vdpa/mlx5: Add support for doorbell bypassing

Implement mlx5_get_vq_notification() to return the doorbell address.
Since the notification area is mapped to userspace, make sure that the
BAR size is at least PAGE_SIZE large.

Signed-off-by: Eli Cohen <elic@nvidia.com>
Link: https://lore.kernel.org/r/20210603081153.5750-1-elic@nvidia.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

diff --git a/drivers/vdpa/mlx5/core/mlx5_vdpa.h b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
index 09a16a3..0002b21 100644 (file)
--- a/drivers/vdpa/mlx5/core/mlx5_vdpa.h
+++ b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
@@ -42,6 +42,7 @@ struct mlx5_vdpa_resources {
        u32 pdn;
        struct mlx5_uars_page *uar;
        void __iomem *kick_addr;
+       u64 phys_kick_addr;
        u16 uid;
        u32 null_mkey;
        bool valid;

diff --git a/drivers/vdpa/mlx5/core/resources.c b/drivers/vdpa/mlx5/core/resources.c
index 836ab9e..d460621 100644 (file)
--- a/drivers/vdpa/mlx5/core/resources.c
+++ b/drivers/vdpa/mlx5/core/resources.c
@@ -253,6 +253,7 @@ int mlx5_vdpa_alloc_resources(struct mlx5_vdpa_dev *mvdev)
                goto err_key;
 
        kick_addr = mdev->bar_addr + offset;
+       res->phys_kick_addr = kick_addr;
 
        res->kick_addr = ioremap(kick_addr, PAGE_SIZE);
        if (!res->kick_addr) {

diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index d404ea7..8e29b57 100644 (file)
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
@@ -1876,8 +1876,22 @@ static void mlx5_vdpa_free(struct vdpa_device *vdev)
 
 static struct vdpa_notification_area mlx5_get_vq_notification(struct vdpa_device *vdev, u16 idx)
 {
+       struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev);
        struct vdpa_notification_area ret = {};
+       struct mlx5_vdpa_net *ndev;
+       phys_addr_t addr;
 
+       /* If SF BAR size is smaller than PAGE_SIZE, do not use direct
+        * notification to avoid the risk of mapping pages that contain BAR of more
+        * than one SF
+        */
+       if (MLX5_CAP_GEN(mvdev->mdev, log_min_sf_size) + 12 < PAGE_SHIFT)
+               return ret;
+
+       ndev = to_mlx5_vdpa_ndev(mvdev);
+       addr = (phys_addr_t)ndev->mvdev.res.phys_kick_addr;
+       ret.addr = addr;
+       ret.size = PAGE_SIZE;
        return ret;
 }