From mboxrd@z Thu Jan  1 00:00:00 1970
From: Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>
Subject: Re: x86: kvm: Revert "remove sched notifier for cross-cpu migrations"
Date: Wed, 25 Mar 2015 13:52:15 +0100
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Cc: Marcelo Tosatti <mtosatti@redhat.com>,
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	Paolo Bonzini <pbonzini@redhat.com>
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2015-03-25 12:08+0100, Radim Kr=C4=8Dm=C3=A1=C5=99:
> Reverting the patch protects us from any migration, but I don't think=
 we
> need to care about changing VCPUs as long as we read a consistent dat=
a
> from kvmclock.  (VCPU can change outside of this loop too, so it does=
n't
> matter if we return a value not fit for this VCPU.)
>=20
> I think we could drop the second __getcpu if our kvmclock was being
> handled better;  maybe with a patch like the one below:

The second __getcpu is not neccessary, but I forgot about rdtsc.
We need to either use rtdscp, know the host has synchronized tsc, or
monitor VCPU migrations.  Only the last one works everywhere.