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From:   Andy Lutomirski <luto@amacapital.net>
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Subject: Re: [RFC v4][PATCH part-1 0/7] ASI - Part I (ASI Infrastructure and PTI)
Date:   Tue, 12 May 2020 13:07:28 -0700
Message-Id: <7F322031-034E-4B36-A60F-663EAA4C99C9@amacapital.net>
References: <a65d6cbf-41de-3001-6792-21a4233d8467@intel.com>
Cc:     Alexandre Chartre <alexandre.chartre@oracle.com>,
        rkrcmar@redhat.com, tglx@linutronix.de, mingo@redhat.com,
        bp@alien8.de, hpa@zytor.com, dave.hansen@linux.intel.com,
        luto@kernel.org, peterz@infradead.org, x86@kernel.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        pbonzini@redhat.com, konrad.wilk@oracle.com,
        jan.setjeeilers@oracle.com, liran.alon@oracle.com,
        junaids@google.com, graf@amazon.de, rppt@linux.vnet.ibm.com,
        kuzuno@gmail.com, mgross@linux.intel.com
In-Reply-To: <a65d6cbf-41de-3001-6792-21a4233d8467@intel.com>
To:     Dave Hansen <dave.hansen@intel.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


> On May 12, 2020, at 10:45 AM, Dave Hansen <dave.hansen@intel.com> wrote:
>=20
> =EF=BB=BFOn 5/4/20 7:49 AM, Alexandre Chartre wrote:
>> This version 4 of the kernel Address Space Isolation (ASI) RFC. I have
>> broken it down into three distinct parts:
>>=20
>> - Part I: ASI Infrastructure and PTI (this part)
>> - Part II: Decorated Page-Table
>> - Part III: ASI Test Driver and CLI
>>=20
>> Part I is similar to RFCv3 [3] with some small bug fixes. Parts II and II=
I
>> extend the initial patchset: part II introduces decorated page-table in
>> order to provide convenient page-table management functions, and part III=

>> provides a driver and CLI for testing ASI (using parts I and II).
>=20
> These look interesting.  I haven't found any holes in your methods,
> although the interrupt depth tracking worries me a bit.  I tried and
> failed to do a similar thing with PTI in the NMI path, but you might
> have just bested me there. :)
>=20
> It's very interesting that you've been able to implement PTI underneath
> all of this, and the "test driver" is really entertaining!
>=20
> That said, this is working in some of the nastiest corners of the x86
> code and this is going to take quite an investment to get reviewed.  I'm
> not *quite* sure it's all worth it.
>=20
> So, this isn't being ignored, I'm just not quite sure what to do with
> it, yet.

I=E2=80=99m going to wait until the dust settles on tglx=E2=80=99s big entry=
 rework before I look at this.=