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dataplane: simplify indirect descriptor read 

Use address_space_read to make sure we handle the case of an indirect
descriptor crossing DIMM boundary correctly.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Tested-by: Igor Mammedov <imammedo@redhat.com>
Message-id: 1446047243-3221-1-git-send-email-mst@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2015-10-28 17:48:02 +02:00 committed by Stefan Hajnoczi
parent c4a7bf54e5
commit 572ec519ed
1 changed files with 18 additions and 10 deletions
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28
hw/virtio/dataplane/vring.c
View File

@ -257,6 +257,21 @@ static void copy_in_vring_desc(VirtIODevice *vdev,
host->next = virtio_lduw_p(vdev, &guest->next);
}
static bool read_vring_desc(VirtIODevice *vdev,
hwaddr guest,
struct vring_desc *host)
{
if (address_space_read(&address_space_memory, guest, MEMTXATTRS_UNSPECIFIED,
(uint8_t *)host, sizeof *host)) {
return false;
}
host->addr = virtio_tswap64(vdev, host->addr);
host->len = virtio_tswap32(vdev, host->len);
host->flags = virtio_tswap16(vdev, host->flags);
host->next = virtio_tswap16(vdev, host->next);
return true;
}
/* This is stolen from linux/drivers/vhost/vhost.c. */
static int get_indirect(VirtIODevice *vdev, Vring *vring,
VirtQueueElement *elem, struct vring_desc *indirect)
@ -284,23 +299,16 @@ static int get_indirect(VirtIODevice *vdev, Vring *vring,
}
do {
struct vring_desc *desc_ptr;
MemoryRegion *mr;
/* Translate indirect descriptor */
desc_ptr = vring_map(&mr,
indirect->addr + found * sizeof(desc),
sizeof(desc), false);
if (!desc_ptr) {
error_report("Failed to map indirect descriptor "
if (!read_vring_desc(vdev, indirect->addr + found * sizeof(desc),
&desc)) {
error_report("Failed to read indirect descriptor "
"addr %#" PRIx64 " len %zu",
(uint64_t)indirect->addr + found * sizeof(desc),
sizeof(desc));
vring->broken = true;
return -EFAULT;
}
copy_in_vring_desc(vdev, desc_ptr, &desc);
memory_region_unref(mr);
/* Ensure descriptor has been loaded before accessing fields */
barrier(); /* read_barrier_depends(); */