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Violators will be prosecuted for from ; Mon, 28 Aug 2017 18:16:06 -0600 From: Michael Roth Date: Mon, 28 Aug 2017 19:14:11 -0500 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> Message-Id: <1503965694-10794-37-git-send-email-mdroth@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH 36/79] s390x/css: catch section mismatch on load List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Halil Pasic , Christian Borntraeger From: Halil Pasic Prior to the virtio-ccw-2.7 machine (and commit 2a79eb1a), our virtio devices residing under the virtual-css bus do not have qdev_path based migration stream identifiers (because their qdev_path is NULL). The ids are instead generated when the device is registered as a composition of the so called idstr, which takes the vmsd name as its value, and an instance_id, which is which is calculated as a maximal instance_id registered with the same idstr plus one, or zero (if none was registered previously). That means, under certain circumstances, one device might try, and even succeed, to load the state of a different device. This can lead to trouble. Let us fail the migration if the above problem is detected during load. How to reproduce the problem: 1) start qemu-system-s390x making sure you have the following devices defined on your command line: -device virtio-rng-ccw,id=rng1,devno=fe.0.0001 -device virtio-rng-ccw,id=rng2,devno=fe.0.0002 2) detach the devices and reattach in reverse order using the monitor: (qemu) device_del rng1 (qemu) device_del rng2 (qemu) device_add virtio-rng-ccw,id=rng2,devno=fe.0.0002 (qemu) device_add virtio-rng-ccw,id=rng1,devno=fe.0.0001 3) save the state of the vm into a temporary file and quit QEMU: (qemu) migrate "exec:gzip -c > /tmp/tmp_vmstate.gz" (qemu) q 4) use your command line from step 1 with -incoming "exec:gzip -c -d /tmp/tmp_vmstate.gz" appended to reproduce the problem (while trying to to load the saved vm) CC: qemu-stable@nongnu.org Signed-off-by: Halil Pasic Reviewed-by: Dong Jia Shi Reviewed-by: Cornelia Huck Message-Id: <20170518111405.56947-1-pasic@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger (cherry picked from commit 8ed179c937830143dc0e03daac30a55272ed89e3) * removed context dep on d8d98db5 Signed-off-by: Michael Roth --- hw/s390x/css.c | 14 ++++++++++++++ hw/s390x/virtio-ccw.c | 6 +++++- 2 files changed, 19 insertions(+), 1 deletion(-) diff --git a/hw/s390x/css.c b/hw/s390x/css.c index 37caa98..b24e8b7 100644 --- a/hw/s390x/css.c +++ b/hw/s390x/css.c @@ -14,6 +14,7 @@ #include "qapi/visitor.h" #include "hw/qdev.h" #include "qemu/bitops.h" +#include "qemu/error-report.h" #include "exec/address-spaces.h" #include "cpu.h" #include "hw/s390x/ioinst.h" @@ -1676,13 +1677,26 @@ void subch_device_save(SubchDev *s, QEMUFile *f) int subch_device_load(SubchDev *s, QEMUFile *f) { SubchDev *old_s; + Error *err = NULL; uint16_t old_schid = s->schid; + uint16_t old_devno = s->devno; int i; s->cssid = qemu_get_byte(f); s->ssid = qemu_get_byte(f); s->schid = qemu_get_be16(f); s->devno = qemu_get_be16(f); + if (s->devno != old_devno) { + /* Only possible if machine < 2.7 (no css_dev_path) */ + + error_setg(&err, "%x != %x", old_devno, s->devno); + error_append_hint(&err, "Devno mismatch, tried to load wrong section!" + " Likely reason: some sequences of plug and unplug" + " can break migration for machine versions prior to" + " 2.7 (known design flaw).\n"); + error_report_err(err); + return -EINVAL; + } /* Re-assign subch. */ if (old_schid != s->schid) { old_s = channel_subsys.css[s->cssid]->sch_set[s->ssid]->sch[old_schid]; diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c index 00b3bde..c0c1db8 100644 --- a/hw/s390x/virtio-ccw.c +++ b/hw/s390x/virtio-ccw.c @@ -1264,9 +1264,13 @@ static int virtio_ccw_load_config(DeviceState *d, QEMUFile *f) SubchDev *s = ccw_dev->sch; VirtIODevice *vdev = virtio_ccw_get_vdev(s); int len; + int ret; s->driver_data = dev; - subch_device_load(s, f); + ret = subch_device_load(s, f); + if (ret) { + return ret; + } len = qemu_get_be32(f); if (len != 0) { dev->indicators = get_indicator(qemu_get_be64(f), len); -- 2.7.4