linux-kernel - Re: [PATCH 1/5] x86/ibrs: Introduce native_rdmsrl, and native

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Date:   Thu, 11 Jan 2018 17:41:34 -0800
From:   Andy Lutomirski <luto@...nel.org>
To:     Ashok Raj <ashok.raj@...el.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Arjan Van De Ven <arjan.van.de.ven@...el.com>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Peter Zijlstra <peterz@...radead.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Jun Nakajima <jun.nakajima@...el.com>,
        Asit Mallick <asit.k.mallick@...el.com>
Subject: Re: [PATCH 1/5] x86/ibrs: Introduce native_rdmsrl, and native_wrmsrl

On Thu, Jan 11, 2018 at 5:32 PM, Ashok Raj <ashok.raj@...el.com> wrote:
> - Remove including microcode.h, and use native macros from asm/msr.h
> - added license header for spec_ctrl.c
>
> Signed-off-by: Ashok Raj <ashok.raj@...el.com>
> ---
>  arch/x86/include/asm/spec_ctrl.h | 17 ++++++++++++++++-
>  arch/x86/kernel/cpu/spec_ctrl.c  |  1 +
>  2 files changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/spec_ctrl.h b/arch/x86/include/asm/spec_ctrl.h
> index 948959b..2dfa31b 100644
> --- a/arch/x86/include/asm/spec_ctrl.h
> +++ b/arch/x86/include/asm/spec_ctrl.h
> @@ -3,12 +3,27 @@
>  #ifndef _ASM_X86_SPEC_CTRL_H
>  #define _ASM_X86_SPEC_CTRL_H
>
> -#include <asm/microcode.h>
> +#include <asm/processor.h>
> +#include <asm/msr.h>
>
>  void spec_ctrl_scan_feature(struct cpuinfo_x86 *c);
>  void spec_ctrl_unprotected_begin(void);
>  void spec_ctrl_unprotected_end(void);
>
> +static inline u64 native_rdmsrl(unsigned int msr)
> +{
> +       u64 val;
> +
> +       val = __rdmsr(msr);
> +
> +       return val;
> +}

What's wrong with native_read_msr()?

> +
> +static inline void native_wrmsrl(unsigned int msr, u64 val)
> +{
> +       __wrmsr(msr, (u32) (val & 0xffffffffULL), (u32) (val >> 32));
> +}

What's wrong with just wrmsrl()?  If you really need a native helper
like this, please add it to arch/x86/asm/msr.h.