* Re: [Qemu-devel] [PATCH v3] virtio-pci: Fix cross-version migration with older machines
2016-12-14 16:30 [Qemu-devel] [PATCH v3] virtio-pci: Fix cross-version migration with older machines Maxime Coquelin
@ 2016-12-14 17:18 ` Stefan Hajnoczi
2016-12-14 22:04 ` Michael S. Tsirkin
2016-12-15 7:38 ` Stefan Hajnoczi
2 siblings, 0 replies; 7+ messages in thread
From: Stefan Hajnoczi @ 2016-12-14 17:18 UTC (permalink / raw)
To: Maxime Coquelin
Cc: Michael Roth, Stefan Hajnoczi, qemu-devel, Michael S. Tsirkin,
Cornelia Huck, Marcel Apfelbaum, Dr . David Alan Gilbert
On Wed, Dec 14, 2016 at 4:30 PM, Maxime Coquelin
<maxime.coquelin@redhat.com> wrote:
> This patch fixes a cross-version migration regression introduced
> by commit d1b4259f ("virtio-bus: Plug devices after features are
> negotiated").
>
> The problem is encountered when host's vhost backend does not support
> VIRTIO_F_VERSION_1, and migration is initiated from a v2.7 or prior
> machine with virtio-pci modern capabilities enabled to a v2.8 machine.
>
> In this case, modern capabilities get exposed to the guest by the source,
> whereas the target will detect version 1 is not supported so will only
> expose legacy capabilities.
>
> The problem is fixed by introducing a new "x-ignore-backend-features"
> property, which is set in v2.7 and prior compatibility modes. Doing this,
> v2.7 machine keeps its broken behaviour (enabling modern while version
> is not supported), and newer machines will behave correctly.
>
> Reported-by: Michael Roth <mdroth@linux.vnet.ibm.com>
> Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
> Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> Tested-by: Michael Roth <mdroth@linux.vnet.ibm.com>
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>
> V3 fixes commit message with the new property name.
> V2 changes the naming as proposed by Michael T.and Cornelia, and
> fixes commit message.
>
> hw/virtio/virtio-pci.c | 5 ++++-
> hw/virtio/virtio-pci.h | 1 +
> include/hw/compat.h | 4 ++++
> 3 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 521ba0b..21c2b9d 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -1580,7 +1580,8 @@ static void virtio_pci_device_plugged(DeviceState *d, Error **errp)
> * Virtio capabilities present without
> * VIRTIO_F_VERSION_1 confuses guests
> */
> - if (!virtio_has_feature(vdev->host_features, VIRTIO_F_VERSION_1)) {
> + if (!proxy->ignore_backend_features &&
> + !virtio_has_feature(vdev->host_features, VIRTIO_F_VERSION_1)) {
> virtio_pci_disable_modern(proxy);
>
> if (!legacy) {
> @@ -1852,6 +1853,8 @@ static Property virtio_pci_properties[] = {
> VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT, false),
> DEFINE_PROP_BIT("page-per-vq", VirtIOPCIProxy, flags,
> VIRTIO_PCI_FLAG_PAGE_PER_VQ_BIT, false),
> + DEFINE_PROP_BOOL("x-ignore-backend-features", VirtIOPCIProxy,
> + ignore_backend_features, false),
> DEFINE_PROP_END_OF_LIST(),
> };
>
> diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h
> index b2a996f..5e07886 100644
> --- a/hw/virtio/virtio-pci.h
> +++ b/hw/virtio/virtio-pci.h
> @@ -153,6 +153,7 @@ struct VirtIOPCIProxy {
> int config_cap;
> uint32_t flags;
> bool disable_modern;
> + bool ignore_backend_features;
> OnOffAuto disable_legacy;
> uint32_t class_code;
> uint32_t nvectors;
> diff --git a/include/hw/compat.h b/include/hw/compat.h
> index 0f06e11..8dfc7a3 100644
> --- a/include/hw/compat.h
> +++ b/include/hw/compat.h
> @@ -18,6 +18,10 @@
> .driver = "intel-iommu",\
> .property = "x-buggy-eim",\
> .value = "true",\
> + },{\
> + .driver = "virtio-pci",\
> + .property = "x-ignore-backend-features",\
> + .value = "on",\
> },
Waiting for Michael Tsirkin's R-b before applying.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [Qemu-devel] [PATCH v3] virtio-pci: Fix cross-version migration with older machines
2016-12-14 16:30 [Qemu-devel] [PATCH v3] virtio-pci: Fix cross-version migration with older machines Maxime Coquelin
2016-12-14 17:18 ` Stefan Hajnoczi
@ 2016-12-14 22:04 ` Michael S. Tsirkin
2016-12-15 7:38 ` Stefan Hajnoczi
2 siblings, 0 replies; 7+ messages in thread
From: Michael S. Tsirkin @ 2016-12-14 22:04 UTC (permalink / raw)
To: Maxime Coquelin
Cc: mdroth, stefanha, qemu-devel, cornelia.huck, marcel,
Dr . David Alan Gilbert
On Wed, Dec 14, 2016 at 05:30:35PM +0100, Maxime Coquelin wrote:
> This patch fixes a cross-version migration regression introduced
> by commit d1b4259f ("virtio-bus: Plug devices after features are
> negotiated").
>
> The problem is encountered when host's vhost backend does not support
> VIRTIO_F_VERSION_1, and migration is initiated from a v2.7 or prior
> machine with virtio-pci modern capabilities enabled to a v2.8 machine.
>
> In this case, modern capabilities get exposed to the guest by the source,
> whereas the target will detect version 1 is not supported so will only
> expose legacy capabilities.
>
> The problem is fixed by introducing a new "x-ignore-backend-features"
> property, which is set in v2.7 and prior compatibility modes. Doing this,
> v2.7 machine keeps its broken behaviour (enabling modern while version
> is not supported), and newer machines will behave correctly.
>
> Reported-by: Michael Roth <mdroth@linux.vnet.ibm.com>
> Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
> Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> Tested-by: Michael Roth <mdroth@linux.vnet.ibm.com>
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>
> V3 fixes commit message with the new property name.
> V2 changes the naming as proposed by Michael T.and Cornelia, and
> fixes commit message.
>
> hw/virtio/virtio-pci.c | 5 ++++-
> hw/virtio/virtio-pci.h | 1 +
> include/hw/compat.h | 4 ++++
> 3 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 521ba0b..21c2b9d 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -1580,7 +1580,8 @@ static void virtio_pci_device_plugged(DeviceState *d, Error **errp)
> * Virtio capabilities present without
> * VIRTIO_F_VERSION_1 confuses guests
> */
> - if (!virtio_has_feature(vdev->host_features, VIRTIO_F_VERSION_1)) {
> + if (!proxy->ignore_backend_features &&
> + !virtio_has_feature(vdev->host_features, VIRTIO_F_VERSION_1)) {
> virtio_pci_disable_modern(proxy);
>
> if (!legacy) {
> @@ -1852,6 +1853,8 @@ static Property virtio_pci_properties[] = {
> VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT, false),
> DEFINE_PROP_BIT("page-per-vq", VirtIOPCIProxy, flags,
> VIRTIO_PCI_FLAG_PAGE_PER_VQ_BIT, false),
> + DEFINE_PROP_BOOL("x-ignore-backend-features", VirtIOPCIProxy,
> + ignore_backend_features, false),
> DEFINE_PROP_END_OF_LIST(),
> };
>
> diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h
> index b2a996f..5e07886 100644
> --- a/hw/virtio/virtio-pci.h
> +++ b/hw/virtio/virtio-pci.h
> @@ -153,6 +153,7 @@ struct VirtIOPCIProxy {
> int config_cap;
> uint32_t flags;
> bool disable_modern;
> + bool ignore_backend_features;
> OnOffAuto disable_legacy;
> uint32_t class_code;
> uint32_t nvectors;
> diff --git a/include/hw/compat.h b/include/hw/compat.h
> index 0f06e11..8dfc7a3 100644
> --- a/include/hw/compat.h
> +++ b/include/hw/compat.h
> @@ -18,6 +18,10 @@
> .driver = "intel-iommu",\
> .property = "x-buggy-eim",\
> .value = "true",\
> + },{\
> + .driver = "virtio-pci",\
> + .property = "x-ignore-backend-features",\
> + .value = "on",\
> },
>
> #define HW_COMPAT_2_6 \
> --
> 2.9.3
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [Qemu-devel] [PATCH v3] virtio-pci: Fix cross-version migration with older machines
2016-12-14 16:30 [Qemu-devel] [PATCH v3] virtio-pci: Fix cross-version migration with older machines Maxime Coquelin
2016-12-14 17:18 ` Stefan Hajnoczi
2016-12-14 22:04 ` Michael S. Tsirkin
@ 2016-12-15 7:38 ` Stefan Hajnoczi
2016-12-15 8:26 ` Cornelia Huck
2 siblings, 1 reply; 7+ messages in thread
From: Stefan Hajnoczi @ 2016-12-15 7:38 UTC (permalink / raw)
To: Maxime Coquelin
Cc: mdroth, stefanha, qemu-devel, mst, cornelia.huck, marcel,
Dr . David Alan Gilbert
[-- Attachment #1: Type: text/plain, Size: 1823 bytes --]
On Wed, Dec 14, 2016 at 05:30:35PM +0100, Maxime Coquelin wrote:
> This patch fixes a cross-version migration regression introduced
> by commit d1b4259f ("virtio-bus: Plug devices after features are
> negotiated").
>
> The problem is encountered when host's vhost backend does not support
> VIRTIO_F_VERSION_1, and migration is initiated from a v2.7 or prior
> machine with virtio-pci modern capabilities enabled to a v2.8 machine.
>
> In this case, modern capabilities get exposed to the guest by the source,
> whereas the target will detect version 1 is not supported so will only
> expose legacy capabilities.
>
> The problem is fixed by introducing a new "x-ignore-backend-features"
> property, which is set in v2.7 and prior compatibility modes. Doing this,
> v2.7 machine keeps its broken behaviour (enabling modern while version
> is not supported), and newer machines will behave correctly.
>
> Reported-by: Michael Roth <mdroth@linux.vnet.ibm.com>
> Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
> Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> Tested-by: Michael Roth <mdroth@linux.vnet.ibm.com>
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>
> V3 fixes commit message with the new property name.
> V2 changes the naming as proposed by Michael T.and Cornelia, and
> fixes commit message.
>
> hw/virtio/virtio-pci.c | 5 ++++-
> hw/virtio/virtio-pci.h | 1 +
> include/hw/compat.h | 4 ++++
> 3 files changed, 9 insertions(+), 1 deletion(-)
Thanks, applied to my staging tree:
https://github.com/stefanha/qemu/commits/staging
Stefan
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^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [Qemu-devel] [PATCH v3] virtio-pci: Fix cross-version migration with older machines
2016-12-15 7:38 ` Stefan Hajnoczi
@ 2016-12-15 8:26 ` Cornelia Huck
2016-12-15 10:31 ` Stefan Hajnoczi
0 siblings, 1 reply; 7+ messages in thread
From: Cornelia Huck @ 2016-12-15 8:26 UTC (permalink / raw)
To: Stefan Hajnoczi
Cc: Maxime Coquelin, mdroth, stefanha, qemu-devel, mst, marcel,
Dr . David Alan Gilbert
On Thu, 15 Dec 2016 07:38:09 +0000
Stefan Hajnoczi <stefanha@gmail.com> wrote:
> On Wed, Dec 14, 2016 at 05:30:35PM +0100, Maxime Coquelin wrote:
> > This patch fixes a cross-version migration regression introduced
> > by commit d1b4259f ("virtio-bus: Plug devices after features are
> > negotiated").
> >
> > The problem is encountered when host's vhost backend does not support
> > VIRTIO_F_VERSION_1, and migration is initiated from a v2.7 or prior
> > machine with virtio-pci modern capabilities enabled to a v2.8 machine.
> >
> > In this case, modern capabilities get exposed to the guest by the source,
> > whereas the target will detect version 1 is not supported so will only
> > expose legacy capabilities.
> >
> > The problem is fixed by introducing a new "x-ignore-backend-features"
> > property, which is set in v2.7 and prior compatibility modes. Doing this,
> > v2.7 machine keeps its broken behaviour (enabling modern while version
> > is not supported), and newer machines will behave correctly.
> >
> > Reported-by: Michael Roth <mdroth@linux.vnet.ibm.com>
> > Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
> > Cc: Michael S. Tsirkin <mst@redhat.com>
> > Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
> > Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
> > Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> > Tested-by: Michael Roth <mdroth@linux.vnet.ibm.com>
> > Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> > ---
> >
> > V3 fixes commit message with the new property name.
> > V2 changes the naming as proposed by Michael T.and Cornelia, and
> > fixes commit message.
> >
> > hw/virtio/virtio-pci.c | 5 ++++-
> > hw/virtio/virtio-pci.h | 1 +
> > include/hw/compat.h | 4 ++++
> > 3 files changed, 9 insertions(+), 1 deletion(-)
>
> Thanks, applied to my staging tree:
> https://github.com/stefanha/qemu/commits/staging
>
> Stefan
Hm, missing my R-b I gave for v2... feel free to add
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
if you still want to change it.
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [Qemu-devel] [PATCH v3] virtio-pci: Fix cross-version migration with older machines
2016-12-15 8:26 ` Cornelia Huck
@ 2016-12-15 10:31 ` Stefan Hajnoczi
2016-12-15 11:03 ` Maxime Coquelin
0 siblings, 1 reply; 7+ messages in thread
From: Stefan Hajnoczi @ 2016-12-15 10:31 UTC (permalink / raw)
To: Cornelia Huck
Cc: Stefan Hajnoczi, Maxime Coquelin, mdroth, qemu-devel, mst,
marcel, Dr . David Alan Gilbert
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On Thu, Dec 15, 2016 at 09:26:56AM +0100, Cornelia Huck wrote:
> On Thu, 15 Dec 2016 07:38:09 +0000
> Stefan Hajnoczi <stefanha@gmail.com> wrote:
>
> > On Wed, Dec 14, 2016 at 05:30:35PM +0100, Maxime Coquelin wrote:
> > > This patch fixes a cross-version migration regression introduced
> > > by commit d1b4259f ("virtio-bus: Plug devices after features are
> > > negotiated").
> > >
> > > The problem is encountered when host's vhost backend does not support
> > > VIRTIO_F_VERSION_1, and migration is initiated from a v2.7 or prior
> > > machine with virtio-pci modern capabilities enabled to a v2.8 machine.
> > >
> > > In this case, modern capabilities get exposed to the guest by the source,
> > > whereas the target will detect version 1 is not supported so will only
> > > expose legacy capabilities.
> > >
> > > The problem is fixed by introducing a new "x-ignore-backend-features"
> > > property, which is set in v2.7 and prior compatibility modes. Doing this,
> > > v2.7 machine keeps its broken behaviour (enabling modern while version
> > > is not supported), and newer machines will behave correctly.
> > >
> > > Reported-by: Michael Roth <mdroth@linux.vnet.ibm.com>
> > > Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
> > > Cc: Michael S. Tsirkin <mst@redhat.com>
> > > Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
> > > Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > > Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
> > > Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> > > Tested-by: Michael Roth <mdroth@linux.vnet.ibm.com>
> > > Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> > > ---
> > >
> > > V3 fixes commit message with the new property name.
> > > V2 changes the naming as proposed by Michael T.and Cornelia, and
> > > fixes commit message.
> > >
> > > hw/virtio/virtio-pci.c | 5 ++++-
> > > hw/virtio/virtio-pci.h | 1 +
> > > include/hw/compat.h | 4 ++++
> > > 3 files changed, 9 insertions(+), 1 deletion(-)
> >
> > Thanks, applied to my staging tree:
> > https://github.com/stefanha/qemu/commits/staging
> >
> > Stefan
>
> Hm, missing my R-b I gave for v2... feel free to add
>
> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
>
> if you still want to change it.
Sorry, the R-b didn't make it into v2.8.0-rc4.
The patch management scripts I use apply all R-b for a single email
thread. They do not look at previous revisions (it would be hard to
tell which R-b still stand and which do not). The usual solution is for
the patch author to include previous R-b in new revisions as long as
code changes aren't substantial.
Stefan
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^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [Qemu-devel] [PATCH v3] virtio-pci: Fix cross-version migration with older machines
2016-12-15 10:31 ` Stefan Hajnoczi
@ 2016-12-15 11:03 ` Maxime Coquelin
0 siblings, 0 replies; 7+ messages in thread
From: Maxime Coquelin @ 2016-12-15 11:03 UTC (permalink / raw)
To: Stefan Hajnoczi, Cornelia Huck
Cc: Stefan Hajnoczi, mdroth, qemu-devel, mst, marcel,
Dr . David Alan Gilbert
On 12/15/2016 11:31 AM, Stefan Hajnoczi wrote:
> On Thu, Dec 15, 2016 at 09:26:56AM +0100, Cornelia Huck wrote:
>> On Thu, 15 Dec 2016 07:38:09 +0000
>> Stefan Hajnoczi <stefanha@gmail.com> wrote:
>>
>>> On Wed, Dec 14, 2016 at 05:30:35PM +0100, Maxime Coquelin wrote:
>>>> This patch fixes a cross-version migration regression introduced
>>>> by commit d1b4259f ("virtio-bus: Plug devices after features are
>>>> negotiated").
>>>>
>>>> The problem is encountered when host's vhost backend does not support
>>>> VIRTIO_F_VERSION_1, and migration is initiated from a v2.7 or prior
>>>> machine with virtio-pci modern capabilities enabled to a v2.8 machine.
>>>>
>>>> In this case, modern capabilities get exposed to the guest by the source,
>>>> whereas the target will detect version 1 is not supported so will only
>>>> expose legacy capabilities.
>>>>
>>>> The problem is fixed by introducing a new "x-ignore-backend-features"
>>>> property, which is set in v2.7 and prior compatibility modes. Doing this,
>>>> v2.7 machine keeps its broken behaviour (enabling modern while version
>>>> is not supported), and newer machines will behave correctly.
>>>>
>>>> Reported-by: Michael Roth <mdroth@linux.vnet.ibm.com>
>>>> Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
>>>> Cc: Michael S. Tsirkin <mst@redhat.com>
>>>> Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
>>>> Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
>>>> Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
>>>> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
>>>> Tested-by: Michael Roth <mdroth@linux.vnet.ibm.com>
>>>> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>>>> ---
>>>>
>>>> V3 fixes commit message with the new property name.
>>>> V2 changes the naming as proposed by Michael T.and Cornelia, and
>>>> fixes commit message.
>>>>
>>>> hw/virtio/virtio-pci.c | 5 ++++-
>>>> hw/virtio/virtio-pci.h | 1 +
>>>> include/hw/compat.h | 4 ++++
>>>> 3 files changed, 9 insertions(+), 1 deletion(-)
>>>
>>> Thanks, applied to my staging tree:
>>> https://github.com/stefanha/qemu/commits/staging
>>>
>>> Stefan
>>
>> Hm, missing my R-b I gave for v2... feel free to add
>>
>> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
>>
>> if you still want to change it.
>
> Sorry, the R-b didn't make it into v2.8.0-rc4.
>
> The patch management scripts I use apply all R-b for a single email
> thread. They do not look at previous revisions (it would be hard to
> tell which R-b still stand and which do not). The usual solution is for
> the patch author to include previous R-b in new revisions as long as
> code changes aren't substantial.
Right that's my fault, sorry Cornelia.
Maxime
>
> Stefan
>
^ permalink raw reply [flat|nested] 7+ messages in thread