drm/msm: Restore error return on invalid fence

When converting to use an idr to map userspace fence seqno values back
to a dma_fence, we lost the error return when userspace passes seqno
that is larger than the last submitted fence.  Restore this check.

Reported-by: Akhil P Oommen <akhilpo@codeaurora.org>
Fixes: a61acbbe9c ("drm/msm: Track "seqno" fences by idr")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Akhil P Oommen <akhilpo@codeaurora.org>
Link: https://lore.kernel.org/r/20211111192457.747899-3-robdclark@gmail.com
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/msm_drv.c

@@ -973,6 +973,12 @@ static int wait_fence(struct msm_gpu_submitqueue *queue, uint32_t fence_id,
 	struct dma_fence *fence;
 	int ret;
 
+	if (fence_id > queue->last_fence) {
+		DRM_ERROR_RATELIMITED("waiting on invalid fence: %u (of %u)\n",
+				      fence_id, queue->last_fence);
+		return -EINVAL;
+	}
+
 	/*
 	 * Map submitqueue scoped "seqno" (which is actually an idr key)
 	 * back to underlying dma-fence

drivers/gpu/drm/msm/msm_gem_submit.c

@@ -904,6 +904,7 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
 	drm_sched_entity_push_job(&submit->base);
 
 	args->fence = submit->fence_id;
+	queue->last_fence = submit->fence_id;
 
 	msm_reset_syncobjs(syncobjs_to_reset, args->nr_in_syncobjs);
 	msm_process_post_deps(post_deps, args->nr_out_syncobjs,

drivers/gpu/drm/msm/msm_gpu.h

@@ -359,6 +359,8 @@ static inline int msm_gpu_convert_priority(struct msm_gpu *gpu, int prio,
  * @ring_nr:   the ringbuffer used by this submitqueue, which is determined
  *             by the submitqueue's priority
  * @faults:    the number of GPU hangs associated with this submitqueue
+ * @last_fence: the sequence number of the last allocated fence (for error
+ *             checking)
  * @ctx:       the per-drm_file context associated with the submitqueue (ie.
  *             which set of pgtables do submits jobs associated with the
  *             submitqueue use)
@@ -374,6 +376,7 @@ struct msm_gpu_submitqueue {
 	u32 flags;
 	u32 ring_nr;
 	int faults;
+	uint32_t last_fence;
 	struct msm_file_private *ctx;
 	struct list_head node;
 	struct idr fence_idr;