From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id 261516B0033 for ; Mon, 27 Nov 2017 13:22:55 -0500 (EST) Received: by mail-pf0-f199.google.com with SMTP id h21so23272209pfk.14 for ; Mon, 27 Nov 2017 10:22:55 -0800 (PST) Received: from mga07.intel.com (mga07.intel.com. [134.134.136.100]) by mx.google.com with ESMTPS id f84si26016097pfh.71.2017.11.27.10.22.54 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 27 Nov 2017 10:22:54 -0800 (PST) Subject: Re: [patch V2 5/5] x86/kaiser: Add boottime disable switch References: <20171126231403.657575796@linutronix.de> <20171126232414.645128754@linutronix.de> From: Dave Hansen Message-ID: <24359653-5b93-7146-8f65-ac38c3af0069@linux.intel.com> Date: Mon, 27 Nov 2017 10:22:52 -0800 MIME-Version: 1.0 In-Reply-To: <20171126232414.645128754@linutronix.de> Content-Type: text/plain; charset=iso-8859-15 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Thomas Gleixner , LKML Cc: Andy Lutomirski , Ingo Molnar , Borislav Petkov , Brian Gerst , Denys Vlasenko , "H. Peter Anvin" , Josh Poimboeuf , Linus Torvalds , Peter Zijlstra , Rik van Riel , daniel.gruss@iaik.tugraz.at, hughd@google.com, keescook@google.com, linux-mm@kvack.org, michael.schwarz@iaik.tugraz.at, moritz.lipp@iaik.tugraz.at, richard.fellner@student.tugraz.at On 11/26/2017 03:14 PM, Thomas Gleixner wrote: > --- a/security/Kconfig > +++ b/security/Kconfig > @@ -56,7 +56,7 @@ config SECURITY_NETWORK > > config KAISER > bool "Remove the kernel mapping in user mode" > - depends on X86_64 && SMP && !PARAVIRT > + depends on X86_64 && SMP && !PARAVIRT && JUMP_LABEL > help > This feature reduces the number of hardware side channels by > ensuring that the majority of kernel addresses are not mapped One of the reasons for doing the runtime-disable was to get rid of the !PARAVIRT dependency. I can add a follow-on here that will act as if we did "nokaiser" whenever Xen is in play so we can remove this dependency. I just hope Xen is detectable early enough to do the static patching. -- 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