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vhost: avoid to start/stop virtqueue which is not ready 

In our Armv8a server, we try to configure the vhost scsi but fail
to boot up the guest (-machine virt-2.10). The guest's boot failure
is very early, even earlier than grub.

There are 3 virtqueues (ctrl, event and cmd) for virtio scsi device,
but ovmf and seabios will only set the physical address for the 3rd
one (cmd). Then in vhost_virtqueue_start(), virtio_queue_get_desc_addr
will be 0 for ctrl and event vq when qemu negotiates with ovmf. So
vhost_memory_map fails with ENOMEM.

This patch just fixs it by early quitting the virtqueue start/stop
when virtio_queue_get_desc_addr is 0.

Btw, after guest kernel starts, all the 3 queues will be initialized
and set address correctly.

Already tested on Arm64 and X86_64 qemu.

Signed-off-by: Jia He <jia.he@hxt-semitech.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Jia He 2018-02-28 01:35:28 -08:00 committed by Michael S. Tsirkin
parent 9e2a2a3e08
commit fb20fbb764
1 changed files with 17 additions and 1 deletions
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18
hw/virtio/vhost.c
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@ -345,6 +345,10 @@ static int vhost_verify_ring_mappings(struct vhost_dev *dev,
for (i = 0; i < dev->nvqs; ++i) {
struct vhost_virtqueue *vq = dev->vqs + i;
if (vq->desc_phys == 0) {
continue;
}
j = 0;
r = vhost_verify_ring_part_mapping(
vq->desc, vq->desc_phys, vq->desc_size,
@ -881,6 +885,11 @@ static int vhost_virtqueue_start(struct vhost_dev *dev,
};
struct VirtQueue *vvq = virtio_get_queue(vdev, idx);
a = virtio_queue_get_desc_addr(vdev, idx);
if (a == 0) {
/* Queue might not be ready for start */
return 0;
}
vq->num = state.num = virtio_queue_get_num(vdev, idx);
r = dev->vhost_ops->vhost_set_vring_num(dev, &state);
@ -906,7 +915,7 @@ static int vhost_virtqueue_start(struct vhost_dev *dev,
}
vq->desc_size = s = l = virtio_queue_get_desc_size(vdev, idx);
vq->desc_phys = a = virtio_queue_get_desc_addr(vdev, idx);
vq->desc_phys = a;
vq->desc = vhost_memory_map(dev, a, &l, 0);
if (!vq->desc || l != s) {
r = -ENOMEM;
@ -989,6 +998,13 @@ static void vhost_virtqueue_stop(struct vhost_dev *dev,
.index = vhost_vq_index,
};
int r;
int a;
a = virtio_queue_get_desc_addr(vdev, idx);
if (a == 0) {
/* Don't stop the virtqueue which might have not been started */
return;
}
r = dev->vhost_ops->vhost_get_vring_base(dev, &state);
if (r < 0) {