On 5/16/23 12:49 AM, Stefano Garzarella wrote:
On Mon, May 15, 2023 at 01:41:12PM -0700, Shannon Nelson wrote:
On 5/9/23 1:46 AM, Stefano Garzarella wrote:
On Mon, Apr 24, 2023 at 03:50:30PM -0700, Shannon Nelson via
Virtualization wrote:
Use the right structs for PACKED or split vqs when setting and
getting the vring base.
Signed-off-by: Shannon Nelson <[email protected]>
---
drivers/vhost/vhost.c | 18 +++++++++++++-----
drivers/vhost/vhost.h | 8 ++++++--
2 files changed, 19 insertions(+), 7 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index f11bdbe4c2c5..f64efda48f21 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1633,17 +1633,25 @@ long vhost_vring_ioctl(struct vhost_dev
*d, unsigned int ioctl, void __user *arg
r = -EFAULT;
break;
}
- if (s.num > 0xffff) {
- r = -EINVAL;
- break;
+ if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) {
+ vq->last_avail_idx = s.num & 0xffff;
+ vq->last_used_idx = (s.num >> 16) & 0xffff;
+ } else {
+ if (s.num > 0xffff) {
+ r = -EINVAL;
+ break;
+ }
+ vq->last_avail_idx = s.num;
}
- vq->last_avail_idx = s.num;
/* Forget the cached index value. */
vq->avail_idx = vq->last_avail_idx;
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 = (u32)vq->last_avail_idx |
((u32)vq->last_used_idx << 16);
+ else
+ s.num = vq->last_avail_idx;
The changes LGTM, but since we are changing the UAPI, should we
update the documentation of VHOST_SET_VRING_BASE and
VHOST_GET_VRING_BASE in include/uapi/linux/vhost.h?
Correct me if I'm wrong, but I don't think we're changing anything in
the UAPI here, just fixing code to work correctly with what is already
happening.
IIUC before this patch VHOST_GET_VRING_BASE and VHOST_SET_VRING_BASE
never worked with packed virtqueue, since we were only handling
last_avail_idx. Now we are supporting packed virtqueue, handling
in vhost_vring_state.num both last_avail_idx and last_used_idx (with
wrap counters).
For example for VHOST_GET_VRING_BASE where is documented that the first
15 bits are last_avail_idx, the 16th the avail_wrap_counter, and the
others are last_used_idx and used_wrap_counter?
Maybe I missed something, but since this is UAPI, IMHO we should
document the parameters of ioctls at least in
include/uapi/linux/vhost.h.
Perhaps Jason already has something written up that could be put in here
from when he first added the wrap_counter a couple of years ago?
sln
Thanks,
Stefano
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