linux-kernel - Re: [PATCH V6 00/10] PKS: Add Protection Key Supervisor support

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Message-ID: <20210514202250.GA1722585@iweiny-DESK2.sc.intel.com>
Date:   Fri, 14 May 2021 13:22:51 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Edgecombe@...iny-DESK2.sc.intel.com,
        Rick P <rick.p.edgecombe@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Dan Williams <dan.j.williams@...el.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, Fenghua Yu <fenghua.yu@...el.com>
Subject: Re: [PATCH V6 00/10] PKS: Add Protection Key Supervisor support

On Fri, Apr 16, 2021 at 03:14:56PM -0700, 'Ira Weiny' wrote:
> On Thu, Apr 01, 2021 at 03:58:23PM -0700, 'Ira Weiny' wrote:
> > From: Ira Weiny <ira.weiny@...el.com>
> > 
> > Introduce a new page protection mechanism for supervisor pages, Protection Key
> > Supervisor (PKS).
> 
> Is there any feedback on this series?

Please disregard this series...  (If you have not done so already).

Along with Rick posting his RFC for page table protections[1] he has raised a
concern with me about pkeys being allocated and then reallocated to another
user.  It turns out the code has a bug in this area and the fix is not trivial.

Because the PMEM use case never needed to free its key and even if it did a
small window of access was not a concern this was not tested.

The best solutions involve changing the API therefore this series is going to
need a respin.

Thank you,
Ira

[1] https://lore.kernel.org/lkml/20210505003032.489164-1-rick.p.edgecombe@intel.com/