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From: Nick Lowe <nick.lowe@gmail.com>
Date: Tue, 13 Feb 2018 13:34:07 +0000
Message-ID: <CADSoG1tjU2G9FUNOFod4ZsYSw7gOSsza_JWUv5H6pAkbftWywA@mail.gmail.com>
Subject: Re: [PATCH 4.9 43/92] x86/pti: Do not enable PTI on CPUs which are
 not vulnerable to Meltdown
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        David Woodhouse <dwmw@amazon.co.uk>,
        Thomas Gleixner <tglx@linutronix.de>,
        Borislav Petkov <bp@suse.de>,
        Dave Hansen <dave.hansen@intel.com>,
        gnomes@lxorguk.ukuu.org.uk, ak@linux.intel.com,
        ashok.raj@intel.com, karahmed@amazon.de, arjan@linux.intel.com,
        torvalds@linux-foundation.org, peterz@infradead.org,
        Borislav Petkov <bp@alien8.de>, pbonzini@redhat.com,
        tim.c.chen@linux.intel.com, gregkh@linux-foundation.org
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Hi,

This does not seem to have subsumed the AMD specific code in

x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown
Commit a8799fd14d9f7f385a5a5c86cde247caf4bb0320

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/?h=v4.9.81&id=a8799fd14d9f7f385a5a5c86cde247caf4bb0320

x86/kaiser: Check boottime cmdline params
Commit 8018307a45a90ab2eecfd03d48b7efb31707df37

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/arch/x86/mm/kaiser.c?h=v4.9.75&id=8018307a45a90ab2eecfd03d48b7efb31707df37

Here, we can see:

+skip:
+ if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
+ goto disable;

Refer to 4.9.81's kaiser.c
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/tree/arch/x86/mm/kaiser.c?h=v4.9.81

Also 4.4.115's kaiser.c
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/tree/arch/x86/mm/kaiser.c?h=v4.4.115

Cheers,

Nick