From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH 2/2] x86: kvm: do not advertise stable clocksource if CPU has TSC drift BUG Date: Thu, 31 Jul 2014 16:38:49 +0200 Message-ID: <53DA54F9.8090605@redhat.com> References: <1406800033-13404-1-git-send-email-imammedo@redhat.com> <1406800033-13404-3-git-send-email-imammedo@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: x86@kernel.org, hpa@zytor.com, mingo@redhat.com, tglx@linutronix.de, kvm@vger.kernel.org, mtosatti@redhat.com To: Igor Mammedov , linux-kernel@vger.kernel.org Return-path: In-Reply-To: <1406800033-13404-3-git-send-email-imammedo@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Il 31/07/2014 11:47, Igor Mammedov ha scritto: > Signed-off-by: Igor Mammedov > --- > arch/x86/kvm/cpuid.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 38a0afe..f519823 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -478,8 +478,9 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, > (1 << KVM_FEATURE_CLOCKSOURCE2) | > (1 << KVM_FEATURE_ASYNC_PF) | > (1 << KVM_FEATURE_PV_EOI) | > - (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) | > (1 << KVM_FEATURE_PV_UNHALT); > + if (!static_cpu_has_bug(X86_BUG_AMD_TSC_DRIFT)) > + entry->eax |= (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT); > > if (sched_info_on()) > entry->eax |= (1 << KVM_FEATURE_STEAL_TIME); > Marcelo, is there anything we can do if the VM migrates from a sane host to a buggy one? Paolo