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SubjectRe: [PATCH v2 0/8] CR4 handling improvements
On Fri, Oct 24, 2014 at 3:58 PM, Andy Lutomirski <luto@amacapital.net> 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


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