From nobody Tue Oct 28 01:48:53 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.zohomail.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 1516211358260808.8743380461347; Wed, 17 Jan 2018 09:49:18 -0800 (PST) Received: from localhost ([::1]:51086 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ebrpp-0006z7-U5 for importer@patchew.org; Wed, 17 Jan 2018 12:49:13 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46778) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ebriO-0008Vl-Gl for qemu-devel@nongnu.org; Wed, 17 Jan 2018 12:41:33 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ebriL-0007s7-BV for qemu-devel@nongnu.org; Wed, 17 Jan 2018 12:41:32 -0500 Received: from mx1.redhat.com ([209.132.183.28]:44706) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ebriL-0007qw-66; Wed, 17 Jan 2018 12:41:29 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 288DBC056820; Wed, 17 Jan 2018 17:41:28 +0000 (UTC) Received: from t460s.redhat.com (ovpn-117-185.ams2.redhat.com [10.36.117.185]) by smtp.corp.redhat.com (Postfix) with ESMTP id 25F8A5D756; Wed, 17 Jan 2018 17:41:25 +0000 (UTC) From: David Hildenbrand To: qemu-s390x@nongnu.org, qemu-devel@nongnu.org Date: Wed, 17 Jan 2018 18:40:36 +0100 Message-Id: <20180117174047.6382-8-david@redhat.com> In-Reply-To: <20180117174047.6382-1-david@redhat.com> References: <20180117174047.6382-1-david@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Wed, 17 Jan 2018 17:41:28 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v2 07/18] s390x/tcg: tolerate wrong wakeups due to floating interrupts 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: Thomas Huth , David Hildenbrand , Cornelia Huck , Alexander Graf , Christian Borntraeger , Richard Henderson 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" This is a prparation for floating interrupt support and only applies to MTTCG, single threaded TCG works just fine. If a floating interrupt wakes up a VCPU and the CPU thinks it can run (clearing cs->halted), at the point where the interrupt would be delivered, already another VCPU might have picked up the interrupt, resulting in a wakeup without an interrupt (executing wrong code). It is wrong to let the VCPU continue to execute (the WAIT PSW). Instead, we have to put the VCPU back to sleep. Signed-off-by: David Hildenbrand --- target/s390x/excp_helper.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/target/s390x/excp_helper.c b/target/s390x/excp_helper.c index a18842ccbd..eeffb49f63 100644 --- a/target/s390x/excp_helper.c +++ b/target/s390x/excp_helper.c @@ -503,6 +503,11 @@ bool s390_cpu_exec_interrupt(CPUState *cs, int interru= pt_request) s390_cpu_do_interrupt(cs); return true; } + if (env->psw.mask & PSW_MASK_WAIT) { + /* Woken up because of a floating interrupt but it has already + * been delivered. Go back to sleep. */ + cpu_interrupt(CPU(cpu), CPU_INTERRUPT_HALT); + } } return false; } --=20 2.14.3