From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754156AbaGKXJe (ORCPT ); Fri, 11 Jul 2014 19:09:34 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:21280 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750866AbaGKXJc (ORCPT ); Fri, 11 Jul 2014 19:09:32 -0400 Message-Id: <201407112309.s6BN9MFb016118@aserz7022.oracle.com> Date: Fri, 11 Jul 2014 19:09:02 -0400 Subject: Re: [PATCH] xen: Introduce 'xen_nopv' to disable PV extensions for HVM guests. From: Konrad Rzeszutek Wilk To: "H. Peter Anvin" Cc: xen-devel@lists.xenproject.org, konrad@kernel.org, boris.ostrovsky@oracle.com, linux-kernel@vger.kernel.org, david.vrabel@citrix.com MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 X-Source-IP: ucsinet22.oracle.com [156.151.31.94] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id s6BN9uMK024572 On Jul 11, 2014 6:52 PM, "H. Peter Anvin" wrote: > > On 07/11/2014 12:53 PM, konrad@kernel.org wrote: > > > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > > index c1b9aa8..5dcfa6e 100644 > > --- a/Documentation/kernel-parameters.txt > > +++ b/Documentation/kernel-parameters.txt > > @@ -3691,6 +3691,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted. > >  Disables the ticketlock slowpath using Xen PV > >  optimizations. > >  > > + xen_nopv [X86,XEN] > > + Disables the PV optimizations forcing the guest to run > > + as generic HVM guest with no PV drivers. > > + > >  xirc2ps_cs= [NET,PCMCIA] > >  Format: > >  ,,,,,[,[,[,]]] > > diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c > > index ffb101e..eb82239 100644 > > --- a/arch/x86/xen/enlighten.c > > +++ b/arch/x86/xen/enlighten.c > > @@ -1826,8 +1826,19 @@ static void __init xen_hvm_guest_init(void) > >  xen_hvm_init_mmu_ops(); > >  } > >  > > +static bool xen_nopv = false; > > +static __init int xen_parse_nopv(char *arg) > > +{ > > +       xen_nopv = true; > > +       return 0; > > +} > > +early_param("xen_nopv", xen_parse_nopv); > > + > >  static uint32_t __init xen_hvm_platform(void) > >  { > > + if (xen_nopv) > > + return 0; > > + > >  if (xen_pv_domain()) > >  return 0; > >  > > @@ -1836,6 +1847,8 @@ static uint32_t __init xen_hvm_platform(void) > >  > >  bool xen_hvm_need_lapic(void) > >  { > > + if (xen_nopv) > > + return false; > >  if (xen_pv_domain()) > >  return false; > >  if (!xen_hvm_domain()) > > > > Any reason to not simply let xen_pv_domain() return false here? It does return false already. Did you mean to collapse them together? > > Also, the latter seems a bit odd? > > -hpa > {.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I