From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linus971@gmail.com>
ARC-Seal: i=1; a=rsa-sha256; t=1516987150; cv=none;
        d=google.com; s=arc-20160816;
        b=QwlIFqbPVvAOSzUuO09rn1eFBRAv/rpUb+c3RwwyriJEC5fUwxGmtmt1cSBr4miyye
         blLs3grOapt+/a+qUctXGB6CPlgChbOCeUmWGuf5yZrsAxJpku0NJdYuYz+30GZlG7bp
         mBsuVSdy0w95ln15Xxhkd3HfmN2F38pjNDDe2cwLGqqmyZv6zubJ3wG1awJjSBNjgmwa
         mb0Bmy/9jBoeh772ziC5pBzQfTPD1z1n6Vi6KsUP8bQhhR6w/UGfD/uDLyseZNhXUgrF
         gOHT773vXT6r4t4UVWihEUuEMn5ShGxV8URwyEga2A09OKlA7j6qBS4qUPOUKFoaIsxN
         k4NQ==
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816;
        h=cc:to:subject:message-id:date:from:references:in-reply-to:sender
         :mime-version:dkim-signature:arc-authentication-results;
        bh=HotFzytKH1QmXoDvZYqvACFg7iIX6uR6TgVTsmGHpeg=;
        b=ZiujDjzNssOeiFxvvzT9qkoN8MoMO31Tfl25rXk5Pn+hoHEhpUTvkoLKwQkILlxGez
         fRz8755V57GcRLQoQRJOgfXhk2S6SuPi6ySS3rMyAO4MrVO2wkKJ0qhmEkHe1KxejiM8
         xv+rqnLRtcpD2ueG2DWxGz5Ualvo15aUurWi7VIjDjsK2Smhe4u+mTheikCxJg5uPLoq
         Cv0+WSi/guXa11GVp/uUmxaoKsV80EP097/+wwvfeyzJZxD27hUfqrr8EESx5Oo0/je/
         gHxRSEblUjmuk+hGxkwCG4QbEv2gJqg9lse4OMQ/KbnJvpXobETSmANggT9yxXgX+8Qp
         /Yyw==
ARC-Authentication-Results: i=1; mx.google.com;
       dkim=pass header.i=@gmail.com header.s=20161025 header.b=U0UOzKIk;
       spf=pass (google.com: domain of linus971@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=linus971@gmail.com
Authentication-Results: mx.google.com;
       dkim=pass header.i=@gmail.com header.s=20161025 header.b=U0UOzKIk;
       spf=pass (google.com: domain of linus971@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=linus971@gmail.com
X-Google-Smtp-Source: AH8x2253JcnQqiF3AXYdvph2LIWv6EfyMp42PA3mSAlaxN6bu21GLohboH8Bz7UuJBj7YPTv7SveAPS4l5c5uGBdzcs=
MIME-Version: 1.0
Sender: linus971@gmail.com
In-Reply-To: <1516957886.30244.161.camel@infradead.org>
References: <7c0b0879-3448-43e4-8380-4708fc787113@default> <50c5d627-8975-184b-b50f-4cc02c5816c5@intel.com>
 <1516957886.30244.161.camel@infradead.org>
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Fri, 26 Jan 2018 09:19:09 -0800
X-Google-Sender-Auth: H0yNY1lbfoain1YWVePKM_JFofg
Message-ID: <CA+55aFxRsAh_dv6aoDNj+yqzcgzctda0ETZ_2DbjMwSZDwPLDA@mail.gmail.com>
Subject: Re: [RFC 09/10] x86/enter: Create macros to restrict/unrestrict
 Indirect Branch Speculation
To: David Woodhouse <dwmw2@infradead.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>, =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <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>, Andi Kleen <ak@linux.intel.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>, Arjan van de Ven <arjan@linux.intel.com>,
	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>
Content-Type: text/plain; charset="UTF-8"
X-getmail-retrieved-from-mailbox: INBOX
X-GMAIL-THRID: =?utf-8?q?1590140582166248265?=
X-GMAIL-MSGID: =?utf-8?q?1590676318387216772?=
X-Mailing-List: linux-kernel@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>

On Fri, Jan 26, 2018 at 1:11 AM, David Woodhouse <dwmw2@infradead.org> wrote:
>
> Do we need to look again at the fact that we've disabled the RSB-
> stuffing for SMEP?

Absolutely. SMEP helps make people a lot less worried about things,
but it doesn't fix the "BTB only contains partial addresses" case.

But did we do that "disable stuffing with SMEP"? I'm not seeing it. In
my tree, it's only conditional on X86_FEATURE_RETPOLINE.

                   Linus