Re: [PATCH v3 6/7] platform/x86/amd/hsmp: Drop ACPI sysfs metrics_bin in favour of the IOCTL
From: M K, Muralidhara
Date: Tue May 26 2026 - 06:00:01 EST
On 5/22/2026 5:14 PM, Ilpo Järvinen wrote:
Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.Sure I will update the changelog to document the rationale for moving away from sysfs files.
On Sun, 17 May 2026, Muralidhara M K wrote:
The HSMP_IOCTL_GET_TELEMETRY_DATA character-device ioctl introduced in
the previous patch is now the canonical interface for reading the
metric table on the ACPI driver path. Unlike the metrics_bin sysfs
binary attribute, the ioctl is not constrained by PAGE_SIZE, so it
works for the ~13 KB hsmp_metric_table_zen6 layout
This was only a secondary reason from moving away from sysfs files? The
main cause for moving to misc device according to my impression was that
you wanted to prevent partial reads which are always possible with files.
Ya Understood. I will make this change as a separate patch.used on Family 1Ah
Model 50h-5Fh as well as for the existing hsmp_metric_table layout
used on protocol version 6.
Drop the metrics_bin bin_attribute from the ACPI hsmp_attr_grp.
Widen the remaining proto_ver gate in init_acpi() from
'== HSMP_PROTO_VER6' to '>= HSMP_PROTO_VER6' so
hsmp_get_tbl_dram_base() is invoked on protocol version 7
(Family 1Ah Model 50h-5Fh) and any future protocol version that
retains a compatible per-socket metric table. This populates
sock->metric_tbl_addr and hsmp_pdev.hsmp_table_size, which the ioctl
handler requires.
These are two logically separate changes so they should not be in the same
patch (but you'll likely need to alter the drop patch anyway, see below).
I will review and ensure that an appropriate error is returned if sysfs is not supported for a particular version.This is an ABI change for users of the ACPI driver:
/sys/bus/platform/devices/AMDI0097:*/metrics_bin no longer exists.
Userspace must read telemetry through the HSMP_IOCTL_GET_TELEMETRY_DATA
ioctl on /dev/hsmp instead, sizing its buffer using the matching UAPI
metric table struct.
I might not be entirely following what's the extent of removal here but it
looks too extensive to me. The number 1 rule is that we cannot take away
existing and working ABI without properly deprecating it first.
You don't have to make it work with version 7 and can return error in
that case as it has never worked. But with version 6, things shouls be
left as is until properly deprecated. You may consider adding a warning
print too to warn about the deprecation and point towards the new way.
This interface probably never was documented in Documentation/ABI where
such deprecations are usually marked... oh well, maybe we need to add
a simple entry for this ABI there to follow the usual deprecation path.
--
i.
The non-ACPI plat.c path is intentionally left
unchanged: it covers Family 1Ah Model 0h-Fh hardware that is fixed at
protocol version 6, and its per-socket metrics_bin remains available
for existing userspace tooling on those systems.
Co-developed-by: Muthusamy Ramalingam <muthusamy.ramalingam@xxxxxxx>
Signed-off-by: Muthusamy Ramalingam <muthusamy.ramalingam@xxxxxxx>
Signed-off-by: Muralidhara M K <muralidhara.mk@xxxxxxx>
---
Changes:
v1->v3: Remove bin attributes
drivers/platform/x86/amd/hsmp/acpi.c | 34 +---------------------------
1 file changed, 1 insertion(+), 33 deletions(-)
diff --git a/drivers/platform/x86/amd/hsmp/acpi.c b/drivers/platform/x86/amd/hsmp/acpi.c
index 97ed71593bdf..49765fefe1fb 100644
--- a/drivers/platform/x86/amd/hsmp/acpi.c
+++ b/drivers/platform/x86/amd/hsmp/acpi.c
@@ -231,25 +231,6 @@ static int hsmp_parse_acpi_table(struct device *dev, u16 sock_ind)
return hsmp_read_acpi_dsd(sock);
}
-static ssize_t hsmp_metric_tbl_acpi_read(struct file *filp, struct kobject *kobj,
- const struct bin_attribute *bin_attr, char *buf,
- loff_t off, size_t count)
-{
- struct device *dev = container_of(kobj, struct device, kobj);
- struct hsmp_socket *sock = dev_get_drvdata(dev);
-
- return hsmp_metric_tbl_read(sock, buf, count);
-}
-
-static umode_t hsmp_is_sock_attr_visible(struct kobject *kobj,
- const struct bin_attribute *battr, int id)
-{
- if (hsmp_pdev->proto_ver == HSMP_PROTO_VER6)
- return battr->attr.mode;
-
- return 0;
-}
-
static umode_t hsmp_is_sock_dev_attr_visible(struct kobject *kobj,
struct attribute *attr, int id)
{
@@ -491,7 +472,7 @@ static int init_acpi(struct device *dev)
return ret;
}
- if (hsmp_pdev->proto_ver == HSMP_PROTO_VER6) {
+ if (hsmp_pdev->proto_ver >= HSMP_PROTO_VER6) {
ret = hsmp_get_tbl_dram_base(sock_ind);
if (ret)
dev_info(dev, "Failed to init metric table\n");
@@ -506,17 +487,6 @@ static int init_acpi(struct device *dev)
return 0;
}
-static const struct bin_attribute hsmp_metric_tbl_attr = {
- .attr = { .name = HSMP_METRICS_TABLE_NAME, .mode = 0444},
- .read = hsmp_metric_tbl_acpi_read,
- .size = sizeof(struct hsmp_metric_table),
-};
-
-static const struct bin_attribute *hsmp_attr_list[] = {
- &hsmp_metric_tbl_attr,
- NULL
-};
-
#define HSMP_DEV_ATTR(_name, _msg_id, _show, _mode) \
static struct hsmp_sys_attr hattr_##_name = { \
.dattr = __ATTR(_name, _mode, _show, NULL), \
@@ -559,9 +529,7 @@ static struct attribute *hsmp_dev_attr_list[] = {
};
static const struct attribute_group hsmp_attr_grp = {
- .bin_attrs = hsmp_attr_list,
.attrs = hsmp_dev_attr_list,
- .is_bin_visible = hsmp_is_sock_attr_visible,
.is_visible = hsmp_is_sock_dev_attr_visible,
};