linux-kernel - Re: [PATCH v2 3/3] X86, mpx: Intel MPX xstate feature definition

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Message-ID: <52A20F80.9000601@zytor.com>
Date:	Fri, 06 Dec 2013 09:55:12 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Paolo Bonzini <pbonzini@...hat.com>,
	Qiaowei Ren <qiaowei.ren@...el.com>
CC:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org, qemu-devel@...gnu.org,
	kvm@...r.kernel.org, Xudong Hao <xudong.hao@...el.com>,
	Liu Jinsong <jinsong.liu@...el.com>
Subject: Re: [PATCH v2 3/3] X86, mpx: Intel MPX xstate feature definition

On 12/06/2013 09:35 AM, Paolo Bonzini wrote:
> 
> Sorry for the back-and-forth, but I think this and the removal of
> XSTATE_FLEXIBLE (perhaps XSTATE_LAZY?) makes your v2 worse than v1.
> 
> Since Peter already said the same, please undo these changes.
> 
> Also, how is XSTATE_EAGER used?  Should MPX be disabled when xsaveopt is
> disabled on the kernel command line?  (Liu, how would this affect the
> KVM patches, too?)
> 

There are two options: we could disable MPX etc. or we could force eager
saving (using xsave) even if xsaveopt is disabled.  It is a hard call to
make, but I guess I'm leaning towards the latter; we could add an
"lazyxsave" option to explicitly disable all eager features if there is
use for that.

	-hpa


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