Re: libvirt-6.5.0 breaks host passthrough migration

On Fri, Jul 10, 2020 at 7:14 AM Jiri Denemark <jdenemar(a)redhat.com&gt; wrote: > > + if (qemuCaps && > > + def->cpu->mode == VIR_CPU_MODE_HOST_PASSTHROUGH && > > + !def->cpu->migratable) { > > + if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_CPU_MIGRATABLE)) > > + def->cpu->migratable = VIR_TRISTATE_SWITCH_ON; > > > > *+ else if (ARCH_IS_X86(def->os.arch))+ > > def->cpu->migratable = VIR_TRISTATE_SWITCH_OFF;* > > + } > > The implementation seems to be doing exactly what the commit message > says. The migratable=off default should be used only when QEMU does not > support -cpu host,migratable=on|off, that is only when QEMU is very old. > Every non-ancient version of libvirt should have the > QEMU_CAPS_CPU_MIGRATABLE set and thus this code should choose > migrateble=on default. > I wasn't sure what QEMU_CAPS_CPU_MIGRATABLE represents. I initially suspected what you are saying, but since it apparently did not work the way I expected, I then presumed it does not work the way I expected. :-) Is QEMU_CAPS_CPU_MIGRATABLE only from the <cpu> element? If so, doesn't this mean that it is not explicitly listed for host-passthrough, and this means the check is not detecting whether it is enabled or not properly?