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

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Date:	Fri, 6 Dec 2013 20:05:19 +0000
From:	"Liu, Jinsong" <jinsong.liu@...el.com>
To:	Paolo Bonzini <pbonzini@...hat.com>,
	"Ren, Qiaowei" <qiaowei.ren@...el.com>
CC:	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	Xudong Hao <xudong.hao@...el.com>,
	"qemu-devel@...gnu.org" <qemu-devel@...gnu.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: RE: [Qemu-devel] [PATCH v2 3/3] X86,	mpx: Intel MPX xstate feature
 definition

Paolo Bonzini wrote:
> Il 07/12/2013 01:20, Qiaowei Ren ha scritto:
>> This patch defines xstate feature and extends struct xsave_hdr_struct
>> to support Intel MPX.
>> 
>> Signed-off-by: Qiaowei Ren <qiaowei.ren@...el.com>
>> Signed-off-by: Xudong Hao <xudong.hao@...el.com>
>> Signed-off-by: Liu Jinsong <jinsong.liu@...el.com>
>> ---
>>  arch/x86/include/asm/processor.h |   12 ++++++++++++
>>  arch/x86/include/asm/xsave.h     |    5 ++++-
>>  2 files changed, 16 insertions(+), 1 deletions(-)
>> 
>> diff --git a/arch/x86/include/asm/processor.h
>> b/arch/x86/include/asm/processor.h index 987c75e..2fe2e75 100644 ---
>> a/arch/x86/include/asm/processor.h +++
>> b/arch/x86/include/asm/processor.h @@ -370,6 +370,15 @@ struct
>>  	ymmh_struct { u32 ymmh_space[64];
>>  };
>> 
>> +struct bndregs_struct {
>> +	u64 bndregs[8];
>> +} __packed;
>> +
>> +struct bndcsr_struct {
>> +	u64 cfg_reg_u;
>> +	u64 status_reg;
>> +} __packed;
>> +
>>  struct xsave_hdr_struct {
>>  	u64 xstate_bv;
>>  	u64 reserved1[2];
>> @@ -380,6 +389,9 @@ struct xsave_struct {
>>  	struct i387_fxsave_struct i387;
>>  	struct xsave_hdr_struct xsave_hdr;
>>  	struct ymmh_struct ymmh;
>> +	u8 lwp_area[128];
> 
> 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?)
> 
> Paolo

Currently seems no, and if needed we can add a new patch at kvm side accordingly when native mpx patches checked in.

Jinsong

> 
>> +#define XSTATE_EAGER	(XSTATE_BNDREGS | XSTATE_BNDCSR)  /*
>>   * These are the features that the OS can handle currently.   */
>> -#define XCNTXT_MASK	(XSTATE_FP | XSTATE_SSE | XSTATE_YMM)
>> +#define XCNTXT_MASK    (XSTATE_FP | XSTATE_SSE | XSTATE_YMM |
>> XSTATE_EAGER) 
>> 
>>  #ifdef CONFIG_X86_64
>>  #define REX_PREFIX	"0x48, "

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