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Description of problem:
If there is one time random hotplug vcpus then other hotplug operation will fail.
for example:
start guest with -smp 1 and maxcpus=160 option.
the first hotplug:
(qemu) cpu_set 10 online
other hotplug
Version-Release number of selected component (if applicable):
How reproducible:
Steps to Reproduce:
1./usr/libexec/qemu-kvm -M rhel6.3.0 -cpu host --enable-kvm -m 4G -smp
1,maxcpus=161 -name rhel6.3 -uuid ddcbfb49-3411-1701-3c36-6bdbc00bedbb -rtc
base=utc,clock=host,driftfix=slew -drive
file=/dev/vg-54/lvtest,if=none,id=ide,format=qcow2,cache=none,werror=stop,rerror=stop
-device ide-drive,drive=ide,id=drive-ide0-0-0,bootindex=1 -netdev
tap,id=hostnet1 -device e1000,netdev=hostnet1,id=net1,mac=86:12:50:a4:32:72
-spice port=5911,disable-ticketing -vga qxl -device sga -chardev
socket,id=serial0,path=/var/test1,server,nowait -device
isa-serial,chardev=serial0 -balloon virtio -monitor
unix:/tmp/monitor2,server,nowait -monitor stdio
2.the first hotplug vcpu
(qemu) cpu_set 100 online
3.continue to hotplug vcpus in order
(qemu) cpu_set 2 online
Actual results:
hotplug fail
Expected results:
hotplug operation is successful within range of maxcpus
Additional info:
after step 2, use 'top' and 'cat /proc/cpuinfo' cann't get vcpu but 'ls /sys/device/system/cpus/' can see added vcpu in guest.
I'd say it is WONTFIX for 6.3 with high chance of regression if I start touch cpu_index and apic code to fix it.
Lets deal with it upstream first, and then maybe rhel7 will have fix for it.
For now plug cpus only in consecutive order or use libvirt which does this.