[PATCH] drm/amd: Refactor find_system_memory()

[Mario Limonciello <superm1@kernel.org>]

From: Mario Limonciello <mario.limonciello@amd.com>

find_system_memory() pulls out two fields from an SMBIOS type 17
device and sets them on KFD devices. This however is pulling from
the middle of the field in the SMBIOS device and leads to an unaligned
access.

Instead use a struct representation to access the members and pull
out the two specific fields.

Link: https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.8.0.pdf p99
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_topology.c | 27 +++++++++++------------
 drivers/gpu/drm/amd/amdkfd/kfd_topology.h | 17 ++++++++++++++
 2 files changed, 30 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_topology.c b/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
index ceb9fb475ef13..93d3924dfcba0 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
@@ -968,24 +968,23 @@ static void kfd_update_system_properties(void)
 	up_read(&topology_lock);
 }
 
-static void find_system_memory(const struct dmi_header *dm,
-	void *private)
+static void find_system_memory(const struct dmi_header *dm, void *private)
 {
+	struct dmi_mem_device *memdev = (struct dmi_mem_device *)(dm);
 	struct kfd_mem_properties *mem;
-	u16 mem_width, mem_clock;
 	struct kfd_topology_device *kdev =
 		(struct kfd_topology_device *)private;
-	const u8 *dmi_data = (const u8 *)(dm + 1);
-
-	if (dm->type == DMI_ENTRY_MEM_DEVICE && dm->length >= 0x15) {
-		mem_width = (u16)(*(const u16 *)(dmi_data + 0x6));
-		mem_clock = (u16)(*(const u16 *)(dmi_data + 0x11));
-		list_for_each_entry(mem, &kdev->mem_props, list) {
-			if (mem_width != 0xFFFF && mem_width != 0)
-				mem->width = mem_width;
-			if (mem_clock != 0)
-				mem->mem_clk_max = mem_clock;
-		}
+
+	if (memdev->header.type != DMI_ENTRY_MEM_DEVICE)
+		return;
+	if (memdev->header.length < sizeof(struct dmi_mem_device))
+		return;
+
+	list_for_each_entry(mem, &kdev->mem_props, list) {
+		if (memdev->total_width != 0xFFFF && memdev->total_width != 0)
+			mem->width = memdev->total_width;
+		if (memdev->speed != 0)
+			mem->mem_clk_max = memdev->speed;
 	}
 }
 
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_topology.h b/drivers/gpu/drm/amd/amdkfd/kfd_topology.h
index 155b5c410af16..f06c9db7ddde9 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_topology.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_topology.h
@@ -24,6 +24,7 @@
 #ifndef __KFD_TOPOLOGY_H__
 #define __KFD_TOPOLOGY_H__
 
+#include <linux/dmi.h>
 #include <linux/types.h>
 #include <linux/list.h>
 #include <linux/kfd_sysfs.h>
@@ -179,6 +180,22 @@ struct kfd_system_properties {
 	struct attribute	attr_props;
 };
 
+struct dmi_mem_device {
+	struct dmi_header header;
+	u16 physical_handle;
+	u16 error_handle;
+	u16 total_width;
+	u16 data_width;
+	u16 size;
+	u8 form_factor;
+	u8 device_set;
+	u8 device_locator;
+	u8 bank_locator;
+	u8 memory_type;
+	u16 type_detail;
+	u16 speed;
+} __packed;
+
 struct kfd_topology_device *kfd_create_topology_device(
 		struct list_head *device_list);
 void kfd_release_topology_device_list(struct list_head *device_list);
-- 
2.43.0