From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762182AbbA3PUk (ORCPT ); Fri, 30 Jan 2015 10:20:40 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58223 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751110AbbA3PUj (ORCPT ); Fri, 30 Jan 2015 10:20:39 -0500 Date: Fri, 30 Jan 2015 16:20:31 +0100 From: Radim =?utf-8?B?S3LEjW3DocWZ?= To: Paolo Bonzini Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Nadav Amit , Gleb Natapov Subject: Re: [PATCH 0/8] KVM: minor APIC fixes and cleanups Message-ID: <20150130152031.GC28519@potion.redhat.com> References: <1422568135-28402-1-git-send-email-rkrcmar@redhat.com> <54CB4D44.1080109@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <54CB4D44.1080109@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2015-01-30 10:22+0100, Paolo Bonzini: > On 29/01/2015 22:48, Radim Krčmář wrote: > > This patch series is made our of three logical parts, > > > > [1-3/8] are just a cleanup and could be omitted > > [4-6/8] improve broadcast detection and unoptimized delivery > > [7-8/8] handle mixed mode (by falling back to improvements from [5-6/9]) > > I applied patches 1-4 and commented on patch 5. > > I'm afraid that patches 7-8 could lead to missed optimizations in some cases. True, I'll do more research on complexity of its assembly. > Regarding patch 6, perhaps there's a way to avoid this: > > + /* XXX: A superset of x2APIC broadcasts is fine in practice as long as > + * we don't support APIC ID > 0xfeffffff. > + */ > > It's ugly. :) Yeah, there is: don't deliver x2APIC broadcasts to xAPIC. (I'm not even sure if it is correct ...) Without that delivery, we could do something like if (irq->dest_id == (x2apic_ipi ? X2APIC_BROADCAST : APIC_BROADCAST))