Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932404AbdCIOB5 (ORCPT ); Thu, 9 Mar 2017 09:01:57 -0500 Received: from www62.your-server.de ([213.133.104.62]:47921 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753913AbdCIOB4 (ORCPT ); Thu, 9 Mar 2017 09:01:56 -0500 Message-ID: <58C157E6.1010909@iogearbox.net> Date: Thu, 09 Mar 2017 14:25:58 +0100 From: Daniel Borkmann User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Thomas Gleixner CC: Kees Cook , Laura Abbott , Linus Torvalds , Ingo Molnar , Peter Anvin , Fengguang Wu , Network Development , LKML , LKP , ast@fb.com, the arch/x86 maintainers , "David S. Miller" Subject: Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request at 0000a7cf References: <20170301125426.l4nf65rx4wahohyl@wfg-t540p.sh.intel.com> <20170302202338.ci6wwb3yzjmdy4n2@wfg-t540p.sh.intel.com> <58B88353.2010508@iogearbox.net> <58C08535.3070000@iogearbox.net> <7af7bcc9-9115-be9f-2240-a022487e9b70@redhat.com> <58C152F1.9090004@iogearbox.net> In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated-Sender: daniel@iogearbox.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1026 Lines: 31 On 03/09/2017 02:10 PM, Thomas Gleixner wrote: > On Thu, 9 Mar 2017, Daniel Borkmann wrote: >> With regard to CPA_FLUSHTLB that Linus mentioned, when I investigated >> code paths in change_page_attr_set_clr(), I did see that CPA_FLUSHTLB >> was set each time we switched attrs and a cpa_flush_range() was >> performed (with the correct number of pages and cache set to 0). That >> would be a __flush_tlb_all() eventually. >> >> Hmm, it indeed might seem likely that this could be an emulation bug. > > Which variant of __flush_tlb_all() is used when the test fails? > > Check for the following flags in /proc/cpuinfo: pge invpcid I added the following and booted with both variants: printk("X86_FEATURE_PGE:%u\n", static_cpu_has(X86_FEATURE_PGE)); printk("X86_FEATURE_INVPCID:%u\n", static_cpu_has(X86_FEATURE_INVPCID)); "-cpu host" gives: [ 8.326117] X86_FEATURE_PGE:1 [ 8.326381] X86_FEATURE_INVPCID:1 "-cpu kvm64" gives: [ 8.517069] X86_FEATURE_PGE:1 [ 8.517393] X86_FEATURE_INVPCID:0 Thanks, Daniel