linux-kernel - Re: [RFC PATCH, x86]: Disable CPA cache flush for selfsnoop targets

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Message-ID: <alpine.DEB.2.21.1907152146010.1767@nanos.tec.linutronix.de>
Date:   Mon, 15 Jul 2019 21:46:33 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Andi Kleen <ak@...ux.intel.com>
cc:     Uros Bizjak <ubizjak@...il.com>, linux-kernel@...r.kernel.org,
        x86@...nel.org, Andrew Lutomirski <luto@...nel.org>
Subject: Re: [RFC PATCH, x86]: Disable CPA cache flush for selfsnoop
 targets

On Mon, 15 Jul 2019, Andi Kleen wrote:

> > Right, we don't know where the PAT invocation comes from and whether they
> > are safe to omit flushing the cache. The module load code would be one
> > obvious candidate.
> 
> Module load just changes the writable/executable status, right? That shouldn't
> need to flush in any case because it doesn't change the caching attributes.

Ah right. We don't flush when the caching attributes are not changed.

Thanks,

	tglx