drm/amdgpu: Fix MMIO access page fault

Add more guards to MMIO access post device
unbind/unplug

Bug: https://bugs.archlinux.org/task/72092?project=1&order=dateopened&sort=desc&pagenum=1Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: James Zhu <James.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c

@@ -22,6 +22,7 @@
  */
 
 #include <linux/firmware.h>
+#include <drm/drm_drv.h>
 
 #include "amdgpu.h"
 #include "amdgpu_vcn.h"
@@ -194,11 +195,14 @@ static int vcn_v2_0_sw_init(void *handle)
  */
 static int vcn_v2_0_sw_fini(void *handle)
 {
-	int r;
+	int r, idx;
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 	volatile struct amdgpu_fw_shared *fw_shared = adev->vcn.inst->fw_shared_cpu_addr;
 
-	fw_shared->present_flag_0 = 0;
+	if (drm_dev_enter(&adev->ddev, &idx)) {
+		fw_shared->present_flag_0 = 0;
+		drm_dev_exit(idx);
+	}
 
 	amdgpu_virt_free_mm_table(adev);
 

drivers/gpu/drm/amd/amdgpu/vcn_v2_5.c

@@ -22,6 +22,7 @@
  */
 
 #include <linux/firmware.h>
+#include <drm/drm_drv.h>
 
 #include "amdgpu.h"
 #include "amdgpu_vcn.h"
@@ -235,17 +236,21 @@ static int vcn_v2_5_sw_init(void *handle)
  */
 static int vcn_v2_5_sw_fini(void *handle)
 {
-	int i, r;
+	int i, r, idx;
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 	volatile struct amdgpu_fw_shared *fw_shared;
 
-	for (i = 0; i < adev->vcn.num_vcn_inst; i++) {
-		if (adev->vcn.harvest_config & (1 << i))
-			continue;
-		fw_shared = adev->vcn.inst[i].fw_shared_cpu_addr;
-		fw_shared->present_flag_0 = 0;
+	if (drm_dev_enter(&adev->ddev, &idx)) {
+		for (i = 0; i < adev->vcn.num_vcn_inst; i++) {
+			if (adev->vcn.harvest_config & (1 << i))
+				continue;
+			fw_shared = adev->vcn.inst[i].fw_shared_cpu_addr;
+			fw_shared->present_flag_0 = 0;
+		}
+		drm_dev_exit(idx);
 	}
 
+
 	if (amdgpu_sriov_vf(adev))
 		amdgpu_virt_free_mm_table(adev);