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GET /api/patches/806858/?format=api
HTTP 200 OK
Allow: GET, PUT, PATCH, HEAD, OPTIONS
Content-Type: application/json
Vary: Accept

{
    "id": 806858,
    "url": "http://patchwork.ozlabs.org/api/patches/806858/?format=api",
    "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/patch/1503965694-10794-37-git-send-email-mdroth@linux.vnet.ibm.com/",
    "project": {
        "id": 14,
        "url": "http://patchwork.ozlabs.org/api/projects/14/?format=api",
        "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": "<1503965694-10794-37-git-send-email-mdroth@linux.vnet.ibm.com>",
    "list_archive_url": null,
    "date": "2017-08-29T00:14:11",
    "name": "[36/79] s390x/css: catch section mismatch on load",
    "commit_ref": null,
    "pull_url": null,
    "state": "new",
    "archived": false,
    "hash": "7d193484ed770266010789d02eaf0503bcf5e4ff",
    "submitter": {
        "id": 5549,
        "url": "http://patchwork.ozlabs.org/api/people/5549/?format=api",
        "name": "Michael Roth",
        "email": "mdroth@linux.vnet.ibm.com"
    },
    "delegate": null,
    "mbox": "http://patchwork.ozlabs.org/project/qemu-devel/patch/1503965694-10794-37-git-send-email-mdroth@linux.vnet.ibm.com/mbox/",
    "series": [
        {
            "id": 281,
            "url": "http://patchwork.ozlabs.org/api/series/281/?format=api",
            "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/list/?series=281",
            "date": "2017-08-29T00:13:45",
            "name": "Patch Round-up for stable 2.9.1, freeze on 2017-09-04",
            "version": 1,
            "mbox": "http://patchwork.ozlabs.org/series/281/mbox/"
        }
    ],
    "comments": "http://patchwork.ozlabs.org/api/patches/806858/comments/",
    "check": "pending",
    "checks": "http://patchwork.ozlabs.org/api/patches/806858/checks/",
    "tags": {},
    "related": [],
    "headers": {
        "Return-Path": "<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>",
        "X-Original-To": "incoming@patchwork.ozlabs.org",
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            "from b03ledav003.gho.boulder.ibm.com\n\t(b03ledav003.gho.boulder.ibm.com [9.17.130.234])\n\tby b03cxnp07028.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with\n\tESMTP id v7T0G3oU2687396; Mon, 28 Aug 2017 17:16:03 -0700",
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        ],
        "From": "Michael Roth <mdroth@linux.vnet.ibm.com>",
        "To": "qemu-devel@nongnu.org",
        "Date": "Mon, 28 Aug 2017 19:14:11 -0500",
        "X-Mailer": "git-send-email 2.7.4",
        "In-Reply-To": "<1503965694-10794-1-git-send-email-mdroth@linux.vnet.ibm.com>",
        "References": "<1503965694-10794-1-git-send-email-mdroth@linux.vnet.ibm.com>",
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        "Message-Id": "<1503965694-10794-37-git-send-email-mdroth@linux.vnet.ibm.com>",
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        "X-detected-operating-system": "by eggs.gnu.org: GNU/Linux 3.x [generic] [fuzzy]",
        "X-Received-From": "148.163.156.1",
        "Subject": "[Qemu-devel] [PATCH 36/79] s390x/css: catch section mismatch on load",
        "X-BeenThere": "qemu-devel@nongnu.org",
        "X-Mailman-Version": "2.1.21",
        "Precedence": "list",
        "List-Id": "<qemu-devel.nongnu.org>",
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        "Cc": "Christian Borntraeger <borntraeger@de.ibm.com>,\n\tHalil Pasic <pasic@linux.vnet.ibm.com>, qemu-stable@nongnu.org",
        "Errors-To": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org",
        "Sender": "\"Qemu-devel\"\n\t<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>"
    },
    "content": "From: Halil Pasic <pasic@linux.vnet.ibm.com>\n\nPrior to the virtio-ccw-2.7 machine (and commit 2a79eb1a), our virtio\ndevices residing under the virtual-css bus do not have qdev_path based\nmigration stream identifiers (because their qdev_path is NULL). The ids\nare instead generated when the device is registered as a composition of\nthe so called idstr, which takes the vmsd name as its value, and an\ninstance_id, which is which is calculated as a maximal instance_id\nregistered with the same idstr plus one, or zero (if none was registered\npreviously).\n\nThat means, under certain circumstances, one device might try, and even\nsucceed, to load the state of a different device. This can lead to\ntrouble.\n\nLet us fail the migration if the above problem is detected during load.\n\nHow to reproduce the problem:\n1) start qemu-system-s390x making sure you have the following devices\n   defined on your command line:\n     -device virtio-rng-ccw,id=rng1,devno=fe.0.0001\n     -device virtio-rng-ccw,id=rng2,devno=fe.0.0002\n2) detach the devices and reattach in reverse order using the monitor:\n     (qemu) device_del rng1\n     (qemu) device_del rng2\n     (qemu) device_add virtio-rng-ccw,id=rng2,devno=fe.0.0002\n     (qemu) device_add virtio-rng-ccw,id=rng1,devno=fe.0.0001\n3) save the state of the vm into a temporary file and quit QEMU:\n     (qemu) migrate \"exec:gzip -c > /tmp/tmp_vmstate.gz\"\n     (qemu) q\n4) use your command line from step 1 with\n     -incoming \"exec:gzip -c -d /tmp/tmp_vmstate.gz\"\n   appended to reproduce the problem (while trying to to load the saved vm)\n\nCC: qemu-stable@nongnu.org\nSigned-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>\nReviewed-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>\nReviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>\nMessage-Id: <20170518111405.56947-1-pasic@linux.vnet.ibm.com>\nSigned-off-by: Christian Borntraeger <borntraeger@de.ibm.com>\n(cherry picked from commit 8ed179c937830143dc0e03daac30a55272ed89e3)\n* removed context dep on d8d98db5\nSigned-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>\n---\n hw/s390x/css.c        | 14 ++++++++++++++\n hw/s390x/virtio-ccw.c |  6 +++++-\n 2 files changed, 19 insertions(+), 1 deletion(-)",
    "diff": "diff --git a/hw/s390x/css.c b/hw/s390x/css.c\nindex 37caa98..b24e8b7 100644\n--- a/hw/s390x/css.c\n+++ b/hw/s390x/css.c\n@@ -14,6 +14,7 @@\n #include \"qapi/visitor.h\"\n #include \"hw/qdev.h\"\n #include \"qemu/bitops.h\"\n+#include \"qemu/error-report.h\"\n #include \"exec/address-spaces.h\"\n #include \"cpu.h\"\n #include \"hw/s390x/ioinst.h\"\n@@ -1676,13 +1677,26 @@ void subch_device_save(SubchDev *s, QEMUFile *f)\n int subch_device_load(SubchDev *s, QEMUFile *f)\n {\n     SubchDev *old_s;\n+    Error *err = NULL;\n     uint16_t old_schid = s->schid;\n+    uint16_t old_devno = s->devno;\n     int i;\n \n     s->cssid = qemu_get_byte(f);\n     s->ssid = qemu_get_byte(f);\n     s->schid = qemu_get_be16(f);\n     s->devno = qemu_get_be16(f);\n+    if (s->devno != old_devno) {\n+        /* Only possible if machine < 2.7 (no css_dev_path) */\n+\n+        error_setg(&err, \"%x != %x\", old_devno,  s->devno);\n+        error_append_hint(&err, \"Devno mismatch, tried to load wrong section!\"\n+                          \" Likely reason: some sequences of plug and unplug\"\n+                          \" can break migration for machine versions prior to\"\n+                          \" 2.7 (known design flaw).\\n\");\n+        error_report_err(err);\n+        return -EINVAL;\n+    }\n     /* Re-assign subch. */\n     if (old_schid != s->schid) {\n         old_s = channel_subsys.css[s->cssid]->sch_set[s->ssid]->sch[old_schid];\ndiff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c\nindex 00b3bde..c0c1db8 100644\n--- a/hw/s390x/virtio-ccw.c\n+++ b/hw/s390x/virtio-ccw.c\n@@ -1264,9 +1264,13 @@ static int virtio_ccw_load_config(DeviceState *d, QEMUFile *f)\n     SubchDev *s = ccw_dev->sch;\n     VirtIODevice *vdev = virtio_ccw_get_vdev(s);\n     int len;\n+    int ret;\n \n     s->driver_data = dev;\n-    subch_device_load(s, f);\n+    ret = subch_device_load(s, f);\n+    if (ret) {\n+        return ret;\n+    }\n     len = qemu_get_be32(f);\n     if (len != 0) {\n         dev->indicators = get_indicator(qemu_get_be64(f), len);\n",
    "prefixes": [
        "36/79"
    ]
}