According to [1], the Intel(R) Xeon(R) CPU E5-2699 v3 has 18 cores per CPU and 2 threads per core. However, a hs_err file generated on a machine with that CPU says:

CPU:total 12 (initial active 12) (64 cores per cpu, 2 threads per core) family 6 model 63 stepping 2, cmov, cx8, fxsr, mmx, sse, sse2, sse3, ssse3, sse4.1, sse4.2, popcnt, avx, avx2, aes, clmul, erms, lzcnt, ht, tsc, bmi1, bmi2, fma
CPU Model and flags from /proc/cpuinfo:
model name : Intel(R) Xeon(R) CPU E5-2699 v3 @ 2.30GHz
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 pdpe1gb rdtscp lm constant_tsc rep_good nopl eagerfpu pni pclmulqdq ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm abm xsaveopt invpcid_single ibrs stibp ibpb pti fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid

The "total 12" is due to virtual machine configuration limiting the number of cores that are available.

The "64 cores per cpu" comes from cores_per_cpu() in vm_version_x86.cpp and is calculated by diving the total number of threads by the number of threads per core. This is described in table 5-18 and 5-19 of [2]. Since the number of threads per core is correct (= 2), it seems that the total number of threads is incorrect.

[1] https://ark.intel.com/products/81061/Intel-Xeon-Processor-E5-2699-v3-45M-Cache-2-30-GHz-
[2] https://www.scss.tcd.ie/Jeremy.Jones/CS4021/processor-identification-cpuid-instruction-note.pdf