[PATCH v3 0/4] Add interfaces for ACPI MRRM table

[PATCH v3 0/4] Add interfaces for ACPI MRRM table

[Tony Luck]

Memory used to be homogeneous. Then NUMA came along. Later different
types of memory (persistent memory, on-package high bandwidth memory,
CXL attached memory).

Each type of memory has its own performance characteristics, and users
will need to monitor and control access by type.

The MRRM solution is to tag physical address ranges with "region IDs"
so that platform firmware[1] can indicate the type of memory for each
range (with separate tags available for local vs. remote access to
each range). Note that these ranges can include addresses reserved
for future hotplugged memory.

The region IDs will be used to provide separate event counts for each
region for "perf" and for the "resctrl" file system to monitor and
control memory bandwidth in each region.

Users will need to know the address range(s) that are part of each
region. This patch series adds
	/sys/firmware/acpi/memory_ranges/rangeX
directories to provide user space accessible enumeration.

-Tony

[1] MRRM definition allow for future expansion for the OS to assign
these region IDs.

Changes since version 2 here:
https://lore.kernel.org/all/20250227224828.306537-1-tony.luck@intel.com/

1) Changes in patch 1 are now in the R2025_04_04 release of the ACPICA
project (plus PR #1015 to fix a naming issue for "acpisrc" conversion
to Linux format).

2) Split the /sys/firmware part into its own patch. Linux resctrl only
needs the enumeration of the number of supported regions.

3) Added a "node" file to each of the rangeX directories to report
which NUMA node the range belongs to.

4) Dropped the debug-only last patch in the series as I now have
other methods to test this code.

Tony Luck (4):
  ACPICA: Define MRRM ACPI table
  ACPI/MRRM: Minimal parse of ACPI MRRM table
  ACPI/MRRM: Add /sys files to describe memory ranges
  ACPI: Add documentation for exposing MRRM data

 include/linux/acpi.h                          |   6 +
 include/acpi/actbl1.h                         |   7 +
 include/acpi/actbl2.h                         |  42 ++++
 drivers/acpi/acpi_mrrm.c                      | 185 ++++++++++++++++++
 Documentation/ABI/testing/sysfs-firmware-acpi |  21 ++
 arch/x86/Kconfig                              |   1 +
 drivers/acpi/Kconfig                          |   3 +
 drivers/acpi/Makefile                         |   1 +
 8 files changed, 266 insertions(+)
 create mode 100644 drivers/acpi/acpi_mrrm.c


base-commit: 0af2f6be1b4281385b618cb86ad946eded089ac8
-- 
2.48.1

[PATCH v3 1/4] ACPICA: Define MRRM ACPI table

[Tony Luck]

Patch for reference, this has already been applied to
https://github.com/acpica/acpica and will in due course make its way
into Linux when the next ACPICA release is ported over.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
 include/acpi/actbl1.h |  7 +++++++
 include/acpi/actbl2.h | 42 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)

diff --git a/include/acpi/actbl1.h b/include/acpi/actbl1.h
index 387fc821703a..4cb36392e9e9 100644
--- a/include/acpi/actbl1.h
+++ b/include/acpi/actbl1.h
@@ -110,6 +110,13 @@ struct acpi_whea_header {
 	u64 mask;		/* Bitmask required for this register instruction */
 };
 
+/* Larger subtable header (when Length can exceed 255) */
+
+struct acpi_subtbl_hdr_16 {
+	u16 type;
+	u16 length;
+};
+
 /* https://docs.microsoft.com/en-us/windows-hardware/drivers/ddi/acpitabl/ns-acpitabl-aspt_table */
 #define ASPT_REVISION_ID 0x01
 struct acpi_table_aspt {
diff --git a/include/acpi/actbl2.h b/include/acpi/actbl2.h
index 2e917a8f8bca..e7423db6e24b 100644
--- a/include/acpi/actbl2.h
+++ b/include/acpi/actbl2.h
@@ -37,6 +37,7 @@
 #define ACPI_SIG_MCHI           "MCHI"	/* Management Controller Host Interface table */
 #define ACPI_SIG_MPAM           "MPAM"	/* Memory System Resource Partitioning and Monitoring Table */
 #define ACPI_SIG_MPST           "MPST"	/* Memory Power State Table */
+#define ACPI_SIG_MRRM           "MRRM"      /* Memory Range and Region Mapping table */
 #define ACPI_SIG_MSDM           "MSDM"	/* Microsoft Data Management Table */
 #define ACPI_SIG_NFIT           "NFIT"	/* NVDIMM Firmware Interface Table */
 #define ACPI_SIG_NHLT           "NHLT"	/* Non HD Audio Link Table */
@@ -1736,6 +1737,47 @@ struct acpi_msct_proximity {
 	u64 memory_capacity;	/* In bytes */
 };
 
+/*******************************************************************************
+ *
+ * MRRM - Memory Range and Region Mapping (MRRM) table
+ * Conforms to "Intel Resource Director Technology Architecture Specification"
+ * Version 1.1, January 2025
+ *
+ ******************************************************************************/
+
+struct acpi_table_mrrm {
+	struct acpi_table_header header;	/* Common ACPI table header */
+	u8 max_mem_region;			/* Max Memory Regions supported */
+	u8 flags;				/* Region assignment type */
+	u8 reserved[26];
+	u8 memory_range_entry[];
+};
+
+/* Flags */
+#define ACPI_MRRM_FLAGS_REGION_ASSIGNMENT_OS (1<<0)
+
+/*******************************************************************************
+	*
+	* Memory Range entry - Memory Range entry in MRRM table
+	*
+	******************************************************************************/
+
+struct acpi_mrrm_mem_range_entry {
+	struct acpi_subtbl_hdr_16 header;
+	u32 reserved0;		/* Reserved */
+	u64 addr_base;		/* Base addr of the mem range */
+	u64 addr_len;		/* Length of the mem range */
+	u16 region_id_flags;	/* Valid local or remote Region-ID */
+	u8 local_region_id;	/* Platform-assigned static local Region-ID */
+	u8 remote_region_id;	/* Platform-assigned static remote Region-ID */
+	u32 reserved1;		/* Reserved */
+	/* Region-ID Programming Registers[] */
+};
+
+/* Values for region_id_flags above */
+#define ACPI_MRRM_VALID_REGION_ID_FLAGS_LOCAL   (1<<0)
+#define ACPI_MRRM_VALID_REGION_ID_FLAGS_REMOTE  (1<<1)
+
 /*******************************************************************************
  *
  * MSDM - Microsoft Data Management table
-- 
2.48.1

[PATCH v3 2/4] ACPI/MRRM: Minimal parse of ACPI MRRM table

[Tony Luck]

The resctrl file system code needs to know how many region tags
are supported. Parse the ACPI MRRM table and save the max_mem_region
value.

Provide a function for resctrl to collect that value.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
 include/linux/acpi.h     |  6 ++++++
 drivers/acpi/acpi_mrrm.c | 42 ++++++++++++++++++++++++++++++++++++++++
 arch/x86/Kconfig         |  1 +
 drivers/acpi/Kconfig     |  3 +++
 drivers/acpi/Makefile    |  1 +
 5 files changed, 53 insertions(+)
 create mode 100644 drivers/acpi/acpi_mrrm.c

diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 3f2e93ed9730..24aa7a0ae272 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -772,6 +772,12 @@ int acpi_get_local_u64_address(acpi_handle handle, u64 *addr);
 int acpi_get_local_address(acpi_handle handle, u32 *addr);
 const char *acpi_get_subsystem_id(acpi_handle handle);
 
+#ifdef CONFIG_ACPI_MRRM
+int acpi_mrrm_max_mem_region(void);
+#else
+static inline int acpi_mrrm_max_mem_region(void) { return -ENOENT; }
+#endif
+
 #else	/* !CONFIG_ACPI */
 
 #define acpi_disabled 1
diff --git a/drivers/acpi/acpi_mrrm.c b/drivers/acpi/acpi_mrrm.c
new file mode 100644
index 000000000000..ab8022e58da5
--- /dev/null
+++ b/drivers/acpi/acpi_mrrm.c
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2025, Intel Corporation.
+ *
+ * Memory Range and Region Mapping (MRRM) structure
+ */
+
+#define pr_fmt(fmt) "acpi/mrrm: " fmt
+
+#include <linux/acpi.h>
+#include <linux/init.h>
+
+static int max_mem_region = -ENOENT;
+
+/* Access for use by resctrl file system */
+int acpi_mrrm_max_mem_region(void)
+{
+	return max_mem_region;
+}
+
+static __init int acpi_parse_mrrm(struct acpi_table_header *table)
+{
+	struct acpi_table_mrrm *mrrm;
+
+	mrrm = (struct acpi_table_mrrm *)table;
+	if (!mrrm)
+		return -ENODEV;
+
+	max_mem_region = mrrm->max_mem_region;
+
+	return 0;
+}
+
+static __init int mrrm_init(void)
+{
+	int ret;
+
+	ret = acpi_table_parse(ACPI_SIG_MRRM, acpi_parse_mrrm);
+
+	return ret;
+}
+device_initcall(mrrm_init);
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 4b9f378e05f6..0e43069082df 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -38,6 +38,7 @@ config X86_64
 	select ARCH_HAS_ELFCORE_COMPAT
 	select ZONE_DMA32
 	select EXECMEM if DYNAMIC_FTRACE
+	select ACPI_MRRM if ACPI
 
 config FORCE_DYNAMIC_FTRACE
 	def_bool y
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 7f10aa38269d..7bc40c2735ac 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -576,6 +576,9 @@ config ACPI_FFH
 	  Enable this feature if you want to set up and install the FFH Address
 	  Space handler to handle FFH OpRegion in the firmware.
 
+config ACPI_MRRM
+	bool
+
 source "drivers/acpi/pmic/Kconfig"
 
 config ACPI_VIOT
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 797070fc9a3f..d1b0affb844f 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -66,6 +66,7 @@ acpi-$(CONFIG_ACPI_WATCHDOG)	+= acpi_watchdog.o
 acpi-$(CONFIG_ACPI_PRMT)	+= prmt.o
 acpi-$(CONFIG_ACPI_PCC)		+= acpi_pcc.o
 acpi-$(CONFIG_ACPI_FFH)		+= acpi_ffh.o
+acpi-$(CONFIG_ACPI_MRRM)	+= acpi_mrrm.o
 
 # Address translation
 acpi-$(CONFIG_ACPI_ADXL)	+= acpi_adxl.o
-- 
2.48.1

[PATCH v3 3/4] ACPI/MRRM: Add /sys files to describe memory ranges

[Tony Luck]

Perf and resctrl users need an enumeration of which memory addresses
are bound to which "region" tag.

Parse the ACPI MRRM table and add /sys entries for each memory range
describing base address, length, NUMA node, and which region tags apply
for same-socket and cross-socket access.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
 drivers/acpi/acpi_mrrm.c | 145 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 144 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/acpi_mrrm.c b/drivers/acpi/acpi_mrrm.c
index ab8022e58da5..9d8d332d383e 100644
--- a/drivers/acpi/acpi_mrrm.c
+++ b/drivers/acpi/acpi_mrrm.c
@@ -3,12 +3,16 @@
  * Copyright (c) 2025, Intel Corporation.
  *
  * Memory Range and Region Mapping (MRRM) structure
+ *
+ * Parse and report the platform's MRRM table in /sys.
  */
 
 #define pr_fmt(fmt) "acpi/mrrm: " fmt
 
 #include <linux/acpi.h>
 #include <linux/init.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
 
 static int max_mem_region = -ENOENT;
 
@@ -18,25 +22,164 @@ int acpi_mrrm_max_mem_region(void)
 	return max_mem_region;
 }
 
+struct mrrm_mem_range_entry {
+	u64 base;
+	u64 length;
+	int node;
+	u8  local_region_id;
+	u8  remote_region_id;
+};
+
+static struct mrrm_mem_range_entry *mrrm_mem_range_entry;
+static u32 mrrm_mem_entry_num;
+
+static int get_node_num(struct mrrm_mem_range_entry *e)
+{
+#ifdef CONFIG_NUMA
+	unsigned int nid;
+
+	for_each_online_node(nid) {
+		for (int z = 0; z < MAX_NR_ZONES; z++) {
+			struct zone *zone = NODE_DATA(nid)->node_zones + z;
+
+			if (!populated_zone(zone))
+				continue;
+			if (zone_intersects(zone, PHYS_PFN(e->base), PHYS_PFN(e->length)))
+				return zone->node;
+		}
+	}
+#endif
+
+	return -ENOENT;
+}
+
 static __init int acpi_parse_mrrm(struct acpi_table_header *table)
 {
+	struct acpi_mrrm_mem_range_entry *mre_entry;
 	struct acpi_table_mrrm *mrrm;
+	void *mre, *mrrm_end;
+	int mre_count = 0;
 
 	mrrm = (struct acpi_table_mrrm *)table;
 	if (!mrrm)
 		return -ENODEV;
 
+	if (mrrm->flags & ACPI_MRRM_FLAGS_REGION_ASSIGNMENT_OS)
+		return -EOPNOTSUPP;
+
+	mrrm_end = (void *)mrrm + mrrm->header.length - 1;
+	mre = (void *)mrrm + sizeof(struct acpi_table_mrrm);
+	while (mre < mrrm_end) {
+		mre_entry = mre;
+		mre_count++;
+		mre += mre_entry->header.length;
+	}
+	if (!mre_count) {
+		pr_info(FW_BUG "No ranges listed in MRRM table\n");
+		return -EINVAL;
+	}
+
+	mrrm_mem_range_entry = kmalloc_array(mre_count, sizeof(*mrrm_mem_range_entry),
+					     GFP_KERNEL | __GFP_ZERO);
+	if (!mrrm_mem_range_entry)
+		return -ENOMEM;
+
+	mre = (void *)mrrm + sizeof(struct acpi_table_mrrm);
+	while (mre < mrrm_end) {
+		struct mrrm_mem_range_entry *e;
+
+		mre_entry = mre;
+		e = mrrm_mem_range_entry + mrrm_mem_entry_num;
+
+		e->base = mre_entry->addr_base;
+		e->length = mre_entry->addr_len;
+		e->node = get_node_num(e);
+
+		if (mre_entry->region_id_flags & ACPI_MRRM_VALID_REGION_ID_FLAGS_LOCAL)
+			e->local_region_id = mre_entry->local_region_id;
+		else
+			e->local_region_id = -1;
+		if (mre_entry->region_id_flags & ACPI_MRRM_VALID_REGION_ID_FLAGS_REMOTE)
+			e->remote_region_id = mre_entry->remote_region_id;
+		else
+			e->remote_region_id = -1;
+
+		mrrm_mem_entry_num++;
+		mre += mre_entry->header.length;
+	}
+
 	max_mem_region = mrrm->max_mem_region;
 
 	return 0;
 }
 
+#define RANGE_ATTR(name, fmt)						\
+static ssize_t name##_show(struct kobject *kobj,			\
+			  struct kobj_attribute *attr, char *buf)	\
+{									\
+	struct mrrm_mem_range_entry *mre;				\
+	const char *kname = kobject_name(kobj);				\
+	int n, ret;							\
+									\
+	ret = kstrtoint(kname + 5, 10, &n);				\
+	if (ret)							\
+		return ret;						\
+									\
+	mre = mrrm_mem_range_entry + n;					\
+									\
+	return sysfs_emit(buf, fmt, mre->name);				\
+}									\
+static struct kobj_attribute name##_attr = __ATTR_RO(name)
+
+RANGE_ATTR(base, "0x%llx\n");
+RANGE_ATTR(length, "0x%llx\n");
+RANGE_ATTR(node, "%d\n");
+RANGE_ATTR(local_region_id, "%d\n");
+RANGE_ATTR(remote_region_id, "%d\n");
+
+static struct attribute *memory_range_attrs[] = {
+	&base_attr.attr,
+	&length_attr.attr,
+	&node_attr.attr,
+	&local_region_id_attr.attr,
+	&remote_region_id_attr.attr,
+	NULL
+};
+
+ATTRIBUTE_GROUPS(memory_range);
+
+static __init int add_boot_memory_ranges(void)
+{
+	struct kobject *pkobj, *kobj;
+	int ret = -EINVAL;
+	char *name;
+
+	pkobj = kobject_create_and_add("memory_ranges", acpi_kobj);
+
+	for (int i = 0; i < mrrm_mem_entry_num; i++) {
+		name = kasprintf(GFP_KERNEL, "range%d", i);
+		if (!name)
+			break;
+
+		kobj = kobject_create_and_add(name, pkobj);
+
+		ret = sysfs_create_groups(kobj, memory_range_groups);
+		if (ret)
+			return ret;
+	}
+
+	return ret;
+}
+
 static __init int mrrm_init(void)
 {
 	int ret;
 
 	ret = acpi_table_parse(ACPI_SIG_MRRM, acpi_parse_mrrm);
 
-	return ret;
+	if (ret < 0)
+		return ret;
+
+	return add_boot_memory_ranges();
 }
 device_initcall(mrrm_init);
-- 
2.48.1

[PATCH v3 4/4] ACPI: Add documentation for exposing MRRM data

[Tony Luck]

Initial implementation provides enumeration of the address ranges
NUMA node numbers, and BIOS assigned region IDs for each range.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
 Documentation/ABI/testing/sysfs-firmware-acpi | 21 +++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-firmware-acpi b/Documentation/ABI/testing/sysfs-firmware-acpi
index 5249ad5a96d9..fffba38f9ce1 100644
--- a/Documentation/ABI/testing/sysfs-firmware-acpi
+++ b/Documentation/ABI/testing/sysfs-firmware-acpi
@@ -248,3 +248,24 @@ Description:
 		  # cat ff_pwr_btn
 		  7	enabled
 
+What:		/sys/firmware/acpi/memory_ranges/rangeX
+Date:		February 2025
+Contact:	Tony Luck <tony.luck@intel.com>
+Description:
+		On systems with the ACPI MRRM table reports the
+		parameters for each range.
+
+		base: Starting system physical address.
+
+		length: Length of this range in bytes.
+
+		node: NUMA node that this range belongs to. Negative numbers
+		indicate that the node number could not be determined (e.g
+		for an address range that is reserved for future hot add of
+		memory).
+
+		local_region_id: ID associated with access by agents
+		local to this range of addresses.
+
+		remote_region_id: ID associated with access by agents
+		non-local to this range of addresses.
-- 
2.48.1