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Message-ID: <1516991212.30244.262.camel@infradead.org>
Subject: Re: [RFC 09/10] x86/enter: Create macros to restrict/unrestrict
 Indirect Branch Speculation
From:   David Woodhouse <dwmw2@infradead.org>
To:     Arjan van de Ven <arjan@linux.intel.com>,
        Andi Kleen <ak@linux.intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Dave Hansen <dave.hansen@intel.com>,
        Liran Alon <liran.alon@oracle.com>,
        Laura Abbott <labbott@redhat.com>,
        Andrew Lutomirski <luto@kernel.org>,
        Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>,
        Borislav Petkov <bp@suse.de>,
        "Mallick, Asit K" <asit.k.mallick@intel.com>,
        Radim =?UTF-8?Q?Kr=C4=8Dm=C3=A1=C5=99?= <rkrcmar@redhat.com>,
        KarimAllah Ahmed <karahmed@amazon.de>,
        Peter Anvin <hpa@zytor.com>,
        Jun Nakajima <jun.nakajima@intel.com>,
        Ingo Molnar <mingo@redhat.com>,
        the arch/x86 maintainers <x86@kernel.org>,
        Ashok Raj <ashok.raj@intel.com>,
        "Van De Ven, Arjan" <arjan.van.de.ven@intel.com>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Joerg Roedel <joro@8bytes.org>,
        Andrea Arcangeli <aarcange@redhat.com>,
        KVM list <kvm@vger.kernel.org>
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Date:   Fri, 26 Jan 2018 18:26:52 +0000
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Sender: linux-kernel-owner@vger.kernel.org
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Content-Type: text/plain; charset="UTF-8"
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On Fri, 2018-01-26 at 10:12 -0800, Arjan van de Ven wrote:
> On 1/26/2018 10:11 AM, David Woodhouse wrote:
> >=C2=A0
> > I am *actively* ignoring Skylake right now. This is about per-SKL
> > userspace even with SMEP, because we think Intel's document lies to us.
>=20
> if you think we lie to you then I think we're done with the conversation?
>=20
> Please tell us then what you deploy in AWS for your customers ?
>=20
> or show us research that shows we lied to you?

As you know well, I mean "we think Intel's document is not correct".=C2=A0

The evidence which made us suspect that is fairly clear in the last few
emails in this thread =E2=80=94 it's about the BTB/RSB only having the low =
bits
of the target, which would mean that userspace *can* put malicious
targets into the RSB, regardless of SMEP.


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