Re: [RFC PATCH 18/24] vhost-vdpa: support ASID based IOTLB API

[Eugenio Perez Martin <eperezma@redhat.com>]

On Thu, Sep 24, 2020 at 5:25 AM Jason Wang <jasowang@redhat.com> wrote:
>
> This patch extends the vhost-vdpa to support ASID based IOTLB API. The
> vhost-vdpa device will allocated multple IOTLBs for vDPA device that
> supports multiple address spaces. The IOTLBs and vDPA device memory
> mappings is determined and maintained through ASID.
>
> Note that we still don't support vDPA device with more than one
> address spaces that depends on platform IOMMU. This work will be done
> by moving the IOMMU logic from vhost-vDPA to vDPA device driver.
>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
>  drivers/vhost/vdpa.c | 106 ++++++++++++++++++++++++++++++++-----------
>  1 file changed, 79 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index 978cf97dc03a..99ac13b2ed11 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -29,7 +29,8 @@
>  enum {
>         VHOST_VDPA_BACKEND_FEATURES =
>         (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2) |
> -       (1ULL << VHOST_BACKEND_F_IOTLB_BATCH),
> +       (1ULL << VHOST_BACKEND_F_IOTLB_BATCH) |
> +       (1ULL << VHOST_BACKEND_F_IOTLB_ASID),
>  };
>
>  #define VHOST_VDPA_DEV_MAX (1U << MINORBITS)
> @@ -58,12 +59,20 @@ struct vhost_vdpa {
>         struct eventfd_ctx *config_ctx;
>         int in_batch;
>         int used_as;
> +       u32 batch_asid;
>  };
>
>  static DEFINE_IDA(vhost_vdpa_ida);
>
>  static dev_t vhost_vdpa_major;
>
> +static inline u32 iotlb_to_asid(struct vhost_iotlb *iotlb)
> +{
> +       struct vhost_vdpa_as *as = container_of(iotlb, struct
> +                                               vhost_vdpa_as, iotlb);
> +       return as->id;
> +}
> +
>  static struct vhost_vdpa_as *asid_to_as(struct vhost_vdpa *v, u32 asid)
>  {
>         struct hlist_head *head = &v->as[asid % VHOST_VDPA_IOTLB_BUCKETS];
> @@ -76,6 +85,16 @@ static struct vhost_vdpa_as *asid_to_as(struct vhost_vdpa *v, u32 asid)
>         return NULL;
>  }
>
> +static struct vhost_iotlb *asid_to_iotlb(struct vhost_vdpa *v, u32 asid)
> +{
> +       struct vhost_vdpa_as *as = asid_to_as(v, asid);
> +
> +       if (!as)
> +               return NULL;
> +
> +       return &as->iotlb;
> +}
> +
>  static struct vhost_vdpa_as *vhost_vdpa_alloc_as(struct vhost_vdpa *v, u32 asid)
>  {
>         struct hlist_head *head = &v->as[asid % VHOST_VDPA_IOTLB_BUCKETS];
> @@ -84,6 +103,9 @@ static struct vhost_vdpa_as *vhost_vdpa_alloc_as(struct vhost_vdpa *v, u32 asid)
>         if (asid_to_as(v, asid))
>                 return NULL;
>
> +       if (asid >= v->vdpa->nas)
> +               return NULL;
> +
>         as = kmalloc(sizeof(*as), GFP_KERNEL);
>         if (!as)
>                 return NULL;
> @@ -96,13 +118,20 @@ static struct vhost_vdpa_as *vhost_vdpa_alloc_as(struct vhost_vdpa *v, u32 asid)
>         return as;
>  }
>
> -static int vhost_vdpa_remove_as(struct vhost_vdpa *v, u32 asid)
> +static struct vhost_vdpa_as *vhost_vdpa_find_alloc_as(struct vhost_vdpa *v,
> +                                                     u32 asid)
>  {
>         struct vhost_vdpa_as *as = asid_to_as(v, asid);
>
> -       /* Remove default address space is not allowed */
> -       if (asid == 0)
> -               return -EINVAL;
> +       if (as)
> +               return as;
> +
> +       return vhost_vdpa_alloc_as(v, asid);
> +}
> +
> +static int vhost_vdpa_remove_as(struct vhost_vdpa *v, u32 asid)
> +{
> +       struct vhost_vdpa_as *as = asid_to_as(v, asid);
>
>         if (!as)
>                 return -EINVAL;
> @@ -623,6 +652,7 @@ static int vhost_vdpa_map(struct vhost_vdpa *v, struct vhost_iotlb *iotlb,
>  {
>         struct vdpa_device *vdpa = v->vdpa;
>         const struct vdpa_config_ops *ops = vdpa->config;
> +       u32 asid = iotlb_to_asid(iotlb);
>         int r = 0;
>
>         r = vhost_iotlb_add_range(iotlb, iova, iova + size - 1,
> @@ -631,10 +661,10 @@ static int vhost_vdpa_map(struct vhost_vdpa *v, struct vhost_iotlb *iotlb,
>                 return r;
>
>         if (ops->dma_map) {
> -               r = ops->dma_map(vdpa, 0, iova, size, pa, perm);
> +               r = ops->dma_map(vdpa, asid, iova, size, pa, perm);
>         } else if (ops->set_map) {
>                 if (!v->in_batch)
> -                       r = ops->set_map(vdpa, 0, iotlb);
> +                       r = ops->set_map(vdpa, asid, iotlb);
>         } else {
>                 r = iommu_map(v->domain, iova, pa, size,
>                               perm_to_iommu_flags(perm));
> @@ -643,23 +673,32 @@ static int vhost_vdpa_map(struct vhost_vdpa *v, struct vhost_iotlb *iotlb,
>         return r;
>  }
>
> -static void vhost_vdpa_unmap(struct vhost_vdpa *v,
> -                            struct vhost_iotlb *iotlb,
> -                            u64 iova, u64 size)
> +static int vhost_vdpa_unmap(struct vhost_vdpa *v,
> +                           struct vhost_iotlb *iotlb,
> +                           u64 iova, u64 size)
>  {
>         struct vdpa_device *vdpa = v->vdpa;
>         const struct vdpa_config_ops *ops = vdpa->config;
> +       u32 asid = (iotlb);
> +
> +       if (!iotlb)
> +               return -EINVAL;

This should be reorder to check for (!iotlb) before use at `asid =
iotlb_to_asid()`, isn't it?

Thanks!

>
>         vhost_vdpa_iotlb_unmap(v, iotlb, iova, iova + size - 1);
>
>         if (ops->dma_map) {
> -               ops->dma_unmap(vdpa, 0, iova, size);
> +               ops->dma_unmap(vdpa, asid, iova, size);
>         } else if (ops->set_map) {
>                 if (!v->in_batch)
> -                       ops->set_map(vdpa, 0, iotlb);
> +                       ops->set_map(vdpa, asid, iotlb);
>         } else {
>                 iommu_unmap(v->domain, iova, size);
>         }
> +
> +       if (!iotlb->nmaps)
> +               vhost_vdpa_remove_as(v, asid);
> +
> +       return 0;
>  }
>
>  static int vhost_vdpa_process_iotlb_update(struct vhost_vdpa *v,
> @@ -755,30 +794,38 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev, u32 asid,
>         struct vhost_vdpa *v = container_of(dev, struct vhost_vdpa, vdev);
>         struct vdpa_device *vdpa = v->vdpa;
>         const struct vdpa_config_ops *ops = vdpa->config;
> -       struct vhost_vdpa_as *as = asid_to_as(v, 0);
> -       struct vhost_iotlb *iotlb = &as->iotlb;
> +       struct vhost_iotlb *iotlb = asid_to_iotlb(v, asid);
> +       struct vhost_vdpa_as *as;
>         int r = 0;
>
> -       if (asid != 0)
> -               return -EINVAL;
> -
>         r = vhost_dev_check_owner(dev);
>         if (r)
>                 return r;
>
> +       if ((msg->type == VHOST_IOTLB_UPDATE) && !iotlb) {
> +               as = vhost_vdpa_find_alloc_as(v, asid);
> +               if (!as)
> +                       return -EINVAL;
> +               iotlb = &as->iotlb;
> +       }
> +
> +       if (v->in_batch && v->batch_asid != asid)
> +               return -EINVAL;
> +
>         switch (msg->type) {
>         case VHOST_IOTLB_UPDATE:
>                 r = vhost_vdpa_process_iotlb_update(v, iotlb, msg);
>                 break;
>         case VHOST_IOTLB_INVALIDATE:
> -               vhost_vdpa_unmap(v, iotlb, msg->iova, msg->size);
> +               r = vhost_vdpa_unmap(v, iotlb, msg->iova, msg->size);
>                 break;
>         case VHOST_IOTLB_BATCH_BEGIN:
> +               v->batch_asid = asid;
>                 v->in_batch = true;
>                 break;
>         case VHOST_IOTLB_BATCH_END:
>                 if (v->in_batch && ops->set_map)
> -                       ops->set_map(vdpa, 0, iotlb);
> +                       ops->set_map(vdpa, asid, iotlb);
>                 v->in_batch = false;
>                 break;
>         default:
> @@ -848,9 +895,17 @@ static void vhost_vdpa_free_domain(struct vhost_vdpa *v)
>
>  static void vhost_vdpa_cleanup(struct vhost_vdpa *v)
>  {
> +       struct vhost_vdpa_as *as;
> +       u32 asid;
> +
>         vhost_dev_cleanup(&v->vdev);
>         kfree(v->vdev.vqs);
> -       vhost_vdpa_remove_as(v, 0);
> +
> +       for (asid = 0; asid < v->vdpa->nas; asid++) {
> +               as = asid_to_as(v, asid);
> +               if (as)
> +                       vhost_vdpa_remove_as(v, asid);
> +       }
>  }
>
>  static int vhost_vdpa_open(struct inode *inode, struct file *filep)
> @@ -883,18 +938,15 @@ static int vhost_vdpa_open(struct inode *inode, struct file *filep)
>         vhost_dev_init(dev, vqs, nvqs, 0, 0, 0, false,
>                        vhost_vdpa_process_iotlb_msg);
>
> -       if (!vhost_vdpa_alloc_as(v, 0))
> -               goto err_alloc_as;
> -
>         r = vhost_vdpa_alloc_domain(v);
>         if (r)
> -               goto err_alloc_as;
> +               goto err_alloc_domain;
>
>         filep->private_data = v;
>
>         return 0;
>
> -err_alloc_as:
> +err_alloc_domain:
>         vhost_vdpa_cleanup(v);
>  err:
>         atomic_dec(&v->opened);
> @@ -1022,8 +1074,8 @@ static int vhost_vdpa_probe(struct vdpa_device *vdpa)
>         int minor;
>         int i, r;
>
> -       /* Only support 1 address space */
> -       if (vdpa->ngroups != 1)
> +       /* We can't support platform IOMMU device with more than 1 group */
> +       if (!ops->set_map && !ops->dma_map && vdpa->ngroups > 1)
>                 return -ENOTSUPP;
>
>         /* Currently, we only accept the network devices. */
> --
> 2.20.1
>