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Re: [Qemu-devel] [Bug] virtio-blk: qemu will crash if hotplug virtio-blk
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [Bug] virtio-blk: qemu will crash if hotplug virtio-blk device failed |
Date: |
Fri, 3 Nov 2017 10:31:29 +0000 |
User-agent: |
Mutt/1.9.1 (2017-09-22) |
On Tue, Oct 31, 2017 at 05:19:08AM +0000, linzhecheng wrote:
> I found that hotplug virtio-blk device will lead to qemu crash.
The author posted a patch in a separate email thread. Please see
"[PATCH] fix: unrealize virtio device if we fail to hotplug it".
> Re-production steps:
>
> 1. Run VM named vm001
>
> 2. Create a virtio-blk.xml which contains wrong configurations:
> <disk device="lun" rawio="yes" type="block">
> <driver cache="none" io="native" name="qemu" type="raw" />
> <source dev="/dev/mapper/11-dm" />
> <target bus="virtio" dev="vdx" />
> </disk>
>
> 3. Run command : virsh attach-device vm001 vm001
>
> Libvirt will return err msg:
>
> error: Failed to attach device from blk-scsi.xml
>
> error: internal error: unable to execute QEMU command 'device_add': Please
> set scsi=off for virtio-blk devices in order to use virtio 1.0
>
> it means hotplug virtio-blk device failed.
>
> 4. Suspend or shutdown VM will leads to qemu crash
>
>
>
> from gdb:
>
>
> (gdb) bt
> #0 object_get_class (address@hidden) at qom/object.c:750
> #1 0x00007f9a72582e01 in virtio_vmstate_change (opaque=0x7f9a73d10960,
> running=0, state=<optimized out>) at
> /mnt/sdb/lzc/code/open/qemu/hw/virtio/virtio.c:2203
> #2 0x00007f9a7261ef52 in vm_state_notify (address@hidden, address@hidden) at
> vl.c:1685
> #3 0x00007f9a7252603a in do_vm_stop (state=RUN_STATE_PAUSED) at
> /mnt/sdb/lzc/code/open/qemu/cpus.c:941
> #4 vm_stop (address@hidden) at /mnt/sdb/lzc/code/open/qemu/cpus.c:1807
> #5 0x00007f9a7262eb1b in qmp_stop (address@hidden) at qmp.c:102
> #6 0x00007f9a7262c70a in qmp_marshal_stop (args=<optimized out>,
> ret=<optimized out>, errp=0x7ffe63e255d8) at qmp-marshal.c:5854
> #7 0x00007f9a72897e79 in do_qmp_dispatch (errp=0x7ffe63e255d0,
> request=0x7f9a76510120, cmds=0x7f9a72ee7980 <qmp_commands>) at
> qapi/qmp-dispatch.c:104
> #8 qmp_dispatch (cmds=0x7f9a72ee7980 <qmp_commands>, address@hidden) at
> qapi/qmp-dispatch.c:131
> #9 0x00007f9a725288d5 in handle_qmp_command (parser=<optimized out>,
> tokens=<optimized out>) at /mnt/sdb/lzc/code/open/qemu/monitor.c:3852
> #10 0x00007f9a7289d514 in json_message_process_token (lexer=0x7f9a73ce4498,
> input=0x7f9a73cc6880, type=JSON_RCURLY, x=36, y=17) at
> qobject/json-streamer.c:105
> #11 0x00007f9a728bb69b in json_lexer_feed_char (address@hidden, ch=125 '}',
> address@hidden) at qobject/json-lexer.c:323
> #12 0x00007f9a728bb75e in json_lexer_feed (lexer=0x7f9a73ce4498,
> buffer=<optimized out>, size=<optimized out>) at qobject/json-lexer.c:373
> #13 0x00007f9a7289d5d9 in json_message_parser_feed (parser=<optimized out>,
> buffer=<optimized out>, size=<optimized out>) at qobject/json-streamer.c:124
> #14 0x00007f9a7252722e in monitor_qmp_read (opaque=<optimized out>,
> buf=<optimized out>, size=<optimized out>) at
> /mnt/sdb/lzc/code/open/qemu/monitor.c:3894
> #15 0x00007f9a7284ee1b in tcp_chr_read (chan=<optimized out>, cond=<optimized
> out>, opaque=<optimized out>) at chardev/char-socket.c:441
> #16 0x00007f9a6e03e99a in g_main_context_dispatch () from
> /usr/lib64/libglib-2.0.so.0
> #17 0x00007f9a728a342c in glib_pollfds_poll () at util/main-loop.c:214
> #18 os_host_main_loop_wait (timeout=<optimized out>) at util/main-loop.c:261
> #19 main_loop_wait (address@hidden) at util/main-loop.c:515
> #20 0x00007f9a724e7547 in main_loop () at vl.c:1999
> #21 main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>)
> at vl.c:4877
>
> Problem happens in virtio_vmstate_change which is called by vm_state_notify,
> static void virtio_vmstate_change(void *opaque, int running, RunState state)
> {
> VirtIODevice *vdev = opaque;
> BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
> VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
> bool backend_run = running && (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK);
> vdev->vm_running = running;
>
> if (backend_run) {
> virtio_set_status(vdev, vdev->status);
> }
>
> if (k->vmstate_change) {
> k->vmstate_change(qbus->parent, backend_run);
> }
>
> if (!backend_run) {
> virtio_set_status(vdev, vdev->status);
> }
> }
>
> Vdev's parent_bus is NULL, so qdev_get_parent_bus(DEVICE(vdev)) will crash.
> virtio_vmstate_change is added to the list vm_change_state_head at
> virtio_blk_device_realize(virtio_init),
> but after hotplug virtio-blk failed, virtio_vmstate_change will not be
> removed from vm_change_state_head.
>
>
> I apply a patch as follews:
>
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 5884ce3..ea532dc 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -2491,6 +2491,7 @@ static void virtio_device_realize(DeviceState *dev,
> Error **errp)
> virtio_bus_device_plugged(vdev, &err);
> if (err != NULL) {
> error_propagate(errp, err);
> + vdc->unrealize(dev, NULL);
> return;
> }
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Stefan Hajnoczi <=