Comment 2 for bug 1968681

This hardware is an AMD system, codename Rome, Second generation Epyc

Fix:
https://github.com/torvalds/linux/commit/9d40b85bb46a99bc95dad3a07787da93b0a018e9
https://github.com/torvalds/linux/commit/0cb8410b90e78948984f35f2c4d50c2c0b7ee675

With patched kernel, the rdpru flag will be available in cpuinfo:
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 constant_tsc rep_good nopl xtopology nonstop_tsc cpuid extd_apicid aperfmperf pni pclmulqdq monitor ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx f16c rdrand lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt tce topoext perfctr_core perfctr_nb bpext perfctr_llc mwaitx cpb cat_l3 cdp_l3 invpcid_single hw_pstate ssbd ibrs ibpb stibp vmmcall fsgsbase bmi1 avx2 smep bmi2 erms invpcid cqm rdt_a rdseed adx smap clflushopt clwb sha_ni xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local clzero irperf xsaveerptr rdpru arat npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold v_vmsave_vmload vgif umip pku ospke vaes vpclmulqdq rdpid overflow_recov succor smca
bugs : sysret_ss_attrs spectre_v1 spectre_v2 spec_store_bypass

$ sudo ./rdpru
BUILD_HEAD=16647354
timeout -k 1s --foreground 90s /usr/bin/qemu-system-x86_64 --no-reboot -nodefaults -device pc-testdev -device isa-debug-exit,iobase=0xf4,iosize=0x4 -vnc none -serial stdio -device pci-testdev -machine accel=kvm -kernel /tmp/tmp.syc17ecDpN -smp 1 -cpu max # -initrd /tmp/tmp.poLG53JqrJ
enabling apic
PASS: RDPRU raises #UD
SUMMARY: 1 tests
PASS rdpru (1 tests)