From: Si-Wei Liu <si-wei.liu@oracle.com>
To: Jason Wang <jasowang@redhat.com>, mst@redhat.com, elic@nvidia.com
Cc: linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org
Subject: Re: [PATCH] vdpa/mlx5: set_features should allow reset to zero
Date: Mon, 22 Feb 2021 09:09:28 -0800 [thread overview]
Message-ID: <ee31e93b-5fbb-1999-0e82-983d3e49ad1e@oracle.com> (raw)
In-Reply-To: <605e7d2d-4f27-9688-17a8-d57191752ee7@redhat.com>
On 2/21/2021 8:14 PM, Jason Wang wrote:
>
> On 2021/2/19 7:54 下午, 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.
>
>
> This looks like a spec violation:
>
> "
>
> The following driver-read-only field, mtu only exists if
> VIRTIO_NET_F_MTU is set. This field specifies the maximum MTU for the
> driver to use.
> "
>
> Do we really want to workaround this?
Isn't the commit 452639a64ad8 itself is a workaround for legacy guest?
I think the point is, since there's legacy guest we'd have to support,
this host side workaround is unavoidable. Although I agree the violating
driver should be fixed (yes, it's in today's upstream kernel which
exists for a while now).
-Siwei
>
> Thanks
>
>
>> 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@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;
>> -}
>> -
>> 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)
>
next prev parent reply other threads:[~2021-02-22 17:10 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-19 11:54 [PATCH] vdpa/mlx5: set_features should allow reset to zero Si-Wei Liu
2021-02-21 14:44 ` Eli Cohen
2021-02-21 21:52 ` Michael S. Tsirkin
2021-02-22 6:05 ` Eli Cohen
2021-02-23 9:26 ` Michael S. Tsirkin
2021-02-23 9:48 ` Jason Wang
2021-02-23 9:55 ` Michael S. Tsirkin
2021-02-22 4:14 ` Jason Wang
2021-02-22 7:34 ` Michael S. Tsirkin
2021-02-23 1:12 ` Si-Wei Liu
2021-02-23 2:03 ` Jason Wang
2021-02-23 13:26 ` Michael S. Tsirkin
2021-02-23 19:35 ` Si-Wei Liu
2021-02-24 3:20 ` Jason Wang
2021-02-24 5:17 ` Michael S. Tsirkin
2021-02-24 6:02 ` Jason Wang
2021-02-24 6:45 ` Eli Cohen
2021-02-24 6:47 ` Michael S. Tsirkin
2021-02-24 6:55 ` Jason Wang
2021-02-24 7:12 ` Michael S. Tsirkin
2021-02-24 12:40 ` Eli Cohen
2021-02-24 7:17 ` Eli Cohen
2021-02-24 5:04 ` Michael S. Tsirkin
2021-02-24 6:04 ` Jason Wang
2021-02-24 6:46 ` Michael S. Tsirkin
2021-02-24 6:53 ` Jason Wang
2021-02-24 7:17 ` Michael S. Tsirkin
[not found] ` <babc654d-8dcd-d8a2-c3b6-d20cc4fc554c@redhat.com>
2021-02-24 8:43 ` Michael S. Tsirkin
2021-02-24 9:30 ` Jason Wang
2021-02-28 21:30 ` Michael S. Tsirkin
2021-03-01 3:53 ` Jason Wang
2021-02-24 18:24 ` Si-Wei Liu
2021-02-26 0:56 ` Si-Wei Liu
2021-02-28 21:27 ` Michael S. Tsirkin
2021-03-01 18:08 ` Si-Wei Liu
2021-02-28 21:28 ` Michael S. Tsirkin
2021-02-28 21:34 ` Michael S. Tsirkin
2021-03-01 3:56 ` Jason Wang
2021-03-02 9:47 ` Michael S. Tsirkin
2021-03-02 10:53 ` Jason Wang
2021-12-11 1:44 ` vdpa legacy guest support (was Re: [PATCH] vdpa/mlx5: set_features should allow reset to zero) Si-Wei Liu
2021-12-12 9:26 ` Michael S. Tsirkin
2021-12-13 3:02 ` Jason Wang
2021-12-13 8:06 ` Michael S. Tsirkin
2021-12-13 8:57 ` Jason Wang
2021-12-13 10:42 ` Michael S. Tsirkin
2021-12-14 1:13 ` Si-Wei Liu
2021-12-14 1:59 ` Si-Wei Liu
2021-12-14 3:01 ` Jason Wang
2021-12-14 5:06 ` Michael S. Tsirkin
2021-12-15 1:05 ` Si-Wei Liu
2021-12-15 2:06 ` Jason Wang
2021-12-15 20:52 ` Si-Wei Liu
2021-12-15 21:33 ` Michael S. Tsirkin
2021-12-16 2:01 ` Si-Wei Liu
2021-12-16 2:53 ` Jason Wang
2021-12-16 22:32 ` Si-Wei Liu
2021-12-17 1:57 ` Jason Wang
2021-12-17 2:00 ` Michael S. Tsirkin
2021-12-17 2:15 ` Jason Wang
2021-12-16 6:35 ` Michael S. Tsirkin
2021-12-16 3:43 ` Jason Wang
2021-12-17 1:08 ` Si-Wei Liu
2021-12-17 2:01 ` Jason Wang
2021-02-22 17:09 ` Si-Wei Liu [this message]
2021-02-23 2:03 ` [PATCH] vdpa/mlx5: set_features should allow reset to zero Jason Wang
2021-02-23 9:25 ` Michael S. Tsirkin
2021-02-23 9:46 ` Jason Wang
2021-02-23 10:01 ` Michael S. Tsirkin
2021-02-23 10:17 ` Jason Wang
2021-02-24 9:40 ` Jason Wang
2021-02-23 10:04 ` [virtio-dev] " Cornelia Huck
2021-02-23 10:31 ` Jason Wang
2021-02-23 10:58 ` Cornelia Huck
2021-02-24 9:29 ` Jason Wang
2021-02-24 11:12 ` Cornelia Huck
2021-02-25 4:36 ` Jason Wang
2021-02-25 13:26 ` Cornelia Huck
2021-02-25 18:53 ` Michael S. Tsirkin
2021-02-26 8:19 ` Jason Wang
2021-02-28 21:25 ` Michael S. Tsirkin
2021-03-01 3:51 ` Jason Wang
2021-03-02 12:08 ` Cornelia Huck
[not found] ` <5f6972fe-7246-b622-958d-9cab8dd98e21@redhat.com>
2021-03-03 8:29 ` Cornelia Huck
2021-03-04 8:24 ` Jason Wang
2021-03-04 13:50 ` Cornelia Huck
2021-03-05 3:01 ` Jason Wang
2021-02-23 12:26 ` Michael S. Tsirkin
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