RE: [PATCH v5 00/34] x86: enable FRED for x86-64

[Li, Xin3]

> The following issues are seen in this round of test.
> +----------------+----------------+----------------+----------------+
> |                | x86:test_      | bpf:test_progs | x86:sysret     |
> |                | vsyscall_32    |                |    _rip_64     |
> +----------------+----------------+----------------+----------------+
> |    the 7th     |                |                |                |
> |    Intel(R)    |      FAIL      |      FAIL      |      PASS      |
> |  Core(TM) CPU  |                |                |                |
> |   6.3.0-rc1+   |                |                |                |
> +----------------+----------------+----------------+----------------+
> |    the 7th     |                |                |                |
> |    Intel(R)    |                |                |                |
> |  Core(TM) CPU  |      FAIL      |      FAIL      |      PASS      |
> | 6.3.0-rc1+ w/  |                |                |                |
> | FRED patch set |                |                |                |
> +----------------+----------------+----------------+----------------+
> | Intel Simics®  |                |                |                |
> | Simulator w/o  |      FAIL      |      FAIL      |      PASS      |
> |   FRED model   |                |                |                |
> |   6.3.0-rc1+   |                |                |                |
> +----------------+----------------+----------------+----------------+
> | Intel Simics®  |                |                |                |
> | Simulator w/o  |                |                |                |
> |   FRED model   |      FAIL      |      FAIL      |      PASS      |
> | 6.3.0-rc1+ w/  |                |                |                |
> | FRED patch set |                |                |                |
> +----------------+----------------+----------------+----------------+
> | Intel Simics®  |                |                |                |
> |  Simulator w/  |      PASS      |      FAIL      |      PASS      |
> |   FRED model   |                |                |                |
> |   6.3.0-rc1+   |                |                |                |
> +----------------+----------------+----------------+----------------+
> | Intel Simics®  |                |                |                |
> |  Simulator w/  |                |                |                |
> |   FRED model   |      PASS      |      FAIL      |      PASS      |
> | 6.3.0-rc1+ w/  |                |                |                |
> | FRED patch set |                |                |                |
> | FRED disabled  |                |                |                |
> +----------------+----------------+----------------+----------------+
> | Intel Simics®  |                |                |                |
> |  Simulator w/  |                |                |                |
> |   FRED model   |      PASS      |      HANG      |      FAIL      |
> | 6.3.0-rc1+ w/  |                |                |                |
> | FRED patch set |                |                |                |
> +----------------+----------------+----------------+----------------+
> 
> The "x86:test_vsyscall_32" is a regression since the v3 FRED patch set.

The "x86:test_vsyscall_32" test passes on the Simics FRED model, no matter
whether FRED is enabled or not, because the Simics FRED model has the RDPID
instruction support.

While on a Simics non-FRED model or the test bare metal machine, which
don't have the RDPID instruction support, the test reads CPU ID from the
GDT_ENTRY_CPUNODE entry, thus it fails due to:
https://lore.kernel.org/lkml/20230311084824.2340-1-xin3.li@xxxxxxxxx/

Thanks!
  Xin