[PATCH 4.8 55/57] drm: virtio: reinstate drm_virtio_set_busid()

From: Greg Kroah-Hartman
Date: Fri Oct 21 2016 - 05:26:18 EST

4.8-stable review patch. If anyone has any objections, please let me know.


From: Laszlo Ersek <lersek@xxxxxxxxxx>

commit c2cbc38b9715bd8318062e600668fc30e5a3fbfa upstream.

Before commit a325725633c2 ("drm: Lobotomize set_busid nonsense for !pci
drivers"), several DRM drivers for platform devices used to expose an
explicit "drm_driver.set_busid" callback, invariably backed by

Commit a325725633c2 removed drm_platform_set_busid(), along with the
referring .set_busid field initializations. This was justified because
interchangeable functionality had been implemented in drm_dev_alloc() /
drm_dev_init(), which DRM_IOCTL_SET_VERSION would rely on going forward.

However, commit a325725633c2 also removed drm_virtio_set_busid(), for
which the same consolidation was not appropriate: this .set_busid callback
had been implemented with drm_pci_set_busid(), and not
drm_platform_set_busid(). The error regressed Xorg/xserver on QEMU's
"virtio-vga" card; the drmGetBusid() function from libdrm would no longer
return stable PCI identifiers like "pci:0000:00:02.0", but rather unstable
platform ones like "virtio0".

Reinstate drm_virtio_set_busid() with judicious use of

git checkout -p a325725633c2^ -- drivers/gpu/drm/virtio

Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Cc: Emil Velikov <emil.l.velikov@xxxxxxxxx>
Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Cc: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
Cc: Hans de Goede <hdegoede@xxxxxxxxxx>
Cc: Joachim Frieben <jfrieben@xxxxxxxxxxx>
Reported-by: Joachim Frieben <jfrieben@xxxxxxxxxxx>
Fixes: a325725633c26aa66ab940f762a6b0778edf76c0
Ref: https://bugzilla.redhat.com/show_bug.cgi?id=1366842
Signed-off-by: Laszlo Ersek <lersek@xxxxxxxxxx>
Reviewed-by: Emil Velikov <emil.l.velikov@xxxxxxxxx>
Signed-off-by: Dave Airlie <airlied@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/gpu/drm/virtio/virtgpu_drm_bus.c | 10 ++++++++++
drivers/gpu/drm/virtio/virtgpu_drv.c | 1 +
drivers/gpu/drm/virtio/virtgpu_drv.h | 1 +
3 files changed, 12 insertions(+)

--- a/drivers/gpu/drm/virtio/virtgpu_drm_bus.c
+++ b/drivers/gpu/drm/virtio/virtgpu_drm_bus.c
@@ -27,6 +27,16 @@

#include "virtgpu_drv.h"

+int drm_virtio_set_busid(struct drm_device *dev, struct drm_master *master)
+ struct pci_dev *pdev = dev->pdev;
+ if (pdev) {
+ return drm_pci_set_busid(dev, master);
+ }
+ return 0;
static void virtio_pci_kick_out_firmware_fb(struct pci_dev *pci_dev)
struct apertures_struct *ap;
--- a/drivers/gpu/drm/virtio/virtgpu_drv.c
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.c
@@ -117,6 +117,7 @@ static const struct file_operations virt

static struct drm_driver driver = {
+ .set_busid = drm_virtio_set_busid,
.load = virtio_gpu_driver_load,
.unload = virtio_gpu_driver_unload,
.open = virtio_gpu_driver_open,
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -49,6 +49,7 @@

/* virtgpu_drm_bus.c */
+int drm_virtio_set_busid(struct drm_device *dev, struct drm_master *master);
int drm_virtio_init(struct drm_driver *driver, struct virtio_device *vdev);

struct virtio_gpu_object {