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Date:   Tue, 20 Jun 2023 10:20:23 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     LKML <linux-kernel@vger.kernel.org>, x86@kernel.org,
        Mario Limonciello <mario.limonciello@amd.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Tony Battersby <tonyb@cybernetics.com>,
        Ashok Raj <ashok.raj@linux.intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Arjan van de Veen <arjan@linux.intel.com>,
        Eric Biederman <ebiederm@xmission.com>
Subject: Re: [patch v3 2/7] x86/smp: Dont access non-existing CPUID leaf
Message-ID: <20230620082023.GTZJFhRxji7SHvvmdk@fat_crate.local>
References: <20230615190036.898273129@linutronix.de>
 <20230615193330.322186388@linutronix.de>
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On Thu, Jun 15, 2023 at 10:33:52PM +0200, Thomas Gleixner wrote:

> Subject: Re: [patch v3 2/7] x86/smp: Dont access non-existing CPUID leaf

"Do not access a non-existing... "

> From: Tony Battersby <tonyb@cybernetics.com>
> 
> stop_this_cpu() tests CPUID leaf 0x8000001f::EAX unconditionally. CPUs
> return the content of the highest supported leaf when a non-existing leaf
> is read.

This should be:

"On Intel, querying an invalid extended CPUID leaf returns the values of the
maximum basic CPUID leaf. On AMD, invalid CPUID leafs return zeros."

Other than that:

Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de>

-- 
Regards/Gruss,
    Boris.

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