From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762330AbbA3OVV (ORCPT ); Fri, 30 Jan 2015 09:21:21 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53302 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754740AbbA3OVU (ORCPT ); Fri, 30 Jan 2015 09:21:20 -0500 Date: Fri, 30 Jan 2015 15:21:05 +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 7/8] KVM: x86: avoid logical_map when it is invalid Message-ID: <20150130142105.GA27414@potion.redhat.com> References: <1422568135-28402-1-git-send-email-rkrcmar@redhat.com> <1422568135-28402-8-git-send-email-rkrcmar@redhat.com> <54CB4CAE.2080200@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <54CB4CAE.2080200@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2015-01-30 10:19+0100, Paolo Bonzini: > On 29/01/2015 22:48, Radim Krčmář wrote: > > We want to support mixed modes and the easiest solution is to avoid > > optimizing those weird and unlikely scenarios. > > Hmm, what happens if use maxcpus to disable some CPUs at startup? Their APICs are kept sw-disabled in xAPIC mode. > Could > the disabled CPUs remain in xapic mode while the others move to x2apic? Yes, but it would only matter if the OS set LDR on them. I mark x2APIC with perfectly configured xAPIC on unused processors as "weird" ... (Linux 3.18 and 2.6.32 doesn't do it.)