linux-kernel - Re: [PATCH v4 10/10] x86/xsaves: Re-enable XSAVES

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Message-ID: <572A748A.1000401@linux.intel.com>
Date:	Wed, 4 May 2016 15:15:38 -0700
From:	Dave Hansen <dave.hansen@...ux.intel.com>
To:	Yu-cheng Yu <yu-cheng.yu@...el.com>
Cc:	x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
	Andy Lutomirski <luto@...nel.org>,
	Borislav Petkov <bp@...e.de>,
	Sai Praneeth Prakhya <sai.praneeth.prakhya@...el.com>,
	"Ravi V. Shankar" <ravi.v.shankar@...el.com>,
	Fenghua Yu <fenghua.yu@...el.com>
Subject: Re: [PATCH v4 10/10] x86/xsaves: Re-enable XSAVES

On 05/02/2016 09:11 AM, Yu-cheng Yu wrote:
> On Fri, Apr 29, 2016 at 05:40:44PM -0700, Dave Hansen wrote:
>> That's better than what we had before, but it relies entirely on testing
>> coverage and runtime checks.
>>
>> Is it too much to ask that you also take a look and audit all the places
>> the XSAVE buffer is accessed in the kernel and ensure that they either
>> have code to handle standard vs. compacted/supervisor or don't care for
>> some reason?
>>
>> I did such an audit once upon a time, but I think it would be a good
>> exercise to repeat both by a second set of eyes and because some time
>> has passed.
> 
> I think there are 12 files that can be directly impacted by XSAVES. 
> 
> 	arch/x86/include/asm/fpu/internal.h
> 	arch/x86/include/asm/fpu/types.h
> 	arch/x86/include/asm/fpu/xstate.h
> 	arch/x86/include/uapi/asm/sigcontext.h
> 	arch/x86/kernel/traps.c
> 	arch/x86/kernel/fpu/core.c
> 	arch/x86/kernel/fpu/init.c
> 	arch/x86/kernel/fpu/regset.c
> 	arch/x86/kernel/fpu/signal.c
> 	arch/x86/kernel/fpu/xstate.c
> 	arch/x86/kvm/x86.c
> 	arch/x86/mm/mpx.c
> 
> They have been reviewed from the perspective of the compacted format.
> Please let me know anything else.

Can you double-check that nothing has changed in mainline (or tip for
that matter) since you first did these checks?