RE: [PATCH RESEND V3 3/3] vdpa/mlx5: Use consistent RQT size

Eli Cohen
2022-05-16T08:17:30Z

Hi Michael,

When are you going to pull this fix?
It fixes a real problem and was reviewed and acked.

> -----Original Message-----
> From: Eli Cohen <elic@nvidia.com>
> Sent: Wednesday, April 6, 2022 11:53 AM
> To: mst@redhat.com; jasowang@redhat.com
> Cc: hdanton@sina.com; virtualization@lists.linux-foundation.org; linux-kernel@vger.kernel.org; Eli Cohen <elic@nvidia.com>
> Subject: [PATCH RESEND V3 3/3] vdpa/mlx5: Use consistent RQT size
>
> The current code evaluates RQT size based on the configured number of
> virtqueues. This can raise an issue in the following scenario:
>
> Assume MQ was negotiated.
> 1. mlx5_vdpa_set_map() gets called.
> 2. handle_ctrl_mq() is called setting cur_num_vqs to some value, lower
> than the configured max VQs.
> 3. A second set_map gets called, but now a smaller number of VQs is used
> to evaluate the size of the RQT.
> 4. handle_ctrl_mq() is called with a value larger than what the RQT can
> hold. This will emit errors and the driver state is compromised.
>
> To fix this, we use a new field in struct mlx5_vdpa_net to hold the
> required number of entries in the RQT. This value is evaluated in
> mlx5_vdpa_set_driver_features() where we have the negotiated features
> all set up.
>
> In addition to that, we take into consideration the max capability of RQT
> entries early when the device is added so we don't need to take consider
> it when creating the RQT.
>
> Last, we remove the use of mlx5_vdpa_max_qps() which just returns the
> max_vas / 2 and make the code clearer.
>
> Fixes: 52893733f2c5 ("vdpa/mlx5: Add multiqueue support")
> Acked-by: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Eli Cohen <elic@nvidia.com>
> ---
> V2 -> V3:
> Fix typo in change log
> Add acked-by Jason
>
> drivers/vdpa/mlx5/net/mlx5_vnet.c | 61 +++++++++++--------------------
> 1 file changed, 21 insertions(+), 40 deletions(-)
>
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index 79001301b383..e0de44000d92 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -161,6 +161,7 @@ struct mlx5_vdpa_net {
> struct mlx5_flow_handle *rx_rule_mcast;
> bool setup;
> u32 cur_num_vqs;
> + u32 rqt_size;
> struct notifier_block nb;
> struct vdpa_callback config_cb;
> struct mlx5_vdpa_wq_ent cvq_ent;
> @@ -204,17 +205,12 @@ static __virtio16 cpu_to_mlx5vdpa16(struct mlx5_vdpa_dev *mvdev, u16 val)
> return __cpu_to_virtio16(mlx5_vdpa_is_little_endian(mvdev), val);
> }
>
> -static inline u32 mlx5_vdpa_max_qps(int max_vqs)
> -{
> - return max_vqs / 2;
> -}
> -
> static u16 ctrl_vq_idx(struct mlx5_vdpa_dev *mvdev)
> {
> if (!(mvdev->actual_features & BIT_ULL(VIRTIO_NET_F_MQ)))
> return 2;
>
> - return 2 * mlx5_vdpa_max_qps(mvdev->max_vqs);
> + return mvdev->max_vqs;
> }
>
> static bool is_ctrl_vq_idx(struct mlx5_vdpa_dev *mvdev, u16 idx)
> @@ -1236,25 +1232,13 @@ static void teardown_vq(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *
> static int create_rqt(struct mlx5_vdpa_net *ndev)
> {
> __be32 *list;
> - int max_rqt;
> void *rqtc;
> int inlen;
> void *in;
> int i, j;
> int err;
> - int num;
> -
> - if (!(ndev->mvdev.actual_features & BIT_ULL(VIRTIO_NET_F_MQ)))
> - num = 1;
> - else
> - num = ndev->cur_num_vqs / 2;
>
> - max_rqt = min_t(int, roundup_pow_of_two(num),
> - 1 << MLX5_CAP_GEN(ndev->mvdev.mdev, log_max_rqt_size));
> - if (max_rqt < 1)
> - return -EOPNOTSUPP;
> -
> - inlen = MLX5_ST_SZ_BYTES(create_rqt_in) + max_rqt * MLX5_ST_SZ_BYTES(rq_num);
> + inlen = MLX5_ST_SZ_BYTES(create_rqt_in) + ndev->rqt_size * MLX5_ST_SZ_BYTES(rq_num);
> in = kzalloc(inlen, GFP_KERNEL);
> if (!in)
> return -ENOMEM;
> @@ -1263,12 +1247,12 @@ static int create_rqt(struct mlx5_vdpa_net *ndev)
> rqtc = MLX5_ADDR_OF(create_rqt_in, in, rqt_context);
>
> MLX5_SET(rqtc, rqtc, list_q_type, MLX5_RQTC_LIST_Q_TYPE_VIRTIO_NET_Q);
> - MLX5_SET(rqtc, rqtc, rqt_max_size, max_rqt);
> + MLX5_SET(rqtc, rqtc, rqt_max_size, ndev->rqt_size);
> list = MLX5_ADDR_OF(rqtc, rqtc, rq_num[0]);
> - for (i = 0, j = 0; i < max_rqt; i++, j += 2)
> - list[i] = cpu_to_be32(ndev->vqs[j % (2 * num)].virtq_id);
> + for (i = 0, j = 0; i < ndev->rqt_size; i++, j += 2)
> + list[i] = cpu_to_be32(ndev->vqs[j % ndev->cur_num_vqs].virtq_id);
>
> - MLX5_SET(rqtc, rqtc, rqt_actual_size, max_rqt);
> + MLX5_SET(rqtc, rqtc, rqt_actual_size, ndev->rqt_size);
> err = mlx5_vdpa_create_rqt(&ndev->mvdev, in, inlen, &ndev->res.rqtn);
> kfree(in);
> if (err)
> @@ -1282,19 +1266,13 @@ static int create_rqt(struct mlx5_vdpa_net *ndev)
> static int modify_rqt(struct mlx5_vdpa_net *ndev, int num)
> {
> __be32 *list;
> - int max_rqt;
> void *rqtc;
> int inlen;
> void *in;
> int i, j;
> int err;
>
> - max_rqt = min_t(int, roundup_pow_of_two(ndev->cur_num_vqs / 2),
> - 1 << MLX5_CAP_GEN(ndev->mvdev.mdev, log_max_rqt_size));
> - if (max_rqt < 1)
> - return -EOPNOTSUPP;
> -
> - inlen = MLX5_ST_SZ_BYTES(modify_rqt_in) + max_rqt * MLX5_ST_SZ_BYTES(rq_num);
> + inlen = MLX5_ST_SZ_BYTES(modify_rqt_in) + ndev->rqt_size * MLX5_ST_SZ_BYTES(rq_num);
> in = kzalloc(inlen, GFP_KERNEL);
> if (!in)
> return -ENOMEM;
> @@ -1305,10 +1283,10 @@ static int modify_rqt(struct mlx5_vdpa_net *ndev, int num)
> MLX5_SET(rqtc, rqtc, list_q_type, MLX5_RQTC_LIST_Q_TYPE_VIRTIO_NET_Q);
>
> list = MLX5_ADDR_OF(rqtc, rqtc, rq_num[0]);
> - for (i = 0, j = 0; i < max_rqt; i++, j += 2)
> + for (i = 0, j = 0; i < ndev->rqt_size; i++, j += 2)
> list[i] = cpu_to_be32(ndev->vqs[j % num].virtq_id);
>
> - MLX5_SET(rqtc, rqtc, rqt_actual_size, max_rqt);
> + MLX5_SET(rqtc, rqtc, rqt_actual_size, ndev->rqt_size);
> err = mlx5_vdpa_modify_rqt(&ndev->mvdev, in, inlen, ndev->res.rqtn);
> kfree(in);
> if (err)
> @@ -1625,7 +1603,7 @@ static virtio_net_ctrl_ack handle_ctrl_mq(struct mlx5_vdpa_dev *mvdev, u8 cmd)
>
> newqps = mlx5vdpa16_to_cpu(mvdev, mq.virtqueue_pairs);
> if (newqps < VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MIN ||
> - newqps > mlx5_vdpa_max_qps(mvdev->max_vqs))
> + newqps > ndev->rqt_size)
> break;
>
> if (ndev->cur_num_vqs == 2 * newqps) {
> @@ -1989,7 +1967,7 @@ static int setup_virtqueues(struct mlx5_vdpa_dev *mvdev)
> int err;
> int i;
>
> - for (i = 0; i < 2 * mlx5_vdpa_max_qps(mvdev->max_vqs); i++) {
> + for (i = 0; i < mvdev->max_vqs; i++) {
> err = setup_vq(ndev, &ndev->vqs[i]);
> if (err)
> goto err_vq;
> @@ -2060,9 +2038,11 @@ static int mlx5_vdpa_set_driver_features(struct vdpa_device *vdev, u64 features)
>
> ndev->mvdev.actual_features = features & ndev->mvdev.mlx_features;
> if (ndev->mvdev.actual_features & BIT_ULL(VIRTIO_NET_F_MQ))
> - ndev->cur_num_vqs = 2 * mlx5vdpa16_to_cpu(mvdev, ndev->config.max_virtqueue_pairs);
> + ndev->rqt_size = mlx5vdpa16_to_cpu(mvdev, ndev->config.max_virtqueue_pairs);
> else
> - ndev->cur_num_vqs = 2;
> + ndev->rqt_size = 1;
> +
> + ndev->cur_num_vqs = 2 * ndev->rqt_size;
>
> update_cvq_info(mvdev);
> return err;
> @@ -2529,7 +2509,7 @@ static void init_mvqs(struct mlx5_vdpa_net *ndev)
> struct mlx5_vdpa_virtqueue *mvq;
> int i;
>
> - for (i = 0; i < 2 * mlx5_vdpa_max_qps(ndev->mvdev.max_vqs); ++i) {
> + for (i = 0; i < ndev->mvdev.max_vqs; ++i) {
> mvq = &ndev->vqs[i];
> memset(mvq, 0, offsetof(struct mlx5_vdpa_virtqueue, ri));
> mvq->index = i;
> @@ -2671,7 +2651,8 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
> return -EOPNOTSUPP;
> }
>
> - max_vqs = MLX5_CAP_DEV_VDPA_EMULATION(mdev, max_num_virtio_queues);
> + max_vqs = min_t(int, MLX5_CAP_DEV_VDPA_EMULATION(mdev, max_num_virtio_queues),
> + 1 << MLX5_CAP_GEN(mdev, log_max_rqt_size));
> if (max_vqs < 2) {
> dev_warn(mdev->device,
> "%d virtqueues are supported. At least 2 are required\n",
> @@ -2742,7 +2723,7 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
> ndev->mvdev.mlx_features |= BIT_ULL(VIRTIO_NET_F_MAC);
> }
>
> - config->max_virtqueue_pairs = cpu_to_mlx5vdpa16(mvdev, mlx5_vdpa_max_qps(max_vqs));
> + config->max_virtqueue_pairs = cpu_to_mlx5vdpa16(mvdev, max_vqs / 2);
> mvdev->vdev.dma_dev = &mdev->pdev->dev;
> err = mlx5_vdpa_alloc_resources(&ndev->mvdev);
> if (err)
> @@ -2769,7 +2750,7 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
> ndev->nb.notifier_call = event_handler;
> mlx5_notifier_register(mdev, &ndev->nb);
> mvdev->vdev.mdev = &mgtdev->mgtdev;
> - err = _vdpa_register_device(&mvdev->vdev, 2 * mlx5_vdpa_max_qps(max_vqs) + 1);
> + err = _vdpa_register_device(&mvdev->vdev, max_vqs + 1);
> if (err)
> goto err_reg;
>
> --
> 2.35.1