在 2022/2/1 上午1:44, Eugenio Perez Martin 写道:
On Sat, Jan 29, 2022 at 9:20 AM Jason Wang <jasowang@xxxxxxxxxx> wrote:
在 2022/1/22 上午4:27, Eugenio Pérez 写道:
Doing that way allows vhost backend to know what address to return.
Signed-off-by: Eugenio Pérez <eperezma@xxxxxxxxxx>
---
hw/virtio/vhost.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 7b03efccec..64b955ba0c 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -798,9 +798,10 @@ static int vhost_virtqueue_set_addr(struct vhost_dev *dev,
struct vhost_virtqueue *vq,
unsigned idx, bool enable_log)
{
- struct vhost_vring_addr addr;
+ struct vhost_vring_addr addr = {
+ .index = idx,
+ };
int r;
- memset(&addr, 0, sizeof(struct vhost_vring_addr));
if (dev->vhost_ops->vhost_vq_get_addr) {
r = dev->vhost_ops->vhost_vq_get_addr(dev, &addr, vq);
@@ -813,7 +814,6 @@ static int vhost_virtqueue_set_addr(struct vhost_dev *dev,
addr.avail_user_addr = (uint64_t)(unsigned long)vq->avail;
addr.used_user_addr = (uint64_t)(unsigned long)vq->used;
}
I'm a bit lost in the logic above, any reason we need call
vhost_vq_get_addr() :) ?
It's the way vhost_virtqueue_set_addr works if the backend has a
vhost_vq_get_addr operation (currently, only vhost-vdpa). vhost first
ask the address to the back end and then set it.
Right it's because vhost-vdpa doesn't use VA but GPA. But I'm not sure
it's worth a dedicated vhost_ops. But consider we introduce shadow
virtqueue stuffs, it should be ok now.
(In the future, we may consider to generalize non vhost-vdpa specific
stuffs to VhostShadowVirtqueue, then we can get rid of this vhost_ops.
Previously, index was not needed because all the information was in
vhost_virtqueue. However to extract queue index from vhost_virtqueue
is tricky, so I think it's easier to simply have that information at
request, something similar to get_base or get_num when asking vdpa
device. We can extract the index from vq - dev->vqs or something
similar if it's prefered.
It looks odd for the caller to tell the index consider vhost_virtqueue
is already passed. So I think we need deduce it from vhost_virtqueue as
you mentioned here.
Thanks
Thanks!
Thanks
- addr.index = idx;
addr.log_guest_addr = vq->used_phys;
addr.flags = enable_log ? (1 << VHOST_VRING_F_LOG) : 0;
r = dev->vhost_ops->vhost_set_vring_addr(dev, &addr);
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