From mboxrd@z Thu Jan 1 00:00:00 1970 From: Radim =?utf-8?Q?Krcm=C3=A1r?= Subject: Re: [PATCH v3 1/4] KVM: Recover IRTE to remapped mode if the interrupt is not single-destination Date: Fri, 22 Jan 2016 14:05:51 +0100 Message-ID: <20160122130551.GA23362@potion.brq.redhat.com> References: <1453254177-103002-1-git-send-email-feng.wu@intel.com> <1453254177-103002-2-git-send-email-feng.wu@intel.com> <20160121161949.GA14104@potion.brq.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: "pbonzini@redhat.com" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" To: "Wu, Feng" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:60671 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753369AbcAVNFz (ORCPT ); Fri, 22 Jan 2016 08:05:55 -0500 Content-Disposition: inline In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: 2016-01-22 01:49+0000, Wu, Feng: >> From: Radim Kr=C4=8Dm=C3=A1=C5=99 [mailto:rkrcmar@redhat.com] >> 2016-01-20 09:42+0800, Feng Wu: >> > - 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)); >>=20 >> What could go wrong if we didn't suppress notifications here? >=20 > This is a good question. I also thought about this before, but after > thinking it a bit more, seems we don't need to do this.=20 > If we don't do this, the in-flight interrupts will continue to be > delivered in PI mode while we are changing it to remapped > mode in IRTE. Even if we do this, the in-flight interrupts are > also delivered in PI mode before setting 'SN' anyway, so seems > we really don't need this, what is your opinion? I'd remove it.