Re: [PATCH RFC] virtio_pci: fix virtio spec compliance on restore
On Wed, Sep 24, 2014 at 02:27:27AM +0100, Ben Hutchings wrote: On Tue, 2014-09-23 at 13:32 +0300, Michael S. Tsirkin wrote: 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: sta...@vger.kernel.org Cc: Amit Shah amit.s...@redhat.com Signed-off-by: Michael S. Tsirkin m...@redhat.com [...] What concrete problem does this fix, such that it should be applied to stable branches? Ben. It will break with hypervisors that assume spec compliant behaviour. I would like this applied to stable branches so hypervisors don't need to support broken behaviour forever. -- MST ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH RFC] virtio_pci: fix virtio spec compliance on restore
On (Tue) 23 Sep 2014 [13:32:22], Michael S. Tsirkin wrote:
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: sta...@vger.kernel.org
Cc: Amit Shah amit.s...@redhat.com
Signed-off-by: Michael S. Tsirkin m...@redhat.com
---
Lightly tested.
Will repost as non-RFC once testing is done, sending
out now for early flames/comments.
What tests are you running?
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);
+
+ /* 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;
So in this case DRIVER_OK will never be set?
+
+ 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;
}
Amit
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[PATCH RFC] 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
Cc: sta...@vger.kernel.org
Cc: Amit Shah amit.s...@redhat.com
Signed-off-by: Michael S. Tsirkin m...@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);
+
+ /* 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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Re: [PATCH RFC] virtio_pci: fix virtio spec compliance on restore
On Tue, Sep 23, 2014 at 09:06:03AM -0700, Eric Northup wrote:
On Tue, Sep 23, 2014 at 3:32 AM, Michael S. Tsirkin m...@redhat.com wrote:
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: sta...@vger.kernel.org
Cc: Amit Shah amit.s...@redhat.com
Signed-off-by: Michael S. Tsirkin m...@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.
this is the order of events in initialization,
it seems better to be consistent.
+
+ /* 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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Re: [PATCH RFC] virtio_pci: fix virtio spec compliance on restore
On Tue, 2014-09-23 at 13:32 +0300, Michael S. Tsirkin wrote: 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: sta...@vger.kernel.org Cc: Amit Shah amit.s...@redhat.com Signed-off-by: Michael S. Tsirkin m...@redhat.com [...] What concrete problem does this fix, such that it should be applied to stable branches? Ben. -- Ben Hutchings Everything should be made as simple as possible, but not simpler. - Albert Einstein signature.asc Description: This is a digitally signed message part ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
