From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f197.google.com (mail-pf0-f197.google.com [209.85.192.197]) by kanga.kvack.org (Postfix) with ESMTP id D811F6B025E for ; Mon, 27 Nov 2017 22:37:03 -0500 (EST) Received: by mail-pf0-f197.google.com with SMTP id s9so12205653pfe.20 for ; Mon, 27 Nov 2017 19:37:03 -0800 (PST) Received: from mail.kernel.org (mail.kernel.org. [198.145.29.99]) by mx.google.com with ESMTPS id d4si2644613pgc.216.2017.11.27.19.37.02 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 27 Nov 2017 19:37:02 -0800 (PST) Received: from mail-it0-f52.google.com (mail-it0-f52.google.com [209.85.214.52]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 419BB219A3 for ; Tue, 28 Nov 2017 03:37:02 +0000 (UTC) Received: by mail-it0-f52.google.com with SMTP id t1so6687211ite.5 for ; Mon, 27 Nov 2017 19:37:02 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20171127223405.231444600@infradead.org> References: <20171127223110.479550152@infradead.org> <20171127223405.231444600@infradead.org> From: Andy Lutomirski Date: Mon, 27 Nov 2017 19:36:40 -0800 Message-ID: Subject: Re: [PATCH 2/5] x86/mm/kaiser: Add a banner Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: "linux-kernel@vger.kernel.org" , Dave Hansen , Andy Lutomirski , Ingo Molnar , Borislav Petkov , Brian Gerst , Denys Vlasenko , "H. Peter Anvin" , Josh Poimboeuf , Linus Torvalds , Rik van Riel , Daniel Gruss , Hugh Dickins , Kees Cook , "linux-mm@kvack.org" , michael.schwarz@iaik.tugraz.at, moritz.lipp@iaik.tugraz.at, richard.fellner@student.tugraz.at On Mon, Nov 27, 2017 at 2:31 PM, Peter Zijlstra wrote: > So we can more easily see if the shiny got enabled. > > Signed-off-by: Peter Zijlstra (Intel) > --- > arch/x86/mm/kaiser.c | 2 ++ > 1 file changed, 2 insertions(+) > > --- a/arch/x86/mm/kaiser.c > +++ b/arch/x86/mm/kaiser.c > @@ -425,6 +425,8 @@ void __init kaiser_init(void) > if (!kaiser_enabled) > return; > > + printk("All your KAISER are belong to us\n"); > + All your incomprehensible academic names are belong to us. On a serious note, can we please banish the name KAISER from all the user-facing bits? No one should be setting a boot option that has a name based on an academic project called "Kernel Address Isolation to have Side-channels Efficiently Removed". We're not efficiently removing side channels. The side channels are still very much there. Heck, the series as currently presented doesn't even rescue kASLR. It could*, if we were to finish the work that I mostly started and completely banish all the normal kernel mappings from the shadow** tables. We're rather inefficiently (and partially!) mitigating the fact that certain CPU designers have had their heads up their collective arses for *years* and have failed to pay attention to numerous academic papers documenting that fact. Let's call the user facing bits "separate user pagetables". If we want to make it conditioned on a future cpu cap called X86_BUG_REALLY_DUMB_SIDE_CHANNELS, great, assuming a better CPU ever shows up. But please let's not make users look up WTF "KAISER" means. * No one ever documented the %*!& side channels AFAIK, so everything we're talking about here is mostly speculation. ** The word "shadow" needs to die, too. I know what shadow page tables are, and they have *nothing* to do with KAISER. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org