linux-kernel - Re: [PATCH v5 5/9] x86/paravirt: Add _safe to the read_msr and write

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Date:	Sun, 3 Apr 2016 10:41:29 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Andy Lutomirski <luto@...nel.org>
Cc:	X86 ML <x86@...nel.org>, Paolo Bonzini <pbonzini@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	KVM list <kvm@...r.kernel.org>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	xen-devel <Xen-devel@...ts.xen.org>,
	linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v5 5/9] x86/paravirt: Add _safe to the read_msr and
 write_msr PV hooks

On Sat, Apr 02, 2016 at 07:01:36AM -0700, Andy Lutomirski wrote:
> These hooks match the _safe variants, so name them accordingly.
> This will make room for unsafe PV hooks.
> 
> Signed-off-by: Andy Lutomirski <luto@...nel.org>
> ---
>  arch/x86/include/asm/paravirt.h       | 33 +++++++++++++++++----------------
>  arch/x86/include/asm/paravirt_types.h |  8 ++++----
>  arch/x86/kernel/paravirt.c            |  4 ++--
>  arch/x86/xen/enlighten.c              |  4 ++--
>  4 files changed, 25 insertions(+), 24 deletions(-)

...

> diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
> index 77db5616a473..5a06cccd36f0 100644
> --- a/arch/x86/include/asm/paravirt_types.h
> +++ b/arch/x86/include/asm/paravirt_types.h
> @@ -155,10 +155,10 @@ struct pv_cpu_ops {
>  	void (*cpuid)(unsigned int *eax, unsigned int *ebx,
>  		      unsigned int *ecx, unsigned int *edx);
>  
> -	/* MSR, PMC and TSR operations.
> -	   err = 0/-EFAULT.  wrmsr returns 0/-EFAULT. */
> -	u64 (*read_msr)(unsigned int msr, int *err);
> -	int (*write_msr)(unsigned int msr, unsigned low, unsigned high);
> +	/* MSR operations.
> +	   err = 0/-EIO.  wrmsr returns 0/-EIO. */

Please reformat this comment properly, while you're at it:

	/*
	 * A sentence.
	 * Another sentence.
	 */

> +	u64 (*read_msr_safe)(unsigned int msr, int *err)Please reformat this
> comment properly, while you're at it:
> +	int (*write_msr_safe)(unsigned int msr, unsigned low, unsigned high);
>  
>  	u64 (*read_pmc)(int counter);
>  

-- 
Regards/Gruss,
    Boris.

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