Red Hat Bugzilla – Bug 921200
[NetKVM] Do not use VIRTIO_PCI_ISR for debug purposes in production code
Last modified: 2013-12-06 02:23:22 EST
Description of problem: Current code will use VIRTIO_PCI_ISR register to notify host regarding two conditions on the guest: 1. BSOD (write 0). 2. Hanged TX transfer (write 1). This is a hacky way that was used for host\guest debugging. Should be removed from production code as such behavior is not described in virtio spec. Version-Release number of selected component (if applicable): How reproducible: Steps to Reproduce: 1. 2. 3. Actual results: Expected results: Additional info:
Guest driver will no longer write to VIRTIO_PCI_ISR register. This behavior could be enabled for debugging in compile time with DBG_USE_VIRTIO_PCI_ISR_FOR_HOST_REPORT define.
Pls provide a way for QE to verify it ,
Testing: 1. Cause BSOD on guest. 2. You QEMU shouldn't see QEMU printouts on the host notifying of incorrect write to virtio register.
Verified this issue on virtio-win-prewhql-0.1.64 Steps same as comment #4 Actual Result: on virtio-win-prewhql-0.1-64 QEMU didn't see QEMU printouts on the host notifying of incorrect write to virtio register. Based on above, this issue has been fixed already.
Reproduced this issue on virtio-win-prewhql-0.1.49 Verified this issue on virtio-win-prewhql-0.1.64 Steps: 1.Boot guest with CLI: /usr/libexec/qemu-kvm -M rhel6.4.0 -m 2G -smp 4,cores=4 -cpu cpu64-rhel6,+x2apic -usb -device usb-tablet -drive file=win2k3-32.raw,format=raw,if=none,id=drive-ide0-0-0,werror=stop,rerror=stop,cache=none -device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 -netdev tap,sndbuf=0,id=hostnet0,vhost=on,script=/etc/qemu-ifup-private,downscript=no -device virtio-net-pci,netdev=hostnet0,mac=00:13:34:25:22:41,bus=pci.0,addr=0x4,id=virtio-net-pci0 -netdev tap,sndbuf=0,id=hostnet2,script=/etc/qemu-ifup,downscript=no -device e1000,netdev=hostnet2,mac=00:23:30:25:12:10,bus=pci.0,addr=0x6 -uuid d9a27a4b-13f5-4d6a-8a8c-25269bcc1535 -rtc-td-hack -no-kvm-pit-reinjection -rtc base=localtime,clock=host,driftfix=slew -chardev socket,id=111a,path=/tmp/monitor-win2k3-32-network,server,nowait -mon chardev=111a,mode=readline -name win2k3-32-network -vnc :1 -vga cirrus -global PIIX4_PM.disable_s3=0 -global PIIX4_PM.disable_s4=0 -monitor stdio 2.Enable the keyboard-initiated crash in the registry. In the registry key HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\i8042prt\Parameters, create a DWORD key named CrashOnCtrlScroll and value is 0x01. 3.reboot 4.Press "CTRL+SCROLL LOCK+SCROLL LOCK" keyboard shortcut to generate a BSOD. Actual Result: on virtio-win-prewhql-0.1-49 QEMU monitor show "virtio_ioport_write: unexpected address 0x13 value 0x1" on the host. on virtio-win-prewhql-0.1-64 QEMU didn't see QEMU printouts on the host notifying of incorrect write to virtio register. Based on above, this issue has been fixed already.
Move Status to VERIFIED according to comment #7
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/RHBA-2013-1729.html