{"id":2224567,"url":"http://patchwork.ozlabs.org/api/1.2/patches/2224567/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20260417154332.849664-2-jhkim@linux.ibm.com/","project":{"id":14,"url":"http://patchwork.ozlabs.org/api/1.2/projects/14/?format=json","name":"QEMU Development","link_name":"qemu-devel","list_id":"qemu-devel.nongnu.org","list_email":"qemu-devel@nongnu.org","web_url":"","scm_url":"","webscm_url":"","list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260417154332.849664-2-jhkim@linux.ibm.com>","list_archive_url":null,"date":"2026-04-17T15:43:08","name":"[RFC,v1,1/1] hw/s390x/ccw: Disable legacy virtio-pci by default (v11.1+)","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"7df9fc37e0d925a6db6173055e6db602e12ae22a","submitter":{"id":91012,"url":"http://patchwork.ozlabs.org/api/1.2/people/91012/?format=json","name":"Jaehoon Kim","email":"jhkim@linux.ibm.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20260417154332.849664-2-jhkim@linux.ibm.com/mbox/","series":[{"id":500368,"url":"http://patchwork.ozlabs.org/api/1.2/series/500368/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/list/?series=500368","date":"2026-04-17T15:43:08","name":"hw/s390x/ccw: Disable legacy mode","version":1,"mbox":"http://patchwork.ozlabs.org/series/500368/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2224567/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2224567/checks/","tags":{},"related":[],"headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256\n header.s=pp1 header.b=jWy4Ph/+;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; helo=lists1p.gnu.org;\n envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n receiver=patchwork.ozlabs.org)"],"Received":["from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17])\n\t(using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fxzhk46ksz1yD3\n\tfor ; Sat, 18 Apr 2026 01:44:37 +1000 (AEST)","from localhost ([::1] helo=lists1p.gnu.org)\n\tby lists1p.gnu.org with esmtp (Exim 4.90_1)\n\t(envelope-from )\n\tid 1wDlMR-0000wf-9k; Fri, 17 Apr 2026 11:44:03 -0400","from eggs.gnu.org ([2001:470:142:3::10])\n by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from )\n id 1wDlMM-0000vl-LQ; Fri, 17 Apr 2026 11:43:58 -0400","from mx0a-001b2d01.pphosted.com ([148.163.156.1])\n by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from )\n id 1wDlML-0006TC-2G; Fri, 17 Apr 2026 11:43:58 -0400","from pps.filterd (m0356517.ppops.net [127.0.0.1])\n by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id\n 63HDV5kb2205111; Fri, 17 Apr 2026 15:43:53 GMT","from ppma12.dal12v.mail.ibm.com\n (dc.9e.1632.ip4.static.sl-reverse.com [50.22.158.220])\n by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4dh89ruc67-1\n (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT);\n Fri, 17 Apr 2026 15:43:52 +0000 (GMT)","from pps.filterd (ppma12.dal12v.mail.ibm.com [127.0.0.1])\n by ppma12.dal12v.mail.ibm.com (8.18.1.2/8.18.1.2) with ESMTP id\n 63HC6VfB015621;\n Fri, 17 Apr 2026 15:43:52 GMT","from smtprelay07.dal12v.mail.ibm.com ([172.16.1.9])\n by ppma12.dal12v.mail.ibm.com (PPS) with ESMTPS id 4dg0mt010e-1\n (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT);\n Fri, 17 Apr 2026 15:43:51 +0000","from smtpav05.dal12v.mail.ibm.com (smtpav05.dal12v.mail.ibm.com\n [10.241.53.104])\n by smtprelay07.dal12v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id\n 63HFhpa210158622\n (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK);\n Fri, 17 Apr 2026 15:43:51 GMT","from smtpav05.dal12v.mail.ibm.com (unknown [127.0.0.1])\n by IMSVA (Postfix) with ESMTP id 1B3E15805D;\n Fri, 17 Apr 2026 15:43:51 +0000 (GMT)","from smtpav05.dal12v.mail.ibm.com (unknown [127.0.0.1])\n by IMSVA (Postfix) with ESMTP id DD26358052;\n Fri, 17 Apr 2026 15:43:50 +0000 (GMT)","from IBM-GLTZVH3.atx-us.ibm.com (unknown [9.16.58.46])\n by smtpav05.dal12v.mail.ibm.com (Postfix) with ESMTP;\n Fri, 17 Apr 2026 15:43:50 +0000 (GMT)"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc\n :content-transfer-encoding:date:from:in-reply-to:message-id\n :mime-version:references:subject:to; s=pp1; bh=BxybZn66XCrc8P0j4\n DwuJFQxCmW6tFhy0lt83D36CrQ=; b=jWy4Ph/+XD2iXFQ0FgJnoOqIhtFW5ywdH\n X98T5COynr0J61oOnSZESgyJfJ+giUYJ5rVoBwkoV9YpwRJIECbN0Jk56/3JhWPm\n 2xfRJFmE+5M37ioGBtnB4dDefHRGS1igLIr6+j4Patdc/5viqky35ZC7mUny8Bia\n 16zxzXGhetAem4I2Rot/VdtvaP8I6J6QQA7GxtLcaiN9StVbFPAGh8tvzCSxGufK\n zZd+3kfRzJbSn7k6VZ60G9RddGM8XLuXXadwLkFijo2ROqrBxpR/GhyOAvenXr1E\n SXPhtHwuHpJF1LwsQAeM4hJGAe6ytAPjeMwB/mtvINnTFDDKWlrwA==","From":"Jaehoon Kim ","To":"qemu-devel@nongnu.org, qemu-s390x@nongnu.org","Cc":"richard.henderson@linaro.org, iii@linux.ibm.com, david@kernel.org,\n pasic@linux.ibm.com, borntraeger@linux.ibm.com, farman@linux.ibm.com,\n mjrosato@linux.ibm.com, cohuck@redhat.com,\n Jaehoon Kim ","Subject":"[PATCH RFC v1 1/1] hw/s390x/ccw: Disable legacy virtio-pci by default\n (v11.1+)","Date":"Fri, 17 Apr 2026 10:43:08 -0500","Message-ID":"<20260417154332.849664-2-jhkim@linux.ibm.com>","X-Mailer":"git-send-email 2.43.0","In-Reply-To":"<20260417154332.849664-1-jhkim@linux.ibm.com>","References":"<20260417154332.849664-1-jhkim@linux.ibm.com>","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit","X-TM-AS-GCONF":"00","X-Proofpoint-Spam-Details-Enc":"AW1haW4tMjYwNDE3MDE1NCBTYWx0ZWRfX6Lc06qA/F7Bh\n A1oo3fj07zfnAbeWscr9/M6C3CGllPNTsT6YIt+lE1jAbXNxT7BBuhVgtx3p7zg4HrHHWi3YHAw\n 290Cu072SoK1rcoqmKtHlxEPRP3rvwja/Wm3tQ1iZf+hee8MzJCkHSriTEcOKji4S3A73160yzL\n yjWvsVpVl+ayHYy3l0BYuzPWV9KI/Vu3T+FCrq0MDxmp412w6uX6V5JdteYuD8Um+Lp3rQx5e+R\n Iy4rXdkPe4W1Pt8KeoQ+GyksQizEfWLxshapKfCMeibarTrO2i84nHQo0+oLSTnllHsQr2ZXAsd\n 0WsQmujLbXYwtGzF+d8j/aZiSrbY0U2EXJ/sZ4QHjj7R28kEhUqVxHw4zwl1kG5Mkg2slcFb8SM\n F+2rpdfuoGKjIaHBikkdi328za/MrohcRArWaURE2i+x7BMfKmRvGGMseFkFx1cfFc21HWy1kdo\n nUb2QAaUCjF7Ii7BlXw==","X-Proofpoint-ORIG-GUID":"zzRtW-IuBlASfYvfDchdnBokwnsWpa6H","X-Proofpoint-GUID":"zzRtW-IuBlASfYvfDchdnBokwnsWpa6H","X-Authority-Analysis":"v=2.4 cv=fYidDUQF c=1 sm=1 tr=0 ts=69e25538 cx=c_pps\n a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17\n a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22\n a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=my5jLqFW4fTaoRaGlZgA:9","X-Proofpoint-Virus-Version":"vendor=baseguard\n engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49\n definitions=2026-04-17_01,2026-04-17_04,2025-10-01_01","X-Proofpoint-Spam-Details":"rule=outbound_notspam policy=outbound score=0\n adultscore=0 impostorscore=0 clxscore=1015 malwarescore=0 phishscore=0\n bulkscore=0 priorityscore=1501 spamscore=0 suspectscore=0 lowpriorityscore=0\n classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0\n reason=mlx scancount=1 engine=8.22.0-2604070000 definitions=main-2604170154","Received-SPF":"pass client-ip=148.163.156.1; envelope-from=jhkim@linux.ibm.com;\n helo=mx0a-001b2d01.pphosted.com","X-Spam_score_int":"-26","X-Spam_score":"-2.7","X-Spam_bar":"--","X-Spam_report":"(-2.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1,\n DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7,\n RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001,\n RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001,\n SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no","X-Spam_action":"no action","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"qemu development ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org"},"content":"On the s390 Linux kernel, IO_SPACE_LIMIT has been 0 since the initial\nzPCI implementation (commit cd24834130ac \"s390/pci: base support\"),\nmaking I/O BARs unusable.\n\nHowever, when virtio-pci devices operate in transitional mode, QEMU\nunconditionally exposes the legacy interface via BAR0. This results in\nfirmware warnings during PCI enumeration, such as:\n\n pci 0005:00:00.0: [Firmware Bug]: BAR 0: invalid; can't size\n\neven though BAR0 is never usable on the s390 kernel.\n\nClose this gap by disabling legacy virtio-pci support starting from\nmachine version 11.1. This effectively makes virtio-pci devices\nnon-transitional and prevents the creation of the unusable legacy I/O\nBAR.\n\nThis introduces s390x-specific global compatibility properties that\nset disable-legacy=on as the default for virtio-pci devices. Machine\nversions v11.0 and earlier set disable-legacy=off to maintain their\noriginal default behavior (legacy support enabled), ensuring VMs\ncreated with those versions continue to work identically.\n\nUsers can override the default on the command line if needed:\n - On v11.1+: -global virtio-pci.disable-legacy=off (to enable legacy)\n - On v11.0-: -global virtio-pci.disable-legacy=on (to disable legacy)\n\nSigned-off-by: Jaehoon Kim \n---\n hw/s390x/s390-virtio-ccw.c | 23 +++++++++++++++++++++++\n 1 file changed, 23 insertions(+)","diff":"diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c\nindex cc768daeb0..6fbea1e289 100644\n--- a/hw/s390x/s390-virtio-ccw.c\n+++ b/hw/s390x/s390-virtio-ccw.c\n@@ -788,6 +788,18 @@ static void machine_set_loadparm(Object *obj, Visitor *v,\n g_free(val);\n }\n \n+/*\n+ * S390x-specific global compatibility properties.\n+ *\n+ * Set disable-legacy=on as the default for virtio-pci devices starting\n+ * from v11.1. Machine versions v11.0 and earlier set disable-legacy=off\n+ * to maintain their original default behavior (legacy support enabled).\n+ */\n+static GlobalProperty hw_compat_s390x[] = {\n+ { TYPE_VIRTIO_PCI, \"disable-legacy\", \"on\", .optional = true},\n+};\n+static const size_t hw_compat_s390x_len = G_N_ELEMENTS(hw_compat_s390x);\n+\n static void ccw_machine_class_init(ObjectClass *oc, const void *data)\n {\n MachineClass *mc = MACHINE_CLASS(oc);\n@@ -878,6 +890,9 @@ static const TypeInfo ccw_machine_info = {\n const void *data) \\\n { \\\n MachineClass *mc = MACHINE_CLASS(oc); \\\n+ /* Apply global s390x-wide default properties */ \\\n+ compat_props_add(mc->compat_props, hw_compat_s390x, \\\n+ hw_compat_s390x_len); \\\n MACHINE_VER_SYM(class_options, ccw, __VA_ARGS__)(mc); \\\n mc->desc = \"Virtual s390x machine (version \" MACHINE_VER_STR(__VA_ARGS__) \")\"; \\\n mc->init = MACHINE_VER_SYM(mach_init, ccw, __VA_ARGS__); \\\n@@ -923,7 +938,15 @@ static void ccw_machine_11_0_instance_options(MachineState *machine)\n \n static void ccw_machine_11_0_class_options(MachineClass *mc)\n {\n+ /*\n+ * Preserve v11.0 and older version behavior:\n+ * keep legacy virtio-pci enabled.\n+ */\n+ static GlobalProperty compat[] = {\n+ { TYPE_VIRTIO_PCI, \"disable-legacy\", \"off\" },\n+ };\n ccw_machine_11_1_class_options(mc);\n+ compat_props_add(mc->compat_props, compat, G_N_ELEMENTS(compat));\n compat_props_add(mc->compat_props, hw_compat_11_0, hw_compat_11_0_len);\n }\n DEFINE_CCW_MACHINE(11, 0);\n","prefixes":["RFC","v1","1/1"]}