This is a note to let you know that I've just added the patch titled
virtio_pci: fix virtio spec compliance on restore
to the 3.17-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
virtio_pci-fix-virtio-spec-compliance-on-restore.patch
and it can be found in the queue-3.17 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 6fbc198cf623944ab60a1db6d306a4d55cdd820d Mon Sep 17 00:00:00 2001
From: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
Date: Tue, 14 Oct 2014 10:40:29 +1030
Subject: virtio_pci: fix virtio spec compliance on restore
From: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/virtio/virtio_pci.c | 33 ++++++++++++++++++++++++++++++---
1 file changed, 30 insertions(+), 3 deletions(-)
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -789,6 +789,7 @@ static int virtio_pci_restore(struct 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 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;
}
Patches currently in stable-queue which might be from mst@xxxxxxxxxx are
queue-3.17/virtio_pci-fix-virtio-spec-compliance-on-restore.patch
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