From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751899AbdFHIWU (ORCPT ); Thu, 8 Jun 2017 04:22:20 -0400 Received: from mail-pf0-f196.google.com ([209.85.192.196]:34789 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751868AbdFHIWP (ORCPT ); Thu, 8 Jun 2017 04:22:15 -0400 From: Wanpeng Li X-Google-Original-From: Wanpeng Li To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Wanpeng Li Subject: [PATCH v2 2/2] KVM: async_pf: rcu irq exit if not triggered from idle task Date: Thu, 8 Jun 2017 01:22:08 -0700 Message-Id: <1496910128-87057-2-git-send-email-wanpeng.li@hotmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1496910128-87057-1-git-send-email-wanpeng.li@hotmail.com> References: <1496910128-87057-1-git-send-email-wanpeng.li@hotmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Wanpeng Li Commit 9b132fbe5419 (Add rcu user eqs exception hooks for async page fault) adds rcu_irq_enter/exit() to kvm_async_pf_task_wait() to exit cpu idle eqs when needed, to protect the code that needs use rcu. There is no need to call this pairs if async page fault is not triggered from idle task. This patch invokes rcu irq exit if it is not triggered from idle task. Cc: Paolo Bonzini Cc: Radim Krčmář Signed-off-by: Wanpeng Li --- v1 -> v2: * update patch description arch/x86/kernel/kvm.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 43e10d6..e70ed72 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -141,6 +141,8 @@ void kvm_async_pf_task_wait(u32 token) n.token = token; n.cpu = smp_processor_id(); n.halted = is_idle_task(current) || preempt_count() > 1; + if (!n.halted) + rcu_irq_exit(); init_swait_queue_head(&n.wq); hlist_add_head(&n.link, &b->list); raw_spin_unlock(&b->lock); @@ -167,8 +169,9 @@ void kvm_async_pf_task_wait(u32 token) } if (!n.halted) finish_swait(&n.wq, &wait); + else + rcu_irq_exit(); - rcu_irq_exit(); return; } EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait); -- 2.7.4