[libvirt PATCH] qemu: ramfb video device doesn't support PCI address

[Jonathon Jongsma]

On Wed, 2020-06-24 at 23:21 -0400, Laine Stump wrote:
> On 6/24/20 6:06 PM, Jonathon Jongsma wrote:
> > Although a ramfb video device is not a PCI device, we don't
> > currently
> > report an error for ramfb device definitions containing a PCI
> > address.
> > However, a guest configured with such a device will fail to start:
> > 
> >      # virsh start test1
> >      error: Failed to start domain test1
> >      error: internal error: qemu unexpectedly closed the monitor:
> > 2020-06-16T05:23:02.759221Z qemu-kvm: -device
> > ramfb,id=video0,bus=pcie.0,addr=0x1: Device 'ramfb' can't go on
> > PCIE bus
> > 
> > A better approach is to reject any device definitions that contain
> > PCI
> > addresses.  While this is a change in behavior, any existing
> > configurations were non-functional.
> > 
> > https://bugzilla.redhat.com/show_bug.cgi?id=1847259
> > 
> > Signed-off-by: Jonathon Jongsma <jjongsma at redhat.com>
> > ---
> >   src/conf/domain_conf.c   | 7 +++++++
> >   tests/qemuxml2argvtest.c | 1 +
> >   2 files changed, 8 insertions(+)
> > 
> > diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> > index fc7fcfb0c6..1a06cb3f4b 100644
> > --- a/src/conf/domain_conf.c
> > +++ b/src/conf/domain_conf.c
> > @@ -6608,6 +6608,13 @@ virDomainVideoDefValidate(const
> > virDomainVideoDef *video,
> >           return -1;
> >       }
> >   
> > +    if (video->type == VIR_DOMAIN_VIDEO_TYPE_RAMFB &&
> > +        video->info.type != VIR_DOMAIN_DEVICE_ADDRESS_TYPE_NONE) {
> > +        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> > +                       _("'address' is not supported for 'ramfb'
> > video devices"));
> > +        return -1;
> > +    }
> > +
> 
> There may be disagreement about this, and in practical terms it makes
> no 
> difference (because no domain type other than QEMU is ever going to
> have 
> one of these devices anyway), but since ramfb is a qemu-specific
> device 
> (isn't it?), I think this check would be better put in 
> qemu_validate.c:qemuValidateDomainDeviceDevVideo(), which is the 
> qemu-specific validation function for video devices.
> 
> 
> (I  see there is already validation in virDomainVideoDefValidate()
> for a 
> qemu-specific (afaik) video type - i is even checking for one
> backend 
> that is named VIR_DOMAIN_VIDEO_BACKEND_TYPE_QEMU)
> 
> 
> I don't really have a strong opinion though, since the other
> hypervisor 
> drivers don't seem all that concerned about fleshing out their 
> validation functions, and what you have works properly for qemu :-P

For what it's worth, I agree with you. I'll re-spin the patch.

Jonathon