linux-kernel - Re: [PATCH 4.9 43/92] x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown

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Date:   Tue, 13 Feb 2018 17:10:55 +0100
From:   Borislav Petkov <bp@...e.de>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Andi Kleen <ak@...ux.intel.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Nick Lowe <nick.lowe@...il.com>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, David Woodhouse <dwmw@...zon.co.uk>,
        Dave Hansen <dave.hansen@...el.com>,
        gnomes@...rguk.ukuu.org.uk, ashok.raj@...el.com,
        karahmed@...zon.de, torvalds@...ux-foundation.org,
        peterz@...radead.org, pbonzini@...hat.com,
        tim.c.chen@...ux.intel.com
Subject: Re: [PATCH 4.9 43/92] x86/pti: Do not enable PTI on CPUs which are
 not vulnerable to Meltdown

On Tue, Feb 13, 2018 at 05:02:59PM +0100, Thomas Gleixner wrote:
> No. The table is basically excluding families <=5 and a few individual
> ones. Anything newer than that should tell via ARCH_CAP_RDCL_NO and not
> need any entry.

It looks to me like Nick wants 4.9 to test X86_BUG_CPU_MELTDOWN in
kaiser_check_boottime_disable() not X86_VENDOR_AMD. I.e., the auto
disable should pay attention to the CPUs in the table like upstream.

4.9 got the kaiser backports which explains the difference.

IMHO, of course.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--