From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH] KVM: x86: always exit on EOIs for interrupts listed in the IOAPIC redir table Date: Thu, 07 Aug 2014 08:13:24 +0200 Message-ID: <53E31904.9040909@redhat.com> References: <1406736728-8516-1-git-send-email-pbonzini@redhat.com> <53E236E6.6050206@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "alex.williamson@redhat.com" , "kvm@vger.kernel.org" , "stable@vger.kernel.org" To: "Zhang, Yang Z" , "linux-kernel@vger.kernel.org" Return-path: In-Reply-To: Sender: stable-owner@vger.kernel.org List-Id: kvm.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