ASRock E350M1: MSR 0x00000175 SYSENTER_ESP has 1 inconsistent values across 2 CPUs

[Paul Menzel]

Dear coreboot folks,

running fwts V16.03.00 [1] on the ASRock E350M1, the following test fails.

```
FAILED [MEDIUM] MSRCPUsInconsistent: Test 1, MSR 0x00000175 SYSENTER_ESP has 1
inconsistent values across 2 CPUs (shift: 0 mask: 0xffffffffffffffff).
MSR CPU 0 -> 0xf77d0ab0 vs CPU 1 -> 0xf77e2ab0
```

The same problem with different values is reported when running the
vendor firmware.

```
FAILED [MEDIUM] MSRCPUsInconsistent: Test 1, MSR 0x00000175 SYSENTER_ESP has 1
inconsistent values across 2 CPUs (shift: 0 mask: 0xffffffffffffffff).
MSR CPU 0 -> 0xf79d076c vs CPU 1 -> 0xf79e276c
```

I wonder if it’s an AGESA problem, or if it’s a false positive.

Have you ever seen this?

Thanks,

Paul

[1] https://wiki.ubuntu.com/FirmwareTestSuite
    Firmware Test Suite (fwts)

[Rudolf Marek]

Hi all,

This MSR is used when SYSENTER instruction is used by OS/application. The ESP
MSR usually points to to the kernel stack of current thread, so if two
different threads execute on different CPUs it will be different. False
positive, and they should fix it.

Thanks
Rudolf

[Paul Menzel]

Dear Rudolf,

Am Sonntag, den 15.05.2016, 19:49 +0200 schrieb Rudolf Marek:
> This MSR is used when SYSENTER instruction is used by OS/application. The ESP
> MSR usually points to to the kernel stack of current thread, so if two
> different threads execute on different CPUs it will be different. False
> positive, and they should fix it.

Thank you very much for clearing that up.

I submitted a bug report [1], and there is a patch up for review
disabling the tests [2].

Could you please confirm that disabling the other two MSR tests for CS
and EIP is also the right thing to do?

Thanks,

Paul

[1] https://bugs.launchpad.net/bugs/1582005
[2] https://lists.ubuntu.com/archives/fwts-devel/2016-May/007917.html

[Rudolf Marek]

Hi all,
> Could you please confirm that disabling the other two MSR tests for CS and
> EIP is also the right thing to do?

Yes I think this is OK. The SYSENTER MSRs are used by the OS and there is
nothing which BIOS needs to setup.

Same case is the SYSCALL MSR, GS/FS base and KERNEL GS base and possibly also
MSR_TSC_AUX.

#define MSR_STAR                0xc0000081 /* legacy mode SYSCALL target */
#define MSR_LSTAR               0xc0000082 /* long mode SYSCALL target */
#define MSR_CSTAR               0xc0000083 /* compat mode SYSCALL target */
#define MSR_SYSCALL_MASK        0xc0000084 /* EFLAGS mask for syscall */
#define MSR_FS_BASE             0xc0000100 /* 64bit FS base */
#define MSR_GS_BASE             0xc0000101 /* 64bit GS base */
#define MSR_KERNEL_GS_BASE      0xc0000102 /* SwapGS GS shadow */
#define MSR_TSC_AUX             0xc0000103 /* Auxiliary TSC */

Thanks
Rudolf