linux-kernel - Re: [PATCH] x86/boot/64: Make level2_kernel_pgt pages invalid outside kernel area.

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Message-ID: <20190912101917.mbobjvkxhfttxddd@box>
Date:   Thu, 12 Sep 2019 13:19:17 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Steve Wahl <steve.wahl@....com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Juergen Gross <jgross@...e.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Jordan Borgner <mail@...dan-borgner.de>,
        Feng Tang <feng.tang@...el.com>, linux-kernel@...r.kernel.org,
        Baoquan He <bhe@...hat.com>, russ.anderson@....com,
        dimitri.sivanich@....com, mike.travis@....com
Subject: Re: [PATCH] x86/boot/64: Make level2_kernel_pgt pages invalid
 outside kernel area.

On Wed, Sep 11, 2019 at 03:08:35PM -0500, Steve Wahl wrote:
> Thank you for your time looking into this with me!

With all this explanation the original patch looks sane to me.

But I would like to see more information from this thread in the commit
message and some comments in the code on why it's crucial not to map more
than needed.

I think we also need to make it clear that this is workaround for a broken
hardware: speculative execution must not trigger a halt.

-- 
 Kirill A. Shutemov