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

["Alex Bennée" <alex.bennee@linaro.org>]

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?

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro