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Date: Tue, 24 Jan 2017 09:08:10 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Kevin Hao <haokexin@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
        Yu-cheng Yu <yu-cheng.yu@intel.com>, fenghua.yu@intel.com,
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Subject: Re: [tip:x86/urgent] x86/fpu: Set the xcomp_bv when we fake up a
 XSAVES area
Message-ID: <20170124080810.GA11694@gmail.com>
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* Kevin Hao <haokexin@gmail.com> wrote:

> > other than helping to hide bugs?
> 
> Why do you think it hide the bug? In contrast, I think my patch fixes what the 
> bug really is. The memory area we fake up is bug, we should fix it there.

The intention is to have a single FPU format set at bootup and xcomp_bv is 
essentially an invariant (constant) inherited by all tasks from early boot. In 
that sense setting xsave.header.xcomp_bv in copyin_to_xsaves() is misplaced.

So I combined the two commits: I kept your original fix but applied Yu-cheng Yu's 
patch that moves the initialization from copyin_to_xsaves() to fpstate_init().

Thanks,

	Ingo