On 2018/10/15 下午6:25, Michael S. Tsirkin wrote:
On Mon, Oct 15, 2018 at 10:51:06AM +0800, Jason Wang wrote:
On 2018年10月15日 10:43, Michael S. Tsirkin wrote:
On Mon, Oct 15, 2018 at 10:22:33AM +0800, Jason Wang wrote:
On 2018年10月13日 01:23, Michael S. Tsirkin wrote:
On Fri, Oct 12, 2018 at 10:32:44PM +0800, Tiwei Bie wrote:
On Mon, Jul 16, 2018 at 11:28:09AM +0800, Jason Wang wrote:
[...]
@@ -1367,10 +1397,48 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg
vq->last_avail_idx = s.num;
/* Forget the cached index value. */
vq->avail_idx = vq->last_avail_idx;
+ if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) {
+ vq->last_avail_wrap_counter = wrap_counter;
+ vq->avail_wrap_counter = vq->last_avail_wrap_counter;
+ }
break;
case VHOST_GET_VRING_BASE:
s.index = idx;
s.num = vq->last_avail_idx;
+ if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
+ s.num |= vq->last_avail_wrap_counter << 31;
+ if (copy_to_user(argp, &s, sizeof(s)))
+ r = -EFAULT;
+ break;
+ case VHOST_SET_VRING_USED_BASE:
+ /* Moving base with an active backend?
+ * You don't want to do that.
+ */
+ if (vq->private_data) {
+ r = -EBUSY;
+ break;
+ }
+ if (copy_from_user(&s, argp, sizeof(s))) {
+ r = -EFAULT;
+ break;
+ }
+ if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) {
+ wrap_counter = s.num >> 31;
+ s.num &= ~(1 << 31);
+ }
+ if (s.num > 0xffff) {
+ r = -EINVAL;
+ break;
+ }
Do we want to put wrap_counter at bit 15?
I think I second that - seems to be consistent with
e.g. event suppression structure and the proposed
extension to driver notifications.
Ok, I assumes packed virtqueue support 64K but looks not. I can change it to
bit 15 and GET_VRING_BASE need to be changed as well.
If put wrap_counter at bit 31, the check (s.num > 0xffff)
won't be able to catch the illegal index 0x8000~0xffff for
packed ring.
Do we need to clarify this in the spec?
Isn't this all internal vhost stuff?
I meant the illegal index 0x8000-0xffff.
It does say packed virtqueues support up to 2 15 entries each.
But yes we can add a requirement that devices do not expose
larger rings. Split does not support 2**16 either, right?
With 2**16 enties avail index becomes 0 and ring looks empty.
Yes, so it's better to clarify this in the spec.
Thanks
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