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From: Rik van Riel <riel@surriel.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
	"Andy Lutomirski" <luto@kernel.org>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	kvm@vger.kernel.org, "Jason A. Donenfeld" <Jason@zx2c4.com>
Subject: Re: [RFC PATCH 04/10 v2 ] x86/fpu: eager switch PKRU state
Date: Tue, 18 Sep 2018 11:11:20 -0400	[thread overview]
Message-ID: <83e271e1298d603c1105dd0dbea32d67da9cf1fa.camel@surriel.com> (raw)
In-Reply-To: <7e9a13f3-93f5-fe4a-20d2-f4f9407bd43b@redhat.com>

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On Tue, 2018-09-18 at 17:07 +0200, Paolo Bonzini wrote:
> On 18/09/2018 16:27, Sebastian Andrzej Siewior wrote:
> > > Likewise, move this to fpu__clear and outside "if
> > > (static_cpu_has(X86_FEATURE_FPU))"?
> > 
> > okay. But if there is no FPU we did not save/restore the pkru
> > value. Is
> > this supposed to be an improvement?
> 
> Honestly it just seemed "more correct", but now that I think about
> it,
> kernel threads should run with PKRU=0.  maybe there's a preexisting
> bug
> that your patch has the occasion to fix.

I don't think it matters what the PKRU state is
for kernel threads, since kernel PTEs should not
be using protection keys anyway.

-- 
All Rights Reversed.

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  reply	other threads:[~2018-09-18 15:11 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-12 13:33 [RFC PATCH] x86: load FPU registers on return to userland Sebastian Andrzej Siewior
2018-09-12 13:33 ` [RFC PATCH 01/10] x86/entry: remove _TIF_ALLWORK_MASK Sebastian Andrzej Siewior
2018-09-27 14:21   ` Sebastian Andrzej Siewior
2018-09-12 13:33 ` [RFC PATCH 02/10] kvm: x86: make kvm_{load|put}_guest_fpu() static Sebastian Andrzej Siewior
2018-09-12 13:33 ` [RFC PATCH 03/10] x86/fpu: add (__)make_fpregs_active helpers Sebastian Andrzej Siewior
2018-09-12 13:33 ` [RFC PATCH 04/10] x86/fpu: eager switch PKRU state Sebastian Andrzej Siewior
2018-09-12 14:18   ` Paolo Bonzini
2018-09-12 15:24     ` Andy Lutomirski
2018-09-12 15:30       ` Paolo Bonzini
2018-09-14 20:35     ` [RFC PATCH 04/10 v2 ] " Sebastian Andrzej Siewior
2018-09-17  8:37       ` Paolo Bonzini
2018-09-18 14:27         ` Sebastian Andrzej Siewior
2018-09-18 15:07           ` Paolo Bonzini
2018-09-18 15:11             ` Rik van Riel [this message]
2018-09-18 15:29               ` Paolo Bonzini
2018-09-18 16:04                 ` Sebastian Andrzej Siewior
2018-09-18 17:29                   ` Rik van Riel
2018-09-19  5:55                     ` Paolo Bonzini
2018-09-19 16:57                       ` Sebastian Andrzej Siewior
2018-09-19 17:00                         ` Paolo Bonzini
2018-09-19 17:19                           ` Sebastian Andrzej Siewior
2018-09-19 19:38                           ` Rik van Riel
2018-09-19 19:49                           ` Andy Lutomirski
2018-09-12 15:20   ` [RFC PATCH 04/10] " Andy Lutomirski
2018-09-12 15:30     ` Rik van Riel
2018-09-12 15:49       ` Andy Lutomirski
2018-09-19 16:58         ` Sebastian Andrzej Siewior
2018-09-12 13:33 ` [RFC PATCH 05/10] x86/pkeys: Drop the preempt-disable section Sebastian Andrzej Siewior
2018-09-12 13:33 ` [RFC PATCH 06/10] x86/fpu: Always store the registers in copy_fpstate_to_sigframe() Sebastian Andrzej Siewior
2018-09-12 13:33 ` [RFC PATCH 07/10] x86/entry: add TIF_LOAD_FPU Sebastian Andrzej Siewior
2018-09-12 13:33 ` [RFC PATCH 08/10] x86/fpu: prepare copy_fpstate_to_sigframe for TIF_LOAD_FPU Sebastian Andrzej Siewior
2018-09-12 13:33 ` [RFC PATCH 09/10] x86/fpu: copy non-resident FPU state at fork time Sebastian Andrzej Siewior
2018-09-12 13:33 ` [RFC PATCH 10/10] x86/fpu: defer FPU state load until return to userspace Sebastian Andrzej Siewior
2018-09-12 15:47   ` Andy Lutomirski
2018-09-19 17:05     ` Sebastian Andrzej Siewior
2018-09-21  3:45       ` Andy Lutomirski
2018-09-21  4:15         ` Andy Lutomirski
2018-09-26 11:12           ` Sebastian Andrzej Siewior
2018-09-26 14:34             ` Andy Lutomirski
2018-09-26 15:32               ` Sebastian Andrzej Siewior
2018-09-26 16:24                 ` Andy Lutomirski

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