On Wed, Oct 28, 2026 at 08:33:30PM +0100, Tim Pambor wrote:
> On Wed, Oct 28, 2026 at 7:44 PM Stefan Hajnoczi <[email protected]> wrote:
> >
> > On Wed, Oct 28, 2026 at 02:23:55PM +0100, Stefano Garzarella wrote:
> > > On Wed, Oct 28, 2026 at 08:33:46AM -0400, Stefan Hajnoczi wrote:
> > > > On Wed, Oct 28, 2026 at 09:32:05AM +0100, Stefano Garzarella wrote:
> > > > > On Tue, Oct 27, 2026 at 03:24:45PM -0400, Stefan Hajnoczi wrote:
> > > > > > On Thu, Oct 22, 2026 at 03:47:26PM +0200, Tim Pambor wrote:
> > > > > > > diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> > > > > > > index 6e05c995f1..788913953d 100644
> > > > > > > --- a/hw/net/vhost_net.c
> > > > > > > +++ b/hw/net/vhost_net.c
> > > > > > > @@ -33,7 +33,13 @@
> > > > > > > #include "standard-headers/linux/virtio_ring.h"
> > > > > > > #include "hw/virtio/vhost.h"
> > > > > > > #include "hw/virtio/virtio-bus.h"
> > > > > > > +#if defined(__linux__)
> > > > > > > #include "linux-headers/linux/vhost.h"
> > > > > > > +#endif
> > > > > > > +
> > > > > > > +#ifndef VHOST_FILE_UNBIND
> > > > > > > +#define VHOST_FILE_UNBIND -1
> > > > > > > +#endif
> > > > > >
> > > > > > This constant is for hw/virtio/vhost.c's vhost_net_set_backend()
> > > > > > API. It
> > > > > > should be defined along with that API. Define it alongside
> > > > > > vhost_net_set_backend() in hw/virtio/vhost.h and call it
> > > > > > VHOST_NET_FILE_UNBIND?
> > > > > >
> > > > >
> > > > > That constant is defined by a Linux header (see
> > > > > linux-headers/linux/vhost.h). Are you suggesting to add another
> > > > > constant
> > > > > that is defined with VHOST_FILE_UNBIND on Linux and -1 on other
> > > > > platforms?
> > > >
> > > > Looking again, we should probably just use -1 instead of a constant
> > >
> > > Yep, this would be fine too.
> > > I don't remember why I did in this way, maybe to keep the diff smaller
> > > enough, but I don't have a strong opinion, we can avoid this ifndef and
> > > use
> > > -1 everywhere if you prefer that.
> >
> > IMO VHOST_FILE_UNBIND doesn't belong in vhost_net.c, so it would be nice
> > to avoid the #ifndef.
>
> So, for v2, is it ok if I replace the one usage of VHOST_FILE_UNBIND in
> vhost_net.c with -1 and remove the #ifndef?
Yes, that sounds good.
>
> > > > since include/standard-headers/linux/vhost_types.h doesn't even define a
> > > > constant:
> > > >
> > > > struct vhost_vring_file {
> > > > unsigned int index;
> > > > int fd; /* Pass -1 to unbind from file. */
> > > >
> > > > };
> > > >
> > > > It's strange that VHOST_FILE_UNBIND was defined in <linux/vhost.h>
> > > > instead of <linux/vhost_types.h> where struct vhost_vring_file is
> > > > defined.
> > >
> > > Oh, VHOST_FILE_UNBIND was introduced after struct vhost_vring_file, with
> > > commit 776f395004d8 ("vhost_vdpa: Support config interrupt in vdpa").
> > >
> > > But I agree that should be moved to vhost_types.h. BTW <linux/vhost.h>
> > > already includes <linux/vhost_types.h>, so maybe we can fix it without too
> > > much trouble.
> >
> > Yes, that change seems safe and will improve things in the long term.
>
> Or should I send a patch to linux adding VHOST_FILE_UNBIND to vhost_types.h
> and then drop it from vhost.h and remove the #ifndef?
Fixing the Linux headers is a long-term solution but there is no need
for QEMU to wait for it.
Thanks,
Stefan
