From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753661AbaKLXi1 (ORCPT ); Wed, 12 Nov 2014 18:38:27 -0500 Received: from mail-lb0-f175.google.com ([209.85.217.175]:51954 "EHLO mail-lb0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752462AbaKLXiZ (ORCPT ); Wed, 12 Nov 2014 18:38:25 -0500 MIME-Version: 1.0 In-Reply-To: References: From: Andy Lutomirski Date: Wed, 12 Nov 2014 15:38:03 -0800 Message-ID: Subject: Re: [PATCH v2 0/8] CR4 handling improvements To: Peter Zijlstra Cc: Valdis Kletnieks , "linux-kernel@vger.kernel.org" , Paul Mackerras , Arnaldo Carvalho de Melo , Ingo Molnar , Kees Cook , Andrea Arcangeli , Vince Weaver , "hillf.zj" , Andy Lutomirski Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 24, 2014 at 3:58 PM, Andy Lutomirski wrote: > This little series tightens up rdpmc permissions. With it applied, > rdpmc can only be used if a perf_event is actually mmapped. For now, > this is only really useful for seccomp. > > At some point this could be further tightened up to only allow rdpmc > if an actual self-monitoring perf event that is compatible with > rdpmc is mapped. > > This should add <50ns to context switches between rdpmc-capable and > rdpmc-non-capable mms. I suspect that this is well under 10% > overhead, given that perf already adds some context switch latency. > > I think that patches 1-3 are a good idea regardless of any rdpmc changes. > > AMD Uncore userspace rdpmc is broken by these patches (cap_user_rdpmc > will be zero), but it was broken anyway. > > Changes from v1 (aka RFC): > - Rebased on top of the KVM CR4 fix. This applies to a very recent -linus. > - Renamed the cr4 helpers (Peter, Borislav) > - Fixed buggy cr4 helpers (Hilf) > - Improved lots of comments (everyone) > - Renamed read_cr4 and write_cr4 to make sure I didn't miss anything. > (NB: This will introduce conflicts with Andi's FSGSBASE work. This is > a good thing.) > > Andy Lutomirski (7): > x86: Clean up cr4 manipulation > x86: Store a per-cpu shadow copy of CR4 > x86: Add a comment clarifying LDT context switching > perf: Add pmu callbacks to track event mapping and unmapping > perf: Pass the event to arch_perf_update_userpage > x86, perf: Only allow rdpmc if a perf_event is mapped > x86, perf: Add /sys/devices/cpu/rdpmc=2 to allow rdpmc for all tasks > > Peter Zijlstra (1): > perf: Clean up pmu::event_idx > What's the status of these? I think that "perf: Clean up pmu::event_idx" and "x86: Add a comment clarifying LDT context switching" are in -tip, the two cr4 cleanups ("x86: Clean up cr4 manipulation" and "x86: Store a per-cpu shadow copy of CR4") are reviewed but will conflict with Andi's fsgsbase work, and the rest are waiting for review. Thanks, Andy > arch/powerpc/perf/hv-24x7.c | 6 --- > arch/powerpc/perf/hv-gpci.c | 6 --- > arch/s390/kernel/perf_cpum_sf.c | 6 --- > arch/x86/include/asm/mmu.h | 2 + > arch/x86/include/asm/mmu_context.h | 32 ++++++++++++++- > arch/x86/include/asm/paravirt.h | 6 +-- > arch/x86/include/asm/processor.h | 33 ---------------- > arch/x86/include/asm/special_insns.h | 6 +-- > arch/x86/include/asm/tlbflush.h | 77 ++++++++++++++++++++++++++++++++---- > arch/x86/include/asm/virtext.h | 5 ++- > arch/x86/kernel/acpi/sleep.c | 2 +- > arch/x86/kernel/cpu/common.c | 17 +++++--- > arch/x86/kernel/cpu/mcheck/mce.c | 3 +- > arch/x86/kernel/cpu/mcheck/p5.c | 3 +- > arch/x86/kernel/cpu/mcheck/winchip.c | 3 +- > arch/x86/kernel/cpu/mtrr/cyrix.c | 6 +-- > arch/x86/kernel/cpu/mtrr/generic.c | 6 +-- > arch/x86/kernel/cpu/perf_event.c | 76 ++++++++++++++++++++++++++--------- > arch/x86/kernel/cpu/perf_event.h | 2 + > arch/x86/kernel/head32.c | 1 + > arch/x86/kernel/head64.c | 2 + > arch/x86/kernel/i387.c | 3 +- > arch/x86/kernel/process.c | 5 ++- > arch/x86/kernel/process_32.c | 2 +- > arch/x86/kernel/process_64.c | 2 +- > arch/x86/kernel/setup.c | 2 +- > arch/x86/kernel/xsave.c | 3 +- > arch/x86/kvm/svm.c | 2 +- > arch/x86/kvm/vmx.c | 10 ++--- > arch/x86/mm/fault.c | 2 +- > arch/x86/mm/init.c | 12 +++++- > arch/x86/mm/tlb.c | 3 -- > arch/x86/power/cpu.c | 11 ++---- > arch/x86/realmode/init.c | 2 +- > arch/x86/xen/enlighten.c | 4 +- > drivers/lguest/x86/core.c | 4 +- > include/linux/perf_event.h | 7 ++++ > kernel/events/core.c | 29 ++++++-------- > kernel/events/hw_breakpoint.c | 7 ---- > 39 files changed, 256 insertions(+), 154 deletions(-) > > -- > 1.9.3 > -- Andy Lutomirski AMA Capital Management, LLC