linux-kernel - Re: [PATCH V2 00/10] PKS: Add Protection Keys Supervisor (PKS) support

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Date:   Wed, 4 Nov 2020 09:46:44 -0800
From:   Ira Weiny <ira.weiny@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        Dan Williams <dan.j.williams@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Fenghua Yu <fenghua.yu@...el.com>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-nvdimm@...ts.01.org,
        linux-mm@...ck.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH V2 00/10] PKS: Add Protection Keys Supervisor (PKS)
 support

On Tue, Nov 03, 2020 at 12:36:16AM +0100, Thomas Gleixner wrote:
> On Mon, Nov 02 2020 at 12:53, ira weiny wrote:
> > Fenghua Yu (2):
> >   x86/pks: Enable Protection Keys Supervisor (PKS)
> >   x86/pks: Add PKS kernel API
> >
> > Ira Weiny (7):
> >   x86/pkeys: Create pkeys_common.h
> >   x86/fpu: Refactor arch_set_user_pkey_access() for PKS support
> >   x86/pks: Preserve the PKRS MSR on context switch
> >   x86/entry: Pass irqentry_state_t by reference
> >   x86/entry: Preserve PKRS MSR across exceptions
> >   x86/fault: Report the PKRS state on fault
> >   x86/pks: Add PKS test code
> >
> > Thomas Gleixner (1):
> >   x86/entry: Move nmi entry/exit into common code
> 
> So the actual patch ordering is:
> 
>    x86/pkeys: Create pkeys_common.h
>    x86/fpu: Refactor arch_set_user_pkey_access() for PKS support
>    x86/pks: Enable Protection Keys Supervisor (PKS)
>    x86/pks: Preserve the PKRS MSR on context switch
>    x86/pks: Add PKS kernel API
> 
>    x86/entry: Move nmi entry/exit into common code
>    x86/entry: Pass irqentry_state_t by reference
> 
>    x86/entry: Preserve PKRS MSR across exceptions
>    x86/fault: Report the PKRS state on fault
>    x86/pks: Add PKS test code
> 
> This is the wrong ordering, really.
> 
>      x86/entry: Move nmi entry/exit into common code
> 
> is a general cleanup and has absolutely nothing to do with PKRS.So this
> wants to go first.
> 

Sorry, yes this should be a pre-patch.

> Also:
> 
>     x86/entry: Move nmi entry/exit into common code
> [from other email]
>    >      x86/entry: Pass irqentry_state_t by reference
>    >      > 
>    >      >
> 
> is a prerequisite for the rest. So why is it in the middle of the
> series?

It is in the middle because passing by reference is not needed until additional
information is added to irqentry_state_t which is done immediately after this
patch by:

    x86/entry: Preserve PKRS MSR across exceptions

I debated squashing the 2 but it made review harder IMO.  But I thought keeping
them in order together made a lot of sense.

> 
> And then you enable all that muck _before_ it is usable:
> 

Strictly speaking you are correct, sorry.  I will reorder the series.

> 
> Bisectability is overrrated, right?

Agreed, bisectability is important.  I thought I had it covered but I was
wrong.

> 
> Once again: Read an understand Documentation/process/*
> 
> Aside of that using a spell checker is not optional.

Agreed.

In looking closer at the entry code I've found a couple of other instances I'll
add another precursor patch.

I've also found other errors with the series which I should have caught.  My
apologies I made some last minute changes which I should have checked more
thoroughly.

Thanks,
Ira