Re: [PATCH RFC] virtio_pci: fix virtio spec compliance on restore
From: Eric Northup <hidden>
Date: 2014-09-23 16:06:08
Also in:
lkml, stable
On Tue, Sep 23, 2014 at 3:32 AM, Michael S. Tsirkin [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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 Cc: stable@vger.kernel.org Cc: Amit Shah <redacted> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- Lightly tested. Will repost as non-RFC once testing is done, sending out now for early flames/comments. Thanks! drivers/virtio/virtio_pci.c | 36 ++++++++++++++++++++++++++++++++---- 1 file changed, 32 insertions(+), 4 deletions(-)diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c index 58f7e45..58cbf6e 100644 --- a/drivers/virtio/virtio_pci.c +++ b/drivers/virtio/virtio_pci.c@@ -785,6 +785,7 @@ 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,@@ -795,14 +796,41 @@ 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);
This should happen before enabling PCI bus mastering.
+
+ /* 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)
- ret = drv->restore(&vp_dev->vdev);
+ if (!drv->restore)
+ return 0;
+
+ 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;
}
--
MST
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