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-cpu ...,+topoext works only with EPYC CPU model
See bug report at:
https://bugzilla.redhat.com/show_bug.cgi?id=1615682
Probably this is caused by the inconsistent legacy cache information on all CPU models except EPYC.
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Description of problem:
Guest should get 2 threads per core and all of them should be on-line when booting guest with old amd cpu model + smt
Steps to Reproduce:
1.Boot rhel7.6 guest with cli:
/usr/libexec/qemu-kvm -name rhel7.6 -m 16G -machine pc,accel=kvm \
-S \
-cpu Opteron_G3,+topoext,xlevel=0x8000001e,enforce \
-smp 2,threads=2 \
-monitor stdio \
-qmp unix:/tmp/qmp2,server,nowait \
-device VGA \
-vnc :0 \
-serial unix:/tmp/console2,server,nowait \
-uuid 115e11b2-a869-41b5-91cd-6a32a907be7f \
-drive file=rhel7.6-20180812.qcow2,if=none,id=drive-scsi-disk0,format=qcow2,cache=none,werror=stop,rerror=stop -device ide-hd,drive=drive-scsi-disk0,id=scsi-disk0 \
-netdev tap,id=idinWyYY,vhost=on -device virtio-net-pci,mac=2e:39:fa:ff:88:a1,id=idlbq7eA,netdev=idinWyYY \
2.check cpu info inside guest
3.
Actual results:
Guest gets one online cpu, one offline cpu and one thread per core:
# lscpu
lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 2
On-line CPU(s) list: 0
Off-line CPU(s) list: 1
Thread(s) per core: 1
Core(s) per socket: 1
Socket(s): 1
NUMA node(s): 1
Vendor ID: AuthenticAMD
CPU family: 16
Model: 2
Model name: AMD Opteron 23xx (Gen 3 Class Opteron)
Stepping: 3
CPU MHz: 2096.060
BogoMIPS: 4192.12
Hypervisor vendor: KVM
Virtualization type: full
L1d cache: 64K
L1i cache: 64K
L2 cache: 512K
L3 cache: 16384K
NUMA node0 CPU(s): 0
Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm art rep_good nopl extd_apicid pni cx16 x2apic popcnt hypervisor lahf_lm cmp_legacy abm sse4a misalignsse topoext retpoline_amd ibp_disable vmmcall
Expected results:
Guest should get 2 threads per core and all of them should be on-line
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