linux-kernel - Re: [PATCH v4 1/5] x86/paravirt: Add _safe to the read_msr and write

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Date:	Mon, 14 Mar 2016 12:57:29 +0100
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" <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v4 1/5] x86/paravirt: Add _safe to the read_msr and
 write_msr PV hooks

On Sat, Mar 12, 2016 at 10:08:48AM -0800, 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.h b/arch/x86/include/asm/paravirt.h
> index f6192502149e..2e49228ed9a3 100644
> --- a/arch/x86/include/asm/paravirt.h
> +++ b/arch/x86/include/asm/paravirt.h
> @@ -129,34 +129,35 @@ static inline void wbinvd(void)
>  
>  #define get_kernel_rpl()  (pv_info.kernel_rpl)
>  
> -static inline u64 paravirt_read_msr(unsigned msr, int *err)
> +static inline u64 paravirt_read_msr_safe(unsigned msr, int *err)
>  {
> -	return PVOP_CALL2(u64, pv_cpu_ops.read_msr, msr, err);
> +	return PVOP_CALL2(u64, pv_cpu_ops.read_msr_safe, msr, err);
>  }
>  
> -static inline int paravirt_write_msr(unsigned msr, unsigned low, unsigned high)
> +static inline int paravirt_write_msr_safe(unsigned msr,
> +					  unsigned low, unsigned high)
>  {
> -	return PVOP_CALL3(int, pv_cpu_ops.write_msr, msr, low, high);
> +	return PVOP_CALL3(int, pv_cpu_ops.write_msr_safe, msr, low, high);
>  }
>  
>  /* These should all do BUG_ON(_err), but our headers are too tangled. */
>  #define rdmsr(msr, val1, val2)			\
>  do {						\
>  	int _err;				\
> -	u64 _l = paravirt_read_msr(msr, &_err);	\
> +	u64 _l = paravirt_read_msr_safe(msr, &_err);	\
>  	val1 = (u32)_l;				\
>  	val2 = _l >> 32;			\
>  } while (0)
>  
>  #define wrmsr(msr, val1, val2)			\
>  do {						\
> -	paravirt_write_msr(msr, val1, val2);	\
> +	paravirt_write_msr_safe(msr, val1, val2);	\
>  } while (0)
>  
>  #define rdmsrl(msr, val)			\
>  do {						\
>  	int _err;				\
> -	val = paravirt_read_msr(msr, &_err);	\
> +	val = paravirt_read_msr_safe(msr, &_err);	\
>  } while (0)
>  
>  static inline void wrmsrl(unsigned msr, u64 val)
> @@ -164,23 +165,23 @@ static inline void wrmsrl(unsigned msr, u64 val)
>  	wrmsr(msr, (u32)val, (u32)(val>>32));
>  }
>  
> -#define wrmsr_safe(msr, a, b)	paravirt_write_msr(msr, a, b)
> +#define wrmsr_safe(msr, a, b)	paravirt_write_msr_safe(msr, a, b)
>  
>  /* rdmsr with exception handling */
> -#define rdmsr_safe(msr, a, b)			\
> -({						\
> -	int _err;				\
> -	u64 _l = paravirt_read_msr(msr, &_err);	\
> -	(*a) = (u32)_l;				\
> -	(*b) = _l >> 32;			\
> -	_err;					\
> +#define rdmsr_safe(msr, a, b)				\
> +({							\
> +	int _err;					\
> +	u64 _l = paravirt_read_msr_safe(msr, &_err);	\
> +	(*a) = (u32)_l;					\
> +	(*b) = _l >> 32;				\
> +	_err;						\
>  })
>  
>  static inline int rdmsrl_safe(unsigned msr, unsigned long long *p)
>  {
>  	int err;
>  
> -	*p = paravirt_read_msr(msr, &err);
> +	*p = paravirt_read_msr_safe(msr, &err);
>  	return err;
>  }
>  
> 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 fix the comment format while you're touching this :

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

Other than that:

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

-- 
Regards/Gruss,
    Boris.

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