Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932906AbbBJOl6 (ORCPT ); Tue, 10 Feb 2015 09:41:58 -0500 Received: from shelob.surriel.com ([74.92.59.67]:40246 "EHLO shelob.surriel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756174AbbBJOl4 (ORCPT ); Tue, 10 Feb 2015 09:41:56 -0500 From: riel@redhat.com To: paulmck@linux.vnet.ibm.com Cc: will.deacon@arm.com, linux-kernel@vger.kernel.org, Catalin.Marinas@arm.com, fweisbec@gmail.com, kvm@vger.kernel.org, mtosatti@redhat.com, borntraeger@de.ibm.com, mingo@kernel.org, oleg@redhat.com, lcapitulino@redhat.com, pbonzini@redhat.com Subject: [PATCH 6/6] kvm,rcu,nohz: use RCU extended quiescent state when running KVM guest Date: Tue, 10 Feb 2015 09:41:50 -0500 Message-Id: <1423579310-24555-7-git-send-email-riel@redhat.com> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1423579310-24555-1-git-send-email-riel@redhat.com> References: <1423579310-24555-1-git-send-email-riel@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2566 Lines: 78 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. Signed-off-by: Rik van Riel --- 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 954253283709..b65fd1420e53 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -80,10 +80,16 @@ static inline void guest_enter(void) vtime_guest_enter(current); else current->flags |= PF_VCPU; + + if (context_tracking_is_enabled()) + context_tracking_enter(IN_GUEST); } static inline void guest_exit(void) { + if (context_tracking_is_enabled()) + context_tracking_exit(IN_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 72ab10fe1e46..90a7bab8779e 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 { IN_KERNEL = 0, IN_USER, + IN_GUEST, } state; }; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 26f106022c88..c7828a6a9614 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -772,7 +772,8 @@ 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) -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/