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

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Date:	Fri, 6 Dec 2013 14:46:31 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Qiaowei Ren <qiaowei.ren@...el.com>
Cc:	Paolo Bonzini <pbonzini@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>, 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 3/3] X86, mpx: Intel MPX xstate feature definition

On Sat, Dec 07, 2013 at 02:52:56AM +0800, Qiaowei Ren wrote:

Commit message please.

> 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 |   23 +++++++++++++++++++++++
>  arch/x86/include/asm/xsave.h     |    6 +++++-
>  2 files changed, 28 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index 987c75e..43be6f6 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -370,6 +370,26 @@ struct ymmh_struct {
>  	u32 ymmh_space[64];
>  };
>  
> +struct lwp_struct {
> +	u64 lwpcb_addr;
> +	u32 flags;
> +	u32 buf_head_offset;
> +	u64 buf_base;
> +	u32 buf_size;
> +	u32 filters;
> +	u64 saved_event_record[4];
> +	u32 event_counter[16];
> +};
> +
> +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 +400,9 @@ struct xsave_struct {
>  	struct i387_fxsave_struct i387;
>  	struct xsave_hdr_struct xsave_hdr;
>  	struct ymmh_struct ymmh;
> +	struct lwp_struct lwp;

I'm guessing this and the struct lwp_struct above is being added so that
you can have the LWP XSAVE area size? If so, you don't need it: LWP
XSAVE area is 128 bytes at offset 832 according to my manuals so I'd
guess having a u8 lwp_area[128] should be fine.


> +	struct bndregs_struct bndregs;
> +	struct bndcsr_struct bndcsr;
>  	/* new processor state extensions will go here */
>  } __attribute__ ((packed, aligned (64)));
>  
> diff --git a/arch/x86/include/asm/xsave.h b/arch/x86/include/asm/xsave.h
> index 0415cda..5cd9de3 100644
> --- a/arch/x86/include/asm/xsave.h
> +++ b/arch/x86/include/asm/xsave.h
> @@ -9,6 +9,8 @@
>  #define XSTATE_FP	0x1
>  #define XSTATE_SSE	0x2
>  #define XSTATE_YMM	0x4
> +#define XSTATE_BNDREGS	0x8
> +#define XSTATE_BNDCSR	0x10
>  
>  #define XSTATE_FPSSE	(XSTATE_FP | XSTATE_SSE)
>  
> @@ -20,10 +22,12 @@
>  #define XSAVE_YMM_SIZE	    256
>  #define XSAVE_YMM_OFFSET    (XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET)
>  
> +#define XSTATE_FLEXIBLE (XSTATE_FP | XSTATE_SSE | XSTATE_YMM)

What's the use of that macro if it is used only once?

> +#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_FLEXIBLE | XSTATE_EAGER)
>  
>  #ifdef CONFIG_X86_64
>  #define REX_PREFIX	"0x48, "

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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