drm/xe: Use bookkeep slots for external BO's in exec IOCTL

Fix external BO's dma-resv usage in exec IOCTL using bookkeep slots
rather than write slots. This leaves syncing to user space rather than
the KMD blindly enforcing write semantics on every external BO.

Fixes: dd08ebf ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Cc: José Roberto de Souza <[email protected]>
Cc: Kenneth Graunke <[email protected]>
Cc: Paulo Zanoni <[email protected]>
Reported-by: Simona Vetter <[email protected]>
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2673
Signed-off-by: Matthew Brost <[email protected]>
Reviewed-by: José Roberto de Souza <[email protected]>
Reviewed-by: Kenneth Graunke <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: mbrost05

drivers/gpu/drm/xe/xe_exec.c

@@ -41,11 +41,6 @@
  * user knows an exec writes to a BO and reads from the BO in the next exec, it
  * is the user's responsibility to pass in / out fence between the two execs).
  *
- * Implicit dependencies for external BOs are handled by using the dma-buf
- * implicit dependency uAPI (TODO: add link). To make this works each exec must
- * install the job's fence into the DMA_RESV_USAGE_WRITE slot of every external
- * BO mapped in the VM.
- *
  * We do not allow a user to trigger a bind at exec time rather we have a VM
  * bind IOCTL which uses the same in / out fence interface as exec. In that
  * sense, a VM bind is basically the same operation as an exec from the user
@@ -59,8 +54,8 @@
  * behind any pending kernel operations on any external BOs in VM or any BOs
  * private to the VM. This is accomplished by the rebinds waiting on BOs
  * DMA_RESV_USAGE_KERNEL slot (kernel ops) and kernel ops waiting on all BOs
- * slots (inflight execs are in the DMA_RESV_USAGE_BOOKING for private BOs and
- * in DMA_RESV_USAGE_WRITE for external BOs).
+ * slots (inflight execs are in the DMA_RESV_USAGE_BOOKKEEP for private BOs and
+ * for external BOs).
  *
  * Rebinds / dma-resv usage applies to non-compute mode VMs only as for compute
  * mode VMs we use preempt fences and a rebind worker (TODO: add link).
@@ -304,7 +299,8 @@ int xe_exec_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
 	xe_sched_job_arm(job);
 	if (!xe_vm_in_lr_mode(vm))
 		drm_gpuvm_resv_add_fence(&vm->gpuvm, exec, &job->drm.s_fence->finished,
-					 DMA_RESV_USAGE_BOOKKEEP, DMA_RESV_USAGE_WRITE);
+					 DMA_RESV_USAGE_BOOKKEEP,
+					 DMA_RESV_USAGE_BOOKKEEP);
 
 	for (i = 0; i < num_syncs; i++) {
 		xe_sync_entry_signal(&syncs[i], &job->drm.s_fence->finished);