linux-kernel - Re: [PATCH 1/7] x86/feature: Detect the x86 feature to control Speculation

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Date:   Fri, 5 Jan 2018 14:51:40 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Andrea Arcangeli <aarcange@...hat.com>
cc:     Tim Chen <tim.c.chen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Arjan Van De Ven <arjan.van.de.ven@...el.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/7] x86/feature: Detect the x86 feature to control
 Speculation

On Fri, 5 Jan 2018, Andrea Arcangeli wrote:
> On Fri, Jan 05, 2018 at 02:09:43PM +0100, Thomas Gleixner wrote:
> Now about the late microcode my preference is not for static_cpu_has
> and forcing the early microcode, but my long term preference is to
> start with this/boot_cpu_has() and then turn static_cpu_has in a true
> static key so that setup_force_cpu_cap shall also flip the static key
> for all static_cpu_has(X86_FEATURE_IBPB_SUPPORT) also if run any time
> after boot and not only if run before the static_cpu_has alternative
> is patched in.

Fair enough. We can avoid the static_cpu_has() to begin with and fix it
later.

Thanks,

	tglx