[PATCH v2 2/4] ACPI/MRRM: Create /sys/firmware/acpi/memory_ranges/rangeX ABI

Tony Luck
2025-02-27T22:48:40Z

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, and which region tags apply for
same-socket and cross-socket access.

[Derived from code developed by Fenghua Yu <fenghua.yu@intel.com>]

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
include/linux/acpi.h | 6 ++
drivers/acpi/acpi_mrrm.c | 161 +++++++++++++++++++++++++++++++++++++++
arch/x86/Kconfig | 1 +
drivers/acpi/Kconfig | 3 +
drivers/acpi/Makefile | 1 +
5 files changed, 172 insertions(+)
create mode 100644 drivers/acpi/acpi_mrrm.c

diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 4e495b29c640..677a9c4fa355 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -773,6 +773,12 @@ 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..1f7d0381a628
--- /dev/null
+++ b/drivers/acpi/acpi_mrrm.c
@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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;
+
+/* Access for use by resctrl file system */
+int acpi_mrrm_max_mem_region(void)
+{
+ return max_mem_region;
+}
+
+struct mrrm_mem_range_entry {
+ u64 base;
+ u64 length;
+ 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 __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;
+
+ 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) \
+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, "0x%lx\n", (unsigned long)mre->name); \
+} \
+static struct kobj_attribute name##_attr = __ATTR_RO(name)
+
+RANGE_ATTR(base);
+RANGE_ATTR(length);
+RANGE_ATTR(local_region_id);
+RANGE_ATTR(remote_region_id);
+
+static struct attribute *memory_range_attrs[] = {
+ &base_attr.attr,
+ &length_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);
+
+ if (ret < 0)
+ return ret;
+
+ return add_boot_memory_ranges();
+}
+device_initcall(mrrm_init);
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index be2c311f5118..f77af6b3c6cb 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -36,6 +36,7 @@ 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 d81b55f5068c..4f9aea2d0bc8 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 40208a0f5dfb..5092b518fc9b 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -62,6 +62,7 @@ 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