From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756771AbcAUDeq (ORCPT ); Wed, 20 Jan 2016 22:34:46 -0500 Received: from mail-pf0-f195.google.com ([209.85.192.195]:33812 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752651AbcAUDem (ORCPT ); Wed, 20 Jan 2016 22:34:42 -0500 Subject: Re: [PATCH v3 1/4] KVM: Recover IRTE to remapped mode if the interrupt is not single-destination To: "Wu, Feng" , "pbonzini@redhat.com" , "rkrcmar@redhat.com" References: <1453254177-103002-1-git-send-email-feng.wu@intel.com> <1453254177-103002-2-git-send-email-feng.wu@intel.com> <56A04B0A.2020505@gmail.com> Cc: "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" From: Yang Zhang Message-ID: <56A051C7.4030004@gmail.com> Date: Thu, 21 Jan 2016 11:34:31 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2016/1/21 11:14, Wu, Feng wrote: > > >> -----Original Message----- >> From: Yang Zhang [mailto:yang.zhang.wz@gmail.com] >> Sent: Thursday, January 21, 2016 11:06 AM >> To: Wu, Feng ; pbonzini@redhat.com; >> rkrcmar@redhat.com >> Cc: linux-kernel@vger.kernel.org; kvm@vger.kernel.org >> Subject: Re: [PATCH v3 1/4] KVM: Recover IRTE to remapped mode if the >> interrupt is not single-destination >> >> On 2016/1/20 9:42, Feng Wu wrote: >>> When the interrupt is not single destination any more, we need >>> to change back IRTE to remapped mode explicitly. >>> >>> Signed-off-by: Feng Wu >>> --- >>> arch/x86/kvm/vmx.c | 11 ++++++++++- >>> 1 file changed, 10 insertions(+), 1 deletion(-) >>> >>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >>> index e2951b6..13d14d4 100644 >>> --- a/arch/x86/kvm/vmx.c >>> +++ b/arch/x86/kvm/vmx.c >>> @@ -10764,8 +10764,17 @@ static int vmx_update_pi_irte(struct kvm >> *kvm, unsigned int host_irq, >>> */ >>> >>> kvm_set_msi_irq(e, &irq); >>> - if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu)) >>> + if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu)) { >>> + /* >>> + * Make sure the IRTE is in remapped mode if >>> + * we don't handle it in posted mode. >>> + */ >>> + pi_set_sn(vcpu_to_pi_desc(vcpu)); >>> + ret = irq_set_vcpu_affinity(host_irq, NULL); >>> + pi_clear_sn(vcpu_to_pi_desc(vcpu)); >>> + >>> continue; >>> + } >>> >>> vcpu_info.pi_desc_addr = __pa(vcpu_to_pi_desc(vcpu)); >>> vcpu_info.vector = irq.vector; >>> >> >> I am still feel weird with this change: according the semantic of VT-d >> posted interrupt, the interrupt will injected to guest through posted >> notification and /proc/interrupts shows the same meaning. But now, >> without being aware of user, the interrupt changes to legacy way and it >> appears on different entry on /proc/interrupts. It looks weird. > > I don't think it has problem here, IMO, this is exactly how it works. > There should be different entry for the interrupts in VT-d PI mode > and leagcy mode. I am not saying any problem here. Just feel weird. From a normal user's point, he has turned on the VT-d pi and according the semantic of VT-d pi, he should not observe the interrupt through legacy mode, but now he do see it. Maybe print out a message here will be helpful, like what you did for disabled lapic found during irq injection. > > For VT-d PI mode, it is delivered by notification event, for legacy mode, > it is delivered by VFIO. > > Thanks, > Feng > >> >> Any comments? Paolo. >> >> -- >> best regards >> yang -- best regards yang