Re: [Qemu-devel] [PATCH] hw/pci: fixed crash when using rombar=0 for hotplugged devices

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Oct 22, 2014 at 12:06:18AM +0200, Paolo Bonzini wrote:
> 
> 
> On 10/21/2014 02:37 PM, Marcel Apfelbaum wrote:
> > ROM images must be loaded at startup. Usage of rombar=0 after that
> > is not allowed, but should not crash QEMU.
> > 
> > Check that the device is not hotplugged before trying to
> > insert the rom file.
> 
> I think it could also make sense to just ignore the option ROM and allow
> the hotplug.
> 
> Sooner or later we should drop the oldest compat machine types...
> everything until 0.12 probably could go.
> 
> Paolo

Unfortunately, we made the mistake of exposing the rombar
attribute to management.

See rom element at
http://libvirt.org/formatdomain.html#elementsHostDevSubsys

and in theory some users might have configured rombar=off
but set file to some value.

I'd be OK with removing support for this combination,
if we want the legacy fw cfg thing, we should have a
separate attribute.


But I'd like someone from libvirt to OK this ...
Eric?


> > Signed-off-by: Marcel Apfelbaum <marcel.a@redhat.com>
> > ---
> >  hw/pci/pci.c | 11 ++++++++++-
> >  1 file changed, 10 insertions(+), 1 deletion(-)
> > 
> > diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> > index 6ce75aa..3907c90 100644
> > --- a/hw/pci/pci.c
> > +++ b/hw/pci/pci.c
> > @@ -1776,7 +1776,12 @@ static int pci_qdev_init(DeviceState *qdev)
> >          pci_dev->romfile = g_strdup(pc->romfile);
> >          is_default_rom = true;
> >      }
> > -    pci_add_option_rom(pci_dev, is_default_rom);
> > +
> > +    rc = pci_add_option_rom(pci_dev, is_default_rom);
> > +    if (rc != 0) {
> > +        pci_unregister_device(DEVICE(pci_dev));
> > +        return rc;
> > +    }
> >  
> >      return 0;
> >  }
> > @@ -1940,6 +1945,10 @@ static int pci_add_option_rom(PCIDevice *pdev, bool is_default_rom)
> >          if (class == 0x0300) {
> >              rom_add_vga(pdev->romfile);
> >          } else {
> > +            if (DEVICE(pdev)->hotplugged) {
> > +                error_report("PCI: rombar can't be 0 for hotplugged devices!");
> > +                return -1;
> > +            }
> >              rom_add_option(pdev->romfile, -1);
> >          }
> >          return 0;
> >