drm/xe: Fix fence reservation accouting

Both execs and the preempt rebind worker can issue rebinds. Rebinds
require a fence, per tile, inserted into dma-resv slots of the VM and
BO (if external). The fence reservation accouting did not take into
account the number of fences required for rebinds, fix this.

v2: Rebase
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reported-by: Christopher Snowhill <kode54@gmail.com>
Link: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/518Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/xe_exec.c

@@ -103,7 +103,11 @@ static int xe_exec_begin(struct drm_exec *exec, struct xe_vm *vm)
 	if (xe_vm_no_dma_fences(vm))
 		return 0;
 
-	err = xe_vm_lock_dma_resv(vm, exec, 1, true);
+	/*
+	 * 1 fence for job from exec plus a fence for each tile from a possible
+	 * rebind
+	 */
+	err = xe_vm_lock_dma_resv(vm, exec, 1 + vm->xe->info.tile_count, true);
 	if (err)
 		return err;
 

drivers/gpu/drm/xe/xe_vm.c

@@ -519,8 +519,13 @@ static int xe_preempt_work_begin(struct drm_exec *exec, struct xe_vm *vm,
 	struct xe_vma *vma;
 	int err;
 
+	/*
+	 * 1 fence for each preempt fence plus a fence for each tile from a
+	 * possible rebind
+	 */
 	err = drm_exec_prepare_obj(exec, xe_vm_obj(vm),
-				   vm->preempt.num_exec_queues);
+				   vm->preempt.num_exec_queues +
+				   vm->xe->info.tile_count);
 	if (err)
 		return err;