linux-kernel - Re: [PATCH] x86: vdso: fix pvclock races with task migration

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Message-ID: <5523BB51.8090703@redhat.com>
Date:	Tue, 07 Apr 2015 13:11:13 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Radim Krčmář <rkrcmar@...hat.com>,
	linux-kernel@...r.kernel.org
CC:	kvm@...r.kernel.org, Marcelo Tosatti <mtosatti@...hat.com>,
	Andy Lutomirski <luto@...capital.net>, stable@...r.kernel.org
Subject: Re: [PATCH] x86: vdso: fix pvclock races with task migration



On 02/04/2015 20:44, Radim Krčmář wrote:
> If we were migrated right after __getcpu, but before reading the
> migration_count, we wouldn't notice that we read TSC of a different
> VCPU, nor that KVM's bug made pvti invalid, as only migration_count
> on source VCPU is increased.
> 
> Change vdso instead of updating migration_count on destination.
> 
> Fixes: 0a4e6be9ca17 ("x86: kvm: Revert "remove sched notifier for cross-cpu migrations"")
> Cc: stable@...r.kernel.org
> Signed-off-by: Radim Krčmář <rkrcmar@...hat.com>

Applying this, but removing the "Fixes" tag because a guest patch cannot
fix a host patch (it can work around it or complement it).

Paolo
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