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Message-ID: <b6f21ec6-2374-69de-c21b-8e917dae8f82@redhat.com>
Date:   Wed, 6 Apr 2022 10:35:33 +0800
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Subject: Re: [PATCH RESEND V2 3/3] vdpa/mlx5: Use consistent RQT size
Content-Language: en-US
To:     "Michael S. Tsirkin" <mst@redhat.com>, Eli Cohen <elic@nvidia.com>
Cc:     "hdanton@sina.com" <hdanton@sina.com>,
        "virtualization@lists.linux-foundation.org" 
        <virtualization@lists.linux-foundation.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <20220329042109.4029-1-jasowang@redhat.com>
 <20220329042109.4029-3-jasowang@redhat.com>
 <20220404063241-mutt-send-email-mst@kernel.org>
 <DM8PR12MB5400ED1195FE612BBC67CB62ABE59@DM8PR12MB5400.namprd12.prod.outlook.com>
 <20220404072402-mutt-send-email-mst@kernel.org>
From:   Jason Wang <jasowang@redhat.com>
In-Reply-To: <20220404072402-mutt-send-email-mst@kernel.org>
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在 2022/4/4 下午7:24, Michael S. Tsirkin 写道:
> On Mon, Apr 04, 2022 at 11:07:36AM +0000, Eli Cohen wrote:
>>> From: Michael S. Tsirkin <mst@redhat.com>
>>> Sent: Monday, April 4, 2022 1:35 PM
>>> To: Jason Wang <jasowang@redhat.com>
>>> Cc: Eli Cohen <elic@nvidia.com>; hdanton@sina.com; virtualization@lists.linux-foundation.org; linux-kernel@vger.kernel.org
>>> Subject: Re: [PATCH RESEND V2 3/3] vdpa/mlx5: Use consistent RQT size
>>>
>>> On Tue, Mar 29, 2022 at 12:21:09PM +0800, Jason Wang wrote:
>>>> From: Eli Cohen <elic@nvidia.com>
>>>>
>>>> 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 addtion
>>> addition?
>> Do you need me to send another version?
> It's a bit easier that way but I can handle it manually too.


Let me send a new version with this fixed.


>
>> If so, let's wait for Jason's reply.
> Right.
>
>>>> 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")
>>>> Signed-off-by: Eli Cohen <elic@nvidia.com>
>>> Jason I don't have your ack or S.O.B on this one.


My bad, for some reason, I miss that.

Will fix.

Thanks


>>>
>>>
>>>> ---
>>>>   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 53b8c1a68f90..61bec1ed0bc9 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)
>>>> @@ -1582,7 +1560,7 @@ 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) {
>>>> @@ -1946,7 +1924,7 @@ 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;
>>>> @@ -2017,9 +1995,11 @@ 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;
>>>> @@ -2486,7 +2466,7 @@ 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;
>>>> @@ -2606,7 +2586,8 @@ 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",
>>>> @@ -2670,7 +2651,7 @@ 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)
>>>> @@ -2697,7 +2678,7 @@ 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;
>>>>
>>>> --
>>>> 2.18.1