Bug 1513861

Summary:	The qemu usb tablet takes no effect when attaches 2 or more qemu usb mouses
Product:	Red Hat Enterprise Linux 7	Reporter:	Gu Nini <ngu>
Component:	qemu-kvm-rhev	Assignee:	Gerd Hoffmann <kraxel>
Status:	CLOSED NOTABUG	QA Contact:	Gu Nini <ngu>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	7.5	CC:	hachen, knoel, michen, virt-maint, xuma
Target Milestone:	rc
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Hardware:	Unspecified
OS:	Unspecified
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Last Closed:	2017-11-17 06:59:04 UTC	Type:	Bug
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
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Description Gu Nini 2017-11-16 07:07:39 UTC

Description of problem:
The qemu usb tablet takes no effect when attaches 2 or more qemu usb mouses.

Version-Release number of selected component (if applicable):
Host kernel: 3.10.0-765.el7.x86_64
Qemu: qemu-kvm-rhev-2.10.0-6.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Start a guest with following cmd:

/usr/libexec/qemu-kvm \
    -name 'avocado-vt-vm1'  \
    -sandbox off  \
    -nodefaults  \
    -vga std  \
    -device nec-usb-xhci,id=usbtest,bus=pci.0,addr=0x3 \
    -device virtio-scsi-pci,id=virtio_scsi_pci0,bus=pci.0,addr=0x4 \
    -drive id=drive_image1,if=none,snapshot=off,aio=native,cache=none,format=qcow2,file=/home/kvm_autotest_root/images/rhel75-64-virtio-scsi.qcow2 \
    -device scsi-hd,id=image1,drive=drive_image1 \
    -device virtio-net-pci,mac=9a:e4:e5:e6:e7:e8,id=idOCesHt,vectors=4,netdev=id4lq6hH,bus=pci.0,addr=0x5  \
    -netdev tap,id=id4lq6hH,vhost=on \
    -m 8192  \
    -smp 4,cores=2,threads=1,sockets=2  \
    -device usb-tablet,id=usb-e1,bus=usbtest.0,port=1 \
    -device usb-mouse,id=usb-d1,bus=usbtest.0,port=2 \
    -device usb-mouse,id=usb-d2,bus=usbtest.0,port=3 \
    -vnc :0  \
    -rtc base=localtime,clock=host,driftfix=slew  \
    -boot menu=off,strict=off,order=cdn,once=c \
    -enable-kvm \
    -monitor stdio

2. After the guest boots up, check the effectiveness of the tablet.


Actual results:
The tablet takes no effect, i.e. there is double cursor.

Expected results:
No double cursor.

Additional info:
Both windows guest and linux guest have the problem, I have tried RHEL7.5/Win2016/Win10.64.

Comment 2 Gerd Hoffmann 2017-11-17 06:59:04 UTC

(In reply to Gu Nini from comment #0)
> Description of problem:
> The qemu usb tablet takes no effect when attaches 2 or more qemu usb mouses.

Not supported.  And there is little reason to change that as it is not very useful to attach multiple mice to a virtual machine.

Some background:  The pointer input events are routed to the most recently activated input device, so typically the ps/2 mouse is active at boot and qemu switches over to the usb tablet as soon as the guest loads the driver and starts talking to the device.  In case multiple usb input devices are present it depends on the guests initialization order which of them ends up being active, so it could be a usb mouse instead of the usb tablet.