linux-kernel - Re: Got FPU related warning on Intel Quark during boot

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Date:	Fri, 11 Mar 2016 11:02:04 +0000
From:	Bryan O'Donoghue <pure.logic@...us-software.ie>
To:	Borislav Petkov <bp@...en8.de>, Ingo Molnar <mingo@...nel.org>
Cc:	Andy Lutomirski <luto@...capital.net>,
	Andy Shevchenko <andy.shevchenko@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	Fenghua Yu <fenghua.yu@...el.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Oleg Nesterov <oleg@...hat.com>,
	"Yu, Yu-cheng" <yu-cheng.yu@...el.com>
Subject: Re: Got FPU related warning on Intel Quark during boot

On Fri, 2016-03-11 at 10:48 +0100, Borislav Petkov wrote:
> On Fri, Mar 11, 2016 at 10:08:40AM +0100, Ingo Molnar wrote:
> > So yes, this needs to be fixed too.
> 
> Yes indeed. So the diff below seems to work with Bryan's simple test
> case.
> 
> Bryan, can you confirm on your box pls?
> 
> ---
> diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
> index dea8e76d60c6..8e37cc8a539a 100644
> --- a/arch/x86/kernel/fpu/core.c
> +++ b/arch/x86/kernel/fpu/core.c
> @@ -474,8 +474,10 @@ static inline void
> copy_init_fpstate_to_fpregs(void)
>  {
>  	if (use_xsave())
>  		copy_kernel_to_xregs(&init_fpstate.xsave, -1);
> -	else
> +	else if (static_cpu_has(X86_FEATURE_FXSR))
>  		copy_kernel_to_fxregs(&init_fpstate.fxsave);
> +	else
> +		copy_kernel_to_fregs(&init_fpstate.fsave);
>  }
>  
>  /*
> diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
> index e12cc0ad368e..c835f61d5feb 100644
> --- a/arch/x86/kernel/fpu/init.c
> +++ b/arch/x86/kernel/fpu/init.c
> @@ -134,7 +134,7 @@ static void __init fpu__init_system_generic(void)
>  	 * Set up the legacy init FPU context. (xstate init might
> overwrite this
>  	 * with a more modern format, if the CPU supports it.)
>  	 */
> -	fpstate_init_fxstate(&init_fpstate.fxsave);
> +	fpstate_init(&init_fpstate);
>  
>  	fpu__init_system_mxcsr();
>  }
> 
> ---
> 
> Thanks.
> 

Hi Boris,

Looks good.

Tested-by: Bryan O'Donoghue <pure.logic@...us-software.ie>