drm/xe: Take ref to VM in delayed snapshot

Kernel BO's don't take a ref to the VM, we need the VM for the
delayed snapshot, so take a ref to the VM in delayed snapshot.

v2:
 - Check for lrc_bo before taking a VM ref (CI)
 - Check lrc_bo->vm before taking / dropping a VM ref (CI)
 - Drop VM in xe_lrc_snapshot_free
v5:
 - Fix commit message wording (Johnathan)

Fixes: 47058633 ("drm/xe: Move lrc snapshot capturing to xe_lrc.c")
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240801154118.2547543-2-matthew.brost@intel.com
(cherry picked from commit c3bc97d2)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/xe_lrc.c

@@ -1634,6 +1634,9 @@ struct xe_lrc_snapshot *xe_lrc_snapshot_capture(struct xe_lrc *lrc)
 	if (!snapshot)
 		return NULL;
 
+	if (lrc->bo && lrc->bo->vm)
+		xe_vm_get(lrc->bo->vm);
+
 	snapshot->context_desc = xe_lrc_ggtt_addr(lrc);
 	snapshot->indirect_context_desc = xe_lrc_indirect_ring_ggtt_addr(lrc);
 	snapshot->head = xe_lrc_ring_head(lrc);
@@ -1653,12 +1656,14 @@ struct xe_lrc_snapshot *xe_lrc_snapshot_capture(struct xe_lrc *lrc)
 void xe_lrc_snapshot_capture_delayed(struct xe_lrc_snapshot *snapshot)
 {
 	struct xe_bo *bo;
+	struct xe_vm *vm;
 	struct iosys_map src;
 
 	if (!snapshot)
 		return;
 
 	bo = snapshot->lrc_bo;
+	vm = bo->vm;
 	snapshot->lrc_bo = NULL;
 
 	snapshot->lrc_snapshot = kvmalloc(snapshot->lrc_size, GFP_KERNEL);
@@ -1678,6 +1683,8 @@ void xe_lrc_snapshot_capture_delayed(struct xe_lrc_snapshot *snapshot)
 	xe_bo_unlock(bo);
 put_bo:
 	xe_bo_put(bo);
+	if (vm)
+		xe_vm_put(vm);
 }
 
 void xe_lrc_snapshot_print(struct xe_lrc_snapshot *snapshot, struct drm_printer *p)
@@ -1727,8 +1734,14 @@ void xe_lrc_snapshot_free(struct xe_lrc_snapshot *snapshot)
 		return;
 
 	kvfree(snapshot->lrc_snapshot);
-	if (snapshot->lrc_bo)
+	if (snapshot->lrc_bo) {
+		struct xe_vm *vm;
+
+		vm = snapshot->lrc_bo->vm;
 		xe_bo_put(snapshot->lrc_bo);
+		if (vm)
+			xe_vm_put(vm);
+	}
 	kfree(snapshot);
 }