From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757896AbbAIPSw (ORCPT ); Fri, 9 Jan 2015 10:18:52 -0500 Received: from mx1.redhat.com ([209.132.183.28]:52928 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751702AbbAIPSu (ORCPT ); Fri, 9 Jan 2015 10:18:50 -0500 Message-ID: <54AFF128.1080603@redhat.com> Date: Fri, 09 Jan 2015 16:18:00 +0100 From: Paolo Bonzini User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= CC: Feng Wu , tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, gleb@kernel.org, dwmw2@infradead.org, joro@8bytes.org, alex.williamson@redhat.com, jiang.liu@linux.intel.com, eric.auger@linaro.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, kvm@vger.kernel.org Subject: Re: [v3 13/26] KVM: Define a new interface kvm_find_dest_vcpu() for VT-d PI References: <1418397300-10870-1-git-send-email-feng.wu@intel.com> <1418397300-10870-14-git-send-email-feng.wu@intel.com> <20150109145435.GA22469@potion.brq.redhat.com> <54AFEC00.80507@redhat.com> <20150109151258.GC9877@potion.brq.redhat.com> In-Reply-To: <20150109151258.GC9877@potion.brq.redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/01/2015 16:12, Radim Krčmář wrote: > > The chipset doesn't support it. :( > > I meant that we need to recompute PI entries for lowest priority > interrupts every time guest's TPR changes. > > Luckily, Linux doesn't use TPR, but other OS might be a reason to drop > lowest priority from PI optimizations. (Or make it more complicated.) Doing vector hashing is a possibility as well. I would like to know what existing chipsets do in practice, then we can mimic it. Paolo