Michael S. Tsirkin
2021-Feb-21 21:52 UTC
[PATCH] vdpa/mlx5: set_features should allow reset to zero
On Sun, Feb 21, 2021 at 04:44:37PM +0200, Eli Cohen wrote:> On Fri, Feb 19, 2021 at 06:54:58AM -0500, Si-Wei Liu wrote: > > Commit 452639a64ad8 ("vdpa: make sure set_features is invoked > > for legacy") made an exception for legacy guests to reset > > features to 0, when config space is accessed before features > > are set. We should relieve the verify_min_features() check > > and allow features reset to 0 for this case. > > > > It's worth noting that not just legacy guests could access > > config space before features are set. For instance, when > > feature VIRTIO_NET_F_MTU is advertised some modern driver > > will try to access and validate the MTU present in the config > > space before virtio features are set. Rejecting reset to 0 > > prematurely causes correct MTU and link status unable to load > > for the very first config space access, rendering issues like > > guest showing inaccurate MTU value, or failure to reject > > out-of-range MTU. > > > > Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices") > > Signed-off-by: Si-Wei Liu <si-wei.liu at oracle.com> > > --- > > drivers/vdpa/mlx5/net/mlx5_vnet.c | 15 +-------------- > > 1 file changed, 1 insertion(+), 14 deletions(-) > > > > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c > > index 7c1f789..540dd67 100644 > > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c > > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c > > @@ -1490,14 +1490,6 @@ static u64 mlx5_vdpa_get_features(struct vdpa_device *vdev) > > return mvdev->mlx_features; > > } > > > > -static int verify_min_features(struct mlx5_vdpa_dev *mvdev, u64 features) > > -{ > > - if (!(features & BIT_ULL(VIRTIO_F_ACCESS_PLATFORM))) > > - return -EOPNOTSUPP; > > - > > - return 0; > > -} > > - > > But what if VIRTIO_F_ACCESS_PLATFORM is not offerred? This does not > support such cases.Did you mean "catch such cases" rather than "support"?> Maybe we should call verify_min_features() from mlx5_vdpa_set_status() > just before attempting to call setup_driver(). > > > static int setup_virtqueues(struct mlx5_vdpa_net *ndev) > > { > > int err; > > @@ -1558,18 +1550,13 @@ static int mlx5_vdpa_set_features(struct vdpa_device *vdev, u64 features) > > { > > struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev); > > struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev); > > - int err; > > > > print_features(mvdev, features, true); > > > > - err = verify_min_features(mvdev, features); > > - if (err) > > - return err; > > - > > ndev->mvdev.actual_features = features & ndev->mvdev.mlx_features; > > ndev->config.mtu = cpu_to_mlx5vdpa16(mvdev, ndev->mtu); > > ndev->config.status |= cpu_to_mlx5vdpa16(mvdev, VIRTIO_NET_S_LINK_UP); > > - return err; > > + return 0; > > } > > > > static void mlx5_vdpa_set_config_cb(struct vdpa_device *vdev, struct vdpa_callback *cb) > > -- > > 1.8.3.1 > >