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Message-ID: <1516733089.9521.162.camel@amazon.co.uk>
Subject: Re: [PATCH v2 5/5] x86/pti: Do not enable PTI on fixed Intel
 processors
To:     Dave Hansen <dave.hansen@intel.com>, <arjan@linux.intel.com>,
        <tglx@linutronix.de>, <karahmed@amazon.de>, <x86@kernel.org>,
        <linux-kernel@vger.kernel.org>, <tim.c.chen@linux.intel.com>,
        <bp@alien8.de>, <peterz@infradead.org>, <pbonzini@redhat.com>,
        <ak@linux.intel.com>, <torvalds@linux-foundation.org>,
        <gregkh@linux-foundation.org>, <thomas.lendacky@amd.com>
In-Reply-To: <736fa9c9-d651-b6ef-802c-d02a27c28ab9@intel.com>
References: <1516726375-25168-1-git-send-email-dwmw@amazon.co.uk>
         <1516726375-25168-6-git-send-email-dwmw@amazon.co.uk>
         <736fa9c9-d651-b6ef-802c-d02a27c28ab9@intel.com>
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Organization: Amazon
Content-Type: multipart/signed; micalg=sha-256; protocol="application/x-pkcs7-signature"; boundary="=-YO4GaE/Tdn0pblbsILMu"
Date:   Tue, 23 Jan 2018 18:44:49 +0000
MIME-Version: 1.0
From:   "Woodhouse, David" <dwmw@amazon.co.uk>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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Content-Type: text/plain; charset="UTF-8"
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On Tue, 2018-01-23 at 10:41 -0800, Dave Hansen wrote:
> On 01/23/2018 08:52 AM, David Woodhouse wrote:
> > When they advertise the IA32_ARCH_CAPABILITIES MSR and it has the RDCL_=
NO
> > bit set, they don't need KPTI either.
>=20
> Also, I hate to ask...=C2=A0 Have you tested this patch?

Nope. I deliberately haven't implemented IBRS_ALL because I have no
suitable hardware for that and there are some non-trivial parts, but
this one really *should* be trivial so seemed OK to do without
hardware.
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