[Bug 1905047] Re: Revision 0x2006a08 cause cpu stall or kernel panic on 06-55-04

[Colin Ian King]

No problem, thanks for reporting back, Can you add the version of the
BIOS to the bug report so that other folk will know which version
addresses the problem if they have the same issue.

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Title:
  Revision 0x2006a08 cause cpu stall or kernel panic on 06-55-04

Status in intel-microcode package in Ubuntu:
  Invalid

Bug description:
  Hello,

  I'm running Ubuntu Focal with latest kernel 5.4.0-54-generic on this
  cpu:

  Architecture:                    x86_64
  CPU op-mode(s):                  32-bit, 64-bit
  Byte Order:                      Little Endian
  Address sizes:                   46 bits physical, 48 bits virtual
  CPU(s):                          56
  On-line CPU(s) list:             0-55
  Thread(s) per core:              2
  Core(s) per socket:              14
  Socket(s):                       2
  NUMA node(s):                    2
  Vendor ID:                       GenuineIntel
  CPU family:                      6
  Model:                           85
  Model name:                      Intel(R) Xeon(R) Gold 5120 CPU @ 2.20GHz
  Stepping:                        4
  CPU MHz:                         1000.066
  CPU max MHz:                     3200.0000
  CPU min MHz:                     1000.0000
  BogoMIPS:                        4400.00
  Virtualization:                  VT-x
  L1d cache:                       896 KiB
  L1i cache:                       896 KiB
  L2 cache:                        28 MiB
  L3 cache:                        38.5 MiB
  NUMA node0 CPU(s):               0-13,28-41
  NUMA node1 CPU(s):               14-27,42-55
  Vulnerability Itlb multihit:     KVM: Mitigation: Split huge pages
  Vulnerability L1tf:              Mitigation; PTE Inversion; VMX conditional cache flushes, SMT vulnerable
  Vulnerability Mds:               Mitigation; Clear CPU buffers; SMT vulnerable
  Vulnerability Meltdown:          Mitigation; PTI
  Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl and seccomp
  Vulnerability Spectre v1:        Mitigation; usercopy/swapgs barriers and __user pointer sanitization
  Vulnerability Spectre v2:        Mitigation; Full generic retpoline, IBPB conditional, IBRS_FW, STIBP conditional, RSB filling
  Vulnerability Srbds:             Not affected
  Vulnerability Tsx async abort:   Mitigation; Clear CPU buffers; SMT vulnerable
  Flags:                           fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm p
                                   be syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aper
                                   fmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2api
                                   c movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l3 cdp_l3 i
                                   nvpcid_single pti intel_ppin ssbd mba ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjus
                                   t bmi1 hle avx2 smep bmi2 erms invpcid rtm cqm mpx rdt_a avx512f avx512dq rdseed adx smap clflushopt clwb intel_pt av
                                   x512cd avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local dtherm ida
                                   arat pln pts pku ospke md_clear flush_l1d

  Using the microcode rev. 0x2006a08 - Ubuntu version intel-microcode-3.20201110.0ubuntu0.20.04.2 - I'm not able to boot on this cpu anymore.
  Doing an early-load update the RCU's CPU stall detector seems to be entering in an infinite loop (see the strace in the attachment).
  This keeps repeting forever and it's neccessary a power reset to regain the machine control.

  Performing a late-load update, with the Ubuntu kernel 5.4.0-52, the machine crashes after a while (see the strace in the attachment).
  The Ubuntu kernel 5.4.0-54, disabling microcode loading - adding cmdline option `dis_ucode_ldr` - boots without any issue.

  Please note: I posted this very same issue upstream:
  https://github.com/intel/Intel-Linux-Processor-Microcode-Data-
  Files/issues/45

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