From nobody Sat Jul 12 14:55:48 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1486016028924348.35209816147085; Wed, 1 Feb 2017 22:13:48 -0800 (PST) Received: from localhost ([::1]:54527 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cZAeQ-0005aO-7v for importer@patchew.org; Thu, 02 Feb 2017 01:13:46 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51881) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cZ9jy-0007Yt-Fc for qemu-devel@nongnu.org; Thu, 02 Feb 2017 00:15:31 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cZ9jt-0003xK-Me for qemu-devel@nongnu.org; Thu, 02 Feb 2017 00:15:26 -0500 Received: from ozlabs.org ([103.22.144.67]:51163) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cZ9jt-0003si-7Z; Thu, 02 Feb 2017 00:15:21 -0500 Received: by ozlabs.org (Postfix, from userid 1007) id 3vDSqS6gK2z9s8R; Thu, 2 Feb 2017 16:15:00 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1486012500; bh=Mta/QDiEQeVeUY/vxXgts7JUywNNmAgRS95rOoq/M08=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bl2azmQFL4H2fWsrM/ISSsl3HZwP7HzFTFTtQ5wWpaibdLh68lQChDv5IzgFePrzY jpdAXjOcfqd5IxZOK3g/0inCxshkgFfIzKsMBfAgOtfz5bVf0vHHMq7QfpNIYlyoXI xnmTtlQnrz/lAReOKMn3qzA64U7ZtitgyIHs5BQ8= From: David Gibson To: peter.maydell@linaro.org Date: Thu, 2 Feb 2017 16:14:04 +1100 Message-Id: <20170202051445.5735-67-david@gibson.dropbear.id.au> X-Mailer: git-send-email 2.9.3 In-Reply-To: <20170202051445.5735-1-david@gibson.dropbear.id.au> References: <20170202051445.5735-1-david@gibson.dropbear.id.au> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 103.22.144.67 Subject: [Qemu-devel] [PULL 066/107] ppc: Prevent inifnite loop in decrementer auto-reload. X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: lvivier@redhat.com, thuth@redhat.com, Roman Kapl , qemu-devel@nongnu.org, mdroth@linux.vnet.ibm.com, agraf@suse.de, aik@ozlabs.ru, qemu-ppc@nongnu.org, David Gibson Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Roman Kapl If the DECAR register is set to 0, QEMU tries to reload the decrementer with zero in an inifinite loop. According to PPC documentation, the decrementer = is triggered on 1->0 transition, so avoid reloading the decrementer if if is already zero. The problem does not manifest under Linux, but it is valid to set DECAR to = zero (and may make sense as part of decrementer initialization when interrupts a= re disabled). Signed-off-by: Roman Kapl [dwg: Fixed style nit] Signed-off-by: David Gibson --- hw/ppc/ppc_booke.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/hw/ppc/ppc_booke.c b/hw/ppc/ppc_booke.c index ab8d026..60baffa 100644 --- a/hw/ppc/ppc_booke.c +++ b/hw/ppc/ppc_booke.c @@ -198,8 +198,12 @@ static void booke_decr_cb(void *opaque) booke_update_irq(cpu); =20 if (env->spr[SPR_BOOKE_TCR] & TCR_ARE) { - /* Auto Reload */ - cpu_ppc_store_decr(env, env->spr[SPR_BOOKE_DECAR]); + /* Do not reload 0, it is already there. It would just trigger + * the timer again and lead to infinite loop */ + if (env->spr[SPR_BOOKE_DECAR] !=3D 0) { + /* Auto Reload */ + cpu_ppc_store_decr(env, env->spr[SPR_BOOKE_DECAR]); + } } } =20 --=20 2.9.3