From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f199.google.com (mail-wr0-f199.google.com [209.85.128.199]) by kanga.kvack.org (Postfix) with ESMTP id 9F92A6B0038 for ; Mon, 27 Nov 2017 14:01:04 -0500 (EST) Received: by mail-wr0-f199.google.com with SMTP id o14so19163042wrf.6 for ; Mon, 27 Nov 2017 11:01:04 -0800 (PST) Received: from Galois.linutronix.de (Galois.linutronix.de. [2a01:7a0:2:106d:700::1]) by mx.google.com with ESMTPS id g192si11697669wmd.16.2017.11.27.11.01.03 for (version=TLS1_2 cipher=AES128-SHA bits=128/128); Mon, 27 Nov 2017 11:01:03 -0800 (PST) Date: Mon, 27 Nov 2017 20:00:19 +0100 (CET) From: Thomas Gleixner Subject: Re: [patch V2 5/5] x86/kaiser: Add boottime disable switch In-Reply-To: <24359653-5b93-7146-8f65-ac38c3af0069@linux.intel.com> Message-ID: References: <20171126231403.657575796@linutronix.de> <20171126232414.645128754@linutronix.de> <24359653-5b93-7146-8f65-ac38c3af0069@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: LKML , 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 Mon, 27 Nov 2017, Dave Hansen wrote: > 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. Yes, it is. I'm currently trying to figure out why it fails on a KVM guest. If I boot with 'nokaiser' on the command line it works. If kaiser is runtime enabled then some early klibc user space in the ramdisk explodes. Not sure yet whats going on. Thanks, tglx -- 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