| Message ID | 20200915130514.80989-1-sgarzare@redhat.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] virtio: skip legacy support check on machine types less than 5.1 | expand |
+Cc qemu-stable@nongnu.org It was not my day... I forgot to cc stable. Thanks, Stefano On Tue, Sep 15, 2020 at 03:05:14PM +0200, Stefano Garzarella wrote: > Commit 9b3a35ec82 ("virtio: verify that legacy support is not accidentally > on") added a check that returns an error if legacy support is on, but the > device is not legacy. > > Unfortunately some devices were wrongly declared legacy even if they > were not (e.g vhost-vsock). > > To avoid migration issues, we disable this error for machine types < 5.1, > but we print a warning. > > Cc: qemu-stable@nongnu.org > Fixes: 9b3a35ec82 ("virtio: verify that legacy support is not accidentally on") > Suggested-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > Suggested-by: Cornelia Huck <cohuck@redhat.com> > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> > --- > v2: > - fixed Cornelia's e-mail address > --- > include/hw/virtio/virtio.h | 1 + > hw/core/machine.c | 1 + > hw/virtio/virtio.c | 18 ++++++++++++++++-- > 3 files changed, 18 insertions(+), 2 deletions(-) > > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h > index 807280451b..ed7cee348b 100644 > --- a/include/hw/virtio/virtio.h > +++ b/include/hw/virtio/virtio.h > @@ -103,6 +103,7 @@ struct VirtIODevice > bool use_started; > bool started; > bool start_on_kick; /* when virtio 1.0 feature has not been negotiated */ > + bool disable_legacy_check; > VMChangeStateEntry *vmstate; > char *bus_name; > uint8_t device_endian; > diff --git a/hw/core/machine.c b/hw/core/machine.c > index ea26d61237..b686eab798 100644 > --- a/hw/core/machine.c > +++ b/hw/core/machine.c > @@ -44,6 +44,7 @@ GlobalProperty hw_compat_5_0[] = { > { "vmport", "x-signal-unsupported-cmd", "off" }, > { "vmport", "x-report-vmx-type", "off" }, > { "vmport", "x-cmds-v2", "off" }, > + { "virtio-device", "x-disable-legacy-check", "true" }, > }; > const size_t hw_compat_5_0_len = G_N_ELEMENTS(hw_compat_5_0); > > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > index e983025217..30ccc43b8c 100644 > --- a/hw/virtio/virtio.c > +++ b/hw/virtio/virtio.c > @@ -3287,6 +3287,8 @@ void virtio_init(VirtIODevice *vdev, const char *name, > */ > bool virtio_legacy_allowed(VirtIODevice *vdev) > { > + bool ret = false; > + > switch (vdev->device_id) { > case VIRTIO_ID_NET: > case VIRTIO_ID_BLOCK: > @@ -3298,10 +3300,20 @@ bool virtio_legacy_allowed(VirtIODevice *vdev) > case VIRTIO_ID_9P: > case VIRTIO_ID_RPROC_SERIAL: > case VIRTIO_ID_CAIF: > + ret = true; > + } > + > + /* > + * For backward compatibility, we allow legacy mode with old machine types > + * to get the migration working. > + */ > + if (!ret && vdev->disable_legacy_check) { > + warn_report("device is modern-only, but for backward compatibility " > + "legacy is allowed"); > return true; > - default: > - return false; > } > + > + return ret; > } > > hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n) > @@ -3713,6 +3725,8 @@ static Property virtio_properties[] = { > DEFINE_VIRTIO_COMMON_FEATURES(VirtIODevice, host_features), > DEFINE_PROP_BOOL("use-started", VirtIODevice, use_started, true), > DEFINE_PROP_BOOL("use-disabled-flag", VirtIODevice, use_disabled_flag, true), > + DEFINE_PROP_BOOL("x-disable-legacy-check", VirtIODevice, > + disable_legacy_check, false), > DEFINE_PROP_END_OF_LIST(), > }; > > -- > 2.26.2 > >
On Tue, 15 Sep 2020 15:05:14 +0200 Stefano Garzarella <sgarzare@redhat.com> wrote: > Commit 9b3a35ec82 ("virtio: verify that legacy support is not accidentally > on") added a check that returns an error if legacy support is on, but the > device is not legacy. > > Unfortunately some devices were wrongly declared legacy even if they > were not (e.g vhost-vsock). > > To avoid migration issues, we disable this error for machine types < 5.1, > but we print a warning. > > Cc: qemu-stable@nongnu.org > Fixes: 9b3a35ec82 ("virtio: verify that legacy support is not accidentally on") > Suggested-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > Suggested-by: Cornelia Huck <cohuck@redhat.com> > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> > --- > v2: > - fixed Cornelia's e-mail address > --- > include/hw/virtio/virtio.h | 1 + > hw/core/machine.c | 1 + > hw/virtio/virtio.c | 18 ++++++++++++++++-- > 3 files changed, 18 insertions(+), 2 deletions(-) > > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h > index 807280451b..ed7cee348b 100644 > --- a/include/hw/virtio/virtio.h > +++ b/include/hw/virtio/virtio.h > @@ -103,6 +103,7 @@ struct VirtIODevice > bool use_started; > bool started; > bool start_on_kick; /* when virtio 1.0 feature has not been negotiated */ > + bool disable_legacy_check; > VMChangeStateEntry *vmstate; > char *bus_name; > uint8_t device_endian; > diff --git a/hw/core/machine.c b/hw/core/machine.c > index ea26d61237..b686eab798 100644 > --- a/hw/core/machine.c > +++ b/hw/core/machine.c > @@ -44,6 +44,7 @@ GlobalProperty hw_compat_5_0[] = { > { "vmport", "x-signal-unsupported-cmd", "off" }, > { "vmport", "x-report-vmx-type", "off" }, > { "vmport", "x-cmds-v2", "off" }, > + { "virtio-device", "x-disable-legacy-check", "true" }, Hm... not sure if we actually should add a new device property for that. Maybe we can use a flag in the base machine type instead? > }; > const size_t hw_compat_5_0_len = G_N_ELEMENTS(hw_compat_5_0); > > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > index e983025217..30ccc43b8c 100644 > --- a/hw/virtio/virtio.c > +++ b/hw/virtio/virtio.c > @@ -3287,6 +3287,8 @@ void virtio_init(VirtIODevice *vdev, const char *name, > */ > bool virtio_legacy_allowed(VirtIODevice *vdev) > { > + bool ret = false; > + > switch (vdev->device_id) { > case VIRTIO_ID_NET: > case VIRTIO_ID_BLOCK: > @@ -3298,10 +3300,20 @@ bool virtio_legacy_allowed(VirtIODevice *vdev) > case VIRTIO_ID_9P: > case VIRTIO_ID_RPROC_SERIAL: > case VIRTIO_ID_CAIF: > + ret = true; > + } > + > + /* > + * For backward compatibility, we allow legacy mode with old machine types > + * to get the migration working. > + */ > + if (!ret && vdev->disable_legacy_check) { > + warn_report("device is modern-only, but for backward compatibility " > + "legacy is allowed"); I don't think we should warn in the function that returns whether legacy is allowed or not. Future code might want to call this function for other purposes, and returning true with a warning is not that useful for code that wants to find out whether legacy is supported for a type in principle. So even though it is more work, I think we should move this warning to the code that is actively trying to fence off misconfigured devices. > return true; > - default: > - return false; > } > + > + return ret; > } > > hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n) > @@ -3713,6 +3725,8 @@ static Property virtio_properties[] = { > DEFINE_VIRTIO_COMMON_FEATURES(VirtIODevice, host_features), > DEFINE_PROP_BOOL("use-started", VirtIODevice, use_started, true), > DEFINE_PROP_BOOL("use-disabled-flag", VirtIODevice, use_disabled_flag, true), > + DEFINE_PROP_BOOL("x-disable-legacy-check", VirtIODevice, > + disable_legacy_check, false), > DEFINE_PROP_END_OF_LIST(), > }; >
On Wed, Sep 16, 2020 at 11:08:48AM +0200, Cornelia Huck wrote: > On Tue, 15 Sep 2020 15:05:14 +0200 > Stefano Garzarella <sgarzare@redhat.com> wrote: > > > Commit 9b3a35ec82 ("virtio: verify that legacy support is not accidentally > > on") added a check that returns an error if legacy support is on, but the > > device is not legacy. > > > > Unfortunately some devices were wrongly declared legacy even if they > > were not (e.g vhost-vsock). > > > > To avoid migration issues, we disable this error for machine types < 5.1, > > but we print a warning. > > > > Cc: qemu-stable@nongnu.org > > Fixes: 9b3a35ec82 ("virtio: verify that legacy support is not accidentally on") > > Suggested-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > > Suggested-by: Cornelia Huck <cohuck@redhat.com> > > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> > > --- > > v2: > > - fixed Cornelia's e-mail address > > --- > > include/hw/virtio/virtio.h | 1 + > > hw/core/machine.c | 1 + > > hw/virtio/virtio.c | 18 ++++++++++++++++-- > > 3 files changed, 18 insertions(+), 2 deletions(-) > > > > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h > > index 807280451b..ed7cee348b 100644 > > --- a/include/hw/virtio/virtio.h > > +++ b/include/hw/virtio/virtio.h > > @@ -103,6 +103,7 @@ struct VirtIODevice > > bool use_started; > > bool started; > > bool start_on_kick; /* when virtio 1.0 feature has not been negotiated */ > > + bool disable_legacy_check; > > VMChangeStateEntry *vmstate; > > char *bus_name; > > uint8_t device_endian; > > diff --git a/hw/core/machine.c b/hw/core/machine.c > > index ea26d61237..b686eab798 100644 > > --- a/hw/core/machine.c > > +++ b/hw/core/machine.c > > @@ -44,6 +44,7 @@ GlobalProperty hw_compat_5_0[] = { > > { "vmport", "x-signal-unsupported-cmd", "off" }, > > { "vmport", "x-report-vmx-type", "off" }, > > { "vmport", "x-cmds-v2", "off" }, > > + { "virtio-device", "x-disable-legacy-check", "true" }, > > Hm... not sure if we actually should add a new device property for > that. Maybe we can use a flag in the base machine type instead? I am not very experienced with machine types. I used the device property to easily access it from virtio devices. Please, can you give me some suggestions where to look for the flags? > > > }; > > const size_t hw_compat_5_0_len = G_N_ELEMENTS(hw_compat_5_0); > > > > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > > index e983025217..30ccc43b8c 100644 > > --- a/hw/virtio/virtio.c > > +++ b/hw/virtio/virtio.c > > @@ -3287,6 +3287,8 @@ void virtio_init(VirtIODevice *vdev, const char *name, > > */ > > bool virtio_legacy_allowed(VirtIODevice *vdev) > > { > > + bool ret = false; > > + > > switch (vdev->device_id) { > > case VIRTIO_ID_NET: > > case VIRTIO_ID_BLOCK: > > @@ -3298,10 +3300,20 @@ bool virtio_legacy_allowed(VirtIODevice *vdev) > > case VIRTIO_ID_9P: > > case VIRTIO_ID_RPROC_SERIAL: > > case VIRTIO_ID_CAIF: > > + ret = true; > > + } > > + > > + /* > > + * For backward compatibility, we allow legacy mode with old machine types > > + * to get the migration working. > > + */ > > + if (!ret && vdev->disable_legacy_check) { > > + warn_report("device is modern-only, but for backward compatibility " > > + "legacy is allowed"); > > I don't think we should warn in the function that returns whether > legacy is allowed or not. Future code might want to call this function > for other purposes, and returning true with a warning is not that > useful for code that wants to find out whether legacy is supported for > a type in principle. > > So even though it is more work, I think we should move this warning to > the code that is actively trying to fence off misconfigured devices. Yes, I got it. At first I did so, but then I wanted to reduce the duplicate code. But you're right, it's ugly. I'll send a v3. Thanks, Stefano
On Thu, 17 Sep 2020 10:48:28 +0200 Stefano Garzarella <sgarzare@redhat.com> wrote: > On Wed, Sep 16, 2020 at 11:08:48AM +0200, Cornelia Huck wrote: > > On Tue, 15 Sep 2020 15:05:14 +0200 > > Stefano Garzarella <sgarzare@redhat.com> wrote: > > > > > Commit 9b3a35ec82 ("virtio: verify that legacy support is not accidentally > > > on") added a check that returns an error if legacy support is on, but the > > > device is not legacy. > > > > > > Unfortunately some devices were wrongly declared legacy even if they > > > were not (e.g vhost-vsock). > > > > > > To avoid migration issues, we disable this error for machine types < 5.1, > > > but we print a warning. > > > > > > Cc: qemu-stable@nongnu.org > > > Fixes: 9b3a35ec82 ("virtio: verify that legacy support is not accidentally on") > > > Suggested-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > > > Suggested-by: Cornelia Huck <cohuck@redhat.com> > > > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> > > > --- > > > v2: > > > - fixed Cornelia's e-mail address > > > --- > > > include/hw/virtio/virtio.h | 1 + > > > hw/core/machine.c | 1 + > > > hw/virtio/virtio.c | 18 ++++++++++++++++-- > > > 3 files changed, 18 insertions(+), 2 deletions(-) > > > > > > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h > > > index 807280451b..ed7cee348b 100644 > > > --- a/include/hw/virtio/virtio.h > > > +++ b/include/hw/virtio/virtio.h > > > @@ -103,6 +103,7 @@ struct VirtIODevice > > > bool use_started; > > > bool started; > > > bool start_on_kick; /* when virtio 1.0 feature has not been negotiated */ > > > + bool disable_legacy_check; > > > VMChangeStateEntry *vmstate; > > > char *bus_name; > > > uint8_t device_endian; > > > diff --git a/hw/core/machine.c b/hw/core/machine.c > > > index ea26d61237..b686eab798 100644 > > > --- a/hw/core/machine.c > > > +++ b/hw/core/machine.c > > > @@ -44,6 +44,7 @@ GlobalProperty hw_compat_5_0[] = { > > > { "vmport", "x-signal-unsupported-cmd", "off" }, > > > { "vmport", "x-report-vmx-type", "off" }, > > > { "vmport", "x-cmds-v2", "off" }, > > > + { "virtio-device", "x-disable-legacy-check", "true" }, > > > > Hm... not sure if we actually should add a new device property for > > that. Maybe we can use a flag in the base machine type instead? > > I am not very experienced with machine types. > I used the device property to easily access it from virtio devices. > > Please, can you give me some suggestions where to look for the flags? I was thinking about adding a new virtio_legacy_check flag into MachineClass to get a machine-wide config and avoid introducing a new config knob. The drawback is that every machine type supporting compat machines would need to take care about disabling the check in their 5.1-or-older machines themselves. Not sure what the preferable solution is; I'm not really opposed to your approach, though.
* Cornelia Huck (cohuck@redhat.com) wrote: > On Thu, 17 Sep 2020 10:48:28 +0200 > Stefano Garzarella <sgarzare@redhat.com> wrote: > > > On Wed, Sep 16, 2020 at 11:08:48AM +0200, Cornelia Huck wrote: > > > On Tue, 15 Sep 2020 15:05:14 +0200 > > > Stefano Garzarella <sgarzare@redhat.com> wrote: > > > > > > > Commit 9b3a35ec82 ("virtio: verify that legacy support is not accidentally > > > > on") added a check that returns an error if legacy support is on, but the > > > > device is not legacy. > > > > > > > > Unfortunately some devices were wrongly declared legacy even if they > > > > were not (e.g vhost-vsock). > > > > > > > > To avoid migration issues, we disable this error for machine types < 5.1, > > > > but we print a warning. > > > > > > > > Cc: qemu-stable@nongnu.org > > > > Fixes: 9b3a35ec82 ("virtio: verify that legacy support is not accidentally on") > > > > Suggested-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > > > > Suggested-by: Cornelia Huck <cohuck@redhat.com> > > > > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> > > > > --- > > > > v2: > > > > - fixed Cornelia's e-mail address > > > > --- > > > > include/hw/virtio/virtio.h | 1 + > > > > hw/core/machine.c | 1 + > > > > hw/virtio/virtio.c | 18 ++++++++++++++++-- > > > > 3 files changed, 18 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h > > > > index 807280451b..ed7cee348b 100644 > > > > --- a/include/hw/virtio/virtio.h > > > > +++ b/include/hw/virtio/virtio.h > > > > @@ -103,6 +103,7 @@ struct VirtIODevice > > > > bool use_started; > > > > bool started; > > > > bool start_on_kick; /* when virtio 1.0 feature has not been negotiated */ > > > > + bool disable_legacy_check; > > > > VMChangeStateEntry *vmstate; > > > > char *bus_name; > > > > uint8_t device_endian; > > > > diff --git a/hw/core/machine.c b/hw/core/machine.c > > > > index ea26d61237..b686eab798 100644 > > > > --- a/hw/core/machine.c > > > > +++ b/hw/core/machine.c > > > > @@ -44,6 +44,7 @@ GlobalProperty hw_compat_5_0[] = { > > > > { "vmport", "x-signal-unsupported-cmd", "off" }, > > > > { "vmport", "x-report-vmx-type", "off" }, > > > > { "vmport", "x-cmds-v2", "off" }, > > > > + { "virtio-device", "x-disable-legacy-check", "true" }, > > > > > > Hm... not sure if we actually should add a new device property for > > > that. Maybe we can use a flag in the base machine type instead? > > > > I am not very experienced with machine types. > > I used the device property to easily access it from virtio devices. > > > > Please, can you give me some suggestions where to look for the flags? > > I was thinking about adding a new virtio_legacy_check flag into > MachineClass to get a machine-wide config and avoid introducing a new > config knob. The drawback is that every machine type supporting compat > machines would need to take care about disabling the check in their > 5.1-or-older machines themselves. > > Not sure what the preferable solution is; I'm not really opposed to > your approach, though. I think a device property is fine - they make it easy to add it to the global compat list. Dave -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
On Thu, Sep 17, 2020 at 11:00:00AM +0100, Dr. David Alan Gilbert wrote: > * Cornelia Huck (cohuck@redhat.com) wrote: > > On Thu, 17 Sep 2020 10:48:28 +0200 > > Stefano Garzarella <sgarzare@redhat.com> wrote: > > > > > On Wed, Sep 16, 2020 at 11:08:48AM +0200, Cornelia Huck wrote: > > > > On Tue, 15 Sep 2020 15:05:14 +0200 > > > > Stefano Garzarella <sgarzare@redhat.com> wrote: > > > > > > > > > Commit 9b3a35ec82 ("virtio: verify that legacy support is not accidentally > > > > > on") added a check that returns an error if legacy support is on, but the > > > > > device is not legacy. > > > > > > > > > > Unfortunately some devices were wrongly declared legacy even if they > > > > > were not (e.g vhost-vsock). > > > > > > > > > > To avoid migration issues, we disable this error for machine types < 5.1, > > > > > but we print a warning. > > > > > > > > > > Cc: qemu-stable@nongnu.org > > > > > Fixes: 9b3a35ec82 ("virtio: verify that legacy support is not accidentally on") > > > > > Suggested-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > > > > > Suggested-by: Cornelia Huck <cohuck@redhat.com> > > > > > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> > > > > > --- > > > > > v2: > > > > > - fixed Cornelia's e-mail address > > > > > --- > > > > > include/hw/virtio/virtio.h | 1 + > > > > > hw/core/machine.c | 1 + > > > > > hw/virtio/virtio.c | 18 ++++++++++++++++-- > > > > > 3 files changed, 18 insertions(+), 2 deletions(-) > > > > > > > > > > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h > > > > > index 807280451b..ed7cee348b 100644 > > > > > --- a/include/hw/virtio/virtio.h > > > > > +++ b/include/hw/virtio/virtio.h > > > > > @@ -103,6 +103,7 @@ struct VirtIODevice > > > > > bool use_started; > > > > > bool started; > > > > > bool start_on_kick; /* when virtio 1.0 feature has not been negotiated */ > > > > > + bool disable_legacy_check; > > > > > VMChangeStateEntry *vmstate; > > > > > char *bus_name; > > > > > uint8_t device_endian; > > > > > diff --git a/hw/core/machine.c b/hw/core/machine.c > > > > > index ea26d61237..b686eab798 100644 > > > > > --- a/hw/core/machine.c > > > > > +++ b/hw/core/machine.c > > > > > @@ -44,6 +44,7 @@ GlobalProperty hw_compat_5_0[] = { > > > > > { "vmport", "x-signal-unsupported-cmd", "off" }, > > > > > { "vmport", "x-report-vmx-type", "off" }, > > > > > { "vmport", "x-cmds-v2", "off" }, > > > > > + { "virtio-device", "x-disable-legacy-check", "true" }, > > > > > > > > Hm... not sure if we actually should add a new device property for > > > > that. Maybe we can use a flag in the base machine type instead? > > > > > > I am not very experienced with machine types. > > > I used the device property to easily access it from virtio devices. > > > > > > Please, can you give me some suggestions where to look for the flags? > > > > I was thinking about adding a new virtio_legacy_check flag into > > MachineClass to get a machine-wide config and avoid introducing a new > > config knob. The drawback is that every machine type supporting compat > > machines would need to take care about disabling the check in their > > 5.1-or-older machines themselves. Thank you for clarifying! > > > > Not sure what the preferable solution is; I'm not really opposed to > > your approach, though. > > I think a device property is fine - they make it easy to add it to the > global compat list. > Okay, so I'll leave the device property. I also need to update a series [1] that I sent to force virtio version 1 on vhost-vsock devices. Also in this case I need to care about migration and force it only on new machine types. Do you think I can reuse the same property also in vhost-vsock-pci and vhost-vsock-ccw to force virtio version 1, or it is better to add a new property for each device. The two things (disable legacy check and force version 1) are related, so maybe I can use a single property in the virtio-device class, Thanks, Stefano [1] https://lists.nongnu.org/archive/html/qemu-devel/2020-08/msg04437.html
On Thu, 17 Sep 2020 12:47:21 +0200 Stefano Garzarella <sgarzare@redhat.com> wrote: > Okay, so I'll leave the device property. > > > I also need to update a series [1] that I sent to force virtio version 1 > on vhost-vsock devices. > Also in this case I need to care about migration and force it only on new > machine types. > > Do you think I can reuse the same property also in vhost-vsock-pci and > vhost-vsock-ccw to force virtio version 1, or it is better to add a new > property for each device. > > The two things (disable legacy check and force version 1) are related, > so maybe I can use a single property in the virtio-device class, So, 'x-disable-legacy-check==false' -> 'we need to force version 1'? Seems reasonable to me. > > Thanks, > Stefano > > [1] https://lists.nongnu.org/archive/html/qemu-devel/2020-08/msg04437.html >
On Thu, Sep 17, 2020 at 01:00:08PM +0200, Cornelia Huck wrote: > On Thu, 17 Sep 2020 12:47:21 +0200 > Stefano Garzarella <sgarzare@redhat.com> wrote: > > > Okay, so I'll leave the device property. > > > > > > I also need to update a series [1] that I sent to force virtio version 1 > > on vhost-vsock devices. > > Also in this case I need to care about migration and force it only on new > > machine types. > > > > Do you think I can reuse the same property also in vhost-vsock-pci and > > vhost-vsock-ccw to force virtio version 1, or it is better to add a new > > property for each device. > > > > The two things (disable legacy check and force version 1) are related, > > so maybe I can use a single property in the virtio-device class, > > So, 'x-disable-legacy-check==false' -> 'we need to force version 1'? Exaclty :-) > Seems reasonable to me. Thanks for the feedback, I'll go this way! Stefano
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h index 807280451b..ed7cee348b 100644 --- a/include/hw/virtio/virtio.h +++ b/include/hw/virtio/virtio.h @@ -103,6 +103,7 @@ struct VirtIODevice bool use_started; bool started; bool start_on_kick; /* when virtio 1.0 feature has not been negotiated */ + bool disable_legacy_check; VMChangeStateEntry *vmstate; char *bus_name; uint8_t device_endian; diff --git a/hw/core/machine.c b/hw/core/machine.c index ea26d61237..b686eab798 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -44,6 +44,7 @@ GlobalProperty hw_compat_5_0[] = { { "vmport", "x-signal-unsupported-cmd", "off" }, { "vmport", "x-report-vmx-type", "off" }, { "vmport", "x-cmds-v2", "off" }, + { "virtio-device", "x-disable-legacy-check", "true" }, }; const size_t hw_compat_5_0_len = G_N_ELEMENTS(hw_compat_5_0); diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index e983025217..30ccc43b8c 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -3287,6 +3287,8 @@ void virtio_init(VirtIODevice *vdev, const char *name, */ bool virtio_legacy_allowed(VirtIODevice *vdev) { + bool ret = false; + switch (vdev->device_id) { case VIRTIO_ID_NET: case VIRTIO_ID_BLOCK: @@ -3298,10 +3300,20 @@ bool virtio_legacy_allowed(VirtIODevice *vdev) case VIRTIO_ID_9P: case VIRTIO_ID_RPROC_SERIAL: case VIRTIO_ID_CAIF: + ret = true; + } + + /* + * For backward compatibility, we allow legacy mode with old machine types + * to get the migration working. + */ + if (!ret && vdev->disable_legacy_check) { + warn_report("device is modern-only, but for backward compatibility " + "legacy is allowed"); return true; - default: - return false; } + + return ret; } hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n) @@ -3713,6 +3725,8 @@ static Property virtio_properties[] = { DEFINE_VIRTIO_COMMON_FEATURES(VirtIODevice, host_features), DEFINE_PROP_BOOL("use-started", VirtIODevice, use_started, true), DEFINE_PROP_BOOL("use-disabled-flag", VirtIODevice, use_disabled_flag, true), + DEFINE_PROP_BOOL("x-disable-legacy-check", VirtIODevice, + disable_legacy_check, false), DEFINE_PROP_END_OF_LIST(), };
Commit 9b3a35ec82 ("virtio: verify that legacy support is not accidentally on") added a check that returns an error if legacy support is on, but the device is not legacy. Unfortunately some devices were wrongly declared legacy even if they were not (e.g vhost-vsock). To avoid migration issues, we disable this error for machine types < 5.1, but we print a warning. Cc: qemu-stable@nongnu.org Fixes: 9b3a35ec82 ("virtio: verify that legacy support is not accidentally on") Suggested-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Suggested-by: Cornelia Huck <cohuck@redhat.com> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> --- v2: - fixed Cornelia's e-mail address --- include/hw/virtio/virtio.h | 1 + hw/core/machine.c | 1 + hw/virtio/virtio.c | 18 ++++++++++++++++-- 3 files changed, 18 insertions(+), 2 deletions(-)