Commit 37ef70be authored by Wolfgang Bumiller's avatar Wolfgang Bumiller Committed by Michael S. Tsirkin
Browse files

virtio: fix descriptor counting in virtqueue_pop 



While changing the s/g list allocation, commit 3b3b0628
also changed the descriptor counting to count iovec entries
as split by cpu_physical_memory_map(). Previously only the
actual descriptor entries were counted and the split into
the iovec happened afterwards in virtqueue_map().
Count the entries again instead to avoid erroneous
"Looped descriptor" errors.

Reported-by: default avatarHans Middelhoek <h.middelhoek@ospito.nl>
Link: https://forum.proxmox.com/threads/vm-crash-with-memory-hotplug.35904/


Fixes: 3b3b0628 ("virtio: slim down allocation of VirtQueueElements")
Signed-off-by: default avatarWolfgang Bumiller <w.bumiller@proxmox.com>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 8e36c336

hw/virtio/virtio.c

+3 −3
Original line number Diff line number Diff line
@@ -834,7 +834,7 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz) 
    int64_t len;

    VirtIODevice *vdev = vq->vdev;

    VirtQueueElement *elem = NULL;

    unsigned out_num, in_num;

    unsigned out_num, in_num, elem_entries;

    hwaddr addr[VIRTQUEUE_MAX_SIZE];

    struct iovec iov[VIRTQUEUE_MAX_SIZE];

    VRingDesc desc;
@@ -852,7 +852,7 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz) 
    smp_rmb();



    /* When we start there are none of either input nor output. */

    out_num = in_num = 0;

    out_num = in_num = elem_entries = 0;



    max = vq->vring.num;
@@ -922,7 +922,7 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz) 
        }



        /* If we've got too many, that implies a descriptor loop. */

        if ((in_num + out_num) > max) {

        if (++elem_entries > max) {

            virtio_error(vdev, "Looped descriptor");

            goto err_undo_map;

        }