drm/amd/display: Guard calls to hdcp_ta and dtm_ta

[Why]
The buffer used when calling psp is a shared buffer. If we have multiple calls
at the same time we can overwrite the buffer.

[How]
Add mutex to guard the shared buffer.
Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -888,6 +888,7 @@ static int psp_hdcp_load(struct psp_context *psp)
 	if (!ret) {
 		psp->hdcp_context.hdcp_initialized = true;
 		psp->hdcp_context.session_id = cmd->resp.session_id;
+		mutex_init(&psp->hdcp_context.mutex);
 	}
 
 	kfree(cmd);
@@ -1033,6 +1034,7 @@ static int psp_dtm_load(struct psp_context *psp)
 	if (!ret) {
 		psp->dtm_context.dtm_initialized = true;
 		psp->dtm_context.session_id = cmd->resp.session_id;
+		mutex_init(&psp->dtm_context.mutex);
 	}
 
 	kfree(cmd);

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

@@ -161,6 +161,7 @@ struct psp_hdcp_context {
 	struct amdgpu_bo	*hdcp_shared_bo;
 	uint64_t		hdcp_shared_mc_addr;
 	void			*hdcp_shared_buf;
+	struct mutex		mutex;
 };
 
 struct psp_dtm_context {
@@ -169,6 +170,7 @@ struct psp_dtm_context {
 	struct amdgpu_bo	*dtm_shared_bo;
 	uint64_t		dtm_shared_mc_addr;
 	void			*dtm_shared_buf;
+	struct mutex		mutex;
 };
 
 #define MEM_TRAIN_SYSTEM_SIGNATURE		0x54534942