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vhost: Decouple vhost_svq_add from VirtQueueElement

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VirtQueueElement comes from the guest, but we're heading SVQ to be able
to modify the element presented to the device without the guest's
knowledge.

To do so, make SVQ accept sg buffers directly, instead of using
VirtQueueElement.

Add vhost_svq_add_element to maintain element convenience.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
This commit is contained in:
Eugenio Pérez 2022-07-20 08:59:33 +02:00 committed by Jason Wang
parent f20b70eb5a
commit 1f46ae65d8
1 changed files with 22 additions and 11 deletions
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33
hw/virtio/vhost-shadow-virtqueue.c
View File

@ -172,30 +172,31 @@ static bool vhost_svq_vring_write_descs(VhostShadowVirtqueue *svq, hwaddr *sg,
}
static bool vhost_svq_add_split(VhostShadowVirtqueue *svq,
VirtQueueElement *elem, unsigned *head)
const struct iovec *out_sg, size_t out_num,
const struct iovec *in_sg, size_t in_num,
unsigned *head)
{
unsigned avail_idx;
vring_avail_t *avail = svq->vring.avail;
bool ok;
g_autofree hwaddr *sgs = g_new(hwaddr, MAX(elem->out_num, elem->in_num));
g_autofree hwaddr *sgs = g_new(hwaddr, MAX(out_num, in_num));
*head = svq->free_head;
/* We need some descriptors here */
if (unlikely(!elem->out_num && !elem->in_num)) {
if (unlikely(!out_num && !in_num)) {
qemu_log_mask(LOG_GUEST_ERROR,
"Guest provided element with no descriptors");
return false;
}
ok = vhost_svq_vring_write_descs(svq, sgs, elem->out_sg, elem->out_num,
elem->in_num > 0, false);
ok = vhost_svq_vring_write_descs(svq, sgs, out_sg, out_num, in_num > 0,
false);
if (unlikely(!ok)) {
return false;
}
ok = vhost_svq_vring_write_descs(svq, sgs, elem->in_sg, elem->in_num, false,
true);
ok = vhost_svq_vring_write_descs(svq, sgs, in_sg, in_num, false, true);
if (unlikely(!ok)) {
return false;
}
@ -237,17 +238,19 @@ static void vhost_svq_kick(VhostShadowVirtqueue *svq)
*
* Return -EINVAL if element is invalid, -ENOSPC if dev queue is full
*/
static int vhost_svq_add(VhostShadowVirtqueue *svq, VirtQueueElement *elem)
static int vhost_svq_add(VhostShadowVirtqueue *svq, const struct iovec *out_sg,
size_t out_num, const struct iovec *in_sg,
size_t in_num, VirtQueueElement *elem)
{
unsigned qemu_head;
unsigned ndescs = elem->in_num + elem->out_num;
unsigned ndescs = in_num + out_num;
bool ok;
if (unlikely(ndescs > vhost_svq_available_slots(svq))) {
return -ENOSPC;
}
ok = vhost_svq_add_split(svq, elem, &qemu_head);
ok = vhost_svq_add_split(svq, out_sg, out_num, in_sg, in_num, &qemu_head);
if (unlikely(!ok)) {
g_free(elem);
return -EINVAL;
@ -258,6 +261,14 @@ static int vhost_svq_add(VhostShadowVirtqueue *svq, VirtQueueElement *elem)
return 0;
}
/* Convenience wrapper to add a guest's element to SVQ */
static int vhost_svq_add_element(VhostShadowVirtqueue *svq,
VirtQueueElement *elem)
{
return vhost_svq_add(svq, elem->out_sg, elem->out_num, elem->in_sg,
elem->in_num, elem);
}
/**
* Forward available buffers.
*
@ -294,7 +305,7 @@ static void vhost_handle_guest_kick(VhostShadowVirtqueue *svq)
break;
}
r = vhost_svq_add(svq, elem);
r = vhost_svq_add_element(svq, elem);
if (unlikely(r != 0)) {
if (r == -ENOSPC) {
/*