From patchwork Mon Nov 3 04:52:00 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Mackerras X-Patchwork-Id: 406019 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 08F7C1400A4 for ; Mon, 3 Nov 2014 15:52:42 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751002AbaKCEwi (ORCPT ); Sun, 2 Nov 2014 23:52:38 -0500 Received: from ozlabs.org ([103.22.144.67]:49442 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751993AbaKCEwg (ORCPT ); Sun, 2 Nov 2014 23:52:36 -0500 Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPSA id 8CB441400A3; Mon, 3 Nov 2014 15:52:34 +1100 (AEDT) From: Paul Mackerras To: Alexander Graf , kvm-ppc@vger.kernel.org Cc: kvm@vger.kernel.org, "Suresh E. Warrier" , Paul Mackerras Subject: [PATCH 5/5] KVM: PPC: Book3S HV: Check wait conditions before sleeping in kvmppc_vcore_blocked Date: Mon, 3 Nov 2014 15:52:00 +1100 Message-Id: <1414990320-6378-6-git-send-email-paulus@samba.org> X-Mailer: git-send-email 2.1.1 In-Reply-To: <1414990320-6378-1-git-send-email-paulus@samba.org> References: <1414990320-6378-1-git-send-email-paulus@samba.org> Sender: kvm-ppc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org From: "Suresh E. Warrier" The kvmppc_vcore_blocked() code does not check for the wait condition after putting the process on the wait queue. This means that it is possible for an external interrupt to become pending, but the vcpu to remain asleep until the next decrementer interrupt. The fix is to make one last check for pending exceptions and ceded state before calling schedule(). Signed-off-by: Suresh Warrier Signed-off-by: Paul Mackerras --- arch/powerpc/kvm/book3s_hv.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index cd7e030..1a7a281 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -1828,9 +1828,29 @@ static void kvmppc_wait_for_exec(struct kvm_vcpu *vcpu, int wait_state) */ static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc) { + struct kvm_vcpu *vcpu; + int do_sleep = 1; + DEFINE_WAIT(wait); prepare_to_wait(&vc->wq, &wait, TASK_INTERRUPTIBLE); + + /* + * Check one last time for pending exceptions and ceded state after + * we put ourselves on the wait queue + */ + list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list) { + if (vcpu->arch.pending_exceptions || !vcpu->arch.ceded) { + do_sleep = 0; + break; + } + } + + if (!do_sleep) { + finish_wait(&vc->wq, &wait); + return; + } + vc->vcore_state = VCORE_SLEEPING; spin_unlock(&vc->lock); schedule();