From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: Nested kvm_intel broken on pre 3.3 hosts Date: Wed, 01 Aug 2012 17:29:18 +0300 Message-ID: <50193D3E.9090100@redhat.com> References: <50191307.5030107@canonical.com> <20120801133940.GB27579@redhat.com> <50193875.3090200@redhat.com> <50193C94.1030809@canonical.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Gleb Natapov , kvm@vger.kernel.org, Andy Whitcroft To: Stefan Bader Return-path: Received: from mx1.redhat.com ([209.132.183.28]:63383 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752330Ab2HAO3V (ORCPT ); Wed, 1 Aug 2012 10:29:21 -0400 In-Reply-To: <50193C94.1030809@canonical.com> Sender: kvm-owner@vger.kernel.org List-ID: On 08/01/2012 05:26 PM, Stefan Bader wrote: >>> According to Intel SDM there was never CPU that didn't support RDPMC >>> exiting. Looks like unfortunate nested VMX bug. >> >> Moreover, that same commit fixes the bug in nested vmx. So if you >> update your host kernel to the same version as your L1 guest (or, at >> your option, any later version) it should work. >> >> We could backport that part of the patch, though as nested vmx is still >> experimential, I don't think it's worth it. >> > Though this is probably what people will (or will have to) do. The host is not > always under your control. Even with it being experimental, it was working (at > least the module was loadable) before and is now broken on Intel hosts. > But ok, so the recommendation is to rather backport support to the host kernel > than to try handling this differently in the guest module, right? Right - it's not just kvm-as-a-guest that will trip on this. But there's no point in everyone backporting it on their own. If you're doing the backport, please post it here and we'll forward it to the stable branch. -- error compiling committee.c: too many arguments to function