Re: [PATCH] vdpa/mlx5: set_features should allow reset to zero
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2021-02-23 12:28:48
Also in:
lkml, virtualization
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")
isn't this more
vdpa: make sure set_features is invoked for legacy
Signed-off-by: Si-Wei Liu <redacted>
I think we at least need to correct the comment in include/linux/vdpa.h then Instead of "we assume a legacy guest" we'd say something like "call set features in case it's a legacy guest". Generally it's unfortunate. Need to think about what to do here. Any idea how else we can cleanly detect a legacy guest?
quoted hunk ↗ jump to hunk
--- 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; -} - static int setup_virtqueues(struct mlx5_vdpa_net *ndev) { int err;
Let's just set VIRTIO_F_ACCESS_PLATFORM in core? Then we don't need to hack mlx5 ...
quoted hunk ↗ jump to hunk
@@ -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