From 53bf06f4d8930eef616f26c2d744b9a10518d1b7 Mon Sep 17 00:00:00 2001
From: Glauber Costa <glommer@redhat.com>
Date: Thu, 29 Jan 2009 12:39:22 -0500
Subject: [PATCH 9/9] Disable kvmclock for non constant tsc cpus.

Currently, this code path is posing us big troubles,
and we won't have a decent patch in time. So, temporarily
disable it.

See:

  https://bugzilla.redhat.com/475598

There's a module parameter for the adventurous who want to force
it.

Signed-off-by: Glauber Costa <glommer@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
---
 arch/x86/kvm/x86.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fc198e8..7b796a5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -957,6 +957,9 @@ out:
 	return r;
 }
 
+static int force_kvmclock = 0;
+module_param(force_kvmclock, bool, 0644);
+
 int kvm_dev_ioctl_check_extension(long ext)
 {
 	int r;
@@ -967,7 +970,6 @@ int kvm_dev_ioctl_check_extension(long ext)
 	case KVM_CAP_MMU_SHADOW_CACHE_CONTROL:
 	case KVM_CAP_SET_TSS_ADDR:
 	case KVM_CAP_EXT_CPUID:
-	case KVM_CAP_CLOCKSOURCE:
 	case KVM_CAP_PIT:
 	case KVM_CAP_NOP_IO_DELAY:
 	case KVM_CAP_MP_STATE:
@@ -992,6 +994,9 @@ int kvm_dev_ioctl_check_extension(long ext)
 	case KVM_CAP_IOMMU:
 		r = iommu_found();
 		break;
+	case KVM_CAP_CLOCKSOURCE:
+		r = force_kvmclock || boot_cpu_has(X86_FEATURE_CONSTANT_TSC);
+		break;
 	default:
 		r = 0;
 		break;
-- 
1.6.1