From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wanpeng Li Subject: [PATCH v7 0/2] x86/apic: x2apic write eoi msr notrace Date: Mon, 31 Oct 2016 09:37:00 +0800 Message-ID: <1477877822-4437-1-git-send-email-wanpeng.li@hotmail.com> Cc: Ingo Molnar , Mike Galbraith , Peter Zijlstra , Thomas Gleixner , Paolo Bonzini , Borislav Petkov , Wanpeng Li To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Return-path: Received: from mail-pf0-f193.google.com ([209.85.192.193]:35250 "EHLO mail-pf0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756822AbcJaBhK (ORCPT ); Sun, 30 Oct 2016 21:37:10 -0400 Sender: kvm-owner@vger.kernel.org List-ID: | RCU used illegally from idle CPU! | rcu_scheduler_active = 1, debug_locks = 0 | RCU used illegally from extended quiescent state! | no locks held by swapper/1/0. | | [] do_trace_write_msr+0x135/0x140 | [] native_write_msr+0x20/0x30 | [] native_apic_msr_eoi_write+0x1d/0x30 | [] smp_reschedule_interrupt+0x1d/0x30 | [] reschedule_interrupt+0x96/0xa0 Reschedule interrupt may be called in cpu idle state. This causes lockdep check warning above. As Peterz pointed out: | The thing is, many many smp_reschedule_interrupt() invocations don't | actually execute anything much at all and are only send to tickle the | return to user path (which does the actual preemption). | | Having to do the whole irq_enter/irq_exit dance just for this unlikely | debug case totally blows. This patchset adds x2apic write eoi msr notrace to avoid the debug codes splash and reverts irq_enter/irq_exit dance to avoid to make a very frequent interrupt slower because of debug code. v6 -> v7: * cleanup storage class should be at the beginning of the declaration v5 -> v6: * split the patch * don't duplicate the inline asm v4 -> v5: * add notrace mark v3 -> v4: * add notrace mark v2 -> v3: * revert irq_enter/irq_exit() since it is merged v1 -> v2: * add write msr notrace to avoid debug codes splash instead of slowdown a very frequent interrupt Wanpeng Li (2): x86/msr: Add write msr notrace x86/apic: x2apic write eoi msr notrace arch/x86/include/asm/apic.h | 3 ++- arch/x86/include/asm/msr.h | 14 +++++++++++++- arch/x86/kernel/apic/apic.c | 1 + arch/x86/kernel/kvm.c | 4 ++-- arch/x86/kernel/smp.c | 2 -- 5 files changed, 18 insertions(+), 6 deletions(-) -- 1.9.1