linux-kernel - Re: [patch 3/3] x86/fpu/xsave: Optimize XSAVEC/S when XGETBV1 is supported

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4cce3734-03e0-ff62-b13e-cd8405d3a8b7@intel.com>
Date:   Sat, 23 Apr 2022 08:20:18 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Andrew Cooper <andrew.cooper3@...rix.com>,
        "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
Subject: Re: [patch 3/3] x86/fpu/xsave: Optimize XSAVEC/S when XGETBV1 is
 supported

On 4/22/22 12:30, Thomas Gleixner wrote:
> So I just go and add the XSAVEC support alone as that's actually
> something which _is_ beneficial for guests.

Yeah, agreed.

When I went to test these patches, a bit loop with XSAVEC was ~10%
faster that XSAVEOPT.  This system has XSAVES, so wouldn't have been
using XSAVEOPT in the first place in the kernel.  But, this is at least
one more data point in favor of XSAVEC.