linux-kernel - Re: [PATCH v2 8/8] x86: Use IBRS for firmware update path

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Message-ID: <20180106085729.GC4380@kroah.com>
Date:   Sat, 6 Jan 2018 09:57:29 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Tim Chen <tim.c.chen@...ux.intel.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Andy Lutomirski <luto@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Arjan Van De Ven <arjan.van.de.ven@...el.com>,
        David Woodhouse <dwmw@...zon.co.uk>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 8/8] x86: Use IBRS for firmware update path

On Fri, Jan 05, 2018 at 06:12:23PM -0800, Tim Chen wrote:
> +void unprotected_firmware_begin(void)
> +{
> +	if (firmware_ibrs) {
> +		__disable_indirect_speculation();
> +	} else {
> +		/*
> +		 * rmb prevent unwanted speculation when we
> +		 * are setting IBRS
> +		 */
> +		rmb();
> +	}
> +}
> +EXPORT_SYMBOL_GPL(unprotected_firmware_begin);

What modules need these functions?

And again, if they are needed, we need a better naming scheme for them.
Prefix them all with "firmware_" perhaps to make it a bit nicer?

thanks,

greg k-h