Re: [PATCH] vdpa/mlx5: Support interrupt bypassing

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On Thu, Jun 08, 2023 at 04:25:55PM +0000, Dragos Tatulea wrote:
> On Wed, 2023-06-07 at 22:00 +0300, Dragos Tatulea via Virtualization wrote:
> > From: Eli Cohen <elic@xxxxxxxxxx>
> > 
> > Add support for generation of interrupts from the device directly to the
> > VM to the VCPU thus avoiding the overhead on the host CPU.
> > 
> > When supported, the driver will attempt to allocate vectors for each
> > data virtqueue. If a vector for a virtqueue cannot be provided it will
> > use the QP mode where notifications go through the driver.
> > 
> > In addition, we add a shutdown callback to make sure allocated
> > interrupts are released in case of shutdown to allow clean shutdown.
> > 
> > Signed-off-by: Eli Cohen <elic@xxxxxxxxxx>
> > Signed-off-by: Saeed Mahameed <saeedm@xxxxxxxxxx>
> > 
> Just realized that this patch should have been marked as a v3. Let me know if I
> should resend it.

no need.

> > ---
> >  drivers/vdpa/mlx5/net/mlx5_vnet.c | 165 ++++++++++++++++++++++++++++--
> >  drivers/vdpa/mlx5/net/mlx5_vnet.h |  15 +++
> >  2 files changed, 171 insertions(+), 9 deletions(-)
> > 
> > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > index 279ac6a558d2..9138ef2fb2c8 100644
> > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > @@ -83,6 +83,7 @@ struct mlx5_vq_restore_info {
> >         u64 driver_addr;
> >         u16 avail_index;
> >         u16 used_index;
> > +       struct msi_map map;
> >         bool ready;
> >         bool restore;
> >  };
> > @@ -118,6 +119,7 @@ struct mlx5_vdpa_virtqueue {
> >         u16 avail_idx;
> >         u16 used_idx;
> >         int fw_state;
> > +       struct msi_map map;
> >  
> >         /* keep last in the struct */
> >         struct mlx5_vq_restore_info ri;
> > @@ -808,6 +810,13 @@ static bool counters_supported(const struct mlx5_vdpa_dev
> > *mvdev)
> >                BIT_ULL(MLX5_OBJ_TYPE_VIRTIO_Q_COUNTERS);
> >  }
> >  
> > +static bool msix_mode_supported(struct mlx5_vdpa_dev *mvdev)
> > +{
> > +       return MLX5_CAP_DEV_VDPA_EMULATION(mvdev->mdev, event_mode) &
> > +               (1 << MLX5_VIRTIO_Q_EVENT_MODE_MSIX_MODE) &&
> > +               pci_msix_can_alloc_dyn(mvdev->mdev->pdev);
> > +}
> > +
> >  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);
> > @@ -849,9 +858,15 @@ static int create_virtqueue(struct mlx5_vdpa_net *ndev,
> > struct mlx5_vdpa_virtque
> >         if (vq_is_tx(mvq->index))
> >                 MLX5_SET(virtio_net_q_object, obj_context, tisn_or_qpn, ndev-
> > >res.tisn);
> >  
> > -       MLX5_SET(virtio_q, vq_ctx, event_mode,
> > MLX5_VIRTIO_Q_EVENT_MODE_QP_MODE);
> > +       if (mvq->map.virq) {
> > +               MLX5_SET(virtio_q, vq_ctx, event_mode,
> > MLX5_VIRTIO_Q_EVENT_MODE_MSIX_MODE);
> > +               MLX5_SET(virtio_q, vq_ctx, event_qpn_or_msix, mvq->map.index);
> > +       } else {
> > +               MLX5_SET(virtio_q, vq_ctx, event_mode,
> > MLX5_VIRTIO_Q_EVENT_MODE_QP_MODE);
> > +               MLX5_SET(virtio_q, vq_ctx, event_qpn_or_msix, mvq-
> > >fwqp.mqp.qpn);
> > +       }
> > +
> >         MLX5_SET(virtio_q, vq_ctx, queue_index, mvq->index);
> > -       MLX5_SET(virtio_q, vq_ctx, event_qpn_or_msix, mvq->fwqp.mqp.qpn);
> >         MLX5_SET(virtio_q, vq_ctx, queue_size, mvq->num_ent);
> >         MLX5_SET(virtio_q, vq_ctx, virtio_version_1_0,
> >                  !!(ndev->mvdev.actual_features &
> > BIT_ULL(VIRTIO_F_VERSION_1)));
> > @@ -1194,6 +1209,56 @@ static void counter_set_dealloc(struct mlx5_vdpa_net
> > *ndev, struct mlx5_vdpa_vir
> >                 mlx5_vdpa_warn(&ndev->mvdev, "dealloc counter set 0x%x\n",
> > mvq->counter_set_id);
> >  }
> >  
> > +static irqreturn_t mlx5_vdpa_int_handler(int irq, void *priv)
> > +{
> > +       struct vdpa_callback *cb = priv;
> > +
> > +       if (cb->callback)
> > +               return cb->callback(cb->private);
> > +
> > +       return IRQ_HANDLED;
> > +}
> > +
> > +static void alloc_vector(struct mlx5_vdpa_net *ndev,
> > +                        struct mlx5_vdpa_virtqueue *mvq)
> > +{
> > +       struct mlx5_vdpa_irq_pool *irqp = &ndev->irqp;
> > +       struct mlx5_vdpa_irq_pool_entry *ent;
> > +       int err;
> > +       int i;
> > +
> > +       for (i = 0; i < irqp->num_ent; i++) {
> > +               ent = &irqp->entries[i];
> > +               if (!ent->used) {
> > +                       snprintf(ent->name, MLX5_VDPA_IRQ_NAME_LEN, "%s-vq-
> > %d",
> > +                                dev_name(&ndev->mvdev.vdev.dev), mvq->index);
> > +                       ent->dev_id = &ndev->event_cbs[mvq->index];
> > +                       err = request_irq(ent->map.virq,
> > mlx5_vdpa_int_handler, 0,
> > +                                         ent->name, ent->dev_id);
> > +                       if (err)
> > +                               return;
> > +
> > +                       ent->used = true;
> > +                       mvq->map = ent->map;
> > +                       return;
> > +               }
> > +       }
> > +}
> > +
> > +static void dealloc_vector(struct mlx5_vdpa_net *ndev,
> > +                          struct mlx5_vdpa_virtqueue *mvq)
> > +{
> > +       struct mlx5_vdpa_irq_pool *irqp = &ndev->irqp;
> > +       int i;
> > +
> > +       for (i = 0; i < irqp->num_ent; i++)
> > +               if (mvq->map.virq == irqp->entries[i].map.virq) {
> > +                       free_irq(mvq->map.virq, irqp->entries[i].dev_id);
> > +                       irqp->entries[i].used = false;
> > +                       return;
> > +               }
> > +}
> > +
> >  static int setup_vq(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue
> > *mvq)
> >  {
> >         u16 idx = mvq->index;
> > @@ -1223,27 +1288,31 @@ static int setup_vq(struct mlx5_vdpa_net *ndev, struct
> > mlx5_vdpa_virtqueue *mvq)
> >  
> >         err = counter_set_alloc(ndev, mvq);
> >         if (err)
> > -               goto err_counter;
> > +               goto err_connect;
> >  
> > +       alloc_vector(ndev, mvq);
> >         err = create_virtqueue(ndev, mvq);
> >         if (err)
> > -               goto err_connect;
> > +               goto err_vq;
> >  
> >         if (mvq->ready) {
> >                 err = modify_virtqueue(ndev, mvq,
> > MLX5_VIRTIO_NET_Q_OBJECT_STATE_RDY);
> >                 if (err) {
> >                         mlx5_vdpa_warn(&ndev->mvdev, "failed to modify to
> > ready vq idx %d(%d)\n",
> >                                        idx, err);
> > -                       goto err_connect;
> > +                       goto err_modify;
> >                 }
> >         }
> >  
> >         mvq->initialized = true;
> >         return 0;
> >  
> > -err_connect:
> > +err_modify:
> > +       destroy_virtqueue(ndev, mvq);
> > +err_vq:
> > +       dealloc_vector(ndev, mvq);
> >         counter_set_dealloc(ndev, mvq);
> > -err_counter:
> > +err_connect:
> >         qp_destroy(ndev, &mvq->vqqp);
> >  err_vqqp:
> >         qp_destroy(ndev, &mvq->fwqp);
> > @@ -1288,6 +1357,7 @@ static void teardown_vq(struct mlx5_vdpa_net *ndev,
> > struct mlx5_vdpa_virtqueue *
> >  
> >         suspend_vq(ndev, mvq);
> >         destroy_virtqueue(ndev, mvq);
> > +       dealloc_vector(ndev, mvq);
> >         counter_set_dealloc(ndev, mvq);
> >         qp_destroy(ndev, &mvq->vqqp);
> >         qp_destroy(ndev, &mvq->fwqp);
> > @@ -2505,6 +2575,7 @@ static int save_channel_info(struct mlx5_vdpa_net *ndev,
> > struct mlx5_vdpa_virtqu
> >         ri->desc_addr = mvq->desc_addr;
> >         ri->device_addr = mvq->device_addr;
> >         ri->driver_addr = mvq->driver_addr;
> > +       ri->map = mvq->map;
> >         ri->restore = true;
> >         return 0;
> >  }
> > @@ -2549,6 +2620,7 @@ static void restore_channels_info(struct mlx5_vdpa_net
> > *ndev)
> >                 mvq->desc_addr = ri->desc_addr;
> >                 mvq->device_addr = ri->device_addr;
> >                 mvq->driver_addr = ri->driver_addr;
> > +               mvq->map = ri->map;
> >         }
> >  }
> >  
> > @@ -2833,6 +2905,25 @@ static struct device *mlx5_get_vq_dma_dev(struct
> > vdpa_device *vdev, u16 idx)
> >         return mvdev->vdev.dma_dev;
> >  }
> >  
> > +static void free_irqs(struct mlx5_vdpa_net *ndev)
> > +{
> > +       struct mlx5_vdpa_irq_pool_entry *ent;
> > +       int i;
> > +
> > +       if (!msix_mode_supported(&ndev->mvdev))
> > +               return;
> > +
> > +       if (!ndev->irqp.entries)
> > +               return;
> > +
> > +       for (i = ndev->irqp.num_ent - 1; i >= 0; i--) {
> > +               ent = ndev->irqp.entries + i;
> > +               if (ent->map.virq)
> > +                       pci_msix_free_irq(ndev->mvdev.mdev->pdev, ent->map);
> > +       }
> > +       kfree(ndev->irqp.entries);
> > +}
> > +
> >  static void mlx5_vdpa_free(struct vdpa_device *vdev)
> >  {
> >         struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev);
> > @@ -2848,6 +2939,7 @@ static void mlx5_vdpa_free(struct vdpa_device *vdev)
> >                 mlx5_mpfs_del_mac(pfmdev, ndev->config.mac);
> >         }
> >         mlx5_vdpa_free_resources(&ndev->mvdev);
> > +       free_irqs(ndev);
> >         kfree(ndev->event_cbs);
> >         kfree(ndev->vqs);
> >  }
> > @@ -2876,9 +2968,23 @@ static struct vdpa_notification_area
> > mlx5_get_vq_notification(struct vdpa_device
> >         return ret;
> >  }
> >  
> > -static int mlx5_get_vq_irq(struct vdpa_device *vdv, u16 idx)
> > +static int mlx5_get_vq_irq(struct vdpa_device *vdev, u16 idx)
> >  {
> > -       return -EOPNOTSUPP;
> > +       struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev);
> > +       struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev);
> > +       struct mlx5_vdpa_virtqueue *mvq;
> > +
> > +       if (!is_index_valid(mvdev, idx))
> > +               return -EINVAL;
> > +
> > +       if (is_ctrl_vq_idx(mvdev, idx))
> > +               return -EOPNOTSUPP;
> > +
> > +       mvq = &ndev->vqs[idx];
> > +       if (!mvq->map.virq)
> > +               return -EOPNOTSUPP;
> > +
> > +       return mvq->map.virq;
> >  }
> >  
> >  static u64 mlx5_vdpa_get_driver_features(struct vdpa_device *vdev)
> > @@ -3155,6 +3261,34 @@ static int config_func_mtu(struct mlx5_core_dev *mdev,
> > u16 mtu)
> >         return err;
> >  }
> >  
> > +static void allocate_irqs(struct mlx5_vdpa_net *ndev)
> > +{
> > +       struct mlx5_vdpa_irq_pool_entry *ent;
> > +       int i;
> > +
> > +       if (!msix_mode_supported(&ndev->mvdev))
> > +               return;
> > +
> > +       if (!ndev->mvdev.mdev->pdev)
> > +               return;
> > +
> > +       ndev->irqp.entries = kcalloc(ndev->mvdev.max_vqs, sizeof(*ndev-
> > >irqp.entries), GFP_KERNEL);
> > +       if (!ndev->irqp.entries)
> > +               return;
> > +
> > +
> > +       for (i = 0; i < ndev->mvdev.max_vqs; i++) {
> > +               ent = ndev->irqp.entries + i;
> > +               snprintf(ent->name, MLX5_VDPA_IRQ_NAME_LEN, "%s-vq-%d",
> > +                        dev_name(&ndev->mvdev.vdev.dev), i);
> > +               ent->map = pci_msix_alloc_irq_at(ndev->mvdev.mdev->pdev,
> > MSI_ANY_INDEX, NULL);
> > +               if (!ent->map.virq)
> > +                       return;
> > +
> > +               ndev->irqp.num_ent++;
> > +       }
> > +}
> > +
> >  static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
> >                              const struct vdpa_dev_set_config *add_config)
> >  {
> > @@ -3233,6 +3367,7 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev
> > *v_mdev, const char *name,
> >         }
> >  
> >         init_mvqs(ndev);
> > +       allocate_irqs(ndev);
> >         init_rwsem(&ndev->reslock);
> >         config = &ndev->config;
> >  
> > @@ -3413,6 +3548,17 @@ static void mlx5v_remove(struct auxiliary_device *adev)
> >         kfree(mgtdev);
> >  }
> >  
> > +static void mlx5v_shutdown(struct auxiliary_device *auxdev)
> > +{
> > +       struct mlx5_vdpa_mgmtdev *mgtdev;
> > +       struct mlx5_vdpa_net *ndev;
> > +
> > +       mgtdev = auxiliary_get_drvdata(auxdev);
> > +       ndev = mgtdev->ndev;
> > +
> > +       free_irqs(ndev);
> > +}
> > +
> >  static const struct auxiliary_device_id mlx5v_id_table[] = {
> >         { .name = MLX5_ADEV_NAME ".vnet", },
> >         {},
> > @@ -3424,6 +3570,7 @@ static struct auxiliary_driver mlx5v_driver = {
> >         .name = "vnet",
> >         .probe = mlx5v_probe,
> >         .remove = mlx5v_remove,
> > +       .shutdown = mlx5v_shutdown,
> >         .id_table = mlx5v_id_table,
> >  };
> >  
> > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.h
> > b/drivers/vdpa/mlx5/net/mlx5_vnet.h
> > index c90a89e1de4d..36c44d9fdd16 100644
> > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.h
> > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.h
> > @@ -26,6 +26,20 @@ static inline u16 key2vid(u64 key)
> >         return (u16)(key >> 48) & 0xfff;
> >  }
> >  
> > +#define MLX5_VDPA_IRQ_NAME_LEN 32
> > +
> > +struct mlx5_vdpa_irq_pool_entry {
> > +       struct msi_map map;
> > +       bool used;
> > +       char name[MLX5_VDPA_IRQ_NAME_LEN];
> > +       void *dev_id;
> > +};
> > +
> > +struct mlx5_vdpa_irq_pool {
> > +       int num_ent;
> > +       struct mlx5_vdpa_irq_pool_entry *entries;
> > +};
> > +
> >  struct mlx5_vdpa_net {
> >         struct mlx5_vdpa_dev mvdev;
> >         struct mlx5_vdpa_net_resources res;
> > @@ -49,6 +63,7 @@ struct mlx5_vdpa_net {
> >         struct vdpa_callback config_cb;
> >         struct mlx5_vdpa_wq_ent cvq_ent;
> >         struct hlist_head macvlan_hash[MLX5V_MACVLAN_SIZE];
> > +       struct mlx5_vdpa_irq_pool irqp;
> >         struct dentry *debugfs;
> >  };
> >  
> 
> 

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