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

Eli Cohen
2022-05-16T08:39:22Z

> From: Michael S. Tsirkin <mst@redhat.com>
> Sent: Monday, May 16, 2022 11:23 AM
> To: Eli Cohen <elic@nvidia.com>
> Cc: jasowang@redhat.com; Cindy Lu <lulu@redhat.com>; hdanton@sina.com; virtualization@lists.linux-foundation.org; linux-
> kernel@vger.kernel.org
> Subject: Re: [PATCH RESEND V3 3/3] vdpa/mlx5: Use consistent RQT size
>
> On Mon, May 16, 2022 at 08:17:18AM +0000, Eli Cohen wrote:
> > Hi Michael,
> >
> > When are you going to pull this fix?
> > It fixes a real problem and was reviewed and acked.
>
> Do I understand it correctly that this is a stand-alone patch?
> Sorry, my process have been thrown off by it being labeled 3/3 but not
> being part of a thread. Do not do this for single patches please.
> And I suspect 0-day machinery didn't process it either.
> Can you repost as a stand-along patch please?
> I will then process ASAP.

Sure.

>
> Thanks!
>
> > > -----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