From: Zachary Amsden <zamsden@redhat.com>
Date: Fri, 20 Aug 2010 08:07:22 +0000 (-1000)
Subject: KVM: x86: Warn about unstable TSC
X-Git-Tag: v3.12-rc1~8394^2~166
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=6755bae8e69093b2994b6f29cd3eaecdf610374e;p=kernel%2Fkernel-generic.git

KVM: x86: Warn about unstable TSC

If creating an SMP guest with unstable host TSC, issue a warning

Signed-off-by: Zachary Amsden <zamsden@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
---

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 699c6b8..a8dee58 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5457,6 +5457,10 @@ void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu)
 struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm,
 						unsigned int id)
 {
+	if (check_tsc_unstable() && atomic_read(&kvm->online_vcpus) != 0)
+		printk_once(KERN_WARNING
+		"kvm: SMP vm created on host with unstable TSC; "
+		"guest TSC will not be reliable\n");
 	return kvm_x86_ops->vcpu_create(kvm, id);
 }