Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.

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 1110219

Summary:	Guest can't receive any character transmitted from host after hot unplugging virtserialport then hot plugging again
Product:	Red Hat Enterprise Linux 7	Reporter:	Libor Miksik <lmiksik>
Component:	qemu-kvm	Assignee:	Virtualization Maintenance <virt-maint>
Status:	CLOSED ERRATA	QA Contact:	Virtualization Bugs <virt-bugs>
Severity:	high	Docs Contact:
Priority:	high
Version:	7.0	CC:	acathrow, amit.shah, areis, bcao, bsarathy, ghammer, hhuang, huding, jherrman, juzhang, knoel, lijin, lmiksik, michen, mkenneth, mrezanin, pm-eus, qzhang, rhod, tdosek, virt-maint, xfu
Target Milestone:	rc	Keywords:	ZStream
Target Release:	---
Hardware:	x86_64
OS:	Linux
Whiteboard:
Fixed In Version:	qemu-kvm-1.5.3-60.el7_0.3	Doc Type:	Bug Fix
Doc Text:	Previously, when a guest device was hot unplugged, QEMU correctly removed the corresponding file descriptor watch but did not re-create it after the device was re-connected. As a consequence, the guest became unable to receive any data from the host over this device. With this update, the file descriptor's watch is re-created and the guest in the above scenario can communicate with the host as expected.	Story Points:	---
Clone Of:	1038914	Environment:
Last Closed:	2014-07-23 16:18:30 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1038914
Bug Blocks:

Description Libor Miksik 2014-06-17 09:21:12 UTC

This bug has been copied from bug #1038914 and has been proposed
to be backported to 7.0 z-stream (EUS).

Comment 3 Miroslav Rezanina 2014-06-17 15:37:49 UTC

Fix included in qemu-kvm-1.5.3-60.el7_0.3

Comment 5 huiqingding 2014-06-23 02:36:23 UTC

Reproduce this bug using the following version:
host:
kernel-3.10.0-128.el7.x86_64
qemu-kvm-1.5.3-60.el7.x86_64
guest:
kernel-3.10.0-123.el7.x86_64

Steps to Reproduce:
1.Boot rhel7 guest with this command line
/usr/libexec/qemu-kvm -M pc -enable-kvm -m 4G -smp 4,sockets=1,cores=4,threads=1 -name test -rtc base=localtime,clock=host,driftfix=slew -k en-us -boot menu=on -spice disable-ticketing,port=5930 -vga qxl -monitor stdio -drive file=/home/rhel7-ga.qcow2,if=none,id=drive-system-disk,media=disk,format=qcow2,aio=native,werror=stop,rerror=stop -device virtio-blk-pci,drive=drive-system-disk,id=system-disk -netdev tap,id=hostnet0,vhost=on,script=/etc/qemu-ifup -device virtio-net-pci,netdev=hostnet0,id=virtio-net-pci0,mac=00:22:15:27:54:9d,bus=pci.0,addr=0x9   -device virtio-serial-pci,id=virtio-serial0,max_ports=16,bus=pci.0 -chardev socket,id=charchannel0,path=/opt/chardev-testing.com.redhat.rhevm.vdsm,server,nowait -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.rhevm.vdsm

2.transfer data from host to guest
2. On host:
# hexdump -C /dev/sda | nc -U /opt/chardev-testing.com.redhat.rhevm.vdsm

3.In guest, receive the data from host by:
# cat /dev/vport0p

4.hot unplug the virtserialport:
(qemu) device_del channel0

5. hot plug virtserialport:
(qemu) device_add virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.rhevm.vdsm.com

6. cat /dev/vport0p1 in guest

Actual results:

after step6, guest cann't receive any data from host.

Comment 6 huiqingding 2014-06-23 02:45:24 UTC

Verify this bug using the following version:
host:
kernel-3.10.0-128.el7.x86_64
qemu-kvm-1.5.3-64.el7.x86_64
guest:
kernel-3.10.0-123.el7.x86_64

Steps to Verify:
1.Boot rhel7 guest with this command line
/usr/libexec/qemu-kvm -M pc -enable-kvm -m 4G -smp 4,sockets=1,cores=4,threads=1 -name test -rtc base=localtime,clock=host,driftfix=slew -k en-us -boot menu=on -spice disable-ticketing,port=5930 -vga qxl -monitor stdio -drive file=/home/rhel7-ga.qcow2,if=none,id=drive-system-disk,media=disk,format=qcow2,aio=native,werror=stop,rerror=stop -device virtio-blk-pci,drive=drive-system-disk,id=system-disk -netdev tap,id=hostnet0,vhost=on,script=/etc/qemu-ifup -device virtio-net-pci,netdev=hostnet0,id=virtio-net-pci0,mac=00:22:15:27:54:9d,bus=pci.0,addr=0x9   -device virtio-serial-pci,id=virtio-serial0,max_ports=16,bus=pci.0 -chardev socket,id=charchannel0,path=/opt/chardev-testing.com.redhat.rhevm.vdsm,server,nowait -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.rhevm.vdsm

2.transfer data from host to guest
2. On host:
# hexdump -C /dev/sda | nc -U /opt/chardev-testing.com.redhat.rhevm.vdsm

3.In guest, receive the data from host by:
# cat /dev/vport0p1

4.hot unplug the virtserialport:
(qemu) device_del channel0

5. hot plug virtserialport:
(qemu) device_add virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.rhevm.vdsm.com

6. cat /dev/vport0p1 in guest

Actual results:

guest can receive data after step 6.

Comment 7 huiqingding 2014-06-23 08:34:42 UTC

(In reply to huiqingding from comment #6)
> Verify this bug using the following version:
> host:
> kernel-3.10.0-128.el7.x86_64
> qemu-kvm-1.5.3-64.el7.x86_64
> guest:
> kernel-3.10.0-123.el7.x86_64
> 

Correction:
Verify this bug using the following version:
host:
kernel-3.10.0-128.el7.x86_64
qemu-kvm-1.5.3-60.el7_0.4.x86_64
guest:
kernel-3.10.0-123.el7.x86_64

Use the following steps, RHEL7 guest can receive the character transmitted from host after hot unplugging virtserialport then hot plugging again

> Steps to Verify:
> 1.Boot rhel7 guest with this command line
> /usr/libexec/qemu-kvm -M pc -enable-kvm -m 4G -smp
> 4,sockets=1,cores=4,threads=1 -name test -rtc
> base=localtime,clock=host,driftfix=slew -k en-us -boot menu=on -spice
> disable-ticketing,port=5930 -vga qxl -monitor stdio -drive
> file=/home/rhel7-ga.qcow2,if=none,id=drive-system-disk,media=disk,
> format=qcow2,aio=native,werror=stop,rerror=stop -device
> virtio-blk-pci,drive=drive-system-disk,id=system-disk -netdev
> tap,id=hostnet0,vhost=on,script=/etc/qemu-ifup -device
> virtio-net-pci,netdev=hostnet0,id=virtio-net-pci0,mac=00:22:15:27:54:9d,
> bus=pci.0,addr=0x9   -device
> virtio-serial-pci,id=virtio-serial0,max_ports=16,bus=pci.0 -chardev
> socket,id=charchannel0,path=/opt/chardev-testing.com.redhat.rhevm.vdsm,
> server,nowait -device
> virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,
> name=com.redhat.rhevm.vdsm
> 
> 2.transfer data from host to guest
> 2. On host:
> # hexdump -C /dev/sda | nc -U /opt/chardev-testing.com.redhat.rhevm.vdsm
> 
> 3.In guest, receive the data from host by:
> # cat /dev/vport0p1
> 
> 4.hot unplug the virtserialport:
> (qemu) device_del channel0
> 
> 5. hot plug virtserialport:
> (qemu) device_add
> virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,
> name=com.redhat.rhevm.vdsm.com
> 
> 6. cat /dev/vport0p1 in guest
> 
> Actual results:
> 
> guest can receive data after step 6.

Comment 8 huiqingding 2014-06-24 06:41:09 UTC

Use win2012 guest and verify this bug using the following version:
host:
kernel-3.10.0-128.el7.x86_64
qemu-kvm-1.5.3-60.el7_0.4.x86_64
guest:
win2012 guest
virtio-win-1.7.1-1.el7.noarch

Steps to Verify:
1.Boot rhel7 guest with this command line
/usr/libexec/qemu-kvm -M pc -enable-kvm -m 4G -smp 4,sockets=1,cores=4,threads=1 -name test -rtc base=localtime,clock=host,driftfix=slew -k en-us -boot menu=on -spice disable-ticketing,port=5930 -vga qxl -monitor stdio -drive file=/home/rhel7-ga.qcow2,if=none,id=drive-system-disk,media=disk,format=qcow2,aio=native,werror=stop,rerror=stop -device virtio-blk-pci,drive=drive-system-disk,id=system-disk -netdev tap,id=hostnet0,vhost=on,script=/etc/qemu-ifup -device virtio-net-pci,netdev=hostnet0,id=virtio-net-pci0,mac=00:22:15:27:54:9d,bus=pci.0,addr=0x9   -device virtio-serial-pci,id=virtio-serial0,max_ports=16,bus=pci.0 -chardev socket,id=charchannel0,path=/opt/chardev-testing.com.redhat.rhevm.vdsm,server,nowait -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.rhevm.vdsm

2.In guest, receive the data from host by:
# python VirtIoChannel_guest_recieve.py com.redhat.rhevm.vdsm

3. On host, transfer data to the guest:
# python serial-host-send.py /opt/chardev-testing.com.redhat.rhevm.vdsm

4.hot unplug the virtserialport:
(qemu) device_del channel0

5. hot plug virtserialport:
(qemu) device_add virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.rhevm.vdsm

6. repeat step2 and step3

Actual results:

guest can receive data after step 6.

Comment 11 errata-xmlrpc 2014-07-23 16:18:30 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.

http://rhn.redhat.com/errata/RHSA-2014-0927.html