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    SubjectRe: [PATCH v1] vdpa/mlx5: Add support for doorbell bypassing
    On Thu, Jun 03, 2021 at 03:11:51PM +0800, Jason Wang wrote:
    >
    > 在 2021/6/2 下午5:53, Eli Cohen 写道:
    > > 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>
    > > ---
    > > v0 --> v1:
    > > Make sure SF bar size is not smaller than PAGE_SIZE
    > >
    > > drivers/vdpa/mlx5/core/mlx5_vdpa.h | 1 +
    > > drivers/vdpa/mlx5/core/resources.c | 1 +
    > > drivers/vdpa/mlx5/net/mlx5_vnet.c | 17 +++++++++++++++++
    > > 3 files changed, 19 insertions(+)
    > >
    > > diff --git a/drivers/vdpa/mlx5/core/mlx5_vdpa.h b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
    > > index 09a16a3d1b2a..0002b2136b48 100644
    > > --- 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 836ab9ef0fa6..d4606213f88a 100644
    > > --- 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 5500bcfe84b4..1936039e05bd 100644
    > > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
    > > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
    > > @@ -1871,8 +1871,25 @@ 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;
    > > + if (addr & ~PAGE_MASK)
    > > + return ret;
    >
    >
    > This has been checked by vhost-vDPA, and it's better to leave those policy
    > checking to them driver instead of checking it in the parent.
    >

    Not in all invocations of get_vq_notification(). For example, in
    vhost_vdpa_fault() you call remap_pfn_range() with notify.addr >>
    PAGE_SHIFT so it it was not aligned you mask this misalignment.

    > Thanks
    >
    >
    > > + ret.addr = (phys_addr_t)ndev->mvdev.res.phys_kick_addr;
    > > + ret.size = PAGE_SIZE;
    > > return ret;
    > > }
    >

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