbm_state(hw_dom, rmid, eventid);
if (am) {
am->chunks += mbm_overflow_count(am->prev_mon_val, mbm_rmid_count,
mmrc->counter_width);
@@ -195,7 +232,8 @@ static int erdt_read_region_mbm(struct rdt_domain_hdr *hdr,
return 0;
}
-int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 rmid, u64 *val)
+int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 rmid,
+ u64 *val, bool first)
{
struct rdt_hw_l3_mon_domain *hw_dom;
const struct erdt_domain_info *d;
@@ -209,7 +247,7 @@ int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 r
return erdt_read_l3_occupancy(d, rmid, val);
if (rmbm_event(evtid))
- return erdt_read_region_mbm(hdr, d, rmid, evtid, val);
+ return erdt_read_region_mbm(hdr, d, rmid, evtid, val, first);
return -EIO;
}
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index b665b19b6f8b..c48e8d4a62d5 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -315,8 +315,10 @@ static inline bool intel_handle_aet_option(bool force_off, char *tok) { return f
bool erdt_support(int flag);
bool erdt_cpu_has(int flag);
+bool erdt_enable_mon(void);
int erdt_get_max_rmid(void);
-int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 rmid, u64 *val);
+int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 rmid,
+ u64 *val, bool first);
int erdt_init(void);
void erdt_exit(void);
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index c60d3d55a96c..21dd33eaafe9 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -179,14 +179,19 @@ void resctrl_arch_reset_rmid(struct rdt_resource *r, struct rdt_l3_mon_domain *d
int cpu = cpumask_any(&d->hdr.cpu_mask);
struct arch_mbm_state *am;
u32 prmid;
+ u64 tmp;
am = get_arch_mbm_state(hw_dom, rmid, eventid);
if (am) {
memset(am, 0, sizeof(*am));
- prmid = logical_rmid_to_physical_rmid(cpu, rmid);
/* Record any initial, non-zero count value. */
- __rmid_read_phys(prmid, eventid, &am->prev_mon_val);
+ if (rmbm_event(eventid) && erdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL)) {
+ erdt_mon_read(&d->hdr, eventid, rmid, &tmp, true);
+ } else {
+ prmid = logical_rmid_to_physical_rmid(cpu, rmid);
+ __rmid_read_phys(prmid, eventid, &am->prev_mon_val);
+ }
}
}
@@ -280,7 +285,10 @@ int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain_hdr *hdr,
case RDT_RESOURCE_L3:
if (eventid == QOS_L3_OCCUP_EVENT_ID &&
erdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC))
- return erdt_mon_read(hdr, eventid, rmid, val);
+ return erdt_mon_read(hdr, eventid, rmid, val, false);
+
+ if (rmbm_event(eventid) && erdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL))
+ return erdt_mon_read(hdr, eventid, rmid, val, false);
return arch_l3_read_event(hdr, rmid, eventid, val, r);
case RDT_RESOURCE_PERF_PKG:
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index aadac544576b..0a5a38b8ffda 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -1031,6 +1031,10 @@ struct mon_evt mon_event_all[QOS_NUM_EVENTS] = {
MON_EVENT(PMT_EVENT_AUTO_C6_RES, "c6_res", RDT_RESOURCE_PERF_PKG, false),
MON_EVENT(PMT_EVENT_UNHALTED_REF_CYCLES, "unhalted_ref_cycles", RDT_RESOURCE_PERF_PKG, false),
MON_EVENT(PMT_EVENT_UOPS_RETIRED, "uops_retired", RDT_RESOURCE_PERF_PKG, false),
+ MON_EVENT(QOS_L3_MBM_R0_EVENT_ID, "mbm_region0_bytes", RDT_RESOURCE_L3, false),
+ MON_EVENT(QOS_L3_MBM_R1_EVENT_ID, "mbm_region1_bytes", RDT_RESOURCE_L3, false),
+ MON_EVENT(QOS_L3_MBM_R2_EVENT_ID, "mbm_region2_bytes", RDT_RESOURCE_L3, false),
+ MON_EVENT(QOS_L3_MBM_R3_EVENT_ID, "mbm_region3_bytes", RDT_RESOURCE_L3, false),
};
bool resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu,
diff --git a/include/linux/resctrl_types.h b/include/linux/resctrl_types.h
index ee8fc7df22f9..95945dd71472 100644
--- a/include/linux/resctrl_types.h
+++ b/include/linux/resctrl_types.h
@@ -82,6 +82,8 @@ static inline bool rmbm_event(unsigned int e)
return (e >= QOS_L3_MBM_R0_EVENT_ID) && (e <= QOS_L3_MBM_R3_EVENT_ID);
}
+#define RMBM_STATE_IDX(evt) ((evt) - QOS_L3_MBM_R0_EVENT_ID)
+
#define QOS_NUM_L3_MBM_EVENTS (QOS_L3_MBM_R3_EVENT_ID - QOS_L3_MBM_TOTAL_EVENT_ID + 1)
#define MBM_STATE_IDX(evt) ((evt) - QOS_L3_MBM_TOTAL_EVENT_ID)
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 20/31] x86/resctrl: Rename msr_update to hw_update
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (18 preceding siblings ...)
2026-08-02 16:06 ` [RFC PATCH 19/31] x86/resctrl: Enable the region based events by adding them into the event Chen Yu
@ 2026-08-02 16:06 ` Chen Yu
2026-08-02 16:07 ` [RFC PATCH 21/31] x86/resctrl: Parse ACPI MARC table Chen Yu
` (10 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:06 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
Prepare for the region aware RDT hardware update, and the region aware
RDT touches the MMIO address rather than MSR registers.
No functional change expected.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/core.c | 28 ++++++++---------
arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 38 +++++++++++------------
arch/x86/kernel/cpu/resctrl/internal.h | 8 ++---
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 14 ++++-----
4 files changed, 44 insertions(+), 44 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 1827e3ea5fee..0bde098db41e 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -50,9 +50,9 @@ DEFINE_PER_CPU(struct resctrl_pqr_state, pqr_state);
*/
bool rdt_alloc_capable;
-static void mba_wrmsr_intel(struct msr_param *m);
-static void cat_wrmsr(struct msr_param *m);
-static void mba_wrmsr_amd(struct msr_param *m);
+static void mba_wrmsr_intel(struct hw_param *m);
+static void cat_wrmsr(struct hw_param *m);
+static void mba_wrmsr_amd(struct hw_param *m);
#define ctrl_init(id) LIST_HEAD_INIT(rdt_resources_all[id].r_resctrl.controls)
#define mon_domain_init(id) LIST_HEAD_INIT(rdt_resources_all[id].r_resctrl.mon_domains)
@@ -226,7 +226,7 @@ static __init bool __get_mem_config_intel(struct rdt_resource *r)
hw_ctrl->r_ctrl.scalar.unit = RESCTRL_CTRL_UNIT_ALL;
hw_ctrl->msr_base = MSR_IA32_MBA_THRTL_BASE;
- hw_ctrl->msr_update = mba_wrmsr_intel;
+ hw_ctrl->hw_update = mba_wrmsr_intel;
list_add(&hw_ctrl->r_ctrl.entry, &r->controls);
r->alloc_capable = true;
@@ -285,10 +285,10 @@ static __init bool __rdt_get_mem_config_amd(struct rdt_resource *r)
if (r->rid == RDT_RESOURCE_MBA) {
hw_ctrl->msr_base = MSR_IA32_MBA_BW_BASE;
- hw_ctrl->msr_update = mba_wrmsr_amd;
+ hw_ctrl->hw_update = mba_wrmsr_amd;
} else { /* r->rid == RDT_RESOURCE_SMBA */
hw_ctrl->msr_base = MSR_IA32_SMBA_BW_BASE;
- hw_ctrl->msr_update = mba_wrmsr_amd;
+ hw_ctrl->hw_update = mba_wrmsr_amd;
}
list_add(&hw_ctrl->r_ctrl.entry, &r->controls);
@@ -339,7 +339,7 @@ static void rdt_get_cache_alloc_cfg(int idx, struct rdt_resource *r)
}
hw_ctrl->msr_base = idx == 1 ? MSR_IA32_L3_CBM_BASE: MSR_IA32_L2_CBM_BASE;
- hw_ctrl->msr_update = cat_wrmsr;
+ hw_ctrl->hw_update = cat_wrmsr;
list_add(&hw_ctrl->r_ctrl.entry, &r->controls);
@@ -371,7 +371,7 @@ static void rdt_get_cdp_l2_config(void)
rdt_get_cdp_config(RDT_RESOURCE_L2);
}
-static void mba_wrmsr_amd(struct msr_param *m)
+static void mba_wrmsr_amd(struct hw_param *m)
{
struct rdt_hw_ctrl_domain *hw_dom = resctrl_to_arch_ctrl_dom(m->dom);
struct resctrl_hw_ctrl *hw_ctrl = resctrl_to_arch_ctrl(m->ctrl);
@@ -395,7 +395,7 @@ static u32 delay_bw_map(unsigned long bw, struct rdt_resource *r)
return MAX_MBA_BW;
}
-static void mba_wrmsr_intel(struct msr_param *m)
+static void mba_wrmsr_intel(struct hw_param *m)
{
struct rdt_hw_ctrl_domain *hw_dom = resctrl_to_arch_ctrl_dom(m->dom);
struct resctrl_hw_ctrl *hw_ctrl = resctrl_to_arch_ctrl(m->ctrl);
@@ -406,7 +406,7 @@ static void mba_wrmsr_intel(struct msr_param *m)
wrmsrq(hw_ctrl->msr_base + i, delay_bw_map(hw_dom->ctrl_val[i], m->res));
}
-static void cat_wrmsr(struct msr_param *m)
+static void cat_wrmsr(struct hw_param *m)
{
struct rdt_hw_ctrl_domain *hw_dom = resctrl_to_arch_ctrl_dom(m->dom);
struct resctrl_hw_ctrl *hw_ctrl = resctrl_to_arch_ctrl(m->ctrl);
@@ -424,10 +424,10 @@ u32 resctrl_arch_get_num_closid(struct rdt_resource *r)
void rdt_ctrl_update(void *arg)
{
struct resctrl_hw_ctrl *hw_ctrl;
- struct msr_param *m = arg;
+ struct hw_param *m = arg;
hw_ctrl = resctrl_to_arch_ctrl(m->ctrl);
- hw_ctrl->msr_update(m);
+ hw_ctrl->hw_update(m);
}
static void setup_default_ctrlval(struct rdt_resource *r, struct resctrl_ctrl *ctrl,
@@ -466,7 +466,7 @@ static int domain_setup_ctrlval(struct rdt_resource *r, struct resctrl_ctrl *ctr
struct rdt_hw_ctrl_domain *hw_dom = resctrl_to_arch_ctrl_dom(d);
struct resctrl_hw_ctrl *hw_ctrl = resctrl_to_arch_ctrl(ctrl);
struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
- struct msr_param m;
+ struct hw_param m;
u32 *dc;
dc = kmalloc_array(hw_res->num_closid, sizeof(*hw_dom->ctrl_val),
@@ -482,7 +482,7 @@ static int domain_setup_ctrlval(struct rdt_resource *r, struct resctrl_ctrl *ctr
m.dom = d;
m.low = 0;
m.high = hw_res->num_closid;
- hw_ctrl->msr_update(&m);
+ hw_ctrl->hw_update(&m);
return 0;
}
diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
index ab765bca2ab5..1dd59d36e86c 100644
--- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
+++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
@@ -26,19 +26,19 @@ int resctrl_arch_update_one(struct rdt_resource *r, struct resctrl_ctrl *ctrl,
struct rdt_hw_ctrl_domain *hw_dom = resctrl_to_arch_ctrl_dom(d);
struct resctrl_hw_ctrl *hw_ctrl = resctrl_to_arch_ctrl(ctrl);
u32 idx = resctrl_get_config_index(closid, t);
- struct msr_param msr_param;
+ struct hw_param hw_param;
if (!cpumask_test_cpu(smp_processor_id(), &d->hdr.cpu_mask))
return -EINVAL;
hw_dom->ctrl_val[idx] = cfg_val;
- msr_param.res = r;
- msr_param.ctrl = ctrl;
- msr_param.dom = d;
- msr_param.low = idx;
- msr_param.high = idx + 1;
- hw_ctrl->msr_update(&msr_param);
+ hw_param.res = r;
+ hw_param.ctrl = ctrl;
+ hw_param.dom = d;
+ hw_param.low = idx;
+ hw_param.high = idx + 1;
+ hw_ctrl->hw_update(&hw_param);
return 0;
}
@@ -48,7 +48,7 @@ static void _resctrl_arch_update_domains(struct rdt_resource *r,
{
struct resctrl_staged_config *cfg;
struct rdt_hw_ctrl_domain *hw_dom;
- struct msr_param msr_param;
+ struct hw_param hw_param;
struct rdt_ctrl_domain *d;
enum resctrl_conf_type t;
u32 idx;
@@ -56,10 +56,10 @@ static void _resctrl_arch_update_domains(struct rdt_resource *r,
/* Walking ctrl->domains, ensure it can't race with cpuhp */
lockdep_assert_cpus_held();
- msr_param.ctrl = ctrl;
+ hw_param.ctrl = ctrl;
list_for_each_entry(d, &ctrl->domains, hdr.list) {
hw_dom = resctrl_to_arch_ctrl_dom(d);
- msr_param.res = NULL;
+ hw_param.res = NULL;
for (t = 0; t < CDP_NUM_TYPES; t++) {
cfg = &hw_dom->d_resctrl.staged_config[t];
if (!cfg->have_new_ctrl)
@@ -70,18 +70,18 @@ static void _resctrl_arch_update_domains(struct rdt_resource *r,
continue;
hw_dom->ctrl_val[idx] = cfg->new_ctrl;
- if (!msr_param.res) {
- msr_param.low = idx;
- msr_param.high = msr_param.low + 1;
- msr_param.res = r;
- msr_param.dom = d;
+ if (!hw_param.res) {
+ hw_param.low = idx;
+ hw_param.high = hw_param.low + 1;
+ hw_param.res = r;
+ hw_param.dom = d;
} else {
- msr_param.low = min(msr_param.low, idx);
- msr_param.high = max(msr_param.high, idx + 1);
+ hw_param.low = min(hw_param.low, idx);
+ hw_param.high = max(hw_param.high, idx + 1);
}
}
- if (msr_param.res)
- smp_call_function_any(&d->hdr.cpu_mask, rdt_ctrl_update, &msr_param, 1);
+ if (hw_param.res)
+ smp_call_function_any(&d->hdr.cpu_mask, rdt_ctrl_update, &hw_param, 1);
}
}
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index c48e8d4a62d5..ca9124e9aea5 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -88,14 +88,14 @@ struct arch_mbm_state {
#define SDCIAE_ENABLE_BIT 1
/**
- * struct msr_param - set a range of MSRs from a domain
+ * struct hw_param - set a range of registers (MSRs, etc) from a domain
* @res: The resource to use
* @ctrl: Properties of the control being updated
* @dom: The domain to update
* @low: Beginning index from base MSR
* @high: End index
*/
-struct msr_param {
+struct hw_param {
struct rdt_resource *res;
struct resctrl_ctrl *ctrl;
struct rdt_ctrl_domain *dom;
@@ -107,12 +107,12 @@ struct msr_param {
* struct resctrl_hw_ctrl - Arch private properties of a resource control
* @r_ctrl: Control properties exposed to resctrl file system
* @msr_base: Base MSR address where control values should be programmed
- * @msr_update: Function pointer to update control values
+ * @hw_update: Function pointer to update QOS hardware, MSRs, etc
*/
struct resctrl_hw_ctrl {
struct resctrl_ctrl r_ctrl;
unsigned int msr_base;
- void (*msr_update)(struct msr_param *m);
+ void (*hw_update)(struct hw_param *m);
};
static inline struct resctrl_hw_ctrl *resctrl_to_arch_ctrl(struct resctrl_ctrl *c)
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 3048aa7b5c34..d06043bd27f8 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -234,7 +234,7 @@ void resctrl_arch_reset_all_ctrls(struct rdt_resource *r)
{
struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
struct rdt_hw_ctrl_domain *hw_dom;
- struct msr_param msr_param;
+ struct hw_param hw_param;
struct resctrl_ctrl *ctrl;
struct rdt_ctrl_domain *d;
int i;
@@ -242,9 +242,9 @@ void resctrl_arch_reset_all_ctrls(struct rdt_resource *r)
/* Walking ctrl->domains, ensure it can't race with cpuhp */
lockdep_assert_cpus_held();
- msr_param.res = r;
- msr_param.low = 0;
- msr_param.high = hw_res->num_closid;
+ hw_param.res = r;
+ hw_param.low = 0;
+ hw_param.high = hw_res->num_closid;
/*
* Disable resource control for this resource by setting all
@@ -252,14 +252,14 @@ void resctrl_arch_reset_all_ctrls(struct rdt_resource *r)
* Pick one CPU from each domain to update the MSRs below.
*/
for_each_resource_ctrl(ctrl, r) {
- msr_param.ctrl = ctrl;
+ hw_param.ctrl = ctrl;
list_for_each_entry(d, &ctrl->domains, hdr.list) {
hw_dom = resctrl_to_arch_ctrl_dom(d);
for (i = 0; i < hw_res->num_closid; i++)
hw_dom->ctrl_val[i] = resctrl_get_default_ctrlval(ctrl);
- msr_param.dom = d;
- smp_call_function_any(&d->hdr.cpu_mask, rdt_ctrl_update, &msr_param, 1);
+ hw_param.dom = d;
+ smp_call_function_any(&d->hdr.cpu_mask, rdt_ctrl_update, &hw_param, 1);
}
}
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 21/31] x86/resctrl: Parse ACPI MARC table
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (19 preceding siblings ...)
2026-08-02 16:06 ` [RFC PATCH 20/31] x86/resctrl: Rename msr_update to hw_update Chen Yu
@ 2026-08-02 16:07 ` Chen Yu
2026-08-02 16:07 ` [RFC PATCH 22/31] fs/resctrl: Add region-based control names and resctrl_ctrl_name_region() Chen Yu
` (9 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:07 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
The MARC table is used to provide Memory Bandwidth Allocation Register
information. Its register addresses are mapped, and the MARC pointer
is saved in the corresponding domain information entry.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/erdt.c | 70 ++++++++++++++++++++++++++
arch/x86/kernel/cpu/resctrl/internal.h | 10 +++-
2 files changed, 79 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
index d16cd6af6648..c44e1d00b89f 100644
--- a/arch/x86/kernel/cpu/resctrl/erdt.c
+++ b/arch/x86/kernel/cpu/resctrl/erdt.c
@@ -25,8 +25,13 @@ static bool erdt_enabled;
#define ERDT_VALID_VERSION 1
#define CMRC_SUPPORTED_INDEX_FN 1
#define MMRC_SUPPORTED_INDEX_FN 1
+#define MARC_SUPPORTED_INDEX_FN 1
#define RMDD_FLAG_CPU_L3_DOMAIN BIT(0)
+#define MARC_FLAG_OPT BIT(0)
+#define MARC_FLAG_MIN BIT(1)
+#define MARC_FLAG_MAX BIT(2)
+
/* Set in a monitoring counter when it holds no valid data to report. */
#define UNAVAILABLE_COUNTER BIT_ULL(63)
#define CMRC_FLAG_UNAVAILABLE_BIT BIT(0)
@@ -283,6 +288,7 @@ static void cleanup_one_domain(struct erdt_domain_info *d)
erdt_iounmap_domain(d);
kfree(d->cmrc);
kfree(d->mmrc);
+ kfree(d->marc);
kfree(d);
}
@@ -396,6 +402,64 @@ static __init int mmrc_init(struct acpi_subtbl_hdr_16 *subtbl,
return 0;
}
+static __init int marc_init(struct acpi_subtbl_hdr_16 *subtbl,
+ struct erdt_domain_info *domain_info)
+{
+ struct acpi_erdt_marc *marc = (struct acpi_erdt_marc *)subtbl;
+
+ if (subtbl->length < sizeof(*marc)) {
+ pr_warn(FW_BUG "Truncated MARC subtable\n");
+ return -EIO;
+ }
+
+ if (marc->index_fn != MARC_SUPPORTED_INDEX_FN) {
+ pr_info("Unsupported MARC index function %d\n", marc->index_fn);
+ return -EIO;
+ }
+
+ if (marc->flags & MARC_FLAG_OPT) {
+ domain_info->base[ERDT_MMIO_MARC_OPT] =
+ erdt_ioremap(marc->reg_base_opt, marc->mba_reg_size, "MARC OPT base");
+ if (!domain_info->base[ERDT_MMIO_MARC_OPT])
+ return -EIO;
+ }
+
+ if (marc->flags & MARC_FLAG_MIN) {
+ domain_info->base[ERDT_MMIO_MARC_MIN] =
+ erdt_ioremap(marc->reg_base_min, marc->mba_reg_size, "MARC MIN base");
+ if (!domain_info->base[ERDT_MMIO_MARC_MIN])
+ goto unmap;
+ }
+
+ if (marc->flags & MARC_FLAG_MAX) {
+ domain_info->base[ERDT_MMIO_MARC_MAX] =
+ erdt_ioremap(marc->reg_base_max, marc->mba_reg_size, "MARC MAX base");
+ if (!domain_info->base[ERDT_MMIO_MARC_MAX])
+ goto unmap;
+ }
+
+ domain_info->marc = kmemdup(marc, subtbl->length, GFP_KERNEL);
+ if (!domain_info->marc)
+ goto unmap;
+
+ return 0;
+
+unmap:
+ if (domain_info->base[ERDT_MMIO_MARC_OPT]) {
+ iounmap(domain_info->base[ERDT_MMIO_MARC_OPT]);
+ domain_info->base[ERDT_MMIO_MARC_OPT] = NULL;
+ }
+ if (domain_info->base[ERDT_MMIO_MARC_MIN]) {
+ iounmap(domain_info->base[ERDT_MMIO_MARC_MIN]);
+ domain_info->base[ERDT_MMIO_MARC_MIN] = NULL;
+ }
+ if (domain_info->base[ERDT_MMIO_MARC_MAX]) {
+ iounmap(domain_info->base[ERDT_MMIO_MARC_MAX]);
+ domain_info->base[ERDT_MMIO_MARC_MAX] = NULL;
+ }
+ return -EIO;
+}
+
static inline struct acpi_subtbl_hdr_16 *rmdd_subtbl(struct acpi_erdt_rmdd *rmdd)
{
return (void *)rmdd + sizeof(*rmdd);
@@ -478,6 +542,12 @@ static __init bool parse_rmdd_table(struct acpi_subtbl_hdr_16 *rmdd_hdr)
!mmrc_init(subtbl, domain_info))
subtbl_mask |= BIT(ACPI_ERDT_TYPE_MMRC);
+ break;
+ case ACPI_ERDT_TYPE_MARC:
+ if (!(subtbl_mask & BIT(ACPI_ERDT_TYPE_MARC)) &&
+ !marc_init(subtbl, domain_info))
+ subtbl_mask |= BIT(ACPI_ERDT_TYPE_MARC);
+
break;
default:
break;
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index ca9124e9aea5..6855022bf07e 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -26,12 +26,18 @@
* @ERDT_MMIO_RMDD_CREG: RMDD control register base address
* @ERDT_MMIO_CMRC_BASE: CMRC monitoring register base address
* @ERDT_MMIO_MMRC_BASE: MMRC monitoring register base address
+ * @ERDT_MMIO_MARC_OPT: MARC optimal BW register base address
+ * @ERDT_MMIO_MARC_MIN: MARC minimum BW register base address
+ * @ERDT_MMIO_MARC_MAX: MARC maximum BW register base address
*/
enum erdt_mmio_type {
ERDT_MMIO_RMDD_CREG,
ERDT_MMIO_CMRC_BASE,
ERDT_MMIO_MMRC_BASE,
- ERDT_MMIO_LAST = ERDT_MMIO_MMRC_BASE
+ ERDT_MMIO_MARC_OPT,
+ ERDT_MMIO_MARC_MIN,
+ ERDT_MMIO_MARC_MAX,
+ ERDT_MMIO_LAST = ERDT_MMIO_MARC_MAX
};
#define ERDT_MMIO_NUM_TYPES (ERDT_MMIO_LAST + 1)
@@ -41,6 +47,7 @@ enum erdt_mmio_type {
* @base: Array of ioremapped MMIO region base addresses, indexed by ERDT_MMIO_* type
* @cmrc: Copy of the ACPI CMRC sub-table for this domain
* @mmrc: Copy of the ACPI MMRC sub-table for this domain
+ * @marc: Copy of the ACPI MARC sub-table for this domain
* @cpu_mask: CPUs belonging to this resource management domain
* @max_rmid: Maximum RMID supported by this domain
* @dom_id: L3 cache ID shared by all CPUs in this domain (-1 if unset)
@@ -50,6 +57,7 @@ struct erdt_domain_info {
void __iomem *base[ERDT_MMIO_NUM_TYPES];
struct acpi_erdt_cmrc *cmrc;
struct acpi_erdt_mmrc *mmrc;
+ struct acpi_erdt_marc *marc;
struct cpumask cpu_mask;
u32 max_rmid;
int dom_id;
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 22/31] fs/resctrl: Add region-based control names and resctrl_ctrl_name_region()
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (20 preceding siblings ...)
2026-08-02 16:07 ` [RFC PATCH 21/31] x86/resctrl: Parse ACPI MARC table Chen Yu
@ 2026-08-02 16:07 ` Chen Yu
2026-08-02 16:07 ` [RFC PATCH 23/31] x86/resctrl: Add region aware MBA controllers Chen Yu
` (8 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:07 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
ERDT exposes per-memory-region bandwidth allocation controls, where each
region has an optimal (OPT), minimum (MIN) and maximum (MAX) control.
Extend enum resctrl_ctrl_name with the REGION<n>_{OPT,MIN,MAX} names (and
their string forms). These enumerators are only assigned to a control when
arch code adds a region control to rdt_resource::controls, which happens
only when the hardware supports ERDT (erdt_cpu_has()); on other platforms
they are simply unused.
Add resctrl_ctrl_name_region() so that the architecture code can retrieve
the control name for a given region and control type when creating the
corresponding controllers.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
fs/resctrl/ctrlmondata.c | 12 ++++++++++++
include/linux/resctrl.h | 29 ++++++++++++++++++++++++++++-
2 files changed, 40 insertions(+), 1 deletion(-)
diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
index 74fa1215e8b2..d65036f7079e 100644
--- a/fs/resctrl/ctrlmondata.c
+++ b/fs/resctrl/ctrlmondata.c
@@ -304,6 +304,18 @@ static const char * const resctrl_ctrl_name[] = {
[RESCTRL_CTRL_NAME_DEF] = "",
[RESCTRL_CTRL_NAME_MIN] = "MIN",
[RESCTRL_CTRL_NAME_MAX] = "MAX",
+ [RESCTRL_CTRL_NAME_REGION0_OPT] = "REGION0_OPT",
+ [RESCTRL_CTRL_NAME_REGION0_MIN] = "REGION0_MIN",
+ [RESCTRL_CTRL_NAME_REGION0_MAX] = "REGION0_MAX",
+ [RESCTRL_CTRL_NAME_REGION1_OPT] = "REGION1_OPT",
+ [RESCTRL_CTRL_NAME_REGION1_MIN] = "REGION1_MIN",
+ [RESCTRL_CTRL_NAME_REGION1_MAX] = "REGION1_MAX",
+ [RESCTRL_CTRL_NAME_REGION2_OPT] = "REGION2_OPT",
+ [RESCTRL_CTRL_NAME_REGION2_MIN] = "REGION2_MIN",
+ [RESCTRL_CTRL_NAME_REGION2_MAX] = "REGION2_MAX",
+ [RESCTRL_CTRL_NAME_REGION3_OPT] = "REGION3_OPT",
+ [RESCTRL_CTRL_NAME_REGION3_MIN] = "REGION3_MIN",
+ [RESCTRL_CTRL_NAME_REGION3_MAX] = "REGION3_MAX",
};
const char *resctrl_ctrl_name_str(enum resctrl_ctrl_name name)
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 7bbda28baccf..3969db01f4cc 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -348,14 +348,41 @@ struct resctrl_mon {
* has the same name as the resource.
* @RESCTRL_CTRL_NAME_MIN: "MIN"
* @RESCTRL_CTRL_NAME_MAX: "MAX"
+ *
+ * The REGION* names describe the region based bandwidth allocation controls of
+ * each memory region has an optimal (OPT), minimum (MIN) andcmaximum (MAX) control.
+ * They are only ever assigned to a control when arch code adds a region control
+ * to rdt_resource::controls, which happens only when the hardware supports ERDT
+ * (erdt_cpu_has()); on other platforms these enumerators are simply unused.
*/
enum resctrl_ctrl_name {
RESCTRL_CTRL_NAME_DEF,
RESCTRL_CTRL_NAME_MIN,
RESCTRL_CTRL_NAME_MAX,
- RESCTRL_CTRL_NAME_LAST = RESCTRL_CTRL_NAME_MAX
+ RESCTRL_CTRL_NAME_REGION0_OPT,
+ RESCTRL_CTRL_NAME_REGION0_MIN,
+ RESCTRL_CTRL_NAME_REGION0_MAX,
+ RESCTRL_CTRL_NAME_REGION1_OPT,
+ RESCTRL_CTRL_NAME_REGION1_MIN,
+ RESCTRL_CTRL_NAME_REGION1_MAX,
+ RESCTRL_CTRL_NAME_REGION2_OPT,
+ RESCTRL_CTRL_NAME_REGION2_MIN,
+ RESCTRL_CTRL_NAME_REGION2_MAX,
+ RESCTRL_CTRL_NAME_REGION3_OPT,
+ RESCTRL_CTRL_NAME_REGION3_MIN,
+ RESCTRL_CTRL_NAME_REGION3_MAX,
+ RESCTRL_CTRL_NAME_LAST = RESCTRL_CTRL_NAME_REGION3_MAX
};
+#define RESCTRL_CTRL_REGION_NR_CTRLS 3
+
+static inline enum resctrl_ctrl_name
+resctrl_ctrl_name_region(unsigned int region, unsigned int type)
+{
+ return RESCTRL_CTRL_NAME_REGION0_OPT +
+ region * RESCTRL_CTRL_REGION_NR_CTRLS + type;
+}
+
/* Flags for rdt_resource::flags and resctrl_ctrl::flags */
#define RESCTRL_CTRL_FLAG_LINEAR BIT(0)
#define RESCTRL_CTRL_FLAG_SPARSE_BITMASKS BIT(1)
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 23/31] x86/resctrl: Add region aware MBA controllers
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (21 preceding siblings ...)
2026-08-02 16:07 ` [RFC PATCH 22/31] fs/resctrl: Add region-based control names and resctrl_ctrl_name_region() Chen Yu
@ 2026-08-02 16:07 ` Chen Yu
2026-08-02 16:07 ` [RFC PATCH 24/31] x86/resctrl: Attach ACPI ERDT information to ctrl domain on CPU online Chen Yu
` (7 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:07 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
Add region aware MBA controllers for ERDT platforms that have the MARC
(Memory-bandwidth Allocation Registers for CPU Agents) ACPI subtable.
For each memory region reported by MRRM, create OPT, MIN, and MAX
controllers (as indicated by MARC flags) using
resctrl_ctrl_name_region(). The controller properties (bandwidth range,
granularity, unit) are derived from the MARC subtable fields.
The hw_update callback is a stub for now; the actual MMIO write
implementation will follow in a subsequent patch.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/core.c | 3 ++
arch/x86/kernel/cpu/resctrl/erdt.c | 67 ++++++++++++++++++++++++++
arch/x86/kernel/cpu/resctrl/internal.h | 5 ++
3 files changed, 75 insertions(+)
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 0bde098db41e..b2c53eab7d8f 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -1063,6 +1063,9 @@ static __init bool get_rdt_alloc_resources(void)
if (get_mem_config())
ret = true;
+ if (erdt_get_mem_config(&rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl))
+ ret = true;
+
if (get_slow_mem_config())
ret = true;
diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
index c44e1d00b89f..b61f75b63f37 100644
--- a/arch/x86/kernel/cpu/resctrl/erdt.c
+++ b/arch/x86/kernel/cpu/resctrl/erdt.c
@@ -21,6 +21,7 @@ static LIST_HEAD(domain_info_list);
/* True when the ERDT ACPI table describes at least one domain with at least one CPU. */
static bool erdt_enabled;
+static u32 erdt_max_clos;
#define ERDT_VALID_VERSION 1
#define CMRC_SUPPORTED_INDEX_FN 1
@@ -57,6 +58,9 @@ bool erdt_support(int flag)
if (flag == X86_FEATURE_CQM_MBM_TOTAL)
return valid_subtbl_mask & BIT(ACPI_ERDT_TYPE_MMRC);
+ if (flag == X86_FEATURE_MBA)
+ return valid_subtbl_mask & BIT(ACPI_ERDT_TYPE_MARC);
+
return false;
}
@@ -257,6 +261,68 @@ int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 r
return -EIO;
}
+static void marc_hw_update(struct hw_param *m)
+{
+}
+
+__init bool erdt_get_mem_config(struct rdt_resource *r)
+{
+ struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
+ struct resctrl_hw_ctrl *hw_ctrl;
+ struct erdt_domain_info *d;
+ struct acpi_erdt_marc *marc;
+ int max_regions, region;
+ unsigned int type;
+
+ if (!erdt_cpu_has(X86_FEATURE_MBA))
+ return false;
+
+ /* Use the first domain's MARC to discover control properties. */
+ d = list_first_entry_or_null(&domain_info_list, struct erdt_domain_info, entry);
+ if (!d || !d->marc)
+ return false;
+
+ marc = d->marc;
+ max_regions = acpi_mrrm_max_mem_region();
+ hw_res->num_closid = max(hw_res->num_closid, erdt_max_clos + 1);
+
+ for (region = 0; region < max_regions; region++) {
+ for (type = RESCTRL_CTRL_REGION_TYPE_OPT; type < RESCTRL_CTRL_REGION_NR_CTRLS; type++) {
+ if (type == RESCTRL_CTRL_REGION_TYPE_OPT && !(marc->flags & MARC_FLAG_OPT))
+ continue;
+ if (type == RESCTRL_CTRL_REGION_TYPE_MIN && !(marc->flags & MARC_FLAG_MIN))
+ continue;
+ if (type == RESCTRL_CTRL_REGION_TYPE_MAX && !(marc->flags & MARC_FLAG_MAX))
+ continue;
+
+ hw_ctrl = kzalloc_obj(*hw_ctrl);
+ if (!hw_ctrl)
+ return false;
+
+ hw_ctrl->r_ctrl.scope = RESCTRL_L3_CACHE;
+ hw_ctrl->r_ctrl.type = RESCTRL_CTRL_SCALAR;
+ hw_ctrl->r_ctrl.name = resctrl_ctrl_name_region(region, type);
+ INIT_LIST_HEAD(&hw_ctrl->r_ctrl.domains);
+ INIT_LIST_HEAD(&hw_ctrl->r_ctrl.emul);
+
+ hw_ctrl->r_ctrl.scalar.max_bw = marc->mba_ctrl_range;
+ hw_ctrl->r_ctrl.scalar.min_bw = 1;
+ hw_ctrl->r_ctrl.scalar.bw_gran = 1;
+ hw_ctrl->r_ctrl.scalar.resolution = 1;
+ hw_ctrl->r_ctrl.scalar.tolerance = 0;
+ hw_ctrl->r_ctrl.scalar.scale = 1;
+ hw_ctrl->r_ctrl.scalar.unit = RESCTRL_CTRL_UNIT_ALL;
+
+ hw_ctrl->hw_update = marc_hw_update;
+ list_add_tail(&hw_ctrl->r_ctrl.entry, &r->controls);
+ }
+ }
+
+ r->alloc_capable = true;
+
+ return true;
+}
+
static void __iomem *erdt_ioremap(phys_addr_t base, u32 num_pages, const char *desc)
{
void __iomem *addr;
@@ -699,6 +765,7 @@ static __init int enumerate_erdt_table(struct acpi_table_header *table_hdr)
if (list_empty(&domain_info_list))
goto cleanup;
+ erdt_max_clos = erdt->max_clos;
erdt_enabled = true;
return 0;
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 6855022bf07e..f09583c95a62 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -30,6 +30,10 @@
* @ERDT_MMIO_MARC_MIN: MARC minimum BW register base address
* @ERDT_MMIO_MARC_MAX: MARC maximum BW register base address
*/
+#define RESCTRL_CTRL_REGION_TYPE_OPT 0
+#define RESCTRL_CTRL_REGION_TYPE_MIN 1
+#define RESCTRL_CTRL_REGION_TYPE_MAX 2
+
enum erdt_mmio_type {
ERDT_MMIO_RMDD_CREG,
ERDT_MMIO_CMRC_BASE,
@@ -324,6 +328,7 @@ static inline bool intel_handle_aet_option(bool force_off, char *tok) { return f
bool erdt_support(int flag);
bool erdt_cpu_has(int flag);
bool erdt_enable_mon(void);
+bool __init erdt_get_mem_config(struct rdt_resource *r);
int erdt_get_max_rmid(void);
int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 rmid,
u64 *val, bool first);
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 24/31] x86/resctrl: Attach ACPI ERDT information to ctrl domain on CPU online
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (22 preceding siblings ...)
2026-08-02 16:07 ` [RFC PATCH 23/31] x86/resctrl: Add region aware MBA controllers Chen Yu
@ 2026-08-02 16:07 ` Chen Yu
2026-08-02 16:07 ` [RFC PATCH 25/31] x86/resctrl: Introduce region-based MBA write implementation on MMIO space Chen Yu
` (6 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:07 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
After the rdt_hw_ctrl_domain has been created during CPU online, attach
the pre-parsed ACPI ERDT table information to the rdt_hw_ctrl_domain
to facilitate MBA control programming via the MARC MMIO registers.
This mirrors the approach used by the monitoring domain
(rdt_hw_l3_mon_domain::d_info) where ERDT domain information is
attached during domain creation.
Add erdt_find_domain_info() to look up the erdt_domain_info for a given
CPU by matching against the CACD-derived cpu_mask in each domain.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/core.c | 1 +
arch/x86/kernel/cpu/resctrl/erdt.c | 12 ++++++++++++
arch/x86/kernel/cpu/resctrl/internal.h | 3 +++
3 files changed, 16 insertions(+)
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index b2c53eab7d8f..86d78107537e 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -575,6 +575,7 @@ static void domain_add_cpu_ctrl(int cpu, struct rdt_resource *r,
d->hdr.type = RESCTRL_CTRL_DOMAIN;
d->hdr.rid = r->rid;
cpumask_set_cpu(cpu, &d->hdr.cpu_mask);
+ hw_dom->d_info = erdt_find_domain_info(cpu);
rdt_domain_reconfigure_cdp(r);
diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
index b61f75b63f37..38720c3b4a3d 100644
--- a/arch/x86/kernel/cpu/resctrl/erdt.c
+++ b/arch/x86/kernel/cpu/resctrl/erdt.c
@@ -261,6 +261,18 @@ int erdt_mon_read(struct rdt_domain_hdr *hdr, enum resctrl_event_id evtid, u32 r
return -EIO;
}
+struct erdt_domain_info *erdt_find_domain_info(int cpu)
+{
+ struct erdt_domain_info *d;
+
+ list_for_each_entry(d, &domain_info_list, entry) {
+ if (cpumask_test_cpu(cpu, &d->cpu_mask))
+ return d;
+ }
+
+ return NULL;
+}
+
static void marc_hw_update(struct hw_param *m)
{
}
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index f09583c95a62..e9602525e4bd 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -137,12 +137,14 @@ static inline struct resctrl_hw_ctrl *resctrl_to_arch_ctrl(struct resctrl_ctrl *
* a resource for a control function
* @d_resctrl: Properties exposed to the resctrl file system
* @ctrl_val: array of cache or mem ctrl values (indexed by CLOSID)
+ * @d_info: ERDT table information of this domain (read-only)
*
* Members of this structure are accessed via helpers that provide abstraction.
*/
struct rdt_hw_ctrl_domain {
struct rdt_ctrl_domain d_resctrl;
u32 *ctrl_val;
+ struct erdt_domain_info *d_info;
};
/**
@@ -325,6 +327,7 @@ static inline void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resour
static inline bool intel_handle_aet_option(bool force_off, char *tok) { return false; }
#endif
+struct erdt_domain_info *erdt_find_domain_info(int cpu);
bool erdt_support(int flag);
bool erdt_cpu_has(int flag);
bool erdt_enable_mon(void);
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 25/31] x86/resctrl: Introduce region-based MBA write implementation on MMIO space
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (23 preceding siblings ...)
2026-08-02 16:07 ` [RFC PATCH 24/31] x86/resctrl: Attach ACPI ERDT information to ctrl domain on CPU online Chen Yu
@ 2026-08-02 16:07 ` Chen Yu
2026-08-04 21:13 ` Luck, Tony
2026-08-02 16:07 ` [RFC PATCH 26/31] x86/resctrl: Allow control writes from any CPU for MMIO controllers Chen Yu
` (5 subsequent siblings)
30 siblings, 1 reply; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:07 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
Implement the marc_hw_update() callback to program per-region MBA
bandwidth values via MMIO.
The MARC register layout packs 4 regions into each 64-bit register,
with a 9-bit bandwidth field per region at (region % 4) * 16 bits.
The MMIO address for a given CLOSID is calculated using the MARC index
function 1:
addr = base + Floor(Region / 4) * 512 + CLOS * 8
Each controller handles a single (region, type) pair, but a write always
touches the whole 64-bit register. The callback therefore does a
read-modify-write: it changes only its own region's field and writes
every other bit back exactly as it was read, so the reserved bits keep
their original values. A shadow copy of the register (marc_buf) holds
the value last written, which spares the read on later updates.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/erdt.c | 52 ++++++++++++++++++++++++++
arch/x86/kernel/cpu/resctrl/internal.h | 4 ++
2 files changed, 56 insertions(+)
diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
index 38720c3b4a3d..c25aff805b12 100644
--- a/arch/x86/kernel/cpu/resctrl/erdt.c
+++ b/arch/x86/kernel/cpu/resctrl/erdt.c
@@ -275,6 +275,49 @@ struct erdt_domain_info *erdt_find_domain_info(int cpu)
static void marc_hw_update(struct hw_param *m)
{
+ struct rdt_hw_ctrl_domain *hw_dom = resctrl_to_arch_ctrl_dom(m->dom);
+ struct resctrl_hw_ctrl *hw_ctrl = resctrl_to_arch_ctrl(m->ctrl);
+ enum resctrl_ctrl_name name = hw_ctrl->r_ctrl.name;
+ unsigned int offset, region, type, region_offset_bits;
+ struct erdt_domain_info *d = hw_dom->d_info;
+ enum erdt_mmio_type mmio_type;
+ void __iomem *addr;
+ int closid_idx;
+ unsigned int i;
+ u64 val;
+
+ if (!d || !d->marc)
+ return;
+
+ offset = name - RESCTRL_CTRL_NAME_REGION0_OPT;
+ region = offset / RESCTRL_CTRL_REGION_NR_CTRLS;
+ type = offset % RESCTRL_CTRL_REGION_NR_CTRLS;
+ mmio_type = ERDT_MMIO_MARC_OPT + type;
+ region_offset_bits = (region % 4) * 16;
+
+ if (d->marc_buf_type != mmio_type) {
+ memset(d->marc_buf, 0,
+ d->marc->mba_reg_size * 512 * sizeof(u64));
+ d->marc_buf_type = mmio_type;
+ }
+
+ for (i = m->low; i < m->high; i++) {
+ closid_idx = (region / 4) * 64 + i;
+ addr = d->base[mmio_type] + closid_idx * 8;
+
+ /* The cached value retains the reserved bits to be preserved. */
+ val = d->marc_buf[closid_idx];
+ if (!val)
+ val = readq(addr);
+
+ if (WARN_ON_ONCE(!val))
+ return;
+
+ val &= ~(0x1ffULL << region_offset_bits);
+ val |= (u64)(hw_dom->ctrl_val[i] & 0x1ff) << region_offset_bits;
+ d->marc_buf[closid_idx] = val;
+ writeq(val, addr);
+ }
}
__init bool erdt_get_mem_config(struct rdt_resource *r)
@@ -364,6 +407,7 @@ static void erdt_iounmap_domain(struct erdt_domain_info *domain)
static void cleanup_one_domain(struct erdt_domain_info *d)
{
erdt_iounmap_domain(d);
+ kfree(d->marc_buf);
kfree(d->cmrc);
kfree(d->mmrc);
kfree(d->marc);
@@ -520,6 +564,14 @@ static __init int marc_init(struct acpi_subtbl_hdr_16 *subtbl,
if (!domain_info->marc)
goto unmap;
+ domain_info->marc_buf = kcalloc(marc->mba_reg_size * 512, sizeof(u64),
+ GFP_KERNEL);
+ if (!domain_info->marc_buf) {
+ kfree(domain_info->marc);
+ domain_info->marc = NULL;
+ goto unmap;
+ }
+
return 0;
unmap:
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index e9602525e4bd..2f6173692d0c 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -52,6 +52,8 @@ enum erdt_mmio_type {
* @cmrc: Copy of the ACPI CMRC sub-table for this domain
* @mmrc: Copy of the ACPI MMRC sub-table for this domain
* @marc: Copy of the ACPI MARC sub-table for this domain
+ * @marc_buf: Shadow copy of the MARC MMIO registers for read-modify-write
+ * @marc_buf_type: MARC MMIO region currently cached in @marc_buf
* @cpu_mask: CPUs belonging to this resource management domain
* @max_rmid: Maximum RMID supported by this domain
* @dom_id: L3 cache ID shared by all CPUs in this domain (-1 if unset)
@@ -62,6 +64,8 @@ struct erdt_domain_info {
struct acpi_erdt_cmrc *cmrc;
struct acpi_erdt_mmrc *mmrc;
struct acpi_erdt_marc *marc;
+ u64 *marc_buf;
+ enum erdt_mmio_type marc_buf_type;
struct cpumask cpu_mask;
u32 max_rmid;
int dom_id;
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* Re: [RFC PATCH 25/31] x86/resctrl: Introduce region-based MBA write implementation on MMIO space
2026-08-02 16:07 ` [RFC PATCH 25/31] x86/resctrl: Introduce region-based MBA write implementation on MMIO space Chen Yu
@ 2026-08-04 21:13 ` Luck, Tony
2026-08-05 6:32 ` Chen, Yu C
0 siblings, 1 reply; 37+ messages in thread
From: Luck, Tony @ 2026-08-04 21:13 UTC (permalink / raw)
To: Chen Yu
Cc: Reinette Chatre, Ben Horgan, James Morse, Dave Martin, Babu Moger,
Fenghua Yu, Borislav Petkov, Thomas Gleixner, Dave Hansen,
Peter Newman, chen.yu, x86, linux-kernel
On Mon, Aug 03, 2026 at 12:07:38AM +0800, Chen Yu wrote:
> Implement the marc_hw_update() callback to program per-region MBA
> bandwidth values via MMIO.
>
> The MARC register layout packs 4 regions into each 64-bit register,
> with a 9-bit bandwidth field per region at (region % 4) * 16 bits.
> The MMIO address for a given CLOSID is calculated using the MARC index
> function 1:
>
> addr = base + Floor(Region / 4) * 512 + CLOS * 8
>
> Each controller handles a single (region, type) pair, but a write always
> touches the whole 64-bit register. The callback therefore does a
> read-modify-write: it changes only its own region's field and writes
> every other bit back exactly as it was read, so the reserved bits keep
> their original values. A shadow copy of the register (marc_buf) holds
> the value last written, which spares the read on later updates.
>
> Signed-off-by: Chen Yu <yu.c.chen@intel.com>
> ---
> arch/x86/kernel/cpu/resctrl/erdt.c | 52 ++++++++++++++++++++++++++
> arch/x86/kernel/cpu/resctrl/internal.h | 4 ++
> 2 files changed, 56 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
> index 38720c3b4a3d..c25aff805b12 100644
> --- a/arch/x86/kernel/cpu/resctrl/erdt.c
> +++ b/arch/x86/kernel/cpu/resctrl/erdt.c
> @@ -275,6 +275,49 @@ struct erdt_domain_info *erdt_find_domain_info(int cpu)
>
> static void marc_hw_update(struct hw_param *m)
> {
> + struct rdt_hw_ctrl_domain *hw_dom = resctrl_to_arch_ctrl_dom(m->dom);
> + struct resctrl_hw_ctrl *hw_ctrl = resctrl_to_arch_ctrl(m->ctrl);
> + enum resctrl_ctrl_name name = hw_ctrl->r_ctrl.name;
> + unsigned int offset, region, type, region_offset_bits;
> + struct erdt_domain_info *d = hw_dom->d_info;
> + enum erdt_mmio_type mmio_type;
> + void __iomem *addr;
> + int closid_idx;
> + unsigned int i;
> + u64 val;
> +
> + if (!d || !d->marc)
> + return;
> +
> + offset = name - RESCTRL_CTRL_NAME_REGION0_OPT;
> + region = offset / RESCTRL_CTRL_REGION_NR_CTRLS;
> + type = offset % RESCTRL_CTRL_REGION_NR_CTRLS;
> + mmio_type = ERDT_MMIO_MARC_OPT + type;
> + region_offset_bits = (region % 4) * 16;
> +
> + if (d->marc_buf_type != mmio_type) {
> + memset(d->marc_buf, 0,
> + d->marc->mba_reg_size * 512 * sizeof(u64));
> + d->marc_buf_type = mmio_type;
> + }
> +
> + for (i = m->low; i < m->high; i++) {
> + closid_idx = (region / 4) * 64 + i;
> + addr = d->base[mmio_type] + closid_idx * 8;
> +
> + /* The cached value retains the reserved bits to be preserved. */
> + val = d->marc_buf[closid_idx];
> + if (!val)
> + val = readq(addr);
> +
> + if (WARN_ON_ONCE(!val))
> + return;
> +
> + val &= ~(0x1ffULL << region_offset_bits);
> + val |= (u64)(hw_dom->ctrl_val[i] & 0x1ff) << region_offset_bits;
> + d->marc_buf[closid_idx] = val;
> + writeq(val, addr);
> + }
> }
There are lots of opinions about bit fields. I'm a fan for h/w registers
accessed in architecture specific code.
I think the version below is easier to read than all the inline masks and
shifts.
-Tony
union bw_ctrl {
u64 reg;
struct {
u16 val : 9;
u16 rsvd : 7;
} regions[4];
};
static void marc_hw_update(struct hw_param *m)
{
struct rdt_hw_ctrl_domain *hw_dom = resctrl_to_arch_ctrl_dom(m->dom);
struct resctrl_hw_ctrl *hw_ctrl = resctrl_to_arch_ctrl(m->ctrl);
enum resctrl_ctrl_name name = hw_ctrl->r_ctrl.name;
struct erdt_domain_info *d = hw_dom->d_info;
unsigned int offset, region, type;
enum erdt_mmio_type mmio_type;
union bw_ctrl mmio_ctrl;
void __iomem *addr;
int closid_idx;
unsigned int i;
if (!d || !d->marc)
return;
offset = name - RESCTRL_CTRL_NAME_REGION0_OPT;
region = offset / RESCTRL_CTRL_REGION_NR_CTRLS;
type = offset % RESCTRL_CTRL_REGION_NR_CTRLS;
mmio_type = ERDT_MMIO_MARC_OPT + type;
if (d->marc_buf_type != mmio_type) {
memset(d->marc_buf, 0,
d->marc->mba_reg_size * 512 * sizeof(u64));
d->marc_buf_type = mmio_type;
}
for (i = m->low; i < m->high; i++) {
closid_idx = (region / 4) * 64 + i;
addr = d->base[mmio_type] + closid_idx * 8;
/* The cached value retains the reserved bits to be preserved. */
mmio_ctrl.reg = d->marc_buf[closid_idx];
if (!mmio_ctrl.reg)
mmio_ctrl.reg = readq(addr);
if (WARN_ON_ONCE(!mmio_ctrl.reg))
return;
mmio_ctrl.regions[region].val = hw_dom->ctrl_val[i];
d->marc_buf[closid_idx] = mmio_ctrl.reg;
writeq(mmio_ctrl.reg, addr);
}
}
^ permalink raw reply [flat|nested] 37+ messages in thread* Re: [RFC PATCH 25/31] x86/resctrl: Introduce region-based MBA write implementation on MMIO space
2026-08-04 21:13 ` Luck, Tony
@ 2026-08-05 6:32 ` Chen, Yu C
0 siblings, 0 replies; 37+ messages in thread
From: Chen, Yu C @ 2026-08-05 6:32 UTC (permalink / raw)
To: Luck, Tony
Cc: Reinette Chatre, Ben Horgan, James Morse, Dave Martin, Babu Moger,
Fenghua Yu, Borislav Petkov, Thomas Gleixner, Dave Hansen,
Peter Newman, chen.yu, x86, linux-kernel
On 8/5/2026 5:13 AM, Luck, Tony wrote:
>> + for (i = m->low; i < m->high; i++) {
>> + closid_idx = (region / 4) * 64 + i;
>> + addr = d->base[mmio_type] + closid_idx * 8;
>> +
>> + /* The cached value retains the reserved bits to be preserved. */
>> + val = d->marc_buf[closid_idx];
>> + if (!val)
>> + val = readq(addr);
>> +
>> + if (WARN_ON_ONCE(!val))
>> + return;
>> +
>> + val &= ~(0x1ffULL << region_offset_bits);
>> + val |= (u64)(hw_dom->ctrl_val[i] & 0x1ff) << region_offset_bits;
>> + d->marc_buf[closid_idx] = val;
>> + writeq(val, addr);
>> + }
>> }
>
> There are lots of opinions about bit fields. I'm a fan for h/w registers
> accessed in architecture specific code.
>
> I think the version below is easier to read than all the inline masks and
> shifts.
>
Got it, learned a lot, I will revise it in this direction.
thanks,
Chenyu
^ permalink raw reply [flat|nested] 37+ messages in thread
* [RFC PATCH 26/31] x86/resctrl: Allow control writes from any CPU for MMIO controllers
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (24 preceding siblings ...)
2026-08-02 16:07 ` [RFC PATCH 25/31] x86/resctrl: Introduce region-based MBA write implementation on MMIO space Chen Yu
@ 2026-08-02 16:07 ` Chen Yu
2026-08-02 16:07 ` [RFC PATCH 27/31] x86/resctrl: Enable region-aware MBM/MBA via the RDT_CTRL register Chen Yu
` (4 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:07 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
Programming a control that lives in domain-local MSR space must run on a
CPU that belongs to the target domain, so resctrl_arch_update_domains()
issues the hw_update() via an IPI. MMIO based controls (e.g. the ERDT
MARC registers) have no such affinity requirement and can be programmed
from the current CPU, making the IPI pure overhead.
Introduce RESCTRL_CTRL_FLAG_ANY_CPU to describe a control whose hardware
can be programmed from any CPU, mirroring the mon_evt::any_cpu flag used
on the monitoring read path. Set it on the MARC controllers at creation
time.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 11 ++++++++++-
arch/x86/kernel/cpu/resctrl/erdt.c | 2 ++
include/linux/resctrl.h | 1 +
3 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
index 1dd59d36e86c..7bacb8bf2e27 100644
--- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
+++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
@@ -19,6 +19,15 @@
#include "internal.h"
+static void ctrl_hw_update(struct resctrl_ctrl *ctrl, struct rdt_ctrl_domain *d,
+ struct hw_param *m)
+{
+ if (ctrl->flags & RESCTRL_CTRL_FLAG_ANY_CPU)
+ rdt_ctrl_update(m);
+ else
+ smp_call_function_any(&d->hdr.cpu_mask, rdt_ctrl_update, m, 1);
+}
+
int resctrl_arch_update_one(struct rdt_resource *r, struct resctrl_ctrl *ctrl,
struct rdt_ctrl_domain *d, u32 closid,
enum resctrl_conf_type t, u32 cfg_val)
@@ -81,7 +90,7 @@ static void _resctrl_arch_update_domains(struct rdt_resource *r,
}
}
if (hw_param.res)
- smp_call_function_any(&d->hdr.cpu_mask, rdt_ctrl_update, &hw_param, 1);
+ ctrl_hw_update(ctrl, d, &hw_param);
}
}
diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
index c25aff805b12..8f087defffac 100644
--- a/arch/x86/kernel/cpu/resctrl/erdt.c
+++ b/arch/x86/kernel/cpu/resctrl/erdt.c
@@ -369,6 +369,8 @@ __init bool erdt_get_mem_config(struct rdt_resource *r)
hw_ctrl->r_ctrl.scalar.unit = RESCTRL_CTRL_UNIT_ALL;
hw_ctrl->hw_update = marc_hw_update;
+ /* MARC controls live in MMIO, program from any CPU. */
+ hw_ctrl->r_ctrl.flags |= RESCTRL_CTRL_FLAG_ANY_CPU;
list_add_tail(&hw_ctrl->r_ctrl.entry, &r->controls);
}
}
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 3969db01f4cc..8260b09aa323 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -386,6 +386,7 @@ resctrl_ctrl_name_region(unsigned int region, unsigned int type)
/* Flags for rdt_resource::flags and resctrl_ctrl::flags */
#define RESCTRL_CTRL_FLAG_LINEAR BIT(0)
#define RESCTRL_CTRL_FLAG_SPARSE_BITMASKS BIT(1)
+#define RESCTRL_CTRL_FLAG_ANY_CPU BIT(2)
/**
* struct resctrl_ctrl - A resource control
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 27/31] x86/resctrl: Enable region-aware MBM/MBA via the RDT_CTRL register
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (25 preceding siblings ...)
2026-08-02 16:07 ` [RFC PATCH 26/31] x86/resctrl: Allow control writes from any CPU for MMIO controllers Chen Yu
@ 2026-08-02 16:07 ` Chen Yu
2026-08-02 16:08 ` [RFC PATCH 28/31] x86/resctrl: Emulate the legacy MBA controller via the region MAX controls Chen Yu
` (3 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:07 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
Region-aware MBM and MBA are exposed through per-RMDD MMIO register
blocks. These MMIO interfaces are only honored by hardware once the
domain is taken out of legacy "Total" mode.
Clear the legacy-mode bit once an RMDD's region-aware ACPI sub-tables
have parsed successfully, so the switch to region-aware mode only
happens for fully validated domains. The specification requires that
region-aware MBM and MBA be enabled together and consistently across
all RMDDs.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/erdt.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
index 8f087defffac..6464463973bb 100644
--- a/arch/x86/kernel/cpu/resctrl/erdt.c
+++ b/arch/x86/kernel/cpu/resctrl/erdt.c
@@ -29,6 +29,8 @@ static u32 erdt_max_clos;
#define MARC_SUPPORTED_INDEX_FN 1
#define RMDD_FLAG_CPU_L3_DOMAIN BIT(0)
+#define RDT_CTRL_LEGACY_MODE BIT(2)
+
#define MARC_FLAG_OPT BIT(0)
#define MARC_FLAG_MIN BIT(1)
#define MARC_FLAG_MAX BIT(2)
@@ -406,8 +408,23 @@ static void erdt_iounmap_domain(struct erdt_domain_info *domain)
}
}
+static void region_aware_enable(void __iomem *addr, bool enable)
+{
+ u64 rdt_ctrl = readq(addr);
+
+ if (enable)
+ rdt_ctrl &= ~RDT_CTRL_LEGACY_MODE;
+ else
+ rdt_ctrl |= RDT_CTRL_LEGACY_MODE;
+
+ writeq(rdt_ctrl, addr);
+}
+
static void cleanup_one_domain(struct erdt_domain_info *d)
{
+ if (d->base[ERDT_MMIO_RMDD_CREG])
+ region_aware_enable(d->base[ERDT_MMIO_RMDD_CREG], false);
+
erdt_iounmap_domain(d);
kfree(d->marc_buf);
kfree(d->cmrc);
@@ -804,6 +821,7 @@ static __init int enumerate_erdt_table(struct acpi_table_header *table_hdr)
{
struct acpi_table_erdt *erdt = (struct acpi_table_erdt *)table_hdr;
struct acpi_subtbl_hdr_16 *subtbl;
+ struct erdt_domain_info *d;
void *table_end;
if (erdt->header.revision != ERDT_VALID_VERSION) {
@@ -831,6 +849,9 @@ static __init int enumerate_erdt_table(struct acpi_table_header *table_hdr)
if (list_empty(&domain_info_list))
goto cleanup;
+ list_for_each_entry(d, &domain_info_list, entry)
+ region_aware_enable(d->base[ERDT_MMIO_RMDD_CREG], true);
+
erdt_max_clos = erdt->max_clos;
erdt_enabled = true;
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 28/31] x86/resctrl: Emulate the legacy MBA controller via the region MAX controls
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (26 preceding siblings ...)
2026-08-02 16:07 ` [RFC PATCH 27/31] x86/resctrl: Enable region-aware MBM/MBA via the RDT_CTRL register Chen Yu
@ 2026-08-02 16:08 ` Chen Yu
2026-08-02 16:08 ` [RFC PATCH 29/31] fs/resctrl: Expose emulation controllers in a resource_schemata subdir Chen Yu
` (2 subsequent siblings)
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:08 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
On ERDT platforms the legacy MBA "default" controller does have hardware of
its own, but the region-based MAX controllers are the preferred way to
throttle memory bandwidth. Rather than programming the legacy MSR, realize
the default controller's effect through the MAX controller of every memory
region, which keeps a single consistent throttling mechanism in use. Link
the default controller to the MAX controller of every available region via
resctrl_ctrl::emul in erdt_get_mem_config() so they are associated once
the controllers are created.
Route the arch control writes accordingly. When a control is emulated
(ctrl->emul is not empty), do not program the legacy MSR; instead
translate the configured value into each emulation controller's units and
program that controller's hardware.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 75 ++++++++++++++++++++---
arch/x86/kernel/cpu/resctrl/erdt.c | 18 ++++++
include/linux/resctrl.h | 3 +
3 files changed, 88 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
index 7bacb8bf2e27..7fe48912d2d5 100644
--- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
+++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
@@ -28,6 +28,48 @@ static void ctrl_hw_update(struct resctrl_ctrl *ctrl, struct rdt_ctrl_domain *d,
smp_call_function_any(&d->hdr.cpu_mask, rdt_ctrl_update, m, 1);
}
+static u32 emul_translate_val(struct resctrl_ctrl *src, struct resctrl_ctrl *dst,
+ u32 val)
+{
+ return val * dst->scalar.max_bw / src->scalar.max_bw;
+}
+
+static void _resctrl_arch_update_emul(struct rdt_resource *r,
+ struct resctrl_ctrl *ctrl,
+ struct rdt_ctrl_domain *d, u32 low, u32 high)
+{
+ struct rdt_hw_ctrl_domain *emul_hw_dom;
+ struct rdt_hw_ctrl_domain *hw_dom;
+ struct rdt_ctrl_domain *emul_d;
+ struct resctrl_ctrl *emul;
+ struct rdt_domain_hdr *hdr;
+ struct hw_param emul_param;
+ unsigned int i;
+
+ hw_dom = resctrl_to_arch_ctrl_dom(d);
+
+ for_each_emul_ctrl(emul, ctrl) {
+ hdr = resctrl_find_domain(&emul->domains, d->hdr.id, NULL);
+ if (!hdr)
+ continue;
+
+ emul_d = container_of(hdr, struct rdt_ctrl_domain, hdr);
+ emul_hw_dom = resctrl_to_arch_ctrl_dom(emul_d);
+
+ for (i = low; i < high; i++)
+ emul_hw_dom->ctrl_val[i] = emul_translate_val(ctrl, emul,
+ hw_dom->ctrl_val[i]);
+
+ emul_param.res = r;
+ emul_param.ctrl = emul;
+ emul_param.dom = emul_d;
+ emul_param.low = low;
+ emul_param.high = high;
+
+ ctrl_hw_update(emul, emul_d, &emul_param);
+ }
+}
+
int resctrl_arch_update_one(struct rdt_resource *r, struct resctrl_ctrl *ctrl,
struct rdt_ctrl_domain *d, u32 closid,
enum resctrl_conf_type t, u32 cfg_val)
@@ -42,12 +84,20 @@ int resctrl_arch_update_one(struct rdt_resource *r, struct resctrl_ctrl *ctrl,
hw_dom->ctrl_val[idx] = cfg_val;
- hw_param.res = r;
- hw_param.ctrl = ctrl;
- hw_param.dom = d;
- hw_param.low = idx;
- hw_param.high = idx + 1;
- hw_ctrl->hw_update(&hw_param);
+ /*
+ * When this control is emulated, program the emulation controllers'
+ * hardware instead.
+ */
+ if (!list_empty(&ctrl->emul)) {
+ _resctrl_arch_update_emul(r, ctrl, d, idx, idx + 1);
+ } else {
+ hw_param.res = r;
+ hw_param.ctrl = ctrl;
+ hw_param.dom = d;
+ hw_param.low = idx;
+ hw_param.high = idx + 1;
+ hw_ctrl->hw_update(&hw_param);
+ }
return 0;
}
@@ -89,8 +139,17 @@ static void _resctrl_arch_update_domains(struct rdt_resource *r,
hw_param.high = max(hw_param.high, idx + 1);
}
}
- if (hw_param.res)
- ctrl_hw_update(ctrl, d, &hw_param);
+ if (hw_param.res) {
+ /*
+ * When this control is emulated, program the emulation
+ * controllers' hardware instead.
+ */
+ if (!list_empty(&ctrl->emul))
+ _resctrl_arch_update_emul(r, ctrl, d,
+ hw_param.low, hw_param.high);
+ else
+ ctrl_hw_update(ctrl, d, &hw_param);
+ }
}
}
diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
index 6464463973bb..4515e3251476 100644
--- a/arch/x86/kernel/cpu/resctrl/erdt.c
+++ b/arch/x86/kernel/cpu/resctrl/erdt.c
@@ -325,6 +325,7 @@ static void marc_hw_update(struct hw_param *m)
__init bool erdt_get_mem_config(struct rdt_resource *r)
{
struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
+ struct resctrl_ctrl *def_ctrl = NULL, *ctrl;
struct resctrl_hw_ctrl *hw_ctrl;
struct erdt_domain_info *d;
struct acpi_erdt_marc *marc;
@@ -343,6 +344,13 @@ __init bool erdt_get_mem_config(struct rdt_resource *r)
max_regions = acpi_mrrm_max_mem_region();
hw_res->num_closid = max(hw_res->num_closid, erdt_max_clos + 1);
+ for_each_resource_ctrl(ctrl, r) {
+ if (ctrl->name == RESCTRL_CTRL_NAME_DEF) {
+ def_ctrl = ctrl;
+ break;
+ }
+ }
+
for (region = 0; region < max_regions; region++) {
for (type = RESCTRL_CTRL_REGION_TYPE_OPT; type < RESCTRL_CTRL_REGION_NR_CTRLS; type++) {
if (type == RESCTRL_CTRL_REGION_TYPE_OPT && !(marc->flags & MARC_FLAG_OPT))
@@ -374,6 +382,16 @@ __init bool erdt_get_mem_config(struct rdt_resource *r)
/* MARC controls live in MMIO, program from any CPU. */
hw_ctrl->r_ctrl.flags |= RESCTRL_CTRL_FLAG_ANY_CPU;
list_add_tail(&hw_ctrl->r_ctrl.entry, &r->controls);
+
+ /*
+ * Throttle memory bandwidth through the region MAX
+ * controls rather than the legacy MBA MSR, so let the
+ * MAX control of every region emulate the legacy MBA
+ * control.
+ */
+ if (def_ctrl && type == RESCTRL_CTRL_REGION_TYPE_MAX)
+ list_add_tail(&hw_ctrl->r_ctrl.emul_entry,
+ &def_ctrl->emul);
}
}
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 8260b09aa323..57615af637ad 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -51,6 +51,9 @@ int proc_resctrl_show(struct seq_file *m,
#define for_each_resource_ctrl(ctrl, r) \
list_for_each_entry(ctrl, &r->controls, entry)
+#define for_each_emul_ctrl(emul, ctrl) \
+ list_for_each_entry(emul, &ctrl->emul, emul_entry)
+
enum resctrl_res_level {
RDT_RESOURCE_L3,
RDT_RESOURCE_L2,
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 29/31] fs/resctrl: Expose emulation controllers in a resource_schemata subdir
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (27 preceding siblings ...)
2026-08-02 16:08 ` [RFC PATCH 28/31] x86/resctrl: Emulate the legacy MBA controller via the region MAX controls Chen Yu
@ 2026-08-02 16:08 ` Chen Yu
2026-08-02 16:08 ` [RFC PATCH 30/31] fs/resctrl: Fix excessive padding in schemata output Chen Yu
2026-08-02 16:08 ` [RFC PATCH 31/31] x86,fs/resctrl: Update Documentation for region aware RDT Chen Yu
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:08 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
The legacy MBA default controller is emulated by other controls (for
ERDT, "MB" is emulated by the MAX control of every memory region).
When a control is emulated (resctrl_ctrl::emul is not empty), do not
expose the control's own properties. Keep the control's own
resource_schemata directory and, underneath it, create a sub-directory
named after each emulation controller that holds that emulation
controller's properties. For example:
[root@ MB]# tree resource_schemata/
resource_schemata/
├── MB
│ ├── MB_REGION0_MAX
│ │ ├── max
│ │ ├── min
│ │ ├── resolution
│ │ ├── scale
│ │ ├── scope
│ │ ├── tolerance
│ │ ├── type
│ │ └── unit
│ └── MB_REGION1_MAX
│ ├── max
│ ├── min
│ ├── resolution
│ ├── scale
│ ├── scope
│ ├── tolerance
│ ├── type
│ └── unit
Controls without an emulation controller keep exposing their own
properties directly.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
fs/resctrl/rdtgroup.c | 31 +++++++++++++++++++++++++++----
1 file changed, 27 insertions(+), 4 deletions(-)
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index c1aac0dcd332..31bea5a9833b 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -2741,13 +2741,36 @@ static int resctrl_mkdir_schemata_dir(struct kernfs_node *kn,
if (IS_ERR(kn_ctrl))
return PTR_ERR(kn_ctrl);
- ret = rdtgroup_kn_set_ugid(kn_subdir);
+ ret = rdtgroup_kn_set_ugid(kn_ctrl);
if (ret)
return ret;
- ret = resctrl_add_ctrl_files(kn_ctrl, ctrl);
- if (ret)
- return ret;
+ if (!list_empty(&ctrl->emul)) {
+ struct kernfs_node *kn_emul;
+ struct resctrl_ctrl *emul;
+
+ for_each_emul_ctrl(emul, ctrl) {
+ snprintf(ctrl_full_name, sizeof(ctrl_full_name), "%s_%s",
+ f->name, resctrl_ctrl_name_str(emul->name));
+
+ kn_emul = kernfs_create_dir(kn_ctrl, ctrl_full_name,
+ kn_ctrl->mode, emul);
+ if (IS_ERR(kn_emul))
+ return PTR_ERR(kn_emul);
+
+ ret = rdtgroup_kn_set_ugid(kn_emul);
+ if (ret)
+ return ret;
+
+ ret = resctrl_add_ctrl_files(kn_emul, emul);
+ if (ret)
+ return ret;
+ }
+ } else {
+ ret = resctrl_add_ctrl_files(kn_ctrl, ctrl);
+ if (ret)
+ return ret;
+ }
}
kernfs_activate(kn_subdir);
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 30/31] fs/resctrl: Fix excessive padding in schemata output
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (28 preceding siblings ...)
2026-08-02 16:08 ` [RFC PATCH 29/31] fs/resctrl: Expose emulation controllers in a resource_schemata subdir Chen Yu
@ 2026-08-02 16:08 ` Chen Yu
2026-08-02 16:08 ` [RFC PATCH 31/31] x86,fs/resctrl: Update Documentation for region aware RDT Chen Yu
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:08 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
When a resource has several controls (such as the region-aware MBA
controls), the schemata and size files pad every line with a large
amount of leading whitespace and the control names no longer line up
into a table.
Compute the column width from the longest single control name and format
the full control name within that width so the output is aligned again.
Reported-by: Tony Luck <luck.tony@intel.com>
Link: https://lore.kernel.org/all/aiB2oJFPF-sqUVQx@agluck-desk3/
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
fs/resctrl/ctrlmondata.c | 19 +++++++++++--------
fs/resctrl/rdtgroup.c | 11 ++++++-----
2 files changed, 17 insertions(+), 13 deletions(-)
diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
index d65036f7079e..66483c83e99d 100644
--- a/fs/resctrl/ctrlmondata.c
+++ b/fs/resctrl/ctrlmondata.c
@@ -405,16 +405,16 @@ static struct resctrl_ctrl *resctrl_resource_ctrl_get(struct rdt_resource *r,
size_t resctrl_resource_ctrl_max_len(struct rdt_resource *r)
{
struct resctrl_ctrl *ctrl;
- size_t total = 0;
+ size_t max = 0;
size_t len;
for_each_resource_ctrl(ctrl,r) {
len = strlen(resctrl_ctrl_name_str(ctrl->name));
if (len)
- total += 1 + len;
+ max = max_t(size_t, max, 1 + len);
}
- return total;
+ return max;
}
static int rdtgroup_parse_ctrl(char *ctrlname, char *tok,
@@ -522,6 +522,7 @@ static void show_doms(struct seq_file *s, struct rdt_resource_final *f,
bool print_ctrl, int closid, struct resctrl_ctrl *ctrl)
{
struct rdt_resource *r = f->res;
+ char ctrl_full_name[20];
struct rdt_ctrl_domain *dom;
bool sep = false;
u32 ctrl_val;
@@ -529,11 +530,13 @@ static void show_doms(struct seq_file *s, struct rdt_resource_final *f,
/* Walking r->domains, ensure it can't race with cpuhp */
lockdep_assert_cpus_held();
- if (print_ctrl)
- seq_printf(s, "%*s%s%s:", max_name_width, f->name,
- resctrl_ctrl_is_default(ctrl) ? "" : "_",
- resctrl_ctrl_is_default(ctrl) ?
- "" : resctrl_ctrl_name_str(ctrl->name));
+ if (print_ctrl) {
+ snprintf(ctrl_full_name, sizeof(ctrl_full_name), "%s%s%s", f->name,
+ resctrl_ctrl_is_default(ctrl) ? "" : "_",
+ resctrl_ctrl_is_default(ctrl) ?
+ "" : resctrl_ctrl_name_str(ctrl->name));
+ seq_printf(s, "%*s:", max_name_width, ctrl_full_name);
+ }
list_for_each_entry(dom, &ctrl->domains, hdr.list) {
if (sep)
seq_puts(s, ";");
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 31bea5a9833b..7d615502a892 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -1653,6 +1653,7 @@ static int rdtgroup_size_show(struct kernfs_open_file *of,
struct resctrl_ctrl *ctrl;
struct rdtgroup *rdtgrp;
struct rdt_resource *r;
+ char ctrl_full_name[20];
unsigned int size;
u32 ctrl_val;
int ret = 0;
@@ -1693,11 +1694,11 @@ static int rdtgroup_size_show(struct kernfs_open_file *of,
type = f->conf_type;
for_each_resource_ctrl(ctrl, r) {
sep = false;
- seq_printf(s, "%*s", max_name_width, f->name);
- if (!resctrl_ctrl_is_default(ctrl))
- seq_printf(s, "_%s:", resctrl_ctrl_name_str(ctrl->name));
- else
- seq_putc(s, ':');
+ snprintf(ctrl_full_name, sizeof(ctrl_full_name), "%s%s%s", f->name,
+ resctrl_ctrl_is_default(ctrl) ? "" : "_",
+ resctrl_ctrl_is_default(ctrl) ?
+ "" : resctrl_ctrl_name_str(ctrl->name));
+ seq_printf(s, "%*s:", max_name_width, ctrl_full_name);
list_for_each_entry(d, &ctrl->domains, hdr.list) {
if (sep)
seq_putc(s, ';');
--
2.43.0
^ permalink raw reply related [flat|nested] 37+ messages in thread* [RFC PATCH 31/31] x86,fs/resctrl: Update Documentation for region aware RDT
2026-08-02 15:57 [RFC PATCH 00/31] Introduce region-aware RDT support Chen Yu
` (29 preceding siblings ...)
2026-08-02 16:08 ` [RFC PATCH 30/31] fs/resctrl: Fix excessive padding in schemata output Chen Yu
@ 2026-08-02 16:08 ` Chen Yu
30 siblings, 0 replies; 37+ messages in thread
From: Chen Yu @ 2026-08-02 16:08 UTC (permalink / raw)
To: Reinette Chatre, Tony Luck
Cc: Ben Horgan, James Morse, Dave Martin, Babu Moger, Fenghua Yu,
Borislav Petkov, Thomas Gleixner, Dave Hansen, Peter Newman,
chen.yu, x86, linux-kernel
Support region based MBM display and MBA schemata, update
the document accordingly.
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
Documentation/filesystems/resctrl.rst | 110 ++++++++++++++++++++++++++
1 file changed, 110 insertions(+)
diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
index e4b66af55ffb..cac008996eba 100644
--- a/Documentation/filesystems/resctrl.rst
+++ b/Documentation/filesystems/resctrl.rst
@@ -28,6 +28,7 @@ SMBA (Slow Memory Bandwidth Allocation) ""
BMEC (Bandwidth Monitoring Event Configuration) ""
ABMC (Assignable Bandwidth Monitoring Counters) ""
SDCIAE (Smart Data Cache Injection Allocation Enforcement) ""
+RMBA (Region Aware Memory Bandwidth Allocation) ""
=============================================================== ================================
Historically, new features were made visible by default in /proc/cpuinfo. This
@@ -651,6 +652,11 @@ When monitoring is enabled all MON groups will also contain:
"core" of the CPU (arithmetic units, TLB, L1 and L2 caches, etc.). They
do not include L3 cache, memory, I/O devices etc.
+ If region aware RDT is enabled, several region related files are created.
+ For example, if there are 4 regions, the corresponding files are
+ mbm_region0_bytes, mbm_region1_bytes, mbm_region2_bytes and
+ mbm_region3_bytes.
+
All other events report decimal integer values.
In a MON group these files provide a read out of the current value of
@@ -993,6 +999,56 @@ is formatted as:
SMBA:<cache_id0>=bandwidth0;<cache_id1>=bandwidth1;...
+Region Aware Memory Bandwidth Allocation and Monitor
+----------------------------------------------------
+Intel hardware supports Region-Aware Memory Bandwidth Allocation (MBA)
+and Region-Aware Memory Bandwidth Monitoring (MBM). With Region-Aware
+MBA, independent bandwidth control (throttling) of L3 domain bandwidth
+to multiple regions is supported, enabling users to dynamically rebalance
+bandwidth control limits across different memory regions, each of which
+may have distinct bandwidth, latency, and capacity characteristics.
+Region-Aware MBM includes the capability to independently track multiple
+domains that are simultaneously accessing several memory regions. These
+memory regions correspond to different levels of memory tiers, such as
+directly attached memory (Tier 1), CXL-attached memory (Tier 2), and
+CXL accelerator devices with attached memory. Note, the region ID is
+per socket scope. Intel platform supports up to 4 regions for now.
+
+Suppose there are 2 regions in each socket:
+
+ +------------------------+------------------------+
+ | +--------+ +--------+ | +--------+ +--------+ |
+ | | L3_00 | | L3_01 | | | L3_02 | | L3_03 | |
+ | +--------+ +--------+ | +--------+ +--------+ |
+ | +-------------------+ | +-------------------+ |
+ | | IMC1 | | | IMC2 | |
+ | +-------------------+ | +-------------------+ |
+ | +-------+ +-------+ | +-------+ +-------+ |
+ | | DDR1 | | CXL1 | | | DDR2 | | CXL2 | |
+ | +-------+ +-------+ | +-------+ +-------+ |
+ | socket0 | socket1 |
+ +------------------------+------------------------+
+
+In above graph, from the perspective of a CPU associated with
+the L3_00 domain, Region 0 typically represents the local memory
+region (DDR1), while Region 2 typically represents the remote
+memory region (DDR2). Similarly, for CPUs attached to L3_00,
+Region 1 represents the local memory region (CXL1), and Region 3
+represents the remote memory region (CXL2). Here the terms "local"
+and "remote" here are defined at the socket level.
+
+Take the region aware MBM for example. For the L3_00 domain, the
+memory bandwidth of Region 0 refers to the data transferred when
+the L3 miss occurs in L3_00 and the data is refilled from DDR1 -
+note, data refilled from L3_01 to L3_00 is not counted in. The
+bandwidth of Region 2, by contrast, refers to the data refilled
+from DDR2. Similarly, the same calculation logic applies to
+Region 1 (CXL1) and Region 3 (CXL2).
+
+For Region-Aware MBA, when setting values for Region 0 on CPUs
+attached to L3_00, this configuration controls the traffic generated
+when data is transferred between cores and L3_00 targeting DDR1.
+
Reading/writing the schemata file
---------------------------------
Reading the schemata file will show the state of all resources
@@ -1048,6 +1104,60 @@ For example, to allocate 8GB/s limit on the first cache id:
MB:0=2048;1=2048;2=2048;3=2048
L3:0=ffff;1=ffff;2=ffff;3=ffff
+Reading/writing the schemata file (on Intel systems) with region MBA feature
+----------------------------------------------------------------------------
+The schemata file provides fine grained control over each memory region.
+Every region has its own set of controls, and each of them appears as a
+separate line named "MB_REGION<n>_<type>", where <n> is the region number
+and <type> is one of OPT, MIN or MAX. Only the control types the hardware
+reports in the MARC ACPI sub-table are present.
+
+The legacy "MB" control is emulated by the MAX control of every region, so
+writing "MB" throttles all regions at once, while writing an individual
+"MB_REGION<n>_MAX" line throttles just that region.
+
+Reading and writing the schemata file is illustrated below for a platform
+with 2 memory regions. For example, to adjust the tier1 local memory
+bandwidth (usually the DDR):
+
+::
+
+ # cat schemata
+ MB:0=100;1=100;2=100;3=100
+ MB_REGION0_OPT:0=511;1=511;2=511;3=511
+ MB_REGION0_MIN:0=511;1=511;2=511;3=511
+ MB_REGION0_MAX:0=511;1=511;2=511;3=511
+ MB_REGION1_OPT:0=511;1=511;2=511;3=511
+ MB_REGION1_MIN:0=511;1=511;2=511;3=511
+ MB_REGION1_MAX:0=511;1=511;2=511;3=511
+ L3:0=3ff;1=3ff;2=3ff;3=3ff
+
+ # echo "MB_REGION0_MAX:1=200" > schemata
+ # cat schemata
+ MB:0=100;1=100;2=100;3=100
+ MB_REGION0_OPT:0=511;1=511;2=511;3=511
+ MB_REGION0_MIN:0=511;1=511;2=511;3=511
+ MB_REGION0_MAX:0=511;1=200;2=511;3=511
+ MB_REGION1_OPT:0=511;1=511;2=511;3=511
+ MB_REGION1_MIN:0=511;1=511;2=511;3=511
+ MB_REGION1_MAX:0=511;1=511;2=511;3=511
+ L3:0=3ff;1=3ff;2=3ff;3=3ff
+
+The value range of a region control is reported by the hardware and is
+available under the resource_schemata directory of that control, together
+with the rest of its properties.
+
+Users can obtain tiering information via sysfs, specifically
+through the path /sys/bus/memory_tier/devices/memory_tier.<id>/nodelist.
+The user can query the /sys/firmware/acpi/memory_ranges to find
+the corresponding node id for a specific region number.
+
+Once users have the corresponding node numbers, they can use the command
+numactl -H to retrieve additional node-related information if they need
+to further understand what each node represents. This information includes
+details such as the CPUs associated with the node (if any), the memory size
+of each node, and the distance between nodes.
+
Cache Pseudo-Locking
====================
CAT enables a user to specify the amount of cache space that an
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2.43.0
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