Hello, On 02/23/2017 01:32 AM, Alex Williamson wrote: > On Wed, 22 Feb 2017 10:03:56 +0100 > Paolo Bonzini <pbonz...@redhat.com> wrote: > >> On 21/02/2017 18:54, Laszlo Ersek wrote: >>> Actually, QEMU segfaults. From the dmesg: >>> >>> [Tue Feb 21 18:47:28 2017] CPU 0/KVM[8298]: segfault at 48 ip >>> 00007fcb5dd02105 sp 00007fcb49efc270 error 4 in >>> qemu-system-x86_64[7fcb5dae3000+905000] >>> >>> Complete backtrace below. (Thread 11 seems to be the one >>> segfaulting.) >> >> Indeed. It's the virtio-blk device that is segfaulting, please try >> this one liner (haven't reproduced it, but it seems obvious with the >> backtrace and some sleep). > > I hit this as well, the patch below resolves it.
I still have migration issues with this patch on ppc, which fails on the target guest with : qemu-system-ppc64: VQ 0 size 0x80 < last_avail_idx 0xe1e - used_idx 0x0 qemu-system-ppc64: Failed to load virtio-blk:virtio qemu-system-ppc64: error while loading state for instance 0x0 of device 'pci@800000020000000:01.0/virtio-blk' qemu-system-ppc64: load of migration failed: Operation not permitted Thanks, C. > Tested-by: Alex Williamson <alex.william...@redhat.com> > >> commit c1aa478c7181c543606ca81404c59e126d66213d >> Author: Paolo Bonzini <pbonz...@redhat.com> >> Date: Wed Feb 22 10:02:37 2017 +0100 >> >> virtio: check for vring setup in virtio_queue_empty >> >> If the vring has not been set up, there is nothing in the virtqueue. >> virtio_queue_host_notifier_aio_poll calls virtio_queue_empty even in >> this case; we have to filter it out just like virtio_queue_notify_aio_vq. >> >> Reported-by: Gerd Hoffmann <kra...@redhat.com> >> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> >> >> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c >> index 23483c7..e487e36 100644 >> --- a/hw/virtio/virtio.c >> +++ b/hw/virtio/virtio.c >> @@ -2291,7 +2291,7 @@ static bool virtio_queue_host_notifier_aio_poll(void >> *opaque) >> VirtQueue *vq = container_of(n, VirtQueue, host_notifier); >> bool progress; >> >> - if (virtio_queue_empty(vq)) { >> + if (!vq->vring.desc || virtio_queue_empty(vq)) { >> return false; >> } >> >> > >