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Commit 6fbc198c authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by Rusty Russell
Browse files

virtio_pci: fix virtio spec compliance on restore 



On restore, virtio pci does the following:
+ set features
+ init vqs etc - device can be used at this point!
+ set ACKNOWLEDGE,DRIVER and DRIVER_OK status bits

This is in violation of the virtio spec, which
requires the following order:
- ACKNOWLEDGE
- DRIVER
- init vqs
- DRIVER_OK

This behaviour will break with hypervisors that assume spec compliant
behaviour.  It seems like a good idea to have this patch applied to
stable branches to reduce the support butden for the hypervisors.

Cc: stable@vger.kernel.org
Cc: Amit Shah <amit.shah@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 7ec62d42

drivers/virtio/virtio_pci.c

+30 −3
Original line number Diff line number Diff line
@@ -789,6 +789,7 @@ static int virtio_pci_restore(struct device *dev) 
	struct pci_dev *pci_dev = to_pci_dev(dev);

	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);

	struct virtio_driver *drv;

	unsigned status = 0;

	int ret;



	drv = container_of(vp_dev->vdev.dev.driver,
@@ -799,14 +800,40 @@ static int virtio_pci_restore(struct device *dev) 
		return ret;



	pci_set_master(pci_dev);

	/* We always start by resetting the device, in case a previous

	 * driver messed it up. */

	vp_reset(&vp_dev->vdev);



	/* Acknowledge that we've seen the device. */

	status |= VIRTIO_CONFIG_S_ACKNOWLEDGE;

	vp_set_status(&vp_dev->vdev, status);



	/* Maybe driver failed before freeze.

	 * Restore the failed status, for debugging. */

	status |= vp_dev->saved_status & VIRTIO_CONFIG_S_FAILED;

	vp_set_status(&vp_dev->vdev, status);



	if (!drv)

		return 0;



	/* We have a driver! */

	status |= VIRTIO_CONFIG_S_DRIVER;

	vp_set_status(&vp_dev->vdev, status);



	vp_finalize_features(&vp_dev->vdev);



	if (drv && drv->restore)

	if (drv->restore) {

		ret = drv->restore(&vp_dev->vdev);

		if (ret) {

			status |= VIRTIO_CONFIG_S_FAILED;

			vp_set_status(&vp_dev->vdev, status);

			return ret;

		}

	}



	/* Finally, tell the device we're all set */

	if (!ret)

		vp_set_status(&vp_dev->vdev, vp_dev->saved_status);

	status |= VIRTIO_CONFIG_S_DRIVER_OK;

	vp_set_status(&vp_dev->vdev, status);



	return ret;

}