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vring: create a common function to parse descriptors

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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Paolo Bonzini 2013-12-10 13:26:58 +01:00 committed by Stefan Hajnoczi
parent e50d7607f1
commit 4d684832e5
1 changed files with 51 additions and 62 deletions
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113
hw/virtio/dataplane/vring.c
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@ -110,6 +110,47 @@ bool vring_should_notify(VirtIODevice *vdev, Vring *vring)
return vring_need_event(vring_used_event(&vring->vr), new, old);
}
static int get_desc(Vring *vring,
struct iovec iov[], struct iovec *iov_end,
unsigned int *out_num, unsigned int *in_num,
struct vring_desc *desc)
{
unsigned *num;
if (desc->flags & VRING_DESC_F_WRITE) {
num = in_num;
} else {
num = out_num;
/* If it's an output descriptor, they're all supposed
* to come before any input descriptors. */
if (unlikely(*in_num)) {
error_report("Descriptor has out after in");
return -EFAULT;
}
}
/* Stop for now if there are not enough iovecs available. */
iov += *in_num + *out_num;
if (iov >= iov_end) {
return -ENOBUFS;
}
/* TODO handle non-contiguous memory across region boundaries */
iov->iov_base = hostmem_lookup(&vring->hostmem, desc->addr, desc->len,
desc->flags & VRING_DESC_F_WRITE);
if (!iov->iov_base) {
error_report("Failed to map descriptor addr %#" PRIx64 " len %u",
(uint64_t)desc->addr, desc->len);
return -EFAULT;
}
iov->iov_len = desc->len;
*num += 1;
return 0;
}
/* This is stolen from linux/drivers/vhost/vhost.c. */
static int get_indirect(Vring *vring,
struct iovec iov[], struct iovec *iov_end,
@ -118,6 +159,7 @@ static int get_indirect(Vring *vring,
{
struct vring_desc desc;
unsigned int i = 0, count, found = 0;
int ret;
/* Sanity check */
if (unlikely(indirect->len % sizeof(desc))) {
@ -170,36 +212,10 @@ static int get_indirect(Vring *vring,
return -EFAULT;
}
/* Stop for now if there are not enough iovecs available. */
if (iov >= iov_end) {
return -ENOBUFS;
}
iov->iov_base = hostmem_lookup(&vring->hostmem, desc.addr, desc.len,
desc.flags & VRING_DESC_F_WRITE);
if (!iov->iov_base) {
error_report("Failed to map indirect descriptor"
"addr %#" PRIx64 " len %u",
(uint64_t)desc.addr, desc.len);
vring->broken = true;
return -EFAULT;
}
iov->iov_len = desc.len;
iov++;
/* If this is an input descriptor, increment that count. */
if (desc.flags & VRING_DESC_F_WRITE) {
*in_num += 1;
} else {
/* If it's an output descriptor, they're all supposed
* to come before any input descriptors. */
if (unlikely(*in_num)) {
error_report("Indirect descriptor "
"has out after in: idx %u", i);
vring->broken = true;
return -EFAULT;
}
*out_num += 1;
ret = get_desc(vring, iov, iov_end, out_num, in_num, &desc);
if (ret < 0) {
vring->broken |= (ret == -EFAULT);
return ret;
}
i = desc.next;
} while (desc.flags & VRING_DESC_F_NEXT);
@ -224,6 +240,7 @@ int vring_pop(VirtIODevice *vdev, Vring *vring,
struct vring_desc desc;
unsigned int i, head, found = 0, num = vring->vr.num;
uint16_t avail_idx, last_avail_idx;
int ret;
/* If there was a fatal error then refuse operation */
if (vring->broken) {
@ -294,40 +311,12 @@ int vring_pop(VirtIODevice *vdev, Vring *vring,
continue;
}
/* If there are not enough iovecs left, stop for now. The caller
* should check if there are more descs available once they have dealt
* with the current set.
*/
if (iov >= iov_end) {
return -ENOBUFS;
ret = get_desc(vring, iov, iov_end, out_num, in_num, &desc);
if (ret < 0) {
vring->broken |= (ret == -EFAULT);
return ret;
}
/* TODO handle non-contiguous memory across region boundaries */
iov->iov_base = hostmem_lookup(&vring->hostmem, desc.addr, desc.len,
desc.flags & VRING_DESC_F_WRITE);
if (!iov->iov_base) {
error_report("Failed to map vring desc addr %#" PRIx64 " len %u",
(uint64_t)desc.addr, desc.len);
vring->broken = true;
return -EFAULT;
}
iov->iov_len = desc.len;
iov++;
if (desc.flags & VRING_DESC_F_WRITE) {
/* If this is an input descriptor,
* increment that count. */
*in_num += 1;
} else {
/* If it's an output descriptor, they're all supposed
* to come before any input descriptors. */
if (unlikely(*in_num)) {
error_report("Descriptor has out after in: idx %d", i);
vring->broken = true;
return -EFAULT;
}
*out_num += 1;
}
i = desc.next;
} while (desc.flags & VRING_DESC_F_NEXT);