From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932071AbaHGGNc (ORCPT ); Thu, 7 Aug 2014 02:13:32 -0400 Received: from mail-wi0-f181.google.com ([209.85.212.181]:55586 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757371AbaHGGNa (ORCPT ); Thu, 7 Aug 2014 02:13:30 -0400 Message-ID: <53E31904.9040909@redhat.com> Date: Thu, 07 Aug 2014 08:13:24 +0200 From: Paolo Bonzini User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: "Zhang, Yang Z" , "linux-kernel@vger.kernel.org" CC: "alex.williamson@redhat.com" , "kvm@vger.kernel.org" , "stable@vger.kernel.org" Subject: Re: [PATCH] KVM: x86: always exit on EOIs for interrupts listed in the IOAPIC redir table References: <1406736728-8516-1-git-send-email-pbonzini@redhat.com> <53E236E6.6050206@redhat.com> In-Reply-To: X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Il 07/08/2014 03:31, Zhang, Yang Z ha scritto: > Let me give an example to see whether my concern is a real problem: > Guest allocates a vector and set it in IOAPIC entry to deliver > interrupt. Later it masks the IOAPIC entry(means stop the > corresponding device) and assign this vector to a MSI device. With > this patch, even the vector is not used by IOAPIC, but it still set > eoi exit bitmap unconditionally. The subsequent EOIs to MSI device > will force vmexit. Could this happen? Yes, I guess it could. I'm not sure whether it could on Linux or Windows. > I think the right fixing is to check the ISR plus TMR to construct > the eoi exit bitmap. Do you care enough to propose a patch? :) Paolo