drm/amdgpu: Add lock around VF RLCG interface

flush_gpu_tlb may be called from another thread while
device_gpu_recover is running.

Both of these threads access registers through the VF
RLCG interface during VF Full Access. Add a lock around this interface
to prevent race conditions between these threads.
Signed-off-by: Victor Skvortsov <victor.skvortsov@amd.com>
Reviewed-by: Zhigang Luo <zhigang.luo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -4049,6 +4049,7 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 	mutex_init(&adev->grbm_idx_mutex);
 	mutex_init(&adev->mn_lock);
 	mutex_init(&adev->virt.vf_errors.lock);
+	mutex_init(&adev->virt.rlcg_reg_lock);
 	hash_init(adev->mn_hash);
 	mutex_init(&adev->psp.mutex);
 	mutex_init(&adev->notifier_lock);

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

@@ -982,6 +982,9 @@ u32 amdgpu_virt_rlcg_reg_rw(struct amdgpu_device *adev, u32 offset, u32 v, u32 f
 	scratch_reg1 = (void __iomem *)adev->rmmio + 4 * reg_access_ctrl->scratch_reg1;
 	scratch_reg2 = (void __iomem *)adev->rmmio + 4 * reg_access_ctrl->scratch_reg2;
 	scratch_reg3 = (void __iomem *)adev->rmmio + 4 * reg_access_ctrl->scratch_reg3;
+
+	mutex_lock(&adev->virt.rlcg_reg_lock);
+
 	if (reg_access_ctrl->spare_int)
 		spare_int = (void __iomem *)adev->rmmio + 4 * reg_access_ctrl->spare_int;
 
@@ -1038,6 +1041,9 @@ u32 amdgpu_virt_rlcg_reg_rw(struct amdgpu_device *adev, u32 offset, u32 v, u32 f
 	}
 
 	ret = readl(scratch_reg0);
+
+	mutex_unlock(&adev->virt.rlcg_reg_lock);
+
 	return ret;
 }
 

drivers/gpu/drm/amd/amdgpu/amdgpu_virt.h

@@ -272,6 +272,8 @@ struct amdgpu_virt {
 
 	/* the ucode id to signal the autoload */
 	uint32_t autoload_ucode_id;
+
+	struct mutex rlcg_reg_lock;
 };
 
 struct amdgpu_video_codec_info;