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

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Date:   Sat, 25 Feb 2023 23:56:37 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Josh Poimboeuf <jpoimboe@...nel.org>
Cc:     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 Sat, Feb 25, 2023 at 09:28:32AM -0800, Josh Poimboeuf wrote:
> All the other "bug" code in identify_secondary_cpu() *is*
> vendor-specific.

I meant "vendor-specific" in the sense that AMD code goes to amd.c, etc.

As to the identify_secondary_cpu()  code - I didn't like it being
slapped there either but it got stuck in there hastily during the
mitigations upstreaming as back then we had bigger fish to fry than
paying too much attention to clean design...

> And for that matter, so is most of the code in bugs.c.
> 
> I'm thinking we should just move all this MSR-writing bug-related code
> into a new cpu_init_bugs() function in bugs.c which can be called by
> identify_secondary_cpu().

I guess.
 
> Then we have more "bug" code together and all the local
> variables/functions like spectre_v2_in_ibrs_mode() can remain local.

They're still local, more or less. Note the special cpu.h header which
is private to arch/x86/kernel/cpu/

Thx.

-- 
Regards/Gruss,
    Boris.

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