linux-kernel - Re: [PATCH] x86/speculation: Add support for STIBP always-on preferred mode

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Message-ID: <20181211211944.GT27375@zn.tnic>
Date:   Tue, 11 Dec 2018 22:19:44 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Lendacky, Thomas" <Thomas.Lendacky@....com>
Cc:     "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Jiri Kosina <jkosina@...e.cz>, Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        David Woodhouse <dwmw@...zon.co.uk>
Subject: Re: [PATCH] x86/speculation: Add support for STIBP always-on
 preferred mode

On Tue, Dec 11, 2018 at 07:19:09PM +0000, Lendacky, Thomas wrote:
> Alternatively, I can reuse SPECTRE_V2_USER_STRICT and issue pr_info_once()
> to show that the method has been switched.  This would reduce the changes
> to the code, but then the sysfs information doesn't show the switch (which
> may be just fine).

You can still query X86_FEATURE_AMD_STIBP_ALWAYS_ON in stibp_state(),
no?

But yeah, forcing SPECTRE_V2_USER_STRICT on STIBP_ALWAYS_ON makes sense
to me, with the already gazillion options we have :-\

-- 
Regards/Gruss,
    Boris.

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