[PATCH vhost 21/23] vdpa/mlx5: Re-create HW VQs under certain conditions

Dragos Tatulea
2024-06-17T15:09:27Z

There are a few conditions under which the hardware VQs need a full
teardown and setup:

- VQ size changed to something else than default value. Hardware VQ size
modification is not supported.

- User turns off certain device features: mergeable buffers, checksum
virtio 1.0 compliance. In these cases, the TIR and RQT need to be
re-created.

Add a needs_teardown configuration variable and set it when detecting
the above scenarios. On next DRIVER_OK, the resources will be torn down
first.

Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Cosmin Ratiu <cratiu@nvidia.com>
---
drivers/vdpa/mlx5/net/mlx5_vnet.c | 15 +++++++++++++++
drivers/vdpa/mlx5/net/mlx5_vnet.h | 1 +
2 files changed, 16 insertions(+)

diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index b2836fd3d1dd..d80d6b47da61 100644
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
@@ -2390,6 +2390,7 @@ static void mlx5_vdpa_set_vq_num(struct vdpa_device *vdev, u16 idx, u32 num)
}

mvq = &ndev->vqs[idx];
+ ndev->needs_teardown = num != mvq->num_ent;
mvq->num_ent = num;
}

@@ -2800,6 +2801,7 @@ static int mlx5_vdpa_set_driver_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);
u64 old_features = mvdev->actual_features;
+ u64 diff_features;
int err;

print_features(mvdev, features, true);
@@ -2822,6 +2824,14 @@ static int mlx5_vdpa_set_driver_features(struct vdpa_device *vdev, u64 features)
}
}

+ /* When below features diverge from initial device features, VQs need a full teardown. */
+#define NEEDS_TEARDOWN_MASK (BIT_ULL(VIRTIO_NET_F_MRG_RXBUF) | \
+ BIT_ULL(VIRTIO_NET_F_CSUM) | \
+ BIT_ULL(VIRTIO_F_VERSION_1))
+
+ diff_features = mvdev->mlx_features ^ mvdev->actual_features;
+ ndev->needs_teardown = !!(diff_features & NEEDS_TEARDOWN_MASK);
+
update_cvq_info(mvdev);
return err;
}
@@ -3038,6 +3048,7 @@ static void teardown_vq_resources(struct mlx5_vdpa_net *ndev)
destroy_rqt(ndev);
teardown_virtqueues(ndev);
ndev->setup = false;
+ ndev->needs_teardown = false;
}

static int setup_cvq_vring(struct mlx5_vdpa_dev *mvdev)
@@ -3078,6 +3089,10 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
goto err_setup;
}
register_link_notifier(ndev);
+
+ if (ndev->needs_teardown)
+ teardown_vq_resources(ndev);
+
if (ndev->setup) {
err = resume_vqs(ndev);
if (err) {
diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.h b/drivers/vdpa/mlx5/net/mlx5_vnet.h
index 2ada29767cc5..da7318f82d2a 100644
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.h
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.h
@@ -56,6 +56,7 @@ struct mlx5_vdpa_net {
struct dentry *rx_dent;
struct dentry *rx_table_dent;
bool setup;
+ bool needs_teardown;
u32 cur_num_vqs;
u32 rqt_size;
u16 default_queue_size;

--
2.45.1