better @subj: try late vq enable only if negotiated On Tue, Feb 06, 2024 at 03:51:54PM +0100, Stefano Garzarella wrote: > If VHOST_BACKEND_F_ENABLE_AFTER_DRIVER_OK is not negotiated, we expect > the driver to enable virtqueue before setting DRIVER_OK. If the driver > tries anyway, better to fail right away as soon as we get the ioctl. > Let's also update the documentation to make it clearer. > > We had a problem in QEMU for not meeting this requirement, see > https://lore.kernel.org/qemu-devel/20240202132521.32714-1-kwolf@xxxxxxxxxx/ > > Fixes: 9f09fd6171fe ("vdpa: accept VHOST_BACKEND_F_ENABLE_AFTER_DRIVER_OK backend feature") > Cc: eperezma@xxxxxxxxxx > Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx> > --- > include/uapi/linux/vhost_types.h | 3 ++- > drivers/vhost/vdpa.c | 4 ++++ > 2 files changed, 6 insertions(+), 1 deletion(-) > > diff --git a/include/uapi/linux/vhost_types.h b/include/uapi/linux/vhost_types.h > index d7656908f730..5df49b6021a7 100644 > --- a/include/uapi/linux/vhost_types.h > +++ b/include/uapi/linux/vhost_types.h > @@ -182,7 +182,8 @@ struct vhost_vdpa_iova_range { > /* Device can be resumed */ > #define VHOST_BACKEND_F_RESUME 0x5 > /* Device supports the driver enabling virtqueues both before and after > - * DRIVER_OK > + * DRIVER_OK. If this feature is not negotiated, the virtqueues must be > + * enabled before setting DRIVER_OK. > */ > #define VHOST_BACKEND_F_ENABLE_AFTER_DRIVER_OK 0x6 > /* Device may expose the virtqueue's descriptor area, driver area and > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c > index bc4a51e4638b..1fba305ba8c1 100644 > --- a/drivers/vhost/vdpa.c > +++ b/drivers/vhost/vdpa.c > @@ -651,6 +651,10 @@ static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd, > case VHOST_VDPA_SET_VRING_ENABLE: > if (copy_from_user(&s, argp, sizeof(s))) > return -EFAULT; > + if (!vhost_backend_has_feature(vq, > + VHOST_BACKEND_F_ENABLE_AFTER_DRIVER_OK) && > + (ops->get_status(vdpa) & VIRTIO_CONFIG_S_DRIVER_OK)) > + return -EINVAL; > ops->set_vq_ready(vdpa, idx, s.num); > return 0; > case VHOST_VDPA_GET_VRING_GROUP: > -- > 2.43.0
