Re: [PATCH v2 06/10] KVM: x86: acknowledgment mechanism for async pf page ready notifications

[Paolo Bonzini]

On 28/05/20 13:39, Vitaly Kuznetsov wrote:
>> How is the pageready_pending flag migrated?  Should we revert the
>> direction of the MSR (i.e. read the flag, and write 0 to clear it)?
> The flag is not migrated so it will be 'false'. This can just cause an
> extra kick in kvm_arch_async_page_present_queued() but this shouldn't be
> a big deal. Also, after migration we will just send 'wakeup all' event,
> async pf queue will be empty.

Ah, that's kvm_pv_enable_async_pf, where the destination writes to
MSR_KVM_ASYNC_PF.  Cool.

> MSR_KVM_ASYNC_PF_ACK by itself is not
> migrated, we don't even store it, not sure how invering it would change
> things.

Yes, it would only be useful to invert it if it needs to be stored and
migrated.

Thanks,

Paolo