This v3 consisting of one single patch only is a follow-up to the v2 of mlx5_vdpa bug fix series as in: https://lore.kernel.org/virtualization/1612993680-29454-1-git-send-email-si-wei.liu at oracle.com which initially attempted to fix a few independent issues in the mlx5_vdpa driver. Presently Patch #1 in the original series was piggybacked and got merged through a separate patchset: https://lore.kernel.org/virtualization/20210406170457.98481-13-parav at nvidia.com/ and the issue Patch #3 tried to fix was addressed by another patch, https://lore.kernel.org/virtualization/a5356a13-6d7d-8086-bfff-ff869aec5449 at redhat.com/ that leaves Patch #2 in the original v2 series unmerged. Since it was already Ack'ed by Jason and Eli in v2, just get it reposted while dropping others after syncing with the current vhost tree. Thanks, -- v2->v3: drop merged patches from previous series; repost with updated commit message v1->v2: move feature capability query to probing (Eli) Si-Wei Liu (1): vdpa/mlx5: fix feature negotiation across device reset drivers/vdpa/mlx5/net/mlx5_vnet.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) -- 1.8.3.1
Si-Wei Liu
2021-Apr-29 01:48 UTC
[PATCH v3 1/1] vdpa/mlx5: fix feature negotiation across device reset
The mlx_features denotes the capability for which set of virtio features is supported by device. In principle, this field needs not be cleared during virtio device reset, as this capability is static and does not change across reset. In fact, the current code seems to wrongly assume that mlx_features can be reloaded or updated on device reset thru the .get_features op. However, the userspace VMM may save a copy of previously advertised backend feature capability and won't need to get it again on reset. In that event, all virtio features reset to zero thus getting disabled upon device reset. This ends up with guest holding a mismatched view of available features with the VMM/host's. For instance, the guest may assume the presence of tx checksum offload feature across reboot, however, since the feature is left disabled on reset, frames with bogus partial checksum are transmitted on the wire. The fix is to retain the features capability on reset, and get it only once from firmware on the vdpa_dev_add path. Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices") Signed-off-by: Si-Wei Liu <si-wei.liu at oracle.com> Acked-by: Eli Cohen <elic at nvidia.com> Acked-by: Jason Wang <jasowang at redhat.com> --- drivers/vdpa/mlx5/net/mlx5_vnet.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c index 25533db..624f521 100644 --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c @@ -1492,16 +1492,8 @@ static u64 mlx_to_vritio_features(u16 dev_features) static u64 mlx5_vdpa_get_features(struct vdpa_device *vdev) { struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev); - struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev); - u16 dev_features; - dev_features = MLX5_CAP_DEV_VDPA_EMULATION(mvdev->mdev, device_features_bits_mask); - ndev->mvdev.mlx_features = mlx_to_vritio_features(dev_features); - if (MLX5_CAP_DEV_VDPA_EMULATION(mvdev->mdev, virtio_version_1_0)) - ndev->mvdev.mlx_features |= BIT_ULL(VIRTIO_F_VERSION_1); - ndev->mvdev.mlx_features |= BIT_ULL(VIRTIO_F_ACCESS_PLATFORM); - print_features(mvdev, ndev->mvdev.mlx_features, false); - return ndev->mvdev.mlx_features; + return mvdev->mlx_features; } static int verify_min_features(struct mlx5_vdpa_dev *mvdev, u64 features) @@ -1783,7 +1775,6 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status) teardown_driver(ndev); mlx5_vdpa_destroy_mr(&ndev->mvdev); ndev->mvdev.status = 0; - ndev->mvdev.mlx_features = 0; ++mvdev->generation; return; } @@ -1902,6 +1893,19 @@ static int mlx5_get_vq_irq(struct vdpa_device *vdv, u16 idx) .free = mlx5_vdpa_free, }; +static void query_virtio_features(struct mlx5_vdpa_net *ndev) +{ + struct mlx5_vdpa_dev *mvdev = &ndev->mvdev; + u16 dev_features; + + dev_features = MLX5_CAP_DEV_VDPA_EMULATION(mvdev->mdev, device_features_bits_mask); + mvdev->mlx_features = mlx_to_vritio_features(dev_features); + if (MLX5_CAP_DEV_VDPA_EMULATION(mvdev->mdev, virtio_version_1_0)) + mvdev->mlx_features |= BIT_ULL(VIRTIO_F_VERSION_1); + mvdev->mlx_features |= BIT_ULL(VIRTIO_F_ACCESS_PLATFORM); + print_features(mvdev, mvdev->mlx_features, false); +} + static int query_mtu(struct mlx5_core_dev *mdev, u16 *mtu) { u16 hw_mtu; @@ -2009,6 +2013,7 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name) init_mvqs(ndev); mutex_init(&ndev->reslock); config = &ndev->config; + query_virtio_features(ndev); err = query_mtu(mdev, &ndev->mtu); if (err) goto err_mtu; -- 1.8.3.1