[Qemu-devel] virtio block device is not working

[joserz@linux.vnet.ibm.com]

Hello people!

I'm not able to boot any guest that sets a virtio block device like:
(branch master)

[PPC64]
qemu-system-ppc64 -cpu POWER8 -nographic -vga none -m 4G -M pseries,accel=kvm,kvm-type=PR -drive file=disk.qcow2,if=virtio
QEMU Starting
 Build Date = Dec 18 2017 13:08:00
 FW Version = git-fa981320a1e0968d
 Press "s" to enter Open Firmware.

Populating /vdevice methods
Populating /vdevice/vty@71000000
Populating /vdevice/nvram@71000001
Populating /vdevice/v-scsi@71000002
       SCSI: Looking for devices
          8200000000000000 CD-ROM   : "QEMU     QEMU CD-ROM      2.5+"
Populating /pci@800000020000000
                     00 0000 (D) : 1af4 1000    virtio [ net ]
Aborted

[x86]

qemu-system-x86_64 -m 4G -enable-kvm -drive file=util.qcow2,if=virtio
Running QEMU with GTK 2.x is deprecated, and will be removed
in a future release. Please switch to GTK 3.x instead
[1]    5282 abort

[Cause]

The commit 4fe6d78b2e introduces the

...
kvm_mem_ioeventfd_del(...) {
    ...
    r = kvm_set_ioeventfd_mmio(fd, ...
    if (r < 0) {
        abort();
    }

+    if (e->cleanup) {
+        e->cleanup(e);
+    }
}

For some reason, not yet clear to me, cleanup() calls the same
kvm_mem_ioeventfd_del again and again until kvm_set_ioeventfd_mmio
returns < 0 and abort().

I was going to send a patch to revert that 'if ()' but I think it could
cause a regression. What do you guys think?

Thanks,

Jose Ricardo Ziviani