[PATCH v7 3/5] platform/x86/amd/hsmp: Source metric-table size from firmware

[Muralidhara M K]

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 table under
protocol version 7, 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, and
store the result in the new per-socket hsmp_socket.metric_tbl_size,
which is then used both for the ioremap() of the region and as the
expected size in hsmp_metric_tbl_read().

The size is stored per socket rather than per platform because
hsmp_get_tbl_dram_base() runs once per socket and each socket maps
its own region. A single platform-wide field would let the last
socket's size be used to copy out of an earlier socket's smaller
mapping.

Bump DRIVER_VERSION to 2.6.

Behaviour on existing protocol-version-6 hardware is unchanged.
Reading a third response word is safe there: for this command SMU
leaves args[2] as 0 rather than a stale value from an earlier
mailbox transaction, so the fallback always applies, yielding the
same value as the previous hard-coded one, and both the ioremap and
the size check produce the same result as before.

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>
---
 arch/x86/include/uapi/asm/amd_hsmp.h |  5 +++--
 drivers/platform/x86/amd/hsmp/hsmp.c | 17 ++++++++++++++---
 drivers/platform/x86/amd/hsmp/hsmp.h |  5 ++++-
 3 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/uapi/asm/amd_hsmp.h b/arch/x86/include/uapi/asm/amd_hsmp.h
index eff35c3c6ce0..d1d3bc60cffc 100644
--- a/arch/x86/include/uapi/asm/amd_hsmp.h
+++ b/arch/x86/include/uapi/asm/amd_hsmp.h
@@ -367,11 +367,12 @@ 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 02425f7e6f14..3e9bdbcd9ea9 100644
--- a/drivers/platform/x86/amd/hsmp/hsmp.c
+++ b/drivers/platform/x86/amd/hsmp/hsmp.c
@@ -429,8 +429,7 @@ 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 != sock->metric_tbl_size) {
 		dev_err(sock->dev, "Wrong buffer size\n");
 		return -EINVAL;
 	}
@@ -484,6 +483,7 @@ void hsmp_unmap_metric_tbls(struct hsmp_plat_device *pdev)
 			iounmap(sock->metric_tbl_addr);
 			sock->metric_tbl_addr = NULL;
 		}
+		sock->metric_tbl_size = 0;
 	}
 }
 EXPORT_SYMBOL_NS_GPL(hsmp_unmap_metric_tbls, "AMD_HSMP");
@@ -493,6 +493,7 @@ int hsmp_get_tbl_dram_base(u16 sock_ind)
 	struct hsmp_socket *sock = &hsmp_pdev.sock[sock_ind];
 	struct hsmp_message msg = { 0 };
 	phys_addr_t dram_addr;
+	size_t tbl_size;
 	int ret;
 
 	msg.sock_ind	= sock_ind;
@@ -524,11 +525,21 @@ int hsmp_get_tbl_dram_base(u16 sock_ind)
 		iounmap(sock->metric_tbl_addr);
 		sock->metric_tbl_addr = NULL;
 	}
-	sock->metric_tbl_addr = ioremap(dram_addr, sizeof(struct hsmp_metric_table));
+	sock->metric_tbl_size = 0;
+
+	/* SMU returns table size from Family 1Ah Model 50h and forward */
+	if (msg.args[2])
+		tbl_size = msg.args[2];
+	else
+		tbl_size = sizeof(struct hsmp_metric_table);
+
+	sock->metric_tbl_addr = ioremap(dram_addr, tbl_size);
 	if (!sock->metric_tbl_addr) {
 		dev_err(sock->dev, "Failed to ioremap metric table addr\n");
 		return -ENOMEM;
 	}
+	sock->metric_tbl_size = tbl_size;
+
 	return 0;
 }
 EXPORT_SYMBOL_NS_GPL(hsmp_get_tbl_dram_base, "AMD_HSMP");
diff --git a/drivers/platform/x86/amd/hsmp/hsmp.h b/drivers/platform/x86/amd/hsmp/hsmp.h
index cfd1a8cbd459..8dbff16a87b1 100644
--- a/drivers/platform/x86/amd/hsmp/hsmp.h
+++ b/drivers/platform/x86/amd/hsmp/hsmp.h
@@ -20,6 +20,7 @@
 #include <linux/rwsem.h>
 #include <linux/semaphore.h>
 #include <linux/sysfs.h>
+#include <linux/types.h>
 
 #define HSMP_METRICS_TABLE_NAME	"metrics_bin"
 
@@ -29,7 +30,7 @@
 #define HSMP_DEVNODE_NAME	"hsmp"
 #define ACPI_HSMP_DEVICE_HID    "AMDI0097"
 
-#define DRIVER_VERSION		"2.5"
+#define DRIVER_VERSION		"2.6"
 
 struct hsmp_mbaddr_info {
 	u32 base_addr;
@@ -43,6 +44,8 @@ struct hsmp_socket {
 	struct bin_attribute hsmp_attr;
 	struct hsmp_mbaddr_info mbinfo;
 	void __iomem *metric_tbl_addr;
+	/* Size of the region mapped at @metric_tbl_addr, as reported by SMU */
+	size_t metric_tbl_size;
 	void __iomem *virt_base_addr;
 	struct semaphore hsmp_sem;
 	/* Serializes HSMP_GET_METRIC_TABLE fill-and-copy for this socket */
-- 
2.34.1