On Thu, Dec 24, 2020 at 10:37 AM Jason Wang <jasowang@xxxxxxxxxx> wrote:
>
>
> On 2020/12/23 下午7:06, Yongji Xie wrote:
> > On Wed, Dec 23, 2020 at 4:37 PM Jason Wang <jasowang@xxxxxxxxxx> wrote:
> >>
> >> On 2020/12/22 下午10:52, Xie Yongji wrote:
> >>> This patch introduces a new method in the vdpa_config_ops to
> >>> support processing the raw vhost memory mapping message in the
> >>> vDPA device driver.
> >>>
> >>> Signed-off-by: Xie Yongji <xieyongji@xxxxxxxxxxxxx>
> >>> ---
> >>> drivers/vhost/vdpa.c | 5 ++++-
> >>> include/linux/vdpa.h | 7 +++++++
> >>> 2 files changed, 11 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> >>> index 448be7875b6d..ccbb391e38be 100644
> >>> --- a/drivers/vhost/vdpa.c
> >>> +++ b/drivers/vhost/vdpa.c
> >>> @@ -728,6 +728,9 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev,
> >>> if (r)
> >>> return r;
> >>>
> >>> + if (ops->process_iotlb_msg)
> >>> + return ops->process_iotlb_msg(vdpa, msg);
> >>> +
> >>> switch (msg->type) {
> >>> case VHOST_IOTLB_UPDATE:
> >>> r = vhost_vdpa_process_iotlb_update(v, msg);
> >>> @@ -770,7 +773,7 @@ static int vhost_vdpa_alloc_domain(struct vhost_vdpa *v)
> >>> int ret;
> >>>
> >>> /* Device want to do DMA by itself */
> >>> - if (ops->set_map || ops->dma_map)
> >>> + if (ops->set_map || ops->dma_map || ops->process_iotlb_msg)
> >>> return 0;
> >>>
> >>> bus = dma_dev->bus;
> >>> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> >>> index 656fe264234e..7bccedf22f4b 100644
> >>> --- a/include/linux/vdpa.h
> >>> +++ b/include/linux/vdpa.h
> >>> @@ -5,6 +5,7 @@
> >>> #include <linux/kernel.h>
> >>> #include <linux/device.h>
> >>> #include <linux/interrupt.h>
> >>> +#include <linux/vhost_types.h>
> >>> #include <linux/vhost_iotlb.h>
> >>> #include <net/genetlink.h>
> >>>
> >>> @@ -172,6 +173,10 @@ struct vdpa_iova_range {
> >>> * @vdev: vdpa device
> >>> * Returns the iova range supported by
> >>> * the device.
> >>> + * @process_iotlb_msg: Process vhost memory mapping message (optional)
> >>> + * Only used for VDUSE device now
> >>> + * @vdev: vdpa device
> >>> + * @msg: vhost memory mapping message
> >>> * @set_map: Set device memory mapping (optional)
> >>> * Needed for device that using device
> >>> * specific DMA translation (on-chip IOMMU)
> >>> @@ -240,6 +245,8 @@ struct vdpa_config_ops {
> >>> struct vdpa_iova_range (*get_iova_range)(struct vdpa_device *vdev);
> >>>
> >>> /* DMA ops */
> >>> + int (*process_iotlb_msg)(struct vdpa_device *vdev,
> >>> + struct vhost_iotlb_msg *msg);
> >>> int (*set_map)(struct vdpa_device *vdev, struct vhost_iotlb *iotlb);
> >>> int (*dma_map)(struct vdpa_device *vdev, u64 iova, u64 size,
> >>> u64 pa, u32 perm);
> >>
> >> Is there any reason that it can't be done via dma_map/dma_unmap or set_map?
> >>
> > To get the shmfd, we need the vma rather than physical address. And
> > it's not necessary to pin the user pages in VDUSE case.
>
>
> Right, actually, vhost-vDPA is planning to support shared virtual
> address space.
>
> So let's try to reuse the existing config ops. How about just introduce
> an attribute to vdpa device that tells the bus tells the bus it can do
> shared virtual memory. Then when the device is probed by vhost-vDPA, use
> pages won't be pinned and we will do VA->VA mapping as IOVA->PA mapping
> in the vhost IOTLB and the config ops. vhost IOTLB needs to be extended
> to accept opaque pointer to store the file. And the file was pass via
> the config ops as well.
>
OK, I see. Will try it in v3.
Thanks,
Yongji
