Re: [PATCH v5 4/7] kvm, mem-hotplug: Reload L1' apic access page on migration in vcpu_enter_guest().

Paolo Bonzini
2014-09-11T13:05:26Z

Il 11/09/2014 13:30, Gleb Natapov ha scritto:
>> > + vmcs_write64(APIC_ACCESS_ADDR, page_to_phys(page));
>> > + /*
>> > + * Do not pin apic access page in memory so that memory
>> > + * hotplug process is able to migrate it.
>> > + */
>> > + put_page(page);
>> > }
> This code is in prepare_vmcs02() and is executed during L1->L2 vmentry. What happens
> when apic access page is migrated while L2 is running? It needs to be update somewhere.

Before it is migrated, the MMU notifier is called and will force a
vmexit on all CPUs. The reload code will call GUP again on the page
again and swap it in.

Paolo