Bug 1128095 - chardev 'chr0' isn't initialized when we try to open rng backend
Summary: chardev 'chr0' isn't initialized when we try to open rng backend
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: qemu-kvm-rhev
Version: 7.1
Hardware: Unspecified
OS: Unspecified
Target Milestone: rc
: ---
Assignee: Amos Kong
QA Contact: Virtualization Bugs
Depends On:
TreeView+ depends on / blocked
Reported: 2014-08-08 09:50 UTC by zhoujunqin
Modified: 2015-05-25 00:08 UTC (History)
20 users (show)

Fixed In Version: qemu 2.1.1
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2015-03-05 09:49:04 UTC
Target Upstream Version:
imammedo: needinfo-

Attachments (Terms of Use)

System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2015:0624 0 normal SHIPPED_LIVE Important: qemu-kvm-rhev security, bug fix, and enhancement update 2015-03-05 14:37:36 UTC

Description zhoujunqin 2014-08-08 09:50:46 UTC
Description of problem:
Failed to start guest after adding RNG hardware:
RNG Type: Entropy Gathering Daemon, Backend type: UDP, Host: port 1708, Bind Host: port 1710.  

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
1. Prepare a health guest and keep in shutdown status.
2. Add the rng device like below:
with Type: Entropy Gathering Daemon, Backend type: UDP, Host: port 1708, Bind Host: port 1710.  

# virsh dumpxml rhel77 | grep rng -A 10
    <rng model='virtio'>
      <backend model='egd' type='udp'>
        <source mode='bind' host='' service='1710'/>
        <source mode='connect' host='' service='1708'/>
3. Start the guest.

Actual results:
Failed to start guest.
# virsh start rhel77
error: Failed to start domain rhel77
error: internal error: process exited while connecting to monitor: 2014-08-08T07:29:39.116348Z qemu-kvm: -object rng-egd,chardev=charrng0,id=rng0: Device 'charrng0' not found

Expected results:
Guest can start successfully.

Additional info:
This issue doesn't hit with following version.
1. Download to qemu-kvm-rhev-1.5.3-60.el7ev.x86_64, guest can start successfully.
2  Remove qemu-kvm-rhev-2.1.0-1.el7.x86_64 and then install qemu-kvm-1.5.3-66.el7.x86_64 instead, guest can start successfully.

Comment 1 Amos Kong 2014-08-08 09:57:03 UTC
What's the full qemu command line? Why the bind and connect port is different?

Comment 2 Amos Kong 2014-08-08 09:59:26 UTC
Please also upload your full xml file as attachment.

Comment 4 Amos Kong 2014-08-09 04:19:30 UTC
A simple way to reproduce this bug:

x86_64-softmmu/qemu-system-x86_64 -monitor stdio -vnc :0 \
   -chardev socket,host=localhost,port=1024,id=chr0 \
   -object rng-egd,chardev=chr0,id=rng0
qemu-system-x86_64: -object rng-egd,chardev=chr0,id=rng0: Device 'chr0' not found

It's an upstream regression which was introduced by the following patch, it's not fixed:

| commit 57d3e1b3f52d07d215ed96df946ee01f8d9f9526
| Author: Igor Mammedov <imammedo@redhat.com>
| Date:   Thu Jan 16 17:34:39 2014 +0100
|     virtio_rng: replace custom backend API with UserCreatable.complete() callback
|     in addition fix default backend leak by releasing it if its
|     initialization failed.
|     Signed-off-by: Igor Mammedov <imammedo@redhat.com>
|     Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
|     Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

Comment 6 Miroslav Rezanina 2014-09-12 12:55:39 UTC
Fix included in qemu-kvm-1.5.3-70.el7

Comment 7 Amos Kong 2014-09-26 08:57:03 UTC
(In reply to Miroslav Rezanina from comment #6)
> Fix included in qemu-kvm-1.5.3-70.el7

The Component is qemu-kvm-rhev, we only need it for qemu-kvm-rhev.
it doesn't need for qemu-kvm-rhel7, but it's harmless.

Did I mark something wrong in bug/patch?

Comment 8 Miroslav Rezanina 2014-09-26 09:19:49 UTC
Hi Amos,
you did nothing wrong. Looks like build -70.el7 was corrupted due other incorrectly submitted patches that cause inclusion of few rhev only patches to rhel build. 

Changing back to POST and putting patch back on queue...rhel build will be fixed with other incorrectly committed patches.

Comment 10 mazhang 2014-10-13 08:09:06 UTC
Reproduced this bug on qemu-kvm-rhev-2.1.0-4.el7.x86_64.


# /usr/libexec/qemu-kvm -monitor stdio -vnc :0 -chardev socket,host=,port=1024,id=chr0 -object rng-egd,chardev=chr0,id=rng0
qemu-kvm: -object rng-egd,chardev=chr0,id=rng0: Device 'chr0' not found

Verified this bug on qemu-kvm-rhev-2.1.2-3.el7.x86_64.


# /usr/libexec/qemu-kvm -monitor stdio -vnc :0 -chardev socket,host=,port=1024,id=chr0 -object rng-egd,chardev=chr0,id=rng0
QEMU 2.1.2 monitor - type 'help' for more information

Comment 11 mazhang 2014-10-14 01:57:19 UTC
Base on comment#10 set this bug verified, any problem please let me know.


Comment 13 errata-xmlrpc 2015-03-05 09:49:04 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.


Note You need to log in before you can comment on or make changes to this bug.