Hi,

Tried this issue on rhel7.3 host with base command, it cannot be reproduced. In a new installed win2012r2 guest, hot add a cpu to it, the system works normal, no BSOD occurs.

Tried on follows version, the same results.
virtio-win-1.9.0-3 (build 124 vioscsi)
virtio-win-prewhql-126 (build 126 vioscsi)

Steps as follow:
1. Boot a win2012r2 guest.
/usr/libexec/qemu-kvm -name win2012r2 -enable-kvm -m 3G -smp 1,maxcpus=2 -cpu SandyBridge -uuid ea78071a-f6e4-4347-8077-9cb9f7959e83 -nodefconfig --nodefaults -boot order=cd,menu=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=isa_serial0 -device usb-tablet,id=input0 -device virtio-scsi-pci,id=scsi0,bus=pci.0 -drive file=win2012r2.raw,if=none,id=system-disk0,format=raw,serial=mike_cao,cache=none -device scsi-hd,bus=scsi0.0,drive=system-disk0,id=scsi-disk0 -drive file=/home/scsi_function/en_windows_server_2012_r2_x64_dvd_2707946.iso,media=cdrom,id=cdrom,if=none -device ide-drive,drive=cdrom,bootindex=1 -vnc 0.0.0.0:0 -vga cirrus -monitor stdio -qmp tcp:0:4445,server,nowait -netdev tap,script=/etc/qemu-ifup,downscript=no,id=hostnet0 -device e1000,netdev=hostnet0,id=net0,mac=00:52:5a:30:4e:58,bus=pci.0 -cdrom /usr/share/virtio-win/virtio-win.iso

2. In qmp, hot-add a cpu:
telnet host_ip 4445
{ 'execute': 'qmp_capabilities' }
{ "execute": "query-hotpluggable-cpus" }
{ "execute": "device_add","arguments":{"driver":"SandyBridge-x86_64-cpu","core-id": 0, "thread-id": 0, "socket-id": 1,"id":"core1"}}

3. after hot added a cpu, check the system status and the new cpu shows in system device management.

Additional info:
We also will reproduce this issue with virsh way, then will update to here~


Best Regards~
Peixiu Hou

I did a little more digging and it seems this specific element is causing the BSOD:

    <controller type='scsi' index='0' model='virtio-scsi'>
      <driver queues='2'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </controller>

The presence of "<driver queues='2'/>" appears to trigger the BSOD when "virsh setvcpus win2k12r2 3" is executed on the command line. When this is removed from the virtio-scsi controller, no BSOD occurs.

(In reply to Nat Meo from comment #3)
> I did a little more digging and it seems this specific element is causing
> the BSOD:
> 
>     <controller type='scsi' index='0' model='virtio-scsi'>
>       <driver queues='2'/>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x05'
> function='0x0'/>
>     </controller>
> 
> The presence of "<driver queues='2'/>" appears to trigger the BSOD when
> "virsh setvcpus win2k12r2 3" is executed on the command line. When this is
> removed from the virtio-scsi controller, no BSOD occurs.

Hi Nat,
Could you please provide the entire qemu command line, and upload compressed dump file?

Thanks,
Vadim.

(In reply to Nat Meo from comment #3)
> I did a little more digging and it seems this specific element is causing
> the BSOD:
> 
>     <controller type='scsi' index='0' model='virtio-scsi'>
>       <driver queues='2'/>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x05'
> function='0x0'/>
>     </controller>
> 
> The presence of "<driver queues='2'/>" appears to trigger the BSOD when
> "virsh setvcpus win2k12r2 3" is executed on the command line. When this is
> removed from the virtio-scsi controller, no BSOD occurs.

Thanks for the digging,QE can reproduce this issue with "num_queues=2":

qemu cli:
/usr/libexec/qemu-kvm -name 122BLKWIN2016 -enable-kvm -m 4G -smp 2,maxcpus=4 -nodefconfig -nodefaults -rtc base=localtime,driftfix=slew -boot order=cd,menu=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=win2012R2-iso.qcow2,if=none,id=drive-ide0-0-0,format=qcow2,serial=mike_cao,cache=none -device virtio-scsi-pci,id=scsi0,num_queues=2 -device scsi-hd,bus=scsi0.0,drive=drive-ide0-0-0,id=ide0-0-0 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=isa_serial0 -device usb-tablet,id=input0 -vnc 0.0.0.0:21 -vga cirrus -cdrom virtio-win-prewhql-126.iso -monitor stdio -qmp tcp:0:4449,server,nowait -fda virtio-win-prewhql-126.vfd -netdev tap,script=/etc/qemu-ifup,downscript=no,id=hostnet0,vhost=on -device e1000,netdev=hostnet0,id=net0,mac=00:52:4c:20:8d:00

the dump is located in http://fileshare.englab.nay.redhat.com/pub/section2/images_backup/virtio-win/bug1395790/

Please try drivers from build130 http://download.eng.bos.redhat.com/brewroot/packages/virtio-win-prewhql/0.1/130/win/virtio-win-prewhql-0.1.zip

Reproduce this issue with virtio-win-prewhql-126
Verify this issue with virtio-win-prewhql-130

steps same as comment#0 and comment#5

with virtio-win-prewhql-126,guest bsod after hotplug a cpu;
with virtio-win-prewhql-126,guest works well after hotplug a cpu,no bsod

So this issue has been fixed already,change status to verified.

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/RHBA-2017:2341