From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH v2 2/2] x86/xstate: also use alternative asm
	on xsave side
Date: Wed, 3 Feb 2016 13:26:28 +0000
Message-ID: <56B20004.40303@citrix.com>
References: <56B2016102000078000CE005@prv-mh.provo.novell.com>
	<56B2032902000078000CE03C@prv-mh.provo.novell.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xen.org>
Received: from mail6.bemta4.messagelabs.com ([85.158.143.247])
	by lists.xen.org with esmtp (Exim 4.72)
	(envelope-from <prvs=8340f39c5=Andrew.Cooper3@citrix.com>)
	id 1aQxS4-0003kc-KG
	for xen-devel@lists.xenproject.org; Wed, 03 Feb 2016 13:26:32 +0000
In-Reply-To: <56B2032902000078000CE03C@prv-mh.provo.novell.com>
List-Unsubscribe: <http://lists.xen.org/cgi-bin/mailman/options/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xen.org>
List-Help: <mailto:xen-devel-request@lists.xen.org?subject=help>
List-Subscribe: <http://lists.xen.org/cgi-bin/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=subscribe>
Sender: xen-devel-bounces@lists.xen.org
Errors-To: xen-devel-bounces@lists.xen.org
To: Jan Beulich <JBeulich@suse.com>, xen-devel <xen-devel@lists.xenproject.org>
Cc: Keir Fraser <keir@xen.org>, Shuai Ruan <shuai.ruan@linux.intel.com>
List-Id: xen-devel@lists.xenproject.org

On 03/02/16 12:39, Jan Beulich wrote:
> From: Shuai Ruan <shuai.ruan@linux.intel.com>
>
> This patch use alternavtive asm on the xsave side.
> As xsaves use modified optimization like xsaveopt, xsaves
> may not writing the FPU portion of the save image too.
> So xsaves also need some extra tweaks.
>
> Signed-off-by: Shuai Ruan <shuai.ruan@linux.intel.com>
>
> Fix XSAVES opcode. Extend the other respective XSAVEOPT conditional to
> cover XSAVES as well. Re-wrap comment being adjusted.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
>
> --- a/xen/arch/x86/xstate.c
> +++ b/xen/arch/x86/xstate.c
> @@ -250,27 +250,29 @@ void xsave(struct vcpu *v, uint64_t mask
>      uint32_t hmask = mask >> 32;
>      uint32_t lmask = mask;
>      int word_size = mask & XSTATE_FP ? (cpu_has_fpu_sel ? 8 : 0) : -1;
> +#define XSAVE(pfx) \
> +        alternative_io_3(".byte " pfx "0x0f,0xae,0x27\n", \
> +                         ".byte " pfx "0x0f,0xae,0x37\n", \
> +                         X86_FEATURE_XSAVEOPT, \
> +                         ".byte " pfx "0x0f,0xc7,0x27\n", \
> +                         X86_FEATURE_XSAVEC, \
> +                         ".byte " pfx "0x0f,0xc7,0x2f\n", \
> +                         X86_FEATURE_XSAVES, \

Given that the options are a little out of order and using raw bytes,
would you mind annotating the lines with the operations. e.g.

+        alternative_io_3(".byte " pfx "0x0f,0xae,0x27\n", /* xsave */ \
+                         ".byte " pfx "0x0f,0xae,0x37\n", /* xsaveopt */ \
+                         X86_FEATURE_XSAVEOPT, \
+                         ".byte " pfx "0x0f,0xc7,0x27\n", /* xsavec */ \
+                         X86_FEATURE_XSAVEC, \
+                         ".byte " pfx "0x0f,0xc7,0x2f\n", /* xsaves */ \
+                         X86_FEATURE_XSAVES, \

IMO, this is somewhat clearer to read.

Otherwise,

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>