@@ -623,20 +623,21 @@ static void *_check_pointer(unsigned long addr, unsigned int size,
/* Each buffer in the virtqueues is actually a chain of descriptors. This
* function returns the next descriptor in the chain, or vq->vring.num if we're
* at the end. */
-static unsigned next_desc(struct virtqueue *vq, unsigned int i)
+static unsigned next_desc(struct vring_desc *desc,
+ unsigned int i, unsigned int max)
{
unsigned int next;
/* If this descriptor says it doesn't chain, we're done. */
- if (!(vq->vring.desc[i].flags & VRING_DESC_F_NEXT))
- return vq->vring.num;
+ if (!(desc[i].flags & VRING_DESC_F_NEXT))
+ return max;
/* Check they're not leading us off end of descriptors. */
- next = vq->vring.desc[i].next;
+ next = desc[i].next;
/* Make sure compiler knows to grab that: we don't want it changing! */
wmb();
- if (next >= vq->vring.num)
+ if (next >= max)
errx(1, "Desc next is %u", next);
return next;
@@ -653,7 +654,8 @@ static unsigned get_vq_desc(struct virtqueue *vq,
struct iovec iov[],
unsigned int *out_num, unsigned int *in_num)
{
- unsigned int i, head;
+ struct vring_desc *desc;
+ unsigned int i, head, max;
u16 last_avail;
/* Check it isn't doing very strange things with descriptor numbers. */
@@ -678,15 +680,28 @@ static unsigned get_vq_desc(struct virtqueue *vq,
/* When we start there are none of either input nor output. */
*out_num = *in_num = 0;
+ max = vq->vring.num;
+ desc = vq->vring.desc;
i = head;
+
+ /* If this is an indirect entry, then this buffer contains a descriptor
+ * table which we handle as if it's any normal descriptor chain. */
+ if (desc[i].flags & VRING_DESC_F_INDIRECT) {
+ if (desc[i].len % sizeof(struct vring_desc))
+ errx(1, "Invalid size for indirect buffer table");
+
+ max = desc[i].len / sizeof(struct vring_desc);
+ desc = check_pointer(desc[i].addr, desc[i].len);
+ i = 0;
+ }
+
do {
/* Grab the first descriptor, and check it's OK. */
- iov[*out_num + *in_num].iov_len = vq->vring.desc[i].len;
+ iov[*out_num + *in_num].iov_len = desc[i].len;
iov[*out_num + *in_num].iov_base
- = check_pointer(vq->vring.desc[i].addr,
- vq->vring.desc[i].len);
+ = check_pointer(desc[i].addr, desc[i].len);
/* If this is an input descriptor, increment that count. */
- if (vq->vring.desc[i].flags & VRING_DESC_F_WRITE)
+ if (desc[i].flags & VRING_DESC_F_WRITE)
(*in_num)++;
else {
/* If it's an output descriptor, they're all supposed
@@ -697,9 +712,9 @@ static unsigned get_vq_desc(struct virtqueue *vq,
}
/* If we've got too many, that implies a descriptor loop. */
- if (*out_num + *in_num > vq->vring.num)
+ if (*out_num + *in_num > max)
errx(1, "Looped descriptor");
- } while ((i = next_desc(vq, i)) != vq->vring.num);
+ } while ((i = next_desc(desc, i, max)) != max);
vq->inflight++;
return head;
@@ -1502,6 +1517,8 @@ static void setup_tun_net(char *arg)
add_feature(dev, VIRTIO_NET_F_HOST_TSO4);
add_feature(dev, VIRTIO_NET_F_HOST_TSO6);
add_feature(dev, VIRTIO_NET_F_HOST_ECN);
+ /* we handle indirect ring entries */
+ add_feature(dev, VIRTIO_RING_F_INDIRECT_DESC);
set_config(dev, sizeof(conf), &conf);
/* We don't need the socket any more; setup is done. */
Support the VIRTIO_RING_F_INDIRECT_DESC feature. This is a simple matter of changing the descriptor walking code to operate on a struct vring_desc* and supplying it with an indirect table if detected. Signed-off-by: Mark McLoughlin <markmc@redhat.com> --- Documentation/lguest/lguest.c | 41 +++++++++++++++++++++++++++++------------ 1 files changed, 29 insertions(+), 12 deletions(-)