drm/xe: Disallow pinning dma-bufs in VRAM

For now only support pinning in TT memory, for two reasons:
1) Avoid pinning in a placement not accessible to some importers.
2) Pinning in VRAM requires PIN accounting which is a to-do.

v2:
- Adjust the dma-buf kunit test accordingly.

Suggested-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230920095001.5539-1-thomas.hellstrom@linux.intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/tests/xe_dma_buf.c

@@ -149,11 +149,19 @@ static void xe_test_dmabuf_import_same_driver(struct xe_device *xe)
 			/* Is everything where we expect it to be? */
 			xe_bo_lock(import_bo, false);
 			err = xe_bo_validate(import_bo, NULL, false);
-			if (err && err != -EINTR && err != -ERESTARTSYS)
-				KUNIT_FAIL(test,
-					   "xe_bo_validate() failed with err=%d\n", err);
 
-			check_residency(test, bo, import_bo, dmabuf);
+			/* Pinning in VRAM is not allowed. */
+			if (!is_dynamic(params) &&
+			    params->force_different_devices &&
+			    !(params->mem_mask & XE_BO_CREATE_SYSTEM_BIT))
+				KUNIT_EXPECT_EQ(test, err, -EINVAL);
+			/* Otherwise only expect interrupts or success. */
+			else if (err && err != -EINTR && err != -ERESTARTSYS)
+				KUNIT_EXPECT_TRUE(test, !err || err == -EINTR ||
+						  err == -ERESTARTSYS);
+
+			if (!err)
+				check_residency(test, bo, import_bo, dmabuf);
 			xe_bo_unlock(import_bo);
 		}
 		drm_gem_object_put(import);

drivers/gpu/drm/xe/xe_dma_buf.c

@@ -49,13 +49,30 @@ static int xe_dma_buf_pin(struct dma_buf_attachment *attach)
 {
 	struct drm_gem_object *obj = attach->dmabuf->priv;
 	struct xe_bo *bo = gem_to_xe_bo(obj);
+	struct xe_device *xe = xe_bo_device(bo);
+	int ret;
 
 	/*
-	 * Migrate to TT first to increase the chance of non-p2p clients
-	 * can attach.
+	 * For now only support pinning in TT memory, for two reasons:
+	 * 1) Avoid pinning in a placement not accessible to some importers.
+	 * 2) Pinning in VRAM requires PIN accounting which is a to-do.
 	 */
-	(void)xe_bo_migrate(bo, XE_PL_TT);
-	xe_bo_pin_external(bo);
+	if (xe_bo_is_pinned(bo) && bo->ttm.resource->placement != XE_PL_TT) {
+		drm_dbg(&xe->drm, "Can't migrate pinned bo for dma-buf pin.\n");
+		return -EINVAL;
+	}
+
+	ret = xe_bo_migrate(bo, XE_PL_TT);
+	if (ret) {
+		if (ret != -EINTR && ret != -ERESTARTSYS)
+			drm_dbg(&xe->drm,
+				"Failed migrating dma-buf to TT memory: %pe\n",
+				ERR_PTR(ret));
+		return ret;
+	}
+
+	ret = xe_bo_pin_external(bo);
+	xe_assert(xe, !ret);
 
 	return 0;
 }