[PATCH v4 6/7] platform/x86/amd/hsmp: Enable HSMP_PROTO_VER7 metric tables on the ACPI driver via the IOCTL

[Muralidhara M K <muralidhara.mk@amd.com>]

The ACPI driver currently prepares the per-socket metric table only
on HSMP_PROTO_VER6. With protocol version 7 in use on Family 1Ah
Model 50h-5Fh, userspace cannot reach the new ~13 KB
hsmp_metric_table_zen6: hsmp_get_tbl_dram_base() is skipped,
sock->metric_tbl_addr stays NULL, and the ioctl added earlier in
this series has nothing to read.

Widen the proto_ver gate in init_acpi() from '== HSMP_PROTO_VER6'
to '>= HSMP_PROTO_VER6' so the DRAM region is mapped and
hsmp_pdev.hsmp_table_size is populated on protocol version 7 (and
any future compatible version), making the ioctl path functional.

hsmp_metric_tbl_acpi_read() now returns -EOPNOTSUPP whenever the
running protocol version is not VER6. v7 userspace gets a clear,
actionable error and a documented pointer to
HSMP_IOCTL_GET_TELEMETRY_DATA; v6 userspace sees no change.

The non-ACPI plat.c path is intentionally left untouched: it covers
Family 1Ah Model 0h-Fh hardware fixed at protocol version 6, where
the existing metrics_bin remains the supported interface.

Co-developed-by: Muthusamy Ramalingam <muthusamy.ramalingam@amd.com>
Signed-off-by: Muthusamy Ramalingam <muthusamy.ramalingam@amd.com>
Signed-off-by: Muralidhara M K <muralidhara.mk@amd.com>
---
 drivers/platform/x86/amd/hsmp/acpi.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/platform/x86/amd/hsmp/acpi.c b/drivers/platform/x86/amd/hsmp/acpi.c
index 97ed71593bdf..8dc6b4a8bd27 100644
--- a/drivers/platform/x86/amd/hsmp/acpi.c
+++ b/drivers/platform/x86/amd/hsmp/acpi.c
@@ -238,13 +238,32 @@ static ssize_t hsmp_metric_tbl_acpi_read(struct file *filp, struct kobject *kobj
 	struct device *dev = container_of(kobj, struct device, kobj);
 	struct hsmp_socket *sock = dev_get_drvdata(dev);
 
+	/*
+	 * metrics_bin is a sysfs binary attribute and is capped at PAGE_SIZE.
+	 * It can therefore only carry the protocol version 6 metric table
+	 * (struct hsmp_metric_table).  Larger tables (HSMP_PROTO_VER7+, e.g.
+	 * struct hsmp_metric_table_zen6 at ~13 KB used on Family 1Ah Model
+	 * 50h-5Fh) do not fit; userspace on those systems must read the
+	 * snapshot through HSMP_IOCTL_GET_TELEMETRY_DATA on /dev/hsmp.
+	 * Surface the unsupported case here as -EOPNOTSUPP rather than
+	 * silently truncating the snapshot.
+	 */
+	if (hsmp_pdev->proto_ver != HSMP_PROTO_VER6)
+		return -EOPNOTSUPP;
+
 	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)
+	/*
+	 * Keep metrics_bin visible for HSMP_PROTO_VER7+ as well, so that
+	 * userspace which expects the file to exist gets a clear
+	 * -EOPNOTSUPP from the read handler instead of -ENOENT, and is
+	 * pointed at HSMP_IOCTL_GET_TELEMETRY_DATA as the supported path.
+	 */
+	if (hsmp_pdev->proto_ver >= HSMP_PROTO_VER6)
 		return battr->attr.mode;
 
 	return 0;
@@ -491,7 +510,7 @@ 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");
-- 
2.34.1