linux-kernel - Re: [RFC PATCH 00/16] x86/split_lock: Enable #AC exception for split locked accesses

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Date:   Tue, 29 May 2018 09:39:01 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Fenghua Yu <fenghua.yu@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...e.hu>,
        "H. Peter Anvin" <hpa@...ux.intel.com>
Cc:     Ashok Raj <ashok.raj@...el.com>,
        Rafael Wysocki <rafael.j.wysocki@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Alan Cox <alan@...ux.intel.com>,
        Ravi V Shankar <ravi.v.shankar@...el.com>,
        Arjan van de Ven <arjan@...radead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org>
Subject: Re: [RFC PATCH 00/16] x86/split_lock: Enable #AC exception for split
 locked accesses

On 05/27/2018 08:45 AM, Fenghua Yu wrote:
> ==Detect Split Lock==
> 
> To detect split lock, a new control bit (bit 29) in per-core TEST_CTL
> MSR 0x33 will be introduced in future x86 processors. When the bit 29
> is set, the processor causes #AC exception for split locked accesses at
> all CPL.
> 
> The bit 29 specification in MSR TEST_CTL is published in the latest
> Intel Architecture Instruction Set Extensions and Future Features
> Programming Reference.

The fact that this is per-core is pretty important, right?  Where does
that get mentioned?