linux-kernel - Re: [patch] x86, avx: don't use avx instructions with "noxsave" boot param

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Date:	Tue, 31 Jul 2012 14:20:49 +1000
From:	NeilBrown <neilb@...e.de>
To:	Suresh Siddha <suresh.b.siddha@...el.com>
Cc:	hpa@...or.com, james.t.kukunas@...ux.intel.com,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [patch] x86, avx: don't use avx instructions with "noxsave"
 boot param

On Mon, 30 Jul 2012 15:46:15 -0700 Suresh Siddha <suresh.b.siddha@...el.com>
wrote:

> Check the kernel has indeed enabled xsave before using AVX instructions.
> 
> Fixes the kernel boot panic with "noxsave" boot parameter.
> 
> Signed-off-by: Suresh Siddha <suresh.b.siddha@...el.com>

Looks consistent with other usage - thanks.
Applied.

Should it go in '-stable' kernels too?

NeilBrown

> ---
>  arch/x86/include/asm/xor_avx.h |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/include/asm/xor_avx.h b/arch/x86/include/asm/xor_avx.h
> index 2510d35..77987cd 100644
> --- a/arch/x86/include/asm/xor_avx.h
> +++ b/arch/x86/include/asm/xor_avx.h
> @@ -197,12 +197,12 @@ static struct xor_block_template xor_block_avx = {
>  
>  #define AVX_XOR_SPEED \
>  do { \
> -	if (cpu_has_avx) \
> +	if (cpu_has_avx && cpu_has_osxsave) \
>  		xor_speed(&xor_block_avx); \
>  } while (0)
>  
>  #define AVX_SELECT(FASTEST) \
> -	(cpu_has_avx ? &xor_block_avx : FASTEST)
> +	((cpu_has_avx && cpu_has_osxsave) ? &xor_block_avx : FASTEST)
>  
>  #else
>  
> 


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