Re: [libvirt] [PATCH v2] send default USB controller in xml to destination during migration

On Fri, Apr 29, 2016 at 01:09:26PM -0400, Cole Robinson wrote: > On 04/29/2016 10:01 AM, Shivaprasad G Bhat wrote: >> 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. So, send the controller >> to destination for all archs except x86. Moreover this is not very applicable >> to x86 as the USB controller has model ich9_ehci1 on q35 and for pc-i440fx, >> there cant be any slots before USB as it is fixed on slot 1. >> >> 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. Seen and verified on PPC64. >> >> Signed-off-by: Shivaprasad G Bhat <sbhat(a)linux.vnet.ibm.com&gt; >> --- >> src/qemu/qemu_domain.c | 6 +++++- >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c >> index 6262bfe..963ff35 100644 >> --- a/src/qemu/qemu_domain.c >> +++ b/src/qemu/qemu_domain.c >> @@ -2599,7 +2599,11 @@ qemuDomainDefFormatBuf(virQEMUDriverPtr driver, >> usb = def->controllers[i]; >> } >> } >> - if (usb && usb->idx == 0 && usb->model == -1) { >> + /* The original purpose of the check was the migration compatibility >> + * with libvirt <= 0.9.4. Limitation doesn't apply to other archs >> + * and can cause problems on PPC64. >> + * >> + if (ARCH_IS_X86(def->os.arch) && usb && usb->idx == 0 && usb->model == -1) { As of commit fcbfd50: qemu: only check for PIIX3-specific device addrs on pc-* machinetypes we only check that the controller is on slot 1 for PIIX3 machines, so qemuDomainMachineIsI440FX(def) should also be one of the conditions. It is possible to specify a usb controller with model='-1' on q35 too, but I do not know if anyone actually uses it in the wild.