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From:   Thomas Gleixner <tglx@linutronix.de>
To:     "Yu\, Yu-cheng" <yu-cheng.yu@intel.com>,
        LKML <linux-kernel@vger.kernel.org>
Cc:     Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Fenghua Yu <fenghua.yu@intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Borislav Petkov <bp@suse.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Kan Liang <kan.liang@linux.intel.com>
Subject: Re: [patch V2 45/52] x86/fpu: Dont restore PKRU in fpregs_restore_userspace()
In-Reply-To: <89da2d23-7de8-8dee-5b6a-361b7ceeae8e@intel.com>
References: <20210614154408.673478623@linutronix.de> <20210614155358.277290739@linutronix.de> <89da2d23-7de8-8dee-5b6a-361b7ceeae8e@intel.com>
Date:   Wed, 16 Jun 2021 10:56:27 +0200
Message-ID: <878s3agpc4.ffs@nanos.tec.linutronix.de>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On Tue, Jun 15 2021 at 17:52, Yu-cheng Yu wrote:
> On 6/14/2021 8:44 AM, Thomas Gleixner wrote:
>> +		 * If PKRU is enabled, then the PKRU value is already
>> +		 * correct because it was either set in switch_to() or in
>> +		 * flush_thread(). So it is excluded because it might be
>> +		 * not up to date in current->thread.fpu.xsave state.
>> +		 */
>> +		__restore_fpregs_from_fpstate(&fpu->state,
>> +					      xfeatures_mask_restore_user());
>
> This needs to be xfeatures_mask_restore_user() | 
> xfeatures_mask_supervisor().

Indeed. Good catch!

Thanks,

        tglx