linux-kernel - [PATCH 06/18] Warn about unstable TSC

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Date:	Mon, 12 Jul 2010 16:08:00 -1000
From:	Zachary Amsden <zamsden@...hat.com>
To:	KVM <kvm@...r.kernel.org>, Avi Kivity <avi@...hat.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Glauber Costa <glommer@...hat.com>
Cc:	Linux-kernel <linux-kernel@...r.kernel.org>,
	Zachary Amsden <zamsden@...hat.com>
Subject: [PATCH 06/18] Warn about unstable TSC

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

Signed-off-by: Zachary Amsden <zamsden@...hat.com>
---
 arch/x86/kvm/x86.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 273dd7d..045b2d6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5458,6 +5458,10 @@ 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() && id != 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);
 }
 
-- 
1.7.1

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