From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: [PATCH] libxc: remove CPUID core information mangling Date: Wed, 25 Aug 2010 13:42:17 +0100 Message-ID: References: <4C7506BA.4000001@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4C7506BA.4000001@amd.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Andre Przywara , Nitin Kamble Cc: xen-devel List-Id: xen-devel@lists.xenproject.org On 25/08/2010 13:04, "Andre Przywara" wrote: > Hi, > > c/s 18560:782599274bf9ae8857c55856c9c7fdf082967808 introduced CPUID > mangling resulting in a doubled number of cores/processor exposed to the > guest. According to comments in this patch the rationale behind this is > to match the APIC numbering used by Xen. > In my understanding the CPUID leafs dealing with number of cores always > talk about logical numbers and not APIC IDs. So we don't need to adjust > the CPUID readout to match the APIC ID enumeration scheme. > If there were any serious reasons resulting in the old patch I'd love to > hear them. > > The attached patch fixes this and solves an issue I saw with certain > NUMA guest configurations. I think you shouldn't change handling of 80000008:ECX[15:12] since that does explicitly refer to APIC ID arrangement. The rest of your changes could be correct as far as I can tell from the reference manuals. The intent by the way was to pass through host cores-per-package info so that software licenses based on #packages would operate correctly in a virtualised environment. It's pretty hacky though indeed. -- Keir > Signed-off-by: Andre Przywara