From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755321AbZDUQLM (ORCPT ); Tue, 21 Apr 2009 12:11:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753197AbZDUQKz (ORCPT ); Tue, 21 Apr 2009 12:10:55 -0400 Received: from mail-gx0-f214.google.com ([209.85.217.214]:48900 "EHLO mail-gx0-f214.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752283AbZDUQKy (ORCPT ); Tue, 21 Apr 2009 12:10:54 -0400 X-Greylist: delayed 372 seconds by postgrey-1.27 at vger.kernel.org; Tue, 21 Apr 2009 12:10:53 EDT Message-ID: <49EDEE93.30103@codemonkey.ws> Date: Tue, 21 Apr 2009 11:04:35 -0500 From: Anthony Liguori User-Agent: Thunderbird 2.0.0.21 (X11/20090320) MIME-Version: 1.0 To: Avi Kivity CC: Huang Ying , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Andi Kleen Subject: Re: [PATCH] Add MCE support to KVM References: <1239155601.6384.3.camel@yhuang-dev.sh.intel.com> <49DE195D.1020303@redhat.com> <1239332455.6384.108.camel@yhuang-dev.sh.intel.com> <49E08762.1010206@redhat.com> <1239590499.6384.4016.camel@yhuang-dev.sh.intel.com> <49E337D7.5050502@redhat.com> <49EA515C.9000507@codemonkey.ws> <49EAE1F6.9050205@redhat.com> In-Reply-To: <49EAE1F6.9050205@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Avi Kivity wrote: > Anthony Liguori wrote: >> Avi Kivity wrote: >>> >>> Then we would need to tell which read-only MSRs are setup writeable >>> and which aren't... >>> >>> I'm okay with an ioctl to setup MCE, but just make sure userspace >>> has all the information to know what the kernel can do rather than >>> the try-and-see-if-it-works approach. We can publish this >>> information via KVM_CAP things, or via another ioctl (see >>> KVM_GET_SUPPORTED_CPUID2 for an example). >> >> Why not introduce a new exit type for MSR reads/writes that aren't >> handled by the kernel? You just need a bit on the return that >> indicates whether to GPF because of an invalid MSR access. >> >> KVM_SET_MSRs should be reserved for MSRs that are performance >> sensitive. Not all of them will be. >> > > Right now everything in the vcpu is emulated in the kernel. > Everything else is emulated either in the kernel (irqchip) or in > userspace. This makes things easier to understand, and is more future > friendly if more cpu features become virtualized by hardware. Except cpuid, which is handled in userspace, sort of :-) I think the same arguments apply here too. Regards, Anthony Liguori