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

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
...@@ -789,6 +789,7 @@ static int virtio_pci_restore(struct device *dev) ...@@ -789,6 +789,7 @@ static int virtio_pci_restore(struct device *dev)
struct pci_dev *pci_dev = to_pci_dev(dev); struct pci_dev *pci_dev = to_pci_dev(dev);
struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev); struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
struct virtio_driver *drv; struct virtio_driver *drv;
unsigned status = 0;
int ret; int ret;
drv = container_of(vp_dev->vdev.dev.driver, drv = container_of(vp_dev->vdev.dev.driver,
...@@ -799,14 +800,40 @@ static int virtio_pci_restore(struct device *dev) ...@@ -799,14 +800,40 @@ static int virtio_pci_restore(struct device *dev)
return ret; return ret;
pci_set_master(pci_dev); 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); vp_finalize_features(&vp_dev->vdev);
if (drv && drv->restore) if (drv->restore) {
ret = drv->restore(&vp_dev->vdev); 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 */ /* Finally, tell the device we're all set */
if (!ret) status |= VIRTIO_CONFIG_S_DRIVER_OK;
vp_set_status(&vp_dev->vdev, vp_dev->saved_status); vp_set_status(&vp_dev->vdev, status);
return ret; return ret;
} }
......
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