linux-kernel - Re: [PATCH] x86/CPU/AMD: Make sure EFER[AIBRSE] is set

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Message-ID: <Y/zO7MtvjiVLCiLg@zn.tnic>
Date:   Mon, 27 Feb 2023 16:40:28 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Josh Poimboeuf <jpoimboe@...nel.org>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Kim Phillips <kim.phillips@....com>, x86@...nel.org,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Joao Martins <joao.m.martins@...cle.com>,
        Jonathan Corbet <corbet@....net>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Juergen Gross <jgross@...e.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Tony Luck <tony.luck@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Alexey Kardashevskiy <aik@....com>, kvm@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/CPU/AMD: Make sure EFER[AIBRSE] is set

On Mon, Feb 27, 2023 at 07:25:00AM -0800, Dave Hansen wrote:
> It will freak some users out, but it does seem like the kind of thing we
> _want_ a bug report for.

You mean, something like:

	if (spectre_v2_in_ibrs_mode(spectre_v2_enabled) &&
	    cpu_has(c, X86_FEATURE_AUTOIBRS))
		WARN_ON_ONCE(msr_set_bit(MSR_EFER, _EFER_AUTOIBRS));

?

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette