From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752197AbeCWRqu (ORCPT ); Fri, 23 Mar 2018 13:46:50 -0400 Received: from mga07.intel.com ([134.134.136.100]:25876 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751790AbeCWRqt (ORCPT ); Fri, 23 Mar 2018 13:46:49 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.48,351,1517904000"; d="scan'208";a="41609357" Subject: [PATCH 00/11] Use global pages with PTI To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Dave Hansen , aarcange@redhat.com, luto@kernel.org, torvalds@linux-foundation.org, keescook@google.com, hughd@google.com, jgross@suse.com, x86@kernel.org, namit@vmware.com From: Dave Hansen Date: Fri, 23 Mar 2018 10:44:47 -0700 Message-Id: <20180323174447.55F35636@viggo.jf.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The later verions of the KAISER pathces (pre-PTI) allowed the user/kernel shared areas to be GLOBAL. The thought was that this would reduce the TLB overhead of keeping two copies of these mappings. During the switch over to PTI, we seem to have lost our ability to have GLOBAL mappings. This adds them back. This adds one major change from the last version of the patch set (present in the last patch). It makes all kernel text global for non- PCID systems. This keeps kernel data protected always, but means that it will be easier to find kernel gadgets via meltdown on old systems without PCIDs. This heuristic is, I think, a reasonable one and it keeps us from having to create any new pti=foo options Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Linus Torvalds Cc: Kees Cook Cc: Hugh Dickins Cc: Juergen Gross Cc: x86@kernel.org Cc: Nadav Amit