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

From: Borislav Petkov <bp@alien8.de>
To: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-mm@kvack.org, linux-arch@vger.kernel.org,
	linux-api@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
	Andy Lutomirski <luto@amacapital.net>,
	Balbir Singh <bsingharora@gmail.com>,
	Cyrill Gorcunov <gorcunov@gmail.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Eugene Syromiatnikov <esyr@redhat.com>,
	Florian Weimer <fweimer@redhat.com>,
	"H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Kees Cook <keescook@chromium.org>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Nadav Amit <nadav.amit@gmail.com>,
	Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
	Peter Zijlstra <peterz@infradead.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
	Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>
Subject: Re: [RFC PATCH v6 04/26] x86/fpu/xstate: Introduce XSAVES system states
Date: Tue, 4 Dec 2018 19:16:41 +0100	[thread overview]
Message-ID: <20181204181641.GA16705@zn.tnic> (raw)
In-Reply-To: <752c38422a6536d8df99b619214f935e4bc882ad.camel@intel.com>

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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