drm/xe: Invalidate userptr VMA on page pin fault

Rather than return an error to the user or ban the VM when userptr VMA
page pin fails with -EFAULT, invalidate VMA mappings. This supports the
UMD use case of freeing userptr while still having bindings.

Now that non-faulting VMs can invalidate VMAs, drop the usm prefix for
the tile_invalidated member.

v2:
 - Fix build error (CI)
v3:
 - Don't invalidate VMA if in fault mode, rather kill VM (Thomas)
 - Update commit message with tile_invalidated name chagne (Thomas)
 - Wait VM bookkeep slots with VM resv lock (Thomas)
v4:
 - Move list_del_init(&userptr.repin_link) after error check (Thomas)
 - Assert not in fault mode (Matthew)

Fixes: dd08ebf6 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240312183907.933835-1-matthew.brost@intel.com
(cherry picked from commit 521db22a)
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

drivers/gpu/drm/xe/xe_gt_pagefault.c

@@ -69,7 +69,7 @@ static bool access_is_atomic(enum access_type access_type)
 static bool vma_is_valid(struct xe_tile *tile, struct xe_vma *vma)
 {
 	return BIT(tile->id) & vma->tile_present &&
-		!(BIT(tile->id) & vma->usm.tile_invalidated);
+		!(BIT(tile->id) & vma->tile_invalidated);
 }
 
 static bool vma_matches(struct xe_vma *vma, u64 page_addr)
@@ -226,7 +226,7 @@ static int handle_pagefault(struct xe_gt *gt, struct pagefault *pf)
 
 	if (xe_vma_is_userptr(vma))
 		ret = xe_vma_userptr_check_repin(to_userptr_vma(vma));
-	vma->usm.tile_invalidated &= ~BIT(tile->id);
+	vma->tile_invalidated &= ~BIT(tile->id);
 
 unlock_dma_resv:
 	drm_exec_fini(&exec);

drivers/gpu/drm/xe/xe_trace.h

@@ -464,7 +464,7 @@ DEFINE_EVENT(xe_vma, xe_vma_userptr_invalidate,
 	     TP_ARGS(vma)
 );
 
-DEFINE_EVENT(xe_vma, xe_vma_usm_invalidate,
+DEFINE_EVENT(xe_vma, xe_vma_invalidate,
 	     TP_PROTO(struct xe_vma *vma),
 	     TP_ARGS(vma)
 );

drivers/gpu/drm/xe/xe_vm.c

@@ -708,6 +708,7 @@ int xe_vm_userptr_pin(struct xe_vm *vm)
 	int err = 0;
 	LIST_HEAD(tmp_evict);
 
+	xe_assert(vm->xe, !xe_vm_in_fault_mode(vm));
 	lockdep_assert_held_write(&vm->lock);
 
 	/* Collect invalidated userptrs */
@@ -724,11 +725,27 @@ int xe_vm_userptr_pin(struct xe_vm *vm)
 	list_for_each_entry_safe(uvma, next, &vm->userptr.repin_list,
 				 userptr.repin_link) {
 		err = xe_vma_userptr_pin_pages(uvma);
-		if (err < 0)
-			return err;
+		if (err == -EFAULT) {
+			list_del_init(&uvma->userptr.repin_link);
 
-		list_del_init(&uvma->userptr.repin_link);
-		list_move_tail(&uvma->vma.combined_links.rebind, &vm->rebind_list);
+			/* Wait for pending binds */
+			xe_vm_lock(vm, false);
+			dma_resv_wait_timeout(xe_vm_resv(vm),
+					      DMA_RESV_USAGE_BOOKKEEP,
+					      false, MAX_SCHEDULE_TIMEOUT);
+
+			err = xe_vm_invalidate_vma(&uvma->vma);
+			xe_vm_unlock(vm);
+			if (err)
+				return err;
+		} else {
+			if (err < 0)
+				return err;
+
+			list_del_init(&uvma->userptr.repin_link);
+			list_move_tail(&uvma->vma.combined_links.rebind,
+				       &vm->rebind_list);
+		}
 	}
 
 	return 0;
@@ -1987,7 +2004,7 @@ static int xe_vm_prefetch(struct xe_vm *vm, struct xe_vma *vma,
 			return err;
 	}
 
-	if (vma->tile_mask != (vma->tile_present & ~vma->usm.tile_invalidated)) {
+	if (vma->tile_mask != (vma->tile_present & ~vma->tile_invalidated)) {
 		return xe_vm_bind(vm, vma, q, xe_vma_bo(vma), syncs, num_syncs,
 				  true, first_op, last_op);
 	} else {
@@ -3185,9 +3202,8 @@ int xe_vm_invalidate_vma(struct xe_vma *vma)
 	u8 id;
 	int ret;
 
-	xe_assert(xe, xe_vm_in_fault_mode(xe_vma_vm(vma)));
 	xe_assert(xe, !xe_vma_is_null(vma));
-	trace_xe_vma_usm_invalidate(vma);
+	trace_xe_vma_invalidate(vma);
 
 	/* Check that we don't race with page-table updates */
 	if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {
@@ -3225,7 +3241,7 @@ int xe_vm_invalidate_vma(struct xe_vma *vma)
 		}
 	}
 
-	vma->usm.tile_invalidated = vma->tile_mask;
+	vma->tile_invalidated = vma->tile_mask;
 
 	return 0;
 }

drivers/gpu/drm/xe/xe_vm_types.h

@@ -83,11 +83,8 @@ struct xe_vma {
 		struct work_struct destroy_work;
 	};
 
-	/** @usm: unified shared memory state */
-	struct {
-		/** @tile_invalidated: VMA has been invalidated */
-		u8 tile_invalidated;
-	} usm;
+	/** @tile_invalidated: VMA has been invalidated */
+	u8 tile_invalidated;
 
 	/** @tile_mask: Tile mask of where to create binding for this VMA */
 	u8 tile_mask;