Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751686AbdLBKiN (ORCPT ); Sat, 2 Dec 2017 05:38:13 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:54279 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751428AbdLBKiM (ORCPT ); Sat, 2 Dec 2017 05:38:12 -0500 Date: Sat, 2 Dec 2017 11:38:09 +0100 (CET) From: Thomas Gleixner To: Andy Lutomirski cc: X86 ML , Borislav Petkov , "linux-kernel@vger.kernel.org" , Brian Gerst , Dave Hansen , Linus Torvalds , Josh Poimboeuf Subject: Re: [PATCH 2/2] x86/kpti: Reference all cpu_entry_area pagetables in the usermode tables In-Reply-To: <6b7540535dccc043cee1a2d2e399e1eebf9eb332.1512195450.git.luto@kernel.org> Message-ID: References: <6b7540535dccc043cee1a2d2e399e1eebf9eb332.1512195450.git.luto@kernel.org> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 732 Lines: 21 On Fri, 1 Dec 2017, Andy Lutomirski wrote: > We were manually configuring cpu_entry_area in the usermode tables. > This was error-prone and wasted memory. (Not much memory, but > still.) Instead, just reference the same pagetables. > > This avoids needing to keep the KPTI code and the normal > cpu_entry_area code in sync, since the KPTI code no longer cares > what's in cpu_entry_area. > > [This does *not* work on the current KPTI series. It requires that > all the kernelmode cpu_entry_tables are pre-allocated. That > happens in the series as I submitted it, but tglx changed it for > reasons that I haven't figured out.] As I said it crashed and burned for yet unknown reasons. I'll dig into that. Thanks, tglx