linux-kernel - Re: patch kvm-svm-fix-tsc-offset-adjustment-when-running-nested.patch added to 2.6.31-stable tree

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Date:	Mon, 12 Oct 2009 11:41:51 +0200
From:	Joerg Roedel <joerg.roedel@....com>
To:	Stefan Lippers-Hollmann <s.L-H@....de>
CC:	gregkh@...e.de, linux-kernel@...r.kernel.org, mtosatti@...hat.com,
	stable@...nel.org
Subject: Re: patch
 kvm-svm-fix-tsc-offset-adjustment-when-running-nested.patch added to
 2.6.31-stable tree

All the nested stuff was moved into its own sub-struct in 2.6.32. Here
is a version that works with 2.6.31.3:

>From 4505a73070f341674e0d22a8c9ee51b2beeb843e Mon Sep 17 00:00:00 2001
From: Joerg Roedel <joerg.roedel@....com>
Date: Mon, 12 Oct 2009 11:19:07 +0200
Subject: [PATCH 1/2] KVM: SVM: Fix tsc offset adjustment when running nested

When svm_vcpu_load is called while the vcpu is running in
guest mode the tsc adjustment made there is lost on the next
emulated #vmexit. This causes the tsc running backwards in
the guest. This patch fixes the issue by also adjusting the
tsc_offset in the emulated hsave area so that it will not
get lost.

Signed-off-by: Joerg Roedel <joerg.roedel@....com>
---
 arch/x86/kvm/svm.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index b1f658a..aafd8bf 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -709,6 +709,8 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 		rdtscll(tsc_this);
 		delta = vcpu->arch.host_tsc - tsc_this;
 		svm->vmcb->control.tsc_offset += delta;
+		if (is_nested(svm))
+			svm->hsave->control.tsc_offset += delta;
 		vcpu->cpu = cpu;
 		kvm_migrate_timers(vcpu);
 		svm->asid_generation = 0;
-- 
1.6.4.3


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