[PATCH v2 1/8] drm: Disable the cursor plane on atomic contexts with virtualized drivers

Zack Rusin zack at kde.org
Tue Jul 12 03:32:39 UTC 2022


From: Zack Rusin <zackr at vmware.com>

Cursor planes on virtualized drivers have special meaning and require
that the clients handle them in specific ways, e.g. the cursor plane
should react to the mouse movement the way a mouse cursor would be
expected to and the client is required to set hotspot properties on it
in order for the mouse events to be routed correctly.

This breaks the contract as specified by the "universal planes". Fix it
by disabling the cursor planes on virtualized drivers while adding
a foundation on top of which it's possible to special case mouse cursor
planes for clients that want it.

Disabling the cursor planes makes some kms compositors which were broken,
e.g. Weston, fallback to software cursor which works fine or at least
better than currently while having no effect on others, e.g. gnome-shell
or kwin, which put virtualized drivers on a deny-list when running in
atomic context to make them fallback to legacy kms and avoid this issue.

Signed-off-by: Zack Rusin <zackr at vmware.com>
Fixes: 681e7ec73044 ("drm: Allow userspace to ask for universal plane list (v2)")
Cc: <stable at vger.kernel.org> # v5.4+
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Maxime Ripard <mripard at kernel.org>
Cc: Thomas Zimmermann <tzimmermann at suse.de>
Cc: David Airlie <airlied at linux.ie>
Cc: Daniel Vetter <daniel at ffwll.ch>
Cc: Dave Airlie <airlied at redhat.com>
Cc: Gerd Hoffmann <kraxel at redhat.com>
Cc: Hans de Goede <hdegoede at redhat.com>
Cc: Gurchetan Singh <gurchetansingh at chromium.org>
Cc: Chia-I Wu <olvaffe at gmail.com>
Cc: dri-devel at lists.freedesktop.org
Cc: virtualization at lists.linux-foundation.org
Cc: spice-devel at lists.freedesktop.org
---
 drivers/gpu/drm/drm_plane.c          | 11 +++++++++++
 drivers/gpu/drm/qxl/qxl_drv.c        |  2 +-
 drivers/gpu/drm/vboxvideo/vbox_drv.c |  2 +-
 drivers/gpu/drm/virtio/virtgpu_drv.c |  3 ++-
 drivers/gpu/drm/vmwgfx/vmwgfx_drv.c  |  2 +-
 include/drm/drm_drv.h                | 10 ++++++++++
 include/drm/drm_file.h               | 12 ++++++++++++
 7 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
index 726f2f163c26..e1e2a65c7119 100644
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -667,6 +667,17 @@ int drm_mode_getplane_res(struct drm_device *dev, void *data,
 		    !file_priv->universal_planes)
 			continue;
 
+		/*
+		 * Unless userspace supports virtual cursor plane
+		 * then if we're running on virtual driver do not
+		 * advertise cursor planes because they'll be broken
+		 */
+		if (plane->type == DRM_PLANE_TYPE_CURSOR &&
+		    drm_core_check_feature(dev, DRIVER_VIRTUAL)	&&
+		    file_priv->atomic &&
+		    !file_priv->supports_virtual_cursor_plane)
+			continue;
+
 		if (drm_lease_held(file_priv, plane->base.id)) {
 			if (count < plane_resp->count_planes &&
 			    put_user(plane->base.id, plane_ptr + count))
diff --git a/drivers/gpu/drm/qxl/qxl_drv.c b/drivers/gpu/drm/qxl/qxl_drv.c
index 1cb6f0c224bb..0e4212e05caa 100644
--- a/drivers/gpu/drm/qxl/qxl_drv.c
+++ b/drivers/gpu/drm/qxl/qxl_drv.c
@@ -281,7 +281,7 @@ static const struct drm_ioctl_desc qxl_ioctls[] = {
 };
 
 static struct drm_driver qxl_driver = {
-	.driver_features = DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
+	.driver_features = DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC | DRIVER_VIRTUAL,
 
 	.dumb_create = qxl_mode_dumb_create,
 	.dumb_map_offset = drm_gem_ttm_dumb_map_offset,
diff --git a/drivers/gpu/drm/vboxvideo/vbox_drv.c b/drivers/gpu/drm/vboxvideo/vbox_drv.c
index f4f2bd79a7cb..84e75bcc3384 100644
--- a/drivers/gpu/drm/vboxvideo/vbox_drv.c
+++ b/drivers/gpu/drm/vboxvideo/vbox_drv.c
@@ -176,7 +176,7 @@ DEFINE_DRM_GEM_FOPS(vbox_fops);
 
 static const struct drm_driver driver = {
 	.driver_features =
-	    DRIVER_MODESET | DRIVER_GEM | DRIVER_ATOMIC,
+	    DRIVER_MODESET | DRIVER_GEM | DRIVER_ATOMIC | DRIVER_VIRTUAL,
 
 	.lastclose = drm_fb_helper_lastclose,
 
diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.c b/drivers/gpu/drm/virtio/virtgpu_drv.c
index 5f25a8d15464..3c5bb006159a 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.c
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.c
@@ -198,7 +198,8 @@ MODULE_AUTHOR("Alon Levy");
 DEFINE_DRM_GEM_FOPS(virtio_gpu_driver_fops);
 
 static const struct drm_driver driver = {
-	.driver_features = DRIVER_MODESET | DRIVER_GEM | DRIVER_RENDER | DRIVER_ATOMIC,
+	.driver_features =
+		DRIVER_MODESET | DRIVER_GEM | DRIVER_RENDER | DRIVER_ATOMIC | DRIVER_VIRTUAL,
 	.open = virtio_gpu_driver_open,
 	.postclose = virtio_gpu_driver_postclose,
 
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
index 01a5b47e95f9..712f6ad0b014 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
@@ -1581,7 +1581,7 @@ static const struct file_operations vmwgfx_driver_fops = {
 
 static const struct drm_driver driver = {
 	.driver_features =
-	DRIVER_MODESET | DRIVER_RENDER | DRIVER_ATOMIC | DRIVER_GEM,
+	DRIVER_MODESET | DRIVER_RENDER | DRIVER_ATOMIC | DRIVER_GEM | DRIVER_VIRTUAL,
 	.ioctls = vmw_ioctls,
 	.num_ioctls = ARRAY_SIZE(vmw_ioctls),
 	.master_set = vmw_master_set,
diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index f6159acb8856..c4cd7fc350d9 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -94,6 +94,16 @@ enum drm_driver_feature {
 	 * synchronization of command submission.
 	 */
 	DRIVER_SYNCOBJ_TIMELINE         = BIT(6),
+	/**
+	 * @DRIVER_VIRTUAL:
+	 *
+	 * Driver is running on top of virtual hardware. The most significant
+	 * implication of this is a requirement of special handling of the
+	 * cursor plane (e.g. cursor plane has to actually track the mouse
+	 * cursor and the clients are required to set hotspot in order for
+	 * the cursor planes to work correctly).
+	 */
+	DRIVER_VIRTUAL                  = BIT(7),
 
 	/* IMPORTANT: Below are all the legacy flags, add new ones above. */
 
diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h
index e0a73a1e2df7..3e5c36891161 100644
--- a/include/drm/drm_file.h
+++ b/include/drm/drm_file.h
@@ -223,6 +223,18 @@ struct drm_file {
 	 */
 	bool is_master;
 
+	/**
+	 * @supports_virtual_cursor_plane:
+	 *
+	 * This client is capable of handling the cursor plane with the
+	 * restrictions imposed on it by the virtualized drivers.
+	 *
+	 * The implies that the cursor plane has to behave like a cursor
+	 * i.e. track cursor movement. It also requires setting of the
+	 * hotspot properties by the client on the cursor plane.
+	 */
+	bool supports_virtual_cursor_plane;
+
 	/**
 	 * @master:
 	 *
-- 
2.34.1



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