From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [PATCH] qemu-kvm: x86: Fix mismerge in cpu_post_load Date: Sun, 6 Dec 2009 12:56:15 +0200 Message-ID: <20091206105615.GL20102@redhat.com> References: <4B18018D.1060305@siemens.com> <4B1B7F65.2040904@redhat.com> <4B1B89DA.6030004@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , Marcelo Tosatti , kvm To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:24250 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933254AbZLFK4L (ORCPT ); Sun, 6 Dec 2009 05:56:11 -0500 Content-Disposition: inline In-Reply-To: <4B1B89DA.6030004@web.de> Sender: kvm-owner@vger.kernel.org List-ID: On Sun, Dec 06, 2009 at 11:39:22AM +0100, Jan Kiszka wrote: > >> Unlike the other states we discussed, this one > >> is not "fixable" in the kernel. So I tend to think there is a real need > >> for my write-back scope abstraction - which would also be able to handle > >> the other states cleanly, both in upstream and here. > >> > > > > Yes. Gleb suggested treating mpstate/nmi as part of the APIC state > > (which makes sense), which would work, as APIC state is not > > automatically written back. But the tsc msr would need special treatment. > > (just realized that I forgot to answer him) > > While this would make sense for mpstate, NMIs are not coupled to the > APICs. The APIC just happens to be one source for them (though a common > one). So if there is no in-kernel APIC state, there would never be a > write-back of the NMI state, which is bad. > I agree about NMI. We never do RMW to NMI anyway. Mpstate/sipi_vector belong to APIC state though. -- Gleb.