Messages in this thread Patch in this message | | | From | Kamal Mostafa <> | Subject | [PATCH 3.13 098/105] virtio_pci: fix virtio spec compliance on restore | Date | Mon, 27 Oct 2014 11:57:13 -0700 |
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3.13.11.10 -stable review patch. If anyone has any objections, please let me know.
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From: "Michael S. Tsirkin" <mst@redhat.com>
commit 6fbc198cf623944ab60a1db6d306a4d55cdd820d upstream.
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: Amit Shah <amit.shah@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/virtio/virtio_pci.c | 33 ++++++++++++++++++++++++++++++--- 1 file changed, 30 insertions(+), 3 deletions(-)
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c index a37c699..a516842 100644 --- a/drivers/virtio/virtio_pci.c +++ b/drivers/virtio/virtio_pci.c @@ -793,6 +793,7 @@ 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, @@ -803,14 +804,40 @@ 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; } -- 1.9.1
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