From patchwork Thu Jan 27 13:09:58 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Kiszka X-Patchwork-Id: 80676 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [199.232.76.165]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 574D2B7139 for ; Fri, 28 Jan 2011 00:13:38 +1100 (EST) Received: from localhost ([127.0.0.1]:35470 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PiRfK-0002tR-QL for incoming@patchwork.ozlabs.org; Thu, 27 Jan 2011 08:13:34 -0500 Received: from [140.186.70.92] (port=49390 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PiRc9-0001SK-SV for qemu-devel@nongnu.org; Thu, 27 Jan 2011 08:10:26 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PiRc7-0000kw-3W for qemu-devel@nongnu.org; Thu, 27 Jan 2011 08:10:17 -0500 Received: from david.siemens.de ([192.35.17.14]:19701) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PiRc6-0000jc-8E for qemu-devel@nongnu.org; Thu, 27 Jan 2011 08:10:14 -0500 Received: from mail1.siemens.de (localhost [127.0.0.1]) by david.siemens.de (8.12.11.20060308/8.12.11) with ESMTP id p0RDAB1e029863; Thu, 27 Jan 2011 14:10:11 +0100 Received: from mchn199C.mchp.siemens.de ([139.25.109.49]) by mail1.siemens.de (8.13.6/8.13.6) with ESMTP id p0RDA730009974; Thu, 27 Jan 2011 14:10:11 +0100 From: Jan Kiszka To: Avi Kivity , Marcelo Tosatti Date: Thu, 27 Jan 2011 14:09:58 +0100 Message-Id: X-Mailer: git-send-email 1.7.1 In-Reply-To: References: In-Reply-To: References: X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.4-2.6 Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org, Stefan Hajnoczi Subject: [Qemu-devel] [PATCH 14/22] kvm: Fix race between timer signals and vcpu entry under !IOTHREAD X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Found by Stefan Hajnoczi: There is a race in kvm_cpu_exec between checking for exit_request on vcpu entry and timer signals arriving before KVM starts to catch them. Plug it by blocking both timer related signals also on !CONFIG_IOTHREAD and process those via signalfd. Signed-off-by: Jan Kiszka CC: Stefan Hajnoczi --- cpus.c | 18 ++++++++++++++++++ 1 files changed, 18 insertions(+), 0 deletions(-) diff --git a/cpus.c b/cpus.c index fc3f222..29b1070 100644 --- a/cpus.c +++ b/cpus.c @@ -254,6 +254,10 @@ static void qemu_kvm_init_cpu_signals(CPUState *env) pthread_sigmask(SIG_BLOCK, NULL, &set); sigdelset(&set, SIG_IPI); sigdelset(&set, SIGBUS); +#ifndef CONFIG_IOTHREAD + sigdelset(&set, SIGIO); + sigdelset(&set, SIGALRM); +#endif r = kvm_set_signal_mask(env, &set); if (r) { fprintf(stderr, "kvm_set_signal_mask: %s\n", strerror(-r)); @@ -351,6 +355,12 @@ static void qemu_kvm_eat_signals(CPUState *env) exit(1); } } while (sigismember(&chkset, SIG_IPI) || sigismember(&chkset, SIGBUS)); + +#ifndef CONFIG_IOTHREAD + if (sigismember(&chkset, SIGIO) || sigismember(&chkset, SIGALRM)) { + qemu_notify_event(); + } +#endif } #else /* _WIN32 */ @@ -398,6 +408,14 @@ int qemu_init_main_loop(void) int ret; sigemptyset(&blocked_signals); + if (kvm_enabled()) { + /* + * We need to process timer signals synchronously to avoid a race + * between exit_request check and KVM vcpu entry. + */ + sigaddset(&blocked_signals, SIGIO); + sigaddset(&blocked_signals, SIGALRM); + } ret = qemu_signalfd_init(blocked_signals); if (ret) {