linux-kernel - Re: [RFC PATCH v6 04/26] x86/fpu/xstate: Introduce XSAVES system states

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Message-ID: <20181204181641.GA16705@zn.tnic>
Date:   Tue, 4 Dec 2018 19:16:41 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Yu-cheng Yu <yu-cheng.yu@...el.com>
Cc:     x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-mm@...ck.org,
        linux-arch@...r.kernel.org, linux-api@...r.kernel.org,
        Arnd Bergmann <arnd@...db.de>,
        Andy Lutomirski <luto@...capital.net>,
        Balbir Singh <bsingharora@...il.com>,
        Cyrill Gorcunov <gorcunov@...il.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Eugene Syromiatnikov <esyr@...hat.com>,
        Florian Weimer <fweimer@...hat.com>,
        "H.J. Lu" <hjl.tools@...il.com>, Jann Horn <jannh@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        Kees Cook <keescook@...omium.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Nadav Amit <nadav.amit@...il.com>,
        Oleg Nesterov <oleg@...hat.com>, Pavel Machek <pavel@....cz>,
        Peter Zijlstra <peterz@...radead.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Vedvyas Shanbhogue <vedvyas.shanbhogue@...el.com>
Subject: Re: [RFC PATCH v6 04/26] x86/fpu/xstate: Introduce XSAVES system
 states

On Tue, Dec 04, 2018 at 09:08:11AM -0800, Yu-cheng Yu wrote:
> Then we will do this very often.  Why don't we create all three in the
> beginning: xfeatures_mask_all, xfeatures_mask_user, and xfeatures_mask_system?

Because the _all thing is the OR-ed product of the two and then you
don't have to update it when the _user and the _system ones change
because you'll be creating it on the fly each time.

-- 
Regards/Gruss,
    Boris.

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