Return-Path: Received: from mail.kernel.org ([198.145.29.99]:32820 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755565AbeFOHGn (ORCPT ); Fri, 15 Jun 2018 03:06:43 -0400 Date: Fri, 15 Jun 2018 09:06:19 +0200 From: 'Greg Kroah-Hartman' To: Daniel Sangorrin Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, 'Andy Lutomirski' , 'Rik van Riel' , 'Borislav Petkov' , 'Brian Gerst' , 'Dave Hansen' , 'Denys Vlasenko' , 'Fenghua Yu' , "'H. Peter Anvin'" , 'Josh Poimboeuf' , 'Linus Torvalds' , 'Oleg Nesterov' , 'Peter Zijlstra' , 'Quentin Casasnovas' , 'Thomas Gleixner' , pbonzini@redhat.com, 'Ingo Molnar' Subject: Re: [PATCH 4.4 10/24] x86/fpu: Hard-disable lazy FPU mode Message-ID: <20180615070619.GA25325@kroah.com> References: <20180614132724.483802160@linuxfoundation.org> <20180614132724.905032027@linuxfoundation.org> <000c01d40460$bfc97710$3f5c6530$@toshiba.co.jp> <20180615045604.GA8664@kroah.com> <000d01d40468$f2109570$d631c050$@toshiba.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <000d01d40468$f2109570$d631c050$@toshiba.co.jp> Sender: stable-owner@vger.kernel.org List-ID: On Fri, Jun 15, 2018 at 02:23:08PM +0900, Daniel Sangorrin wrote: > > -----Original Message----- > > From: stable-owner@vger.kernel.org [mailto:stable-owner@vger.kernel.org] On > > Behalf Of 'Greg Kroah-Hartman' > > Sent: Friday, June 15, 2018 1:56 PM > > To: Daniel Sangorrin > > Cc: linux-kernel@vger.kernel.org; stable@vger.kernel.org; 'Andy Lutomirski' > > ; 'Rik van Riel' ; 'Borislav Petkov' > > ; 'Brian Gerst' ; 'Dave Hansen' > > ; 'Denys Vlasenko' ; > > 'Fenghua Yu' ; 'H. Peter Anvin' ; 'Josh > > Poimboeuf' ; 'Linus Torvalds' > > ; 'Oleg Nesterov' ; 'Peter > > Zijlstra' ; 'Quentin Casasnovas' > > ; 'Thomas Gleixner' ; > > pbonzini@redhat.com; 'Ingo Molnar' > > Subject: Re: [PATCH 4.4 10/24] x86/fpu: Hard-disable lazy FPU mode > > > > On Fri, Jun 15, 2018 at 01:24:27PM +0900, Daniel Sangorrin wrote: > > > Hi Greg, > > > > > > > /* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */ > > > > --- a/arch/x86/include/asm/fpu/internal.h > > > > +++ b/arch/x86/include/asm/fpu/internal.h > > > > @@ -58,7 +58,7 @@ extern u64 fpu__get_supported_xfeatures_ > > > > */ > > > > static __always_inline __pure bool use_eager_fpu(void) > > > > { > > > > - return static_cpu_has_safe(X86_FEATURE_EAGER_FPU); > > > > + return true; > > > > } > > > > > > Since this function returns always true then we can remove the code depending on > > lazy FPU mode. > > > Actually this has already been done in "x86/fpu: Remove use_eager_fpu()" > > > Ref: https://patchwork.kernel.org/patch/9365883/ > > > > > > > static void __init fpu__init_parse_early_param(void) > > > > { > > > > - if (cmdline_find_option_bool(boot_command_line, "eagerfpu=off")) { > > > > - eagerfpu = DISABLE; > > > > - fpu__clear_eager_fpu_features(); > > > > - } > > > > > > Since this patch removes the kernel boot parameter "eagerfpu", maybe we should > > remove it from the Documentation. > > > This has also been done by commit "x86/fpu: Finish excising 'eagerfpu'" > > > Ref: https://patchwork.kernel.org/patch/9380673/ > > > > > > I will try backporting those patches unless anyone has any objections. > > > > What are the git commit ids of those patches in Linus's tree? No need > > to point to patchwork links, I don't use that tool. > > OK, I got it. > > "x86/fpu: Remove use_eager_fpu()": c592b57347069abfc0dcad3b3a302cf882602597 > "x86/fpu: Finish excising 'eagerfpu'": e63650840e8b053aa09ad934877e87e9941ed135 Minor nit. For kernel commits, the "normal" way we reference them looks like this: c592b5734706 ("x86/fpu: Remove use_eager_fpu()") e63650840e8b ("x86/fpu: Finish excising 'eagerfpu'") Which makes it much easier to read and understand. That's what we use for the "Fixes:" tag in commits and in other places (text in commit messages.) To automatically generate that format, you can just do: git show -s --abbrev-commit --abbrev=12 --pretty=format:"%h (\"%s\")%n" I recommend just setting up an alias for the above line, otherwise it's a pain to have to remember how to do it all the time. Here's what I do: $ alias gsr='git show -s --abbrev-commit --abbrev=12 --pretty=format:"%h (\"%s\")%n"' $ gsr c592b57347069abfc0dcad3b3a302cf882602597 c592b5734706 ("x86/fpu: Remove use_eager_fpu()") > Unfortunately, they don't apply cleanly to stable kernels. Should be very simple to backport if you want to. Also I need copies for the 4.9.y tree as well if you do so. thanks, greg k-h