[PATCH v2 0/7] AMD HSMP: metrics table improvements and Family 1Ah Model 50h-5Fh support

Muralidhara M K
2026-04-27T15:52:00Z

This series adds HSMP protocol version 7 support for AMD Family 1Ah
Model 50h-5Fh processors and replaces offset-based chunked reading
with a single read method for variable-sized metrics data larger than
4 KB, and addresses locking to allow concurrent reads safely.

The zen6 metric table (~13 KB) exceeds the PAGE_SIZE (4096 bytes) read
cap imposed by kernfs_file_read_iter(). Commit 3124eb1679b2 ("sysfs:
remove bin_attribute.size") cleared i_size for sysfs binary files,
which made kernfs_file_read_iter() fall back to PAGE_SIZE as the
maximum single-read length. This means userspace gets a silently
truncated snapshot when reading the metric table via sysfs.

To solve this, the series introduces SYSFS_HUGE_BIN_FILE, a new sysfs
mode flag that routes binary attribute reads through the seq_file path
(seq_read_iter) instead of kernfs_file_read_iter(). The seq_file
buffer grows dynamically (doubling from PAGE_SIZE) and has no built-in
size cap, so it can serve arbitrarily large binary attributes in a
single read.

Additionally, the series retrieves the actual metric table size from
the SMU at init time (via args[2] of HSMP_GET_METRIC_TABLE_DRAM_ADDR)
rather than relying on a compiled-in sizeof(), and adds per-socket
mutex serialization for metric table reads using the scoped guard(mutex)
API.

Link: https://lore.kernel.org/platform-driver-x86/81915669-87e0-f06d-7a91-eaec41ecc0e1@linux.intel.com/T/#m28341c51bcf27862ef6615414b1970d3db279fd7

Patch breakdown:

1/7 HSMP messages - Define HSMP protocol v7 message IDs and
response sizes in the UAPI header.
2/7 UAPI structs - Add hsmp_metric_table_zen6 UAPI structures
and widen acpi.c proto_ver checks to >= VER6.
3/7 response_sz - Unify response_sz validation to an upper-bound
check, allowing HSMP_GET_METRIC_TABLE_DRAM_ADDR
to return 3 dwords (including table size).
4/7 SYSFS_HUGE_BIN_FILE - Add the sysfs infrastructure: new flag,
seq_show callback, and kernfs_ops for binary
files larger than PAGE_SIZE.
5/7 Dynamic size - Read actual table size from SMU args[2] at
init time; use bin_size callback to report it
to sysfs.
6/7 Read locking - Add per-socket guard(mutex) serialization for
metric table reads to prevent torn snapshots.
7/7 Wire it up - Set SYSFS_HUGE_BIN_FILE mode on metric table
bin_attributes in both acpi.c and plat.c.

Build-tested each patch individually with W=1, zero warnings.
Tested on AMD Family 1Ah Model 50h platform with HSMP protocol v7.

Muralidhara M K (6):
platform/x86/amd/hsmp: Add metrics table support for Family 1Ah Model
50h-5Fh
platform/x86/amd/hsmp: Unify response_sz validation to an upper-bound
check
sysfs: Add SYSFS_HUGE_BIN_FILE flag for binary attributes larger than
PAGE_SIZE
platform/x86/amd/hsmp: Add dynamic table size for metric table
platform/x86/amd/hsmp: Make metric table read locking use guard(mutex)
platform/x86/amd/hsmp: Support SYSFS_HUGE_BIN_FILE for metric table
reads

Suma Hegde (1):
platform/x86/amd/hsmp: Add new HSMP messages for Family 1Ah, Model
50h-5Fh

arch/x86/include/uapi/asm/amd_hsmp.h | 235 ++++++++++++++++++++++++---
drivers/platform/x86/amd/hsmp/acpi.c | 14 +-
drivers/platform/x86/amd/hsmp/hsmp.c | 36 ++--
drivers/platform/x86/amd/hsmp/hsmp.h | 6 +-
drivers/platform/x86/amd/hsmp/plat.c | 13 +-
fs/sysfs/file.c | 45 +++++
fs/sysfs/group.c | 8 +-
include/linux/sysfs.h | 1 +
8 files changed, 312 insertions(+), 46 deletions(-)

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2.34.1