linux-kernel - Re: [PATCH v4 07/10] x86/xsaves: Fix PTRACE frames for XSAVES

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Date:	Fri, 29 Apr 2016 13:16:59 -0700
From:	Dave Hansen <dave.hansen@...ux.intel.com>
To:	Yu-cheng Yu <yu-cheng.yu@...el.com>, x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org
Cc:	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 07/10] x86/xsaves: Fix PTRACE frames for XSAVES

On 03/04/2016 10:12 AM, Yu-cheng Yu wrote:
> +	if (boot_cpu_has(X86_FEATURE_XSAVES)) {
> +		ret = copyout_from_xsaves(pos, count, kbuf, ubuf, xsave);

On a higher level, we really should stop using
"boot_cpu_has(X86_FEATURE_XSAVES)" as a proxy for "the kernel XSAVE
buffer is in the XSAVES format".  I think our use of the _hardware_
CPUID bit is confusing at least the KVM folks.

We probably want a software X86_FEATURE_OS_XSAVES or something.