From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754274AbbCECPe (ORCPT ); Wed, 4 Mar 2015 21:15:34 -0500 Received: from mail-we0-f169.google.com ([74.125.82.169]:35392 "EHLO mail-we0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754007AbbCECPU (ORCPT ); Wed, 4 Mar 2015 21:15:20 -0500 From: Frederic Weisbecker To: LKML Cc: Rik van Riel , Paolo Bonzini , Alexander Graf , Luiz Capitulino , Christian Borntraeger , Benjamin Herrenschmidt , Marcelo Tosatti , "Paul E . McKenney" , Andy Lutomirski , Will deacon , Frederic Weisbecker Subject: [PATCH 7/7] kvm,rcu,nohz: use RCU extended quiescent state when running KVM guest Date: Thu, 5 Mar 2015 03:14:56 +0100 Message-Id: <1425521696-4471-8-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1425521696-4471-1-git-send-email-fweisbec@gmail.com> References: <1425521696-4471-1-git-send-email-fweisbec@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rik van Riel The host kernel is not doing anything while the CPU is executing a KVM guest VCPU, so it can be marked as being in an extended quiescent state, identical to that used when running user space code. The only exception to that rule is when the host handles an interrupt, which is already handled by the irq code, which calls rcu_irq_enter and rcu_irq_exit. The guest_enter and guest_exit functions already switch vtime accounting independent of context tracking. Leave those calls where they are, instead of moving them into the context tracking code. Reviewed-by: Paul E. McKenney Signed-off-by: Rik van Riel Cc: Paul E. McKenney Cc: Andy Lutomirski Cc: Will deacon Cc: Marcelo Tosatti Cc: Christian Borntraeger Cc: Luiz Capitulino Cc: Paolo Bonzini Signed-off-by: Frederic Weisbecker --- include/linux/context_tracking.h | 6 ++++++ include/linux/context_tracking_state.h | 1 + include/linux/kvm_host.h | 3 ++- 3 files changed, 9 insertions(+), 1 deletion(-) diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h index 7f1810a..2821838 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -81,10 +81,16 @@ static inline void guest_enter(void) vtime_guest_enter(current); else current->flags |= PF_VCPU; + + if (context_tracking_is_enabled()) + context_tracking_enter(CONTEXT_GUEST); } static inline void guest_exit(void) { + if (context_tracking_is_enabled()) + context_tracking_exit(CONTEXT_GUEST); + if (vtime_accounting_enabled()) vtime_guest_exit(current); else diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h index ad44585..6b7b96a 100644 --- a/include/linux/context_tracking_state.h +++ b/include/linux/context_tracking_state.h @@ -15,6 +15,7 @@ struct context_tracking { enum ctx_state { CONTEXT_KERNEL = 0, CONTEXT_USER, + CONTEXT_GUEST, } state; }; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index d12b210..cc8c61c 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -766,7 +766,8 @@ static inline void kvm_guest_enter(void) * one time slice). Lets treat guest mode as quiescent state, just like * we do with user-mode execution. */ - rcu_virt_note_context_switch(smp_processor_id()); + if (!context_tracking_cpu_is_enabled()) + rcu_virt_note_context_switch(smp_processor_id()); } static inline void kvm_guest_exit(void) -- 2.1.4