[PATCH v4 4/7] platform/x86/amd/hsmp: Source metric-table size from firmware

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

The driver hard-codes the metric-table region size to
sizeof(struct hsmp_metric_table). That is correct for HSMP protocol
version 6 but mis-sizes the ioremap of the SMU DRAM region on newer
platforms: Family 1Ah Model 50h-5Fh exposes a ~13 KB
hsmp_metric_table_zen6, and the table is expected to keep growing
on future firmware. The same hard-coded value also forces
hsmp_metric_tbl_read() to reject any read that follows the actual
firmware layout.

Pick up the table size from firmware instead. SMU on Family 1Ah
Model 50h and later populates HSMP_GET_METRIC_TABLE_DRAM_ADDR's
args[2] with the DRAM region size in bytes; older firmware leaves
it 0. Bump the descriptor's response_sz to 3 so the field is read,
store the value in hsmp_pdev.hsmp_table_size at probe time, and
fall back to sizeof(struct hsmp_metric_table) when firmware reports
0. Use hsmp_table_size both for the devm_ioremap() of the region
and as the upper bound for hsmp_metric_tbl_read().

Behaviour on existing protocol-version-6 hardware is unchanged:
firmware returns 0, the fallback yields the same value as the
previous hard-coded one, and both the ioremap and the size check
produce the same result as before.

The ioctl interface added later in this series uses the same
hsmp_table_size to validate the userspace request and to copy out
the full firmware-reported region.

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>
---
 arch/x86/include/uapi/asm/amd_hsmp.h |  5 +++--
 drivers/platform/x86/amd/hsmp/hsmp.c | 11 ++++++++---
 drivers/platform/x86/amd/hsmp/hsmp.h |  1 +
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/uapi/asm/amd_hsmp.h b/arch/x86/include/uapi/asm/amd_hsmp.h
index fce271282348..438ac38d0dc8 100644
--- a/arch/x86/include/uapi/asm/amd_hsmp.h
+++ b/arch/x86/include/uapi/asm/amd_hsmp.h
@@ -365,11 +365,12 @@ static const struct hsmp_msg_desc hsmp_msg_desc_table[]
 	{0, 0, HSMP_GET},
 
 	/*
-	 * HSMP_GET_METRIC_TABLE_DRAM_ADDR, num_args = 0, response_sz = 2
+	 * HSMP_GET_METRIC_TABLE_DRAM_ADDR, num_args = 0, response_sz = 3
 	 * output: args[0] = lower 32 bits of the address
 	 * output: args[1] = upper 32 bits of the address
+	 * output: args[2] = DRAM region size in bytes
 	 */
-	{0, 2, HSMP_GET},
+	{0, 3, HSMP_GET},
 
 	/*
 	 * HSMP_SET_XGMI_PSTATE_RANGE, num_args = 1, response_sz = 0
diff --git a/drivers/platform/x86/amd/hsmp/hsmp.c b/drivers/platform/x86/amd/hsmp/hsmp.c
index 9bad58fef304..cf9392f99298 100644
--- a/drivers/platform/x86/amd/hsmp/hsmp.c
+++ b/drivers/platform/x86/amd/hsmp/hsmp.c
@@ -356,8 +356,7 @@ ssize_t hsmp_metric_tbl_read(struct hsmp_socket *sock, char *buf, size_t size)
 		return -ENOMEM;
 	}
 
-	/* Do not support lseek(), also don't allow more than the size of metric table */
-	if (size != sizeof(struct hsmp_metric_table)) {
+	if (size != hsmp_pdev.hsmp_table_size) {
 		dev_err(sock->dev, "Wrong buffer size\n");
 		return -EINVAL;
 	}
@@ -398,8 +397,14 @@ int hsmp_get_tbl_dram_base(u16 sock_ind)
 		dev_err(sock->dev, "Invalid DRAM address for metric table\n");
 		return -ENOMEM;
 	}
+	/* SMU returns table size from Family 1Ah Model 50h and forward */
+	if (msg.args[2])
+		hsmp_pdev.hsmp_table_size = msg.args[2];
+	else
+		hsmp_pdev.hsmp_table_size = sizeof(struct hsmp_metric_table);
+
 	sock->metric_tbl_addr = devm_ioremap(sock->dev, dram_addr,
-					     sizeof(struct hsmp_metric_table));
+					     hsmp_pdev.hsmp_table_size);
 	if (!sock->metric_tbl_addr) {
 		dev_err(sock->dev, "Failed to ioremap metric table addr\n");
 		return -ENOMEM;
diff --git a/drivers/platform/x86/amd/hsmp/hsmp.h b/drivers/platform/x86/amd/hsmp/hsmp.h
index b153527e0a0d..e7f051475728 100644
--- a/drivers/platform/x86/amd/hsmp/hsmp.h
+++ b/drivers/platform/x86/amd/hsmp/hsmp.h
@@ -55,6 +55,7 @@ struct hsmp_plat_device {
 	u32 proto_ver;
 	u16 num_sockets;
 	bool is_probed;
+	size_t hsmp_table_size;
 };
 
 int hsmp_cache_proto_ver(u16 sock_ind);
-- 
2.34.1