linux-kernel - Re: [patch V3 4/6] x86/pkru: Make PKRU=0 actually work

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Message-ID: <87wnr4xjjy.ffs@nanos.tec.linutronix.de>
Date:   Tue, 08 Jun 2021 21:06:41 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Dave Hansen <dave.hansen@...el.com>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Yu-cheng Yu <yu-cheng.yu@...el.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Rik van Riel <riel@...riel.com>, Borislav Petkov <bp@...e.de>
Subject: Re: [patch V3 4/6] x86/pkru: Make PKRU=0 actually work

On Tue, Jun 08 2021 at 09:06, Dave Hansen wrote:
> On 6/8/21 7:36 AM, Thomas Gleixner wrote:
>> When user space brings PKRU into init state, then the kernel handling is
>> broken:
>
> Nit: while setting PKRU=0 _can_ trigger this issue (on AMD), the
> underlying problem is truly with the init state and not simply with any
> wrpkru(0).  IOW, I like the changelog better than the subject.
>
> Maybe something like this would be more precise:
>
> 	x86/pkru: Write hardware init value to PKRU when xstate is init

Indeed.