From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752302AbbGaIBn (ORCPT ); Fri, 31 Jul 2015 04:01:43 -0400 Received: from mail-wi0-f171.google.com ([209.85.212.171]:38370 "EHLO mail-wi0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750724AbbGaIBl (ORCPT ); Fri, 31 Jul 2015 04:01:41 -0400 Subject: Re: [PATCH 1/2] KVM: x86: set TMR when the interrupt is accepted To: "Zhang, Yang Z" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" References: <1438177055-26764-1-git-send-email-pbonzini@redhat.com> <1438177055-26764-2-git-send-email-pbonzini@redhat.com> Cc: "alex.williamson@redhat.com" , "srutherford@intel.com" From: Paolo Bonzini Message-ID: <55BB2B62.1030605@redhat.com> Date: Fri, 31 Jul 2015 10:01:38 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 31/07/2015 01:26, Zhang, Yang Z wrote: >>> Do not compute TMR in advance. Instead, set the TMR just before >>> the interrupt is accepted into the IRR. This limits the coupling >>> between IOAPIC and LAPIC. > > Uh.., it back to original way which is wrong. You cannot modify the > apic page(here is the TMR reg) directly when the corresponding VMCS > may be used at same time. Where is this documented? The TMR is not part of the set of virtualized APIC registers (TPR, PPR, EOI, ISR, IRR, ICR+ICR2; SDM 29.1.1). Only virtualized APIC register reads use the virtual TMR registers (SDM 29.4.2 or 29.5), but these just read data from the corresponding field in the virtual APIC page. Paolo