RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.
Bug 1447592 - vhost-user/reply-ack: Wait for ack even if no request sent (one-time requests)
Summary: vhost-user/reply-ack: Wait for ack even if no request sent (one-time requests)
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: qemu-kvm-rhev
Version: 7.4
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Jens Freimann
QA Contact: Pei Zhang
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2017-05-03 09:35 UTC by Maxime Coquelin
Modified: 2017-08-02 04:38 UTC (History)
13 users (show)

Fixed In Version: qemu-kvm-rhev-2.9.0-8.el7
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2017-08-02 04:38:29 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2017:2392 0 normal SHIPPED_LIVE Important: qemu-kvm-rhev security, bug fix, and enhancement update 2017-08-01 20:04:36 UTC

Description Maxime Coquelin 2017-05-03 09:35:08 UTC 
Description of problem:

When vhost-user backend supports VHOST_USER_PROTOCOL_F_REPLY_ACK,
QEMU (for some requests) sets the VHOST_USER_NEED_REPLY flag in the
message request. Once message sent, it waits for the reply from the backend.

The problem is that this feature implementation is currently broken 
in QEMU, when used with one-time requests.
When a requests listed as one-time is sent a second time, like 
VHOST_USER_SET_MEM_TABLE and VHOST_USER_NET_SET_MTU with multiqueue,
the request is not sent by QEMU, but QEMU waits for a ACK from the backend
(which will never arrive).

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

Reproducible with vhost-user backends supporting REPLY_ACK feature,
like upstream DPDK v17.02. Note that QEMU's libvhost-user doesn't implement
the feature, so should not be used to reproduce/test the bug.

How reproducible:

Start DPDK v17.02's testpmd application with a vhost interface with multiple queues.
See: http://dpdk.org/doc/guides/nics/vhost.html

Steps to Reproduce:
1.
2.
3.

Actual results:


Expected results:


Additional info:

Upstream discussions:
DPDK ML: http://dpdk.org/dev/patchwork/patch/23941/
QEMU ML: http://patchwork.ozlabs.org/patch/756249/
Comment 2 Jens Freimann 2017-05-04 12:35:08 UTC 
Steps to Reproduce:
1. Start testpmd:
#> testpmd -l 0-3 -n 2 -m 4096 --vdev 'net_vhost0,iface=/tmp/sock0,queues=2' -- -i

2. Start QEMU:
#> qemu-system-x86_64 \
        -enable-kvm \
        -cpu host \
        -m 3072 \
        -smp 2 \
        -object memory-backend-file,id=mem,size=3072M,mem-path=/dev/hugepages,share=on \
        -numa node,memdev=mem \
        -mem-prealloc \
        -chardev socket,id=chr0,path=/tmp/sock0 \
        -netdev vhost-user,id=net0,chardev=chr0,vhostforce,queues=$1 \
        -device virtio-net-pci,netdev=net0,mq=on,vectors=6 \
        <image file>
3. Wait for system to boot

Actual results: Guest hangs during boot, qemu waiting for reply from dpdk
Expected results: Guest is started with functioning network device
Comment 3 Jens Freimann 2017-05-09 08:14:29 UTC 
https://patchwork.kernel.org/patch/9712283/

Patch is reviewed upstream but not yet applied.
Comment 4 Jens Freimann 2017-05-09 14:38:54 UTC 
Patch was only posted upstream but not yet internally, so I'm changing the status back to ASSIGNED
Comment 5 Jens Freimann 2017-05-18 15:52:32 UTC 
patch posted to rhvirt-patches
Comment 6 Miroslav Rezanina 2017-05-23 08:15:26 UTC 
Fix included in qemu-kvm-rhev-2.9.0-6.el7
Comment 8 Jens Freimann 2017-05-24 09:11:59 UTC 
Changing back to Assigned because follow-up patch fixing this one was posted upstream

https://www.mail-archive.com/qemu-devel@nongnu.org/msg452448.html

Let's wait for it to be applied upstream then apply both patches.
Comment 9 Jens Freimann 2017-06-01 13:52:14 UTC 
Follow-on patch mentioned in comment #8 posted to rhvirt-patches
Comment 10 Miroslav Rezanina 2017-06-06 08:54:12 UTC 
Fix included in qemu-kvm-rhev-2.9.0-8.el7
Comment 12 Pei Zhang 2017-06-17 12:18:06 UTC 
==Reproduce==

Versions:
dpdk-17.02.1.tar.xz
qemu-kvm-rhev-2.8.0-6.el7.x86_64

Steps:
1. Boot testpmd with net_vhost0 using 2 queues

# /root/dpdk-stable-17.02.1/x86_64-native-linuxapp-gcc/build/app/test-pmd/testpmd \
-l 2,4,6,8 \
-d /root/dpdk-stable-17.02.1/x86_64-native-linuxapp-gcc/lib/librte_pmd_vhost.so \
--vdev 'net_vhost0,iface=/tmp/sock0,queues=2' \
-n 4 \
--socket-mem 1024,1024 \
-- -i \

2. Boot VM using this socket
# /usr/libexec/qemu-kvm \
-cpu host \
-m 3072 \
-smp 8 \
-object memory-backend-file,id=mem,size=3072M,mem-path=/dev/hugepages,share=on \
-numa node,memdev=mem \
-mem-prealloc \
-chardev socket,id=chr0,path=/tmp/sock0 \
-netdev vhost-user,id=net0,chardev=chr0,vhostforce,queues=2 \
-device virtio-net-pci,netdev=net0,mq=on,vectors=6 \
/mnt/nfv/rhel7.4_nonrt.qcow2 \
-monitor stdio \
-vnc :2


3. Both qemu and guest become hang. 

So this bug has been reproduced.

==Verification==
Versions:
dpdk-17.02.1.tar.xz
qemu-kvm-rhev-2.9.0-10.el7.x86_64

Steps:
1. Boot testpmd with net_vhost0 using 2 queues

2. Boot VM using this socket

3. Both qemu and VM works well


So this bug has been fixed well. 

Thanks Maxime for helping me in irc to reproduce this bug.
Comment 13 Pei Zhang 2017-06-17 12:18:43 UTC 
Move status of this bug to 'VERIFIED' as Comment 12.
Comment 15 errata-xmlrpc 2017-08-02 04:38:29 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.

https://access.redhat.com/errata/RHSA-2017:2392
Note You need to log in before you can comment on or make changes to this bug.