在 2021/10/25 上午10:44, Wu Zongyong 写道:
On Mon, Oct 25, 2021 at 10:22:30AM +0800, Jason Wang wrote:
On Fri, Oct 22, 2021 at 10:45 AM Wu Zongyong
<wuzongyong@xxxxxxxxxxxxxxxxx> wrote:
For the devices which implement the get_vq_num_min callback, the driver
should not negotiate with virtqueue size with the backend vdpa device if
the value returned by get_vq_num_min equals to the value returned by
get_vq_num_max.
This is useful for vdpa devices based on legacy virtio specfication.
Signed-off-by: Wu Zongyong <wuzongyong@xxxxxxxxxxxxxxxxx>
---
drivers/virtio/virtio_vdpa.c | 21 ++++++++++++++++-----
1 file changed, 16 insertions(+), 5 deletions(-)
diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
index 72eaef2caeb1..e42ace29daa1 100644
--- a/drivers/virtio/virtio_vdpa.c
+++ b/drivers/virtio/virtio_vdpa.c
@@ -145,7 +145,8 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
/* Assume split virtqueue, switch to packed if necessary */
struct vdpa_vq_state state = {0};
unsigned long flags;
- u32 align, num;
+ u32 align, max_num, min_num = 0;
+ bool may_reduce_num = true;
int err;
if (!name)
@@ -163,22 +164,32 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
if (!info)
return ERR_PTR(-ENOMEM);
- num = ops->get_vq_num_max(vdpa);
- if (num == 0) {
+ max_num = ops->get_vq_num_max(vdpa);
+ if (max_num == 0) {
err = -ENOENT;
goto error_new_virtqueue;
}
+ if (ops->get_vq_num_min)
+ min_num = ops->get_vq_num_min(vdpa);
+
+ may_reduce_num = (max_num == min_num) ? false : true;
+
/* Create the vring */
align = ops->get_vq_align(vdpa);
- vq = vring_create_virtqueue(index, num, align, vdev,
- true, true, ctx,
+ vq = vring_create_virtqueue(index, max_num, align, vdev,
+ true, may_reduce_num, ctx,
virtio_vdpa_notify, callback, name);
if (!vq) {
err = -ENOMEM;
goto error_new_virtqueue;
}
+ if (virtqueue_get_vring_size(vq) < min_num) {
+ err = -EINVAL;
+ goto err_vq;
+ }
I wonder under which case can we hit this?
Thanks
If min_vq_num < max_vq_num, may_reduce_num should be true, then it is
possible to allocate a virtqueue with a small size which value is less
than the min_vq_num since we only set the upper bound for virtqueue size
when creating virtqueue.
Refers to vring_create_virtqueue_split in driver/virtio/virtio_vring.c:
for (; num && vring_size(num, vring_align) > PAGE_SIZE; num /= 2) {
queue = vring_alloc_queue(vdev, vring_size(num, vring_align),
&dma_addr,
GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
if (queue)
break;
if (!may_reduce_num)
return NULL;
}
It looks to me it's better to fix this function instead of checking it
in the caller?
BTW, I have replied this mail on Nov.18, have you ever received it?
For some reason I dont' get that.
Thanks
+
/* Setup virtqueue callback */
cb.callback = virtio_vdpa_virtqueue_cb;
cb.private = info;
--
2.31.1
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