On 09/06/2016 09:16, Haozhong Zhang wrote: > On 06/08/16 13:36, Paolo Bonzini wrote: >> >> >> On 03/06/2016 08:09, Haozhong Zhang wrote: >>> LMCE is disabled by default, but a cpu option 'lmce=on/off' is provided >>> to enable/disable it. Migration is only allowed between VCPUs with the >>> same lmce option. >> >> This is not needed at all if you do the change in patch 1 that Eduardo >> requested (refuse to start if the host doesn't have the required >> capabilities). >> >> So if you do that you can just move the lmce property to patch 1. >> > > But it doesn't cover the migration from lmce-enabled qemu to > lmce-disabled qemu where KVM on both hosts support LMCE.
That's a configuration problem; configuration is not migrated and is assumed to be the same on the source and the destination. You don't need to test for this scenario. Paolo In that case, > both qemu can start without failure, but the guest OS will run in a VM > with different configurations after migration. To avoid this, I didn't > leave the lmce property in patch 1, so that users have no way to > enable LMCE without this patch 2.
