Re: [PATCH v4 03/12] libvhost-user: mask F_INFLIGHT_SHMFD if memfd is not supported

[Stefano Garzarella]

On Wed, May 08, 2024 at 12:39:33PM GMT, Philippe Mathieu-Daudé wrote:
> On 8/5/24 09:44, Stefano Garzarella wrote:
> > libvhost-user will panic when receiving VHOST_USER_GET_INFLIGHT_FD
> > message if MFD_ALLOW_SEALING is not defined, since it's not able
> > to create a memfd.
> >
> > VHOST_USER_GET_INFLIGHT_FD is used only if
> > VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD is negotiated. So, let's mask
> > that feature if the backend is not able to properly handle these
> > messages.
> >
> > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> > ---
> >  subprojects/libvhost-user/libvhost-user.c | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> >
> > diff --git a/subprojects/libvhost-user/libvhost-user.c 
> > b/subprojects/libvhost-user/libvhost-user.c
> > index a11afd1960..1c361ffd51 100644
> > --- a/subprojects/libvhost-user/libvhost-user.c
> > +++ b/subprojects/libvhost-user/libvhost-user.c
> > @@ -1674,6 +1674,16 @@ vu_get_protocol_features_exec(VuDev *dev, VhostUserMsg 
> > *vmsg)
> >          features |= dev->iface->get_protocol_features(dev);
> >      }
>
> Maybe move the #ifndef here?

Yep, I'll do.

> > +    /*
> > +     * If MFD_ALLOW_SEALING is not defined, we are not able to handle
> > +     * VHOST_USER_GET_INFLIGHT_FD messages, since we can't create a memfd.
> > +     * Those messages are used only if VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD
> > +     * is negotiated. A device implementation can enable it, so let's mask
> > +     * it to avoid a runtime panic.
> > +     */
> > +#ifndef MFD_ALLOW_SEALING
> > +    features &= ~(1ULL << VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD);
> > +#endif
> >      vmsg_set_reply_u64(vmsg, features);
> >      return true;
> >  }
>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Thanks,
Stefano