On Wed, Jul 26, 2023 at 2:21 AM Eugenio Pérez <epere...@redhat.com> wrote:
>
> The device already has a virtio status set by vhost_vdpa_init by the
> time vhost_vdpa_probe_cvq_isolation is called. vhost_vdpa_init set
> S_ACKNOWLEDGE and S_DRIVER, so it is invalid to just reset it.
>
> It is invalid to start the device after it, but all devices seems to be
> fine with it. Fixing qemu so it follows virtio start procedure.
>
> Fixes: 152128d64697 ("vdpa: move CVQ isolation check to net_init_vhost_vdpa")
> Reported-by: Dragos Tatulea <dtatu...@nvidia.com>
> Signed-off-by: Eugenio Pérez <epere...@redhat.com>
> ---
> net/vhost-vdpa.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> index 9795306742..d7e2b714b4 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -1333,6 +1333,8 @@ static int vhost_vdpa_probe_cvq_isolation(int
> device_fd, uint64_t features,
> out:
> status = 0;
> ioctl(device_fd, VHOST_VDPA_SET_STATUS, &status);
> + status = VIRTIO_CONFIG_S_ACKNOWLEDGE | VIRTIO_CONFIG_S_DRIVER;
> + ioctl(device_fd, VHOST_VDPA_SET_STATUS, &status);
So if we fail after FEATURES_OK, this basically clears that bit. Spec
doesn't say it can or not, I wonder if a reset is better?
Btw, spec requires a read of status after setting FEATURES_OK, this
seems to be missed in the current code.
Thanks
> return r;
> }
>
> --
> 2.39.3
>
