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 @@
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);
}