[libvirt] [PATCH] send default USB controller in xml to destination during migration on PPC64

[Shivaprasad G Bhat]

The default USB controller is not sent to destination as the older versions
of libvirt(0.9.4 or earlier as I see in commit log of 409b5f54) didn't
support them. For some archs where the support started much later can
safely send the USB controllers without this worry. For now, changing the
checks to allow PPC64 here. If we can track the historical support for
other archs, the changes can be extrapolated to them too.

The patch fixes a bug that, if the USB controller happens to occupy
a slot after disks/interfaces and one of them is hot-unplugged, then
the default USB controller added on destination takes the smallest slot
number and that would lead to savestate mismatch and migration
failure.

Signed-off-by: Shivaprasad G Bhat <sbhat at linux.vnet.ibm.com>
---
 src/qemu/qemu_domain.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 9044792..6ecc0e2 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -2226,7 +2226,7 @@ qemuDomainDefFormatBuf(virQEMUDriverPtr driver,
                 usb = def->controllers[i];
             }
         }
-        if (usb && usb->idx == 0 && usb->model == -1) {
+        if (!ARCH_IS_PPC64(def->os.arch) && usb && usb->idx == 0 && usb->model == -1) {
             VIR_DEBUG("Removing default USB controller from domain '%s'"
                       " for migration compatibility", def->name);
             toremove++;