Bug 1294419

Summary: qemu promt "processing error - resetting ehci HC " after send "ctrl-alt-delete" to guest
Product: Red Hat Enterprise Linux 6 Reporter: Qianqian Zhu <qizhu>
Component: qemu-kvmAssignee: Gerd Hoffmann <kraxel>
Status: CLOSED NEXTRELEASE QA Contact: Virtualization Bugs <virt-bugs>
Severity: low Docs Contact:
Priority: low    
Version: 6.8CC: ailan, mkenneth, qizhu, rbalakri, virt-maint
Target Milestone: rc   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2016-01-15 11:37:19 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:

Description Qianqian Zhu 2015-12-28 07:13:23 UTC 
Description of problem:
boot a guest with usb device, boot failed from usb device, then send "ctrl-alt-delete" to guest via remote-viewer, qemu promt "Request for more bytes than allowed, processing error - resetting ehci HC "

Version-Release number of selected component (if applicable):
kernel-2.6.32-590.el6.x86_64
qemu-kvm-rhev-0.12.1.2-2.482.el6.x86_64

How reproducible:
100%

Steps to Reproduce:
1.launch guest with: 
/usr/libexec/qemu-kvm -name virtio -m 1024 -cpu Westmere,check -realtime mlock=off -smp 2 -global PIIX4_PM.disable_s4=1 -boot order=c,menu=on -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x6 -drive file=/home/sn1_rhel6.7_virtio.qcow2,format=qcow2,if=none,id=block-virtio,cache=none,werror=stop,rerror=stop -device virtio-blk-pci,bus=pci.0,addr=0x8,drive=block-virtio,id=block-virtio -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x7 -monitor stdio -vnc :4 -vga cirrus -device usb-ehci,id=ehci -drive file=/home/usb.qcow2,if=none,id=drive-usb-2-0,media=disk,format=raw,cache=none -device usb-storage,drive=drive-usb-2-0,id=usb-0-0,removable=on,bus=ehci.0,port=1 -device e1000,netdev=hostnet0,id=net0,mac=D4:AE:52:E9:57:36 -netdev tap,id=hostnet0,vhost=on

2.send "ctrl-alt-delete" after boot failed.
3.

Actual results:
(qemu) Request for more bytes than allowed
processing error - resetting ehci HC

Expected results:
no error prompt

Additional info:
Comment 2 Gerd Hoffmann 2016-01-04 12:39:26 UTC 
It's probably ehci data structures being overwritten, therefore ehci going to read and trying to process gibberish.  Happens because we do a soft reset on ctrl-alt-del in RHEL-6.  Should be fixed in RHEL-7 because we do a hard reset there.

It should have no side effects other than printing this debug message, i.e. the guest should re-initialize ehci and should be able to continue using it.

Is that correct?
Comment 3 Qianqian Zhu 2016-01-05 01:13:47 UTC 
(In reply to Gerd Hoffmann from comment #2)
> It's probably ehci data structures being overwritten, therefore ehci going
> to read and trying to process gibberish.  Happens because we do a soft reset
> on ctrl-alt-del in RHEL-6.  Should be fixed in RHEL-7 because we do a hard
> reset there.
> 
> It should have no side effects other than printing this debug message, i.e.
> the guest should re-initialize ehci and should be able to continue using it.
> 
> Is that correct?

Yes, guest was able to continue using it, it could not be noticed by user if there is no debug message.
Comment 4 Ademar Reis 2016-01-15 11:37:19 UTC 
Cornercase, harmless, fixed in rhel7/upstream already.