Message-ID: <bcaa20e6-7861-1a3c-e103-8db8870bb0c1@oracle.com>
Date:   Thu, 12 May 2022 18:10:51 -0700
From:   Si-Wei Liu <si-wei.liu@...cle.com>
To:     Jason Wang <jasowang@...hat.com>
Cc:     Eli Cohen <elic@...dia.com>, mst <mst@...hat.com>,
        virtualization <virtualization@...ts.linux-foundation.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 3/3] vdpa/mlx5: Add support for reading descriptor
 statistics



On 5/11/2022 7:27 PM, Jason Wang wrote:
> On Thu, May 12, 2022 at 1:26 AM Si-Wei Liu <si-wei.liu@...cle.com> wrote:
>>
>>
>> On 5/10/2022 4:27 AM, Eli Cohen wrote:
>>> Implement the get_vq_stats calback of vdpa_config_ops to return the
>>> statistics for a virtqueue.
>>>
>>> The statistics are provided as vendor specific statistics where the
>>> driver provides a pair of attribute name and attribute value.
>>>
>>> In addition to the attribute name/attribute value pair, the driver
>>> returns the negotiated features and max virtqueue pairs for userspace
>>> can decide for a given queue index whether it is a data or control
>>> virtqueue.
>>>
>>> Currently supported are received descriptors and completed descriptors.
>>>
>>> Acked-by: Jason Wang <jasowang@...hat.com>
>>> Signed-off-by: Eli Cohen <elic@...dia.com>
>>> ---
>>> v4 -> v5:
>>>    Remove numq_lock mutex. Use reslock instread.
>>>
>>>
>>>    drivers/vdpa/mlx5/core/mlx5_vdpa.h |   2 +
>>>    drivers/vdpa/mlx5/net/mlx5_vnet.c  | 165 +++++++++++++++++++++++++++++
>>>    include/linux/mlx5/mlx5_ifc.h      |   1 +
>>>    include/linux/mlx5/mlx5_ifc_vdpa.h |  39 +++++++
>>>    4 files changed, 207 insertions(+)
>>>
>>> diff --git a/drivers/vdpa/mlx5/core/mlx5_vdpa.h b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
>>> index daaf7b503677..44104093163b 100644
>>> --- a/drivers/vdpa/mlx5/core/mlx5_vdpa.h
>>> +++ b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
>>> @@ -61,6 +61,8 @@ struct mlx5_control_vq {
>>>        struct vringh_kiov riov;
>>>        struct vringh_kiov wiov;
>>>        unsigned short head;
>>> +     unsigned int received_desc;
>>> +     unsigned int completed_desc;
>>>    };
>>>
>>>    struct mlx5_vdpa_wq_ent {
>>> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
>>> index 79001301b383..99b0621e7a87 100644
>>> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
>>> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
>>> @@ -119,6 +119,7 @@ struct mlx5_vdpa_virtqueue {
>>>        struct mlx5_vdpa_umem umem2;
>>>        struct mlx5_vdpa_umem umem3;
>>>
>>> +     u32 counter_set_id;
>>>        bool initialized;
>>>        int index;
>>>        u32 virtq_id;
>>> @@ -164,6 +165,7 @@ struct mlx5_vdpa_net {
>>>        struct notifier_block nb;
>>>        struct vdpa_callback config_cb;
>>>        struct mlx5_vdpa_wq_ent cvq_ent;
>>> +     /* sync access to virtqueues statistics */
>> Dangling code change?
>>
>>>    };
>>>
>>>    static void free_resources(struct mlx5_vdpa_net *ndev);
>>> @@ -822,6 +824,12 @@ static u16 get_features_12_3(u64 features)
>>>               (!!(features & BIT_ULL(VIRTIO_NET_F_GUEST_CSUM)) << 6);
>>>    }
>>>
>>> +static bool counters_supported(const struct mlx5_vdpa_dev *mvdev)
>>> +{
>>> +     return MLX5_CAP_GEN_64(mvdev->mdev, general_obj_types) &
>>> +            BIT_ULL(MLX5_OBJ_TYPE_VIRTIO_Q_COUNTERS);
>>> +}
>>> +
>>>    static int create_virtqueue(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *mvq)
>>>    {
>>>        int inlen = MLX5_ST_SZ_BYTES(create_virtio_net_q_in);
>>> @@ -876,6 +884,8 @@ static int create_virtqueue(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtque
>>>        MLX5_SET(virtio_q, vq_ctx, umem_3_id, mvq->umem3.id);
>>>        MLX5_SET(virtio_q, vq_ctx, umem_3_size, mvq->umem3.size);
>>>        MLX5_SET(virtio_q, vq_ctx, pd, ndev->mvdev.res.pdn);
>>> +     if (counters_supported(&ndev->mvdev))
>>> +             MLX5_SET(virtio_q, vq_ctx, counter_set_id, mvq->counter_set_id);
>>>
>>>        err = mlx5_cmd_exec(ndev->mvdev.mdev, in, inlen, out, sizeof(out));
>>>        if (err)
>>> @@ -1139,6 +1149,47 @@ static int modify_virtqueue(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtque
>>>        return err;
>>>    }
>>>
>>> +static int counter_set_alloc(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *mvq)
>>> +{
>>> +     u32 in[MLX5_ST_SZ_DW(create_virtio_q_counters_in)] = {};
>>> +     u32 out[MLX5_ST_SZ_DW(create_virtio_q_counters_out)] = {};
>>> +     void *cmd_hdr;
>>> +     int err;
>>> +
>>> +     if (!counters_supported(&ndev->mvdev))
>>> +             return 0;
>>> +
>>> +     cmd_hdr = MLX5_ADDR_OF(create_virtio_q_counters_in, in, hdr);
>>> +
>>> +     MLX5_SET(general_obj_in_cmd_hdr, cmd_hdr, opcode, MLX5_CMD_OP_CREATE_GENERAL_OBJECT);
>>> +     MLX5_SET(general_obj_in_cmd_hdr, cmd_hdr, obj_type, MLX5_OBJ_TYPE_VIRTIO_Q_COUNTERS);
>>> +     MLX5_SET(general_obj_in_cmd_hdr, cmd_hdr, uid, ndev->mvdev.res.uid);
>>> +
>>> +     err = mlx5_cmd_exec(ndev->mvdev.mdev, in, sizeof(in), out, sizeof(out));
>>> +     if (err)
>>> +             return err;
>>> +
>>> +     mvq->counter_set_id = MLX5_GET(general_obj_out_cmd_hdr, out, obj_id);
>>> +
>>> +     return 0;
>>> +}
>>> +
>>> +static void counter_set_dealloc(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *mvq)
>>> +{
>>> +     u32 in[MLX5_ST_SZ_DW(destroy_virtio_q_counters_in)] = {};
>>> +     u32 out[MLX5_ST_SZ_DW(destroy_virtio_q_counters_out)] = {};
>>> +
>>> +     if (!counters_supported(&ndev->mvdev))
>>> +             return;
>>> +
>>> +     MLX5_SET(destroy_virtio_q_counters_in, in, hdr.opcode, MLX5_CMD_OP_DESTROY_GENERAL_OBJECT);
>>> +     MLX5_SET(destroy_virtio_q_counters_in, in, hdr.obj_id, mvq->counter_set_id);
>>> +     MLX5_SET(destroy_virtio_q_counters_in, in, hdr.uid, ndev->mvdev.res.uid);
>>> +     MLX5_SET(destroy_virtio_q_counters_in, in, hdr.obj_type, MLX5_OBJ_TYPE_VIRTIO_Q_COUNTERS);
>>> +     if (mlx5_cmd_exec(ndev->mvdev.mdev, in, sizeof(in), out, sizeof(out)))
>>> +             mlx5_vdpa_warn(&ndev->mvdev, "dealloc counter set 0x%x\n", mvq->counter_set_id);
>>> +}
>>> +
>>>    static int setup_vq(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *mvq)
>>>    {
>>>        u16 idx = mvq->index;
>>> @@ -1166,6 +1217,10 @@ static int setup_vq(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *mvq)
>>>        if (err)
>>>                goto err_connect;
>>>
>>> +     err = counter_set_alloc(ndev, mvq);
>>> +     if (err)
>>> +             goto err_counter;
>>> +
>>>        err = create_virtqueue(ndev, mvq);
>>>        if (err)
>>>                goto err_connect;
>>> @@ -1183,6 +1238,8 @@ static int setup_vq(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *mvq)
>>>        return 0;
>>>
>>>    err_connect:
>>> +     counter_set_dealloc(ndev, mvq);
>>> +err_counter:
>>>        qp_destroy(ndev, &mvq->vqqp);
>>>    err_vqqp:
>>>        qp_destroy(ndev, &mvq->fwqp);
>>> @@ -1227,6 +1284,7 @@ static void teardown_vq(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *
>>>
>>>        suspend_vq(ndev, mvq);
>>>        destroy_virtqueue(ndev, mvq);
>>> +     counter_set_dealloc(ndev, mvq);
>>>        qp_destroy(ndev, &mvq->vqqp);
>>>        qp_destroy(ndev, &mvq->fwqp);
>>>        cq_destroy(ndev, mvq->index);
>>> @@ -1681,6 +1739,7 @@ static void mlx5_cvq_kick_handler(struct work_struct *work)
>>>                if (read != sizeof(ctrl))
>>>                        break;
>>>
>>> +             cvq->received_desc++;
>>>                switch (ctrl.class) {
>>>                case VIRTIO_NET_CTRL_MAC:
>>>                        status = handle_ctrl_mac(mvdev, ctrl.cmd);
>>> @@ -1704,6 +1763,7 @@ static void mlx5_cvq_kick_handler(struct work_struct *work)
>>>                if (vringh_need_notify_iotlb(&cvq->vring))
>>>                        vringh_notify(&cvq->vring);
>>>
>>> +             cvq->completed_desc++;
>>>                queue_work(mvdev->wq, &wqent->work);
>>>                break;
>>>        }
>>> @@ -2323,6 +2383,8 @@ static int mlx5_vdpa_reset(struct vdpa_device *vdev)
>>>        mlx5_vdpa_destroy_mr(&ndev->mvdev);
>>>        ndev->mvdev.status = 0;
>>>        ndev->cur_num_vqs = 0;
>>> +     ndev->mvdev.cvq.received_desc = 0;
>>> +     ndev->mvdev.cvq.completed_desc = 0;
>>>        memset(ndev->event_cbs, 0, sizeof(*ndev->event_cbs) * (mvdev->max_vqs + 1));
>>>        ndev->mvdev.actual_features = 0;
>>>        ++mvdev->generation;
>>> @@ -2442,6 +2504,108 @@ static u64 mlx5_vdpa_get_driver_features(struct vdpa_device *vdev)
>>>        return mvdev->actual_features;
>>>    }
>>>
>>> +static int counter_set_query(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *mvq,
>>> +                          u64 *received_desc, u64 *completed_desc)
>>> +{
>>> +     u32 in[MLX5_ST_SZ_DW(query_virtio_q_counters_in)] = {};
>>> +     u32 out[MLX5_ST_SZ_DW(query_virtio_q_counters_out)] = {};
>>> +     void *cmd_hdr;
>>> +     void *ctx;
>>> +     int err;
>>> +
>>> +     if (!counters_supported(&ndev->mvdev))
>>> +             return -EOPNOTSUPP;
>>> +
>>> +     if (mvq->fw_state != MLX5_VIRTIO_NET_Q_OBJECT_STATE_RDY)
>>> +             return -EAGAIN;
>>> +
>>> +     cmd_hdr = MLX5_ADDR_OF(query_virtio_q_counters_in, in, hdr);
>>> +
>>> +     MLX5_SET(general_obj_in_cmd_hdr, cmd_hdr, opcode, MLX5_CMD_OP_QUERY_GENERAL_OBJECT);
>>> +     MLX5_SET(general_obj_in_cmd_hdr, cmd_hdr, obj_type, MLX5_OBJ_TYPE_VIRTIO_Q_COUNTERS);
>>> +     MLX5_SET(general_obj_in_cmd_hdr, cmd_hdr, uid, ndev->mvdev.res.uid);
>>> +     MLX5_SET(general_obj_in_cmd_hdr, cmd_hdr, obj_id, mvq->counter_set_id);
>>> +
>>> +     err = mlx5_cmd_exec(ndev->mvdev.mdev, in, sizeof(in), out, sizeof(out));
>>> +     if (err)
>>> +             return err;
>>> +
>>> +     ctx = MLX5_ADDR_OF(query_virtio_q_counters_out, out, counters);
>>> +     *received_desc = MLX5_GET64(virtio_q_counters, ctx, received_desc);
>>> +     *completed_desc = MLX5_GET64(virtio_q_counters, ctx, completed_desc);
>>> +     return 0;
>>> +}
>>> +
>>> +static int mlx5_vdpa_get_vendor_vq_stats(struct vdpa_device *vdev, u16 idx,
>>> +                                      struct sk_buff *msg,
>>> +                                      struct netlink_ext_ack *extack)
>>> +{
>>> +     struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev);
>>> +     struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev);
>>> +     struct mlx5_vdpa_virtqueue *mvq;
>>> +     struct mlx5_control_vq *cvq;
>>> +     u64 received_desc;
>>> +     u64 completed_desc;
>>> +     int err = 0;
>>> +     u16 max_vqp;
>>> +
>>> +     mutex_lock(&ndev->reslock);
>> I wonder if we can change this lock to r/w semaphore too, otherwise it
>> almost defeats the merit of converting vdpa_dev_mutex to the same. This
>> change would benefit multiple parallel readers.
>>> +     if (!(ndev->mvdev.status & VIRTIO_CONFIG_S_FEATURES_OK)) {
>>> +             NL_SET_ERR_MSG_MOD(extack, "feature negotiation not complete");
>>> +             err = -EAGAIN;
>>> +             goto out_err;
>>> +     }
>>> +
>>> +     if (!is_index_valid(mvdev, idx)) {
>>> +             NL_SET_ERR_MSG_MOD(extack, "virtqueue index is not valid");
>>> +             err = -EINVAL;
>>> +             goto out_err;
>>> +     }
>>> +
>>> +     if (idx == ctrl_vq_idx(mvdev)) {
>>> +             cvq = &mvdev->cvq;
>>> +             received_desc = cvq->received_desc;
>>> +             completed_desc = cvq->completed_desc;
>>> +             goto out;
>>> +     }
>>> +
>>> +     mvq = &ndev->vqs[idx];
>>> +     err = counter_set_query(ndev, mvq, &received_desc, &completed_desc);
>>> +     if (err) {
>>> +             NL_SET_ERR_MSG_MOD(extack, "failed to query hardware");
>>> +             goto out_err;
>>> +     }
>>> +
>>> +out:
>>> +     err = -EMSGSIZE;
>>> +     if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_NEGOTIATED_FEATURES,
>>> +                           mvdev->actual_features, VDPA_ATTR_PAD))
>>> +             goto out_err;
>>> +
>>> +     max_vqp = mlx5vdpa16_to_cpu(mvdev, ndev->config.max_virtqueue_pairs);
>>> +     if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MAX_VQP, max_vqp))
>>> +             goto out_err;
>> Your userspace reference patch doesn't actually use this attribute, but
>> instead calls the VDPA_CMD_DEV_CONFIG_GET in prior to get this
>> information, which will break consistency. Is it your plan to change the
>> userspace code to accommodate what's already piggybacked here and
>> display stat query in just one atomic call? Hope all the available attrs
>> here would satisfy the userspace need.
> Right, I mentioned this in V4. If we depend on the vendor driver to
> report the negotiated features, we will end up driver specific code in
> the userspace which is sub-optimal.
>
> I think we need to do this in the vdpa core so userspace knows for
> sure it can get this.
Yes, that's what I thought and once suggested, too. This would make 
userspace simple and also ease driver implementation.

-Siwei

>
> THanks
>
>> Thanks,
>> -Siwei
>>
>>> +
>>> +     if (nla_put_string(msg, VDPA_ATTR_DEV_VENDOR_ATTR_NAME, "received_desc"))
>>> +             goto out_err;
>>> +
>>> +     if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_VENDOR_ATTR_VALUE, received_desc,
>>> +                           VDPA_ATTR_PAD))
>>> +             goto out_err;
>>> +
>>> +     if (nla_put_string(msg, VDPA_ATTR_DEV_VENDOR_ATTR_NAME, "completed_desc"))
>>> +             goto out_err;
>>> +
>>> +     if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_VENDOR_ATTR_VALUE, completed_desc,
>>> +                           VDPA_ATTR_PAD))
>>> +             goto out_err;
>>> +
>>> +     err = 0;
>>> +out_err:
>>> +     mutex_unlock(&ndev->reslock);
>>> +     return err;
>>> +}
>>> +
>>>    static const struct vdpa_config_ops mlx5_vdpa_ops = {
>>>        .set_vq_address = mlx5_vdpa_set_vq_address,
>>>        .set_vq_num = mlx5_vdpa_set_vq_num,
>>> @@ -2451,6 +2615,7 @@ static const struct vdpa_config_ops mlx5_vdpa_ops = {
>>>        .get_vq_ready = mlx5_vdpa_get_vq_ready,
>>>        .set_vq_state = mlx5_vdpa_set_vq_state,
>>>        .get_vq_state = mlx5_vdpa_get_vq_state,
>>> +     .get_vendor_vq_stats = mlx5_vdpa_get_vendor_vq_stats,
>>>        .get_vq_notification = mlx5_get_vq_notification,
>>>        .get_vq_irq = mlx5_get_vq_irq,
>>>        .get_vq_align = mlx5_vdpa_get_vq_align,
>>> diff --git a/include/linux/mlx5/mlx5_ifc.h b/include/linux/mlx5/mlx5_ifc.h
>>> index 49a48d7709ac..1d193d9b6029 100644
>>> --- a/include/linux/mlx5/mlx5_ifc.h
>>> +++ b/include/linux/mlx5/mlx5_ifc.h
>>> @@ -94,6 +94,7 @@ enum {
>>>    enum {
>>>        MLX5_OBJ_TYPE_GENEVE_TLV_OPT = 0x000b,
>>>        MLX5_OBJ_TYPE_VIRTIO_NET_Q = 0x000d,
>>> +     MLX5_OBJ_TYPE_VIRTIO_Q_COUNTERS = 0x001c,
>>>        MLX5_OBJ_TYPE_MATCH_DEFINER = 0x0018,
>>>        MLX5_OBJ_TYPE_MKEY = 0xff01,
>>>        MLX5_OBJ_TYPE_QP = 0xff02,
>>> diff --git a/include/linux/mlx5/mlx5_ifc_vdpa.h b/include/linux/mlx5/mlx5_ifc_vdpa.h
>>> index 1a9c9d94cb59..4414ed5b6ed2 100644
>>> --- a/include/linux/mlx5/mlx5_ifc_vdpa.h
>>> +++ b/include/linux/mlx5/mlx5_ifc_vdpa.h
>>> @@ -165,4 +165,43 @@ struct mlx5_ifc_modify_virtio_net_q_out_bits {
>>>        struct mlx5_ifc_general_obj_out_cmd_hdr_bits general_obj_out_cmd_hdr;
>>>    };
>>>
>>> +struct mlx5_ifc_virtio_q_counters_bits {
>>> +     u8    modify_field_select[0x40];
>>> +     u8    reserved_at_40[0x40];
>>> +     u8    received_desc[0x40];
>>> +     u8    completed_desc[0x40];
>>> +     u8    error_cqes[0x20];
>>> +     u8    bad_desc_errors[0x20];
>>> +     u8    exceed_max_chain[0x20];
>>> +     u8    invalid_buffer[0x20];
>>> +     u8    reserved_at_180[0x280];
>>> +};
>>> +
>>> +struct mlx5_ifc_create_virtio_q_counters_in_bits {
>>> +     struct mlx5_ifc_general_obj_in_cmd_hdr_bits hdr;
>>> +     struct mlx5_ifc_virtio_q_counters_bits virtio_q_counters;
>>> +};
>>> +
>>> +struct mlx5_ifc_create_virtio_q_counters_out_bits {
>>> +     struct mlx5_ifc_general_obj_in_cmd_hdr_bits hdr;
>>> +     struct mlx5_ifc_virtio_q_counters_bits virtio_q_counters;
>>> +};
>>> +
>>> +struct mlx5_ifc_destroy_virtio_q_counters_in_bits {
>>> +     struct mlx5_ifc_general_obj_in_cmd_hdr_bits hdr;
>>> +};
>>> +
>>> +struct mlx5_ifc_destroy_virtio_q_counters_out_bits {
>>> +     struct mlx5_ifc_general_obj_out_cmd_hdr_bits hdr;
>>> +};
>>> +
>>> +struct mlx5_ifc_query_virtio_q_counters_in_bits {
>>> +     struct mlx5_ifc_general_obj_in_cmd_hdr_bits hdr;
>>> +};
>>> +
>>> +struct mlx5_ifc_query_virtio_q_counters_out_bits {
>>> +     struct mlx5_ifc_general_obj_in_cmd_hdr_bits hdr;
>>> +     struct mlx5_ifc_virtio_q_counters_bits counters;
>>> +};
>>> +
>>>    #endif /* __MLX5_IFC_VDPA_H_ */

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