linux-kernel - Re: [PATCH v8 02/28] x86/boot: Relocate definition of the initial state of CR0

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Message-ID: <20170825174133.r5xhcv5utfipsujo@pd.tnic>
Date:   Fri, 25 Aug 2017 19:41:34 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Brian Gerst <brgerst@...il.com>,
        Chris Metcalf <cmetcalf@...lanox.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Liang Z Li <liang.z.li@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Huang Rui <ray.huang@....com>, Jiri Slaby <jslaby@...e.cz>,
        Jonathan Corbet <corbet@....net>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Chen Yucong <slaoub@...il.com>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Shuah Khan <shuah@...nel.org>, linux-kernel@...r.kernel.org,
        x86@...nel.org, ricardo.neri@...el.com,
        Andy Lutomirski <luto@...capital.net>,
        Dave Hansen <dave.hansen@...el.com>,
        Denys Vlasenko <dvlasenk@...hat.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-arch@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v8 02/28] x86/boot: Relocate definition of the initial
 state of CR0

On Fri, Aug 18, 2017 at 05:27:43PM -0700, Ricardo Neri wrote:
> Both head_32.S and head_64.S utilize the same value to initialize the
> control register CR0. Also, other parts of the kernel might want to access
> to this initial definition (e.g., emulation code for User-Mode Instruction

s/to //

> Prevention uses this state to provide a sane dummy value for CR0 when
> emulating the smsw instruction). Thus, relocate this definition to a
> header file from which it can be conveniently accessed.
> 
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Andy Lutomirski <luto@...capital.net>
> Cc: Andy Lutomirski <luto@...nel.org>
> Cc: Borislav Petkov <bp@...en8.de>
> Cc: Brian Gerst <brgerst@...il.com>
> Cc: Dave Hansen <dave.hansen@...el.com>
> Cc: Denys Vlasenko <dvlasenk@...hat.com>
> Cc: H. Peter Anvin <hpa@...or.com>
> Cc: Josh Poimboeuf <jpoimboe@...hat.com>
> Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: linux-arch@...r.kernel.org
> Cc: linux-mm@...ck.org
> Suggested-by: Borislav Petkov <bp@...en8.de>
> Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
> ---
>  arch/x86/include/uapi/asm/processor-flags.h | 6 ++++++
>  arch/x86/kernel/head_32.S                   | 3 ---
>  arch/x86/kernel/head_64.S                   | 3 ---
>  3 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/include/uapi/asm/processor-flags.h b/arch/x86/include/uapi/asm/processor-flags.h
> index 185f3d10c194..aae1f2aa7563 100644
> --- a/arch/x86/include/uapi/asm/processor-flags.h
> +++ b/arch/x86/include/uapi/asm/processor-flags.h
> @@ -151,5 +151,11 @@
>  #define CX86_ARR_BASE	0xc4
>  #define CX86_RCR_BASE	0xdc
>  
> +/*
> + * Initial state of CR0 for head_32/64.S
> + */

No need for that comment.

With the minor nitpicks addressed, you can add:

Reviewed-by: Borislav Petkov <bp@...e.de>

Thx.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--