Tobias, just to be sure you noticed it, a respin of oVirt Node 4.2.3 absed on CentOS 7.5 has been released this morning.

1) Make sure your node and your engine are running under RedHat/CentOS 7.5

[root@ovirt ~]# cat /etc/redhat-release
CentOS Linux release 7.5.1804 (Core)

2) Get your PostgreSQL credentials

less /etc/ovirt-engine/engine.conf.d/10-setup-database.conf

3) Make the PostgreSQL libs available, so that we can start the PostgreSQL client later.

echo '/opt/rh/rh-postgresql95/root/lib64/' >/etc/ld.so.conf.d/postgresql_opt.conf

4) Become PostgreSQL user.

su - postgres

5) Connect to the PostgreSQL database.

/opt/rh/rh-postgresql95/root/bin/psql -h localhost -p 5432 -U engine -W

6) Run the database update:

select fn_db_update_config_value('ServerCPUList', '3:Intel Conroe Family:vmx,nx,model_Conroe:Conroe:x86_64; 4:Intel Penryn Family:vmx,nx,model_Penryn:Penryn:x86_64; 5:Intel Nehalem Family:vmx,nx,model_Nehalem:Nehalem:x86_64; 6:Intel Nehalem IBRS Family:vmx,nx,spec_ctrl,model_Nehalem:Nehalem,+spec-ctrl:x86_64; 7:Intel Nehalem IBRS SSBD Family:vmx,nx,spec_ctrl,ssbd,model_Nehalem:Nehalem,+spec-ctrl,+ssbd:x86_64; 8:Intel Westmere Family:aes,vmx,nx,model_Westmere:Westmere:x86_64; 9:Intel Westmere IBRS Family:aes,vmx,nx,spec_ctrl,model_Westmere:Westmere,+spec-ctrl:x86_64; 10:Intel Westmere IBRS SSBD Family:aes,vmx,nx,spec_ctrl,ssbd,model_Westmere:Westmere,+pcid,+spec-ctrl,+ssbd:x86_64; 11:Intel SandyBridge Family:vmx,nx,model_SandyBridge:SandyBridge:x86_64; 12:Intel SandyBridge IBRS Family:vmx,nx,spec_ctrl,model_SandyBridge:SandyBridge,+spec-ctrl:x86_64; 13:Intel SandyBridge IBRS SSBD Family:vmx,nx,spec_ctrl,ssbd,model_SandyBridge:SandyBridge,+pcid,+spec-ctrl,+ssbd:x86_64; 14:Intel Haswell-noTSX Family:vmx,nx,model_Haswell-noTSX:Haswell-noTSX:x86_64; 15:Intel Haswell-noTSX IBRS Family:vmx,nx,spec_ctrl,model_Haswell-noTSX:Haswell-noTSX,+spec-ctrl:x86_64; 16:Intel Haswell-noTSX IBRS SSBD Family:vmx,nx,spec_ctrl,ssbd,model_Haswell-noTSX:Haswell-noTSX,+spec-ctrl,+ssbd:x86_64; 17:Intel Haswell Family:vmx,nx,model_Haswell:Haswell:x86_64; 18:Intel Haswell IBRS Family:vmx,nx,spec_ctrl,model_Haswell:Haswell,+spec-ctrl:x86_64; 19:Intel Haswell IBRS SSBD Family:vmx,nx,spec_ctrl,ssbd,model_Haswell:Haswell,+spec-ctrl,+ssbd:x86_64; 20:Intel Broadwell-noTSX Family:vmx,nx,model_Broadwell-noTSX:Broadwell-noTSX:x86_64; 21:Intel Broadwell-noTSX IBRS Family:vmx,nx,spec_ctrl,model_Broadwell-noTSX:Broadwell-noTSX,+spec-ctrl:x86_64; 22:Intel Broadwell-noTSX IBRS SSBD Family:vmx,nx,spec_ctrl,ssbd,model_Broadwell-noTSX:Broadwell-noTSX,+spec-ctrl,+ssbd:x86_64; 23:Intel Broadwell Family:vmx,nx,model_Broadwell:Broadwell:x86_64; 24:Intel Broadwell IBRS Family:vmx,nx,spec_ctrl,model_Broadwell:Broadwell,+spec-ctrl:x86_64; 25:Intel Broadwell IBRS SSBD Family:vmx,nx,spec_ctrl,ssbd,model_Broadwell:Broadwell,+spec-ctrl,+ssbd:x86_64; 26:Intel Skylake Client Family:vmx,nx,model_Skylake-Client:Skylake-Client:x86_64; 27:Intel Skylake Client IBRS Family:vmx,nx,spec_ctrl,model_Skylake-Client:Skylake-Client,+spec-ctrl:x86_64; 28:Intel Skylake Client IBRS SSBD Family:vmx,nx,spec_ctrl,ssbd,model_Skylake-Client:Skylake-Client,+spec-ctrl,+ssbd:x86_64; 29:Intel Skylake Server Family:vmx,nx,model_Skylake-Server:Skylake-Server:x86_64; 30:Intel Skylake Server IBRS Family:vmx,nx,spec_ctrl,model_Skylake-Server:Skylake-Server,+spec-ctrl:x86_64; 31:Intel Skylake Server IBRS SSBD Family:vmx,nx,spec_ctrl,ssbd,model_Skylake-Server:Skylake-Server,+spec-ctrl,+ssbd:x86_64; 2:AMD Opteron G1:svm,nx,model_Opteron_G1:Opteron_G1:x86_64; 3:AMD Opteron G2:svm,nx,model_Opteron_G2:Opteron_G2:x86_64; 4:AMD Opteron G3:svm,nx,model_Opteron_G3:Opteron_G3:x86_64; 5:AMD Opteron G4:svm,nx,model_Opteron_G4:Opteron_G4:x86_64; 6:AMD Opteron G5:svm,nx,model_Opteron_G5:Opteron_G5:x86_64; 7:AMD EPYC:svm,nx,model_EPYC:EPYC:x86_64; 8:AMD EPYC IBPB:svm,nx,ibpb,model_EPYC:EPYC,+ibpb:x86_64; 3:IBM POWER8:powernv,model_POWER8:POWER8:ppc64; 4:IBM POWER9:powernv,model_POWER9:POWER9:ppc64; 2:IBM z114, z196:sie,model_z196-base:z196-base:s390x; 3:IBM zBC12, zEC12:sie,model_zEC12-base:zEC12-base:s390x; 4:IBM z13s, z13:sie,model_z13-base:z13-base:s390x; 5:IBM z14:sie,model_z14-base:z14-base:s390x;', '4.2');

7) Exit PostgreSQL and the PostgreSQL user, restart the ovirt-engine

systemctl restart ovirt-engine

After that we are able to use the AMD EPYC processor model.

[root@virtual-machine ~]# cat /proc/cpuinfo
processor : 0
vendor_id : AuthenticAMD
cpu family : 23
model : 1
model name : AMD EPYC Processor
stepping : 2
microcode : 0x1000065
cpu MHz : 2399.998
cache size : 512 KB
physical id : 0
siblings : 8
core id : 0
cpu cores : 8
apicid : 0
initial apicid : 0
fpu : yes
fpu_exception : yes
cpuid level : 13
wp : yes
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 mmxext fxsr_opt pdpe1gb rdtscp lm art rep_good nopl extd_apicid eagerfpu pni pclmulqdq ssse3 fma cx16 sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm cmp_legacy cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw retpoline_amd vmmcall fsgsbase bmi1 avx2 smep bmi2 rdseed adx smap clflushopt sha_ni xsaveopt xsavec xgetbv1 arat
bogomips : 4799.99
TLB size : 1024 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 48 bits physical, 48 bits virtual
power management:

Keep in mind that next database update will overwrite the changes that you made, so maybe apply this again.

It will not get overwritten on every update, only in exceptional cases like the 4.2.3.7 CVE fix adding new CPU types.