From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752906AbbDCAKm (ORCPT ); Thu, 2 Apr 2015 20:10:42 -0400 Received: from g4t3427.houston.hp.com ([15.201.208.55]:40282 "EHLO g4t3427.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752656AbbDCAKj (ORCPT ); Thu, 2 Apr 2015 20:10:39 -0400 Message-ID: <1428018736.31093.102.camel@misato.fc.hp.com> Subject: Re: [PATCH v1 02/47] x86: mtrr: generalize run time disabling of MTRR From: Toshi Kani To: "Luis R. Rodriguez" Cc: "Luis R. Rodriguez" , luto@amacapital.net, mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com, jgross@suse.com, JBeulich@suse.com, bp@suse.de, suresh.b.siddha@intel.com, venkatesh.pallipadi@intel.com, airlied@redhat.com, linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org, x86@kernel.org, xen-devel@lists.xenproject.org, Ingo Molnar , Daniel Vetter , Antonino Daplas , Jean-Christophe Plagniol-Villard , Tomi Valkeinen , Dave Hansen , Stefan Bader , konrad.wilk@oracle.com, ville.syrjala@linux.intel.com, david.vrabel@citrix.com, bhelgaas@google.com, Roger Pau =?ISO-8859-1?Q?Monn=E9?= , xen-devel@lists.xensource.com Date: Thu, 02 Apr 2015 17:52:16 -0600 In-Reply-To: <20150402214912.GZ5622@wotan.suse.de> References: <1426893517-2511-1-git-send-email-mcgrof@do-not-panic.com> <1426893517-2511-3-git-send-email-mcgrof@do-not-panic.com> <1427488817.31093.54.camel@misato.fc.hp.com> <20150327235630.GR5622@wotan.suse.de> <20150402214912.GZ5622@wotan.suse.de> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4 (3.10.4-4.fc20) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2015-04-02 at 23:49 +0200, Luis R. Rodriguez wrote: > On Sat, Mar 28, 2015 at 12:56:30AM +0100, Luis R. Rodriguez wrote: > > On Fri, Mar 27, 2015 at 02:40:17PM -0600, Toshi Kani wrote: > > > On Fri, 2015-03-20 at 16:17 -0700, Luis R. Rodriguez wrote: > > > : > > > > @@ -734,6 +742,7 @@ void __init mtrr_bp_init(void) > > > > } > > > > > > > > if (mtrr_if) { > > > > + mtrr_enabled = true; > > > > set_num_var_ranges(); > > > > init_table(); > > > > if (use_intel()) { > > > get_mtrr_state(); > > > > > > After setting mtrr_enabled to true, get_mtrr_state() reads > > > MSR_MTRRdefType and sets 'mtrr_state.enabled', which also indicates if > > > MTRRs are enabled or not on the system. So, potentially, we could have > > > a case that mtrr_enabled is set to true, but mtrr_state.enabled is set > > > to disabled when MTRRs are disabled by BIOS. > > > > Thanks for the review, in this case then we should update mtrr_enabled to false. > > > > > ps. > > > I recently cleaned up this part of the MTRR code in the patch below, > > > which is currently available in the -mm & -next trees. > > > https://lkml.org/lkml/2015/3/24/1063 > > > > Great I will rebase and work with that and try to address this > > consideration you have raised. > > OK I'll mesh in this change as well in my next respin: > > diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c > index a83f27a..ecf7cb9 100644 > --- a/arch/x86/kernel/cpu/mtrr/generic.c > +++ b/arch/x86/kernel/cpu/mtrr/generic.c > @@ -438,7 +438,7 @@ static void __init print_mtrr_state(void) > } > > /* Grab all of the MTRR state for this CPU into *state */ > -void __init get_mtrr_state(void) > +bool __init get_mtrr_state(void) > { > struct mtrr_var_range *vrs; > unsigned long flags; > @@ -482,6 +482,8 @@ void __init get_mtrr_state(void) > > post_set(); > local_irq_restore(flags); > + > + return !!mtrr_state.enabled; This should be: return mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED; because the MTRR_STATE_MTRR_FIXED_ENABLED flag is ignored when the MTRR_STATE_MTRR_ENABLED flag is clear. Thanks, -Toshi From mboxrd@z Thu Jan 1 00:00:00 1970 From: Toshi Kani Date: Thu, 02 Apr 2015 23:52:16 +0000 Subject: Re: [PATCH v1 02/47] x86: mtrr: generalize run time disabling of MTRR Message-Id: <1428018736.31093.102.camel@misato.fc.hp.com> List-Id: References: <1426893517-2511-1-git-send-email-mcgrof@do-not-panic.com> <1426893517-2511-3-git-send-email-mcgrof@do-not-panic.com> <1427488817.31093.54.camel@misato.fc.hp.com> <20150327235630.GR5622@wotan.suse.de> <20150402214912.GZ5622@wotan.suse.de> In-Reply-To: <20150402214912.GZ5622@wotan.suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: "Luis R. Rodriguez" Cc: "Luis R. Rodriguez" , luto@amacapital.net, mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com, jgross@suse.com, JBeulich@suse.com, bp@suse.de, suresh.b.siddha@intel.com, venkatesh.pallipadi@intel.com, airlied@redhat.com, linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org, x86@kernel.org, xen-devel@lists.xenproject.org, Ingo Molnar , Daniel Vetter , Antonino Daplas , Jean-Christophe Plagniol-Villard , Tomi Valkeinen , Dave Hansen , Stefan Bader , konrad.wilk@oracle.com, ville.syrjala@linux.intel.com, david.vrabel@citrix.com, bhelgaas@google.com, Roger Pau =?ISO-8859-1?Q?Monn=E9?= , xen-devel@lists.xensource.com On Thu, 2015-04-02 at 23:49 +0200, Luis R. Rodriguez wrote: > On Sat, Mar 28, 2015 at 12:56:30AM +0100, Luis R. Rodriguez wrote: > > On Fri, Mar 27, 2015 at 02:40:17PM -0600, Toshi Kani wrote: > > > On Fri, 2015-03-20 at 16:17 -0700, Luis R. Rodriguez wrote: > > > : > > > > @@ -734,6 +742,7 @@ void __init mtrr_bp_init(void) > > > > } > > > > > > > > if (mtrr_if) { > > > > + mtrr_enabled = true; > > > > set_num_var_ranges(); > > > > init_table(); > > > > if (use_intel()) { > > > get_mtrr_state(); > > > > > > After setting mtrr_enabled to true, get_mtrr_state() reads > > > MSR_MTRRdefType and sets 'mtrr_state.enabled', which also indicates if > > > MTRRs are enabled or not on the system. So, potentially, we could have > > > a case that mtrr_enabled is set to true, but mtrr_state.enabled is set > > > to disabled when MTRRs are disabled by BIOS. > > > > Thanks for the review, in this case then we should update mtrr_enabled to false. > > > > > ps. > > > I recently cleaned up this part of the MTRR code in the patch below, > > > which is currently available in the -mm & -next trees. > > > https://lkml.org/lkml/2015/3/24/1063 > > > > Great I will rebase and work with that and try to address this > > consideration you have raised. > > OK I'll mesh in this change as well in my next respin: > > diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c > index a83f27a..ecf7cb9 100644 > --- a/arch/x86/kernel/cpu/mtrr/generic.c > +++ b/arch/x86/kernel/cpu/mtrr/generic.c > @@ -438,7 +438,7 @@ static void __init print_mtrr_state(void) > } > > /* Grab all of the MTRR state for this CPU into *state */ > -void __init get_mtrr_state(void) > +bool __init get_mtrr_state(void) > { > struct mtrr_var_range *vrs; > unsigned long flags; > @@ -482,6 +482,8 @@ void __init get_mtrr_state(void) > > post_set(); > local_irq_restore(flags); > + > + return !!mtrr_state.enabled; This should be: return mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED; because the MTRR_STATE_MTRR_FIXED_ENABLED flag is ignored when the MTRR_STATE_MTRR_ENABLED flag is clear. Thanks, -Toshi