Re: [RFC PATCH for 8.0] backends/vhost-user: relax the ioeventfd check

[Michael S. Tsirkin]

On Mon, Dec 19, 2022 at 05:48:50PM +0000, Alex Bennée wrote:
> 
> Alex Bennée <alex.bennee@linaro.org> writes:
> 
> > While you certainly need ioeventfds to work for KVM guests it
> > shouldn't be limited to that. We can run vhost-user backends for TCG
> > guests and either use ioeventfds or in band signalling.
> >
> > Maybe we should apply the same fix as b0aa77d36d (vhost-user: fix
> > ioeventfd_enabled)?
> >
> > With this change I can run:
> >
> >   $QEMU $OPTS \
> >     -display gtk,gl=on \
> >     -device vhost-user-gpu-pci,chardev=vhgpu \
> >     -chardev socket,id=vhgpu,path=vhgpu.sock
> >
> > with:
> >
> >   ./contrib/vhost-user-gpu/vhost-user-gpu \
> >     -s vhgpu.sock \
> >     -v
> >
> > and at least see things start-up (although the display gets rotated by
> > 180 degrees).
> >
> > Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> > ---
> >  backends/vhost-user.c | 10 ++--------
> >  1 file changed, 2 insertions(+), 8 deletions(-)
> >
> > diff --git a/backends/vhost-user.c b/backends/vhost-user.c
> > index 5dedb2d987..87d43fb03a 100644
> > --- a/backends/vhost-user.c
> > +++ b/backends/vhost-user.c
> > @@ -21,12 +21,6 @@
> >  #include "io/channel-command.h"
> >  #include "hw/virtio/virtio-bus.h"
> >  
> > -static bool
> > -ioeventfd_enabled(void)
> > -{
> > -    return kvm_enabled() && kvm_eventfds_enabled();
> > -}
> > -
> >  int
> >  vhost_user_backend_dev_init(VhostUserBackend *b, VirtIODevice *vdev,
> >                              unsigned nvqs, Error **errp)
> > @@ -35,8 +29,8 @@ vhost_user_backend_dev_init(VhostUserBackend *b, 
> > VirtIODevice *vdev,
> >  
> >      assert(!b->vdev && vdev);
> >  
> > -    if (!ioeventfd_enabled()) {
> > -        error_setg(errp, "vhost initialization failed: requires kvm");
> > +    if (kvm_enabled() && !kvm_eventfds_enabled()) {
> > +        error_setg(errp, "vhost initialization failed: kvm required 
> > ioeventfds");
> >          return -1;
> >      }
> 
> Gentle ping?
> 

Yea why not. Pls post a non RFC patch.

-- 
MST