From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756729AbbIUPan (ORCPT ); Mon, 21 Sep 2015 11:30:43 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:35354 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753417AbbIUPam (ORCPT ); Mon, 21 Sep 2015 11:30:42 -0400 Date: Mon, 21 Sep 2015 11:30:35 -0400 From: Konrad Rzeszutek Wilk To: Boris Ostrovsky Cc: david.vrabel@citrix.com, xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] xen/x86: Don't try to write syscall-related MSRs for PV guests Message-ID: <20150921153034.GD13722@l.oracle.com> References: <1442840968-23052-1-git-send-email-boris.ostrovsky@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1442840968-23052-1-git-send-email-boris.ostrovsky@oracle.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 21, 2015 at 09:09:28AM -0400, Boris Ostrovsky wrote: > For PV guests these registers are set up by hypervisor and thus > should not be written by the guest. The comment in xen_write_msr_safe() > says so but we still write the MSRs, causing the hypervisor to > print a warning. > > Signed-off-by: Boris Ostrovsky Reviewed-by: Konrad Rzeszutek Wilk > --- > arch/x86/xen/enlighten.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c > index 30d12af..1f1dbd2 100644 > --- a/arch/x86/xen/enlighten.c > +++ b/arch/x86/xen/enlighten.c > @@ -1077,6 +1077,7 @@ static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high) > /* Fast syscall setup is all done in hypercalls, so > these are all ignored. Stub them out here to stop > Xen console noise. */ > + break; > > default: > if (!pmu_msr_write(msr, low, high, &ret)) > -- > 2.1.0 >