[Natty SRU] KVM: fix kvmclock regression due to missing clock update

Stefan Bader stefan.bader at canonical.com
Wed Aug 10 20:02:04 UTC 2011

SRU Justification:

Impact: An upstream change in the kvm code in 2.6.37 causes regressions
running 32bit guest under 11.04 (Natty) KVM.

Fix: Cherry-picking a single upstream patch (which went into 2.6.39)
fixes the issue.

Testcase: Booting 32bit rhel and centos 5.(5|6) guests under Natty used
to hang, but has been verified to succeed with a test kernel including
the upstream patch.

Note: Submission to upstream stable is not considered as there are no
longterm kernels between 2.6.37 and 2.6.39 which are supported.


>From 626a3425d512ad12effebf90ba6aa0c4c4052118 Mon Sep 17 00:00:00 2001
From: Nikola Ciprich <extmaillist at linuxbox.cz>
Date: Wed, 9 Mar 2011 23:36:51 +0100
Subject: [PATCH] KVM: fix kvmclock regression due to missing clock update

commit 387b9f97750444728962b236987fbe8ee8cc4f8c moved kvm_request_guest_time_update(vcpu),
breaking 32bit SMP guests using kvm-clock. Fix this by moving (new) clock update function
to proper place.

Signed-off-by: Nikola Ciprich <nikola.ciprich at linuxbox.cz>
Acked-by: Zachary Amsden <zamsden at redhat.com>
Signed-off-by: Avi Kivity <avi at redhat.com>

BugLink: http://bugs.launchpad.net/bugs/795717

(cherry-picked from commit 1aa8ceef0312a6aae7dd863a120a55f1637b361d upstream)
Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
 arch/x86/kvm/x86.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 980317a..0556e05 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2100,8 +2100,8 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 		if (check_tsc_unstable()) {
 			kvm_x86_ops->adjust_tsc_offset(vcpu, -tsc_delta);
 			vcpu->arch.tsc_catchup = 1;
-			kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
+		kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
 		if (vcpu->cpu != cpu)
 		vcpu->cpu = cpu;

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