Two RAS related fixes:

  - Shut down the per CPU thermal throttling poll work properly when a CPU
    goes offline. The missing shutdown caused the poll work to be migrated
    to a unbound worker which triggered warnings about the usage of
    smp_processor_id() in preemptible context

  - Fix the PPIN feature initialization which missed to enable the
    functionality when PPIN_CTL was enabled but the MSR locked against
    updates.
x86/mce: Fix logic and comments around MSR_PPIN_CTL

There are two implemented bits in the PPIN_CTL MSR:

Bit 0: LockOut (R/WO)
      Set 1 to prevent further writes to MSR_PPIN_CTL.

Bit 1: Enable_PPIN (R/W)
       If 1, enables MSR_PPIN to be accessible using RDMSR.
       If 0, an attempt to read MSR_PPIN will cause #GP.

So there are four defined values:
	0: PPIN is disabled, PPIN_CTL may be updated
	1: PPIN is disabled. PPIN_CTL is locked against updates
	2: PPIN is enabled. PPIN_CTL may be updated
	3: PPIN is enabled. PPIN_CTL is locked against updates

Code would only enable the X86_FEATURE_INTEL_PPIN feature for case "2".
When it should have done so for both case "2" and case "3".

Fix the final test to just check for the enable bit. Also fix some of
the other comments in this function.

Fixes: 3f5a7896a509 ("x86/mce: Include the PPIN in MCE records when available")
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200226011737.9958-1-tony.luck@intel.com
1 file changed