[PATCH v4 3/4] ACPI/MRRM: Add /sys files to describe memory ranges

Tony Luck
2025-04-29T20:24:23Z

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 | 143 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 142 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/acpi_mrrm.c b/drivers/acpi/acpi_mrrm.c
index ab8022e58da5..f04645a0407f 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 +22,162 @@ 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)
+{
+ 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_to_nid(zone);
+ }
+ }
+
+ 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