From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [PATCH] KVM: VMX: blocked-by-sti must not defer NMI injections Date: Tue, 11 May 2010 16:46:36 +0300 Message-ID: <20100511134636.GO2504@redhat.com> References: <4BE958BE.9020503@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , Marcelo Tosatti , kvm To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:47357 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757736Ab0EKNqm (ORCPT ); Tue, 11 May 2010 09:46:42 -0400 Content-Disposition: inline In-Reply-To: <4BE958BE.9020503@siemens.com> Sender: kvm-owner@vger.kernel.org List-ID: On Tue, May 11, 2010 at 03:16:46PM +0200, Jan Kiszka wrote: > As the processor may not consider GUEST_INTR_STATE_STI as a reason for > blocking NMI, it could return immediately with EXIT_REASON_NMI_WINDOW > when we asked for it. But as we consider this state as NMI-blocking, we > can run into an endless loop. > > Resolve this by allowing NMI injection if just GUEST_INTR_STATE_STI is > active (originally suggested by Gleb). Intel confirmed that this is > safe, the processor will never complain about NMI injection in this > state. > > Signed-off-by: Jan Kiszka Acked-by: Gleb Natapov > KVM-Stable-Tag > --- > arch/x86/kvm/vmx.c | 3 +-- > 1 files changed, 1 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 777e00d..fa3959b 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -2824,8 +2824,7 @@ static int vmx_nmi_allowed(struct kvm_vcpu *vcpu) > return 0; > > return !(vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & > - (GUEST_INTR_STATE_STI | GUEST_INTR_STATE_MOV_SS | > - GUEST_INTR_STATE_NMI)); > + (GUEST_INTR_STATE_MOV_SS | GUEST_INTR_STATE_NMI)); > } > > static bool vmx_get_nmi_mask(struct kvm_vcpu *vcpu) -- Gleb.