drm/amdgpu/psp: add a mutex to protect access to the psp ring

We need to serialize access to the psp ring if there are multiple
callers at runtime.
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -2537,6 +2537,7 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 	hash_init(adev->mn_hash);
 	mutex_init(&adev->lock_reset);
 	mutex_init(&adev->virt.dpm_mutex);
+	mutex_init(&adev->psp.mutex);
 
 	r = amdgpu_device_check_arguments(adev);
 	if (r)

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

@@ -130,6 +130,8 @@ psp_cmd_submit_buf(struct psp_context *psp,
 	int index;
 	int timeout = 2000;
 
+	mutex_lock(&psp->mutex);
+
 	memset(psp->cmd_buf_mem, 0, PSP_CMD_BUFFER_SIZE);
 
 	memcpy(psp->cmd_buf_mem, cmd, sizeof(struct psp_gfx_cmd_resp));
@@ -139,6 +141,7 @@ psp_cmd_submit_buf(struct psp_context *psp,
 			     fence_mc_addr, index);
 	if (ret) {
 		atomic_dec(&psp->fence_value);
+		mutex_unlock(&psp->mutex);
 		return ret;
 	}
 
@@ -161,8 +164,10 @@ psp_cmd_submit_buf(struct psp_context *psp,
 				  ucode->ucode_id);
 		DRM_WARN("psp command failed and response status is (%d)\n",
 			  psp->cmd_buf_mem->resp.status);
-		if (!timeout)
+		if (!timeout) {
+			mutex_unlock(&psp->mutex);
 			return -EINVAL;
+		}
 	}
 
 	/* get xGMI session id from response buffer */
@@ -172,6 +177,7 @@ psp_cmd_submit_buf(struct psp_context *psp,
 		ucode->tmr_mc_addr_lo = psp->cmd_buf_mem->resp.fw_addr_lo;
 		ucode->tmr_mc_addr_hi = psp->cmd_buf_mem->resp.fw_addr_hi;
 	}
+	mutex_unlock(&psp->mutex);
 
 	return ret;
 }
@@ -1188,10 +1194,16 @@ static int psp_resume(void *handle)
 
 int psp_gpu_reset(struct amdgpu_device *adev)
 {
+	int ret;
+
 	if (adev->firmware.load_type != AMDGPU_FW_LOAD_PSP)
 		return 0;
 
-	return psp_mode1_reset(&adev->psp);
+	mutex_lock(&adev->psp.mutex);
+	ret = psp_mode1_reset(&adev->psp);
+	mutex_unlock(&adev->psp.mutex);
+
+	return ret;
 }
 
 int psp_rlc_autoload_start(struct psp_context *psp)

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

@@ -201,6 +201,7 @@ struct psp_context
 	uint8_t				*ta_ras_start_addr;
 	struct psp_xgmi_context		xgmi_context;
 	struct psp_ras_context		ras;
+	struct mutex			mutex;
 };
 
 struct amdgpu_psp_funcs {