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Date: Thu, 4 Jan 2018 21:00:36 +0100
From: Greg KH <gregkh@linuxfoundation.org>
To: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
        Andy Lutomirski <luto@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
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        Andi Kleen <ak@linux.intel.com>,
        Arjan Van De Ven <arjan.van.de.ven@intel.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/7] x86/enter: Use IBRS on syscall and interrupts
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On Thu, Jan 04, 2018 at 09:56:44AM -0800, Tim Chen wrote:
> 
> That is a minor inefficiency only, but we can eliminate it by saving
> the MSR when entering the NMI in save_paranoid and restoring it when
> exiting the NMI.

Any hints as to what exactly "minor" means in cycles here?  :)

thanks,

greg k-h