Re: [PATCH v6] x86/mm: Don't disable INVLPG if "incomplete Global INVLPG flushes" is fixed by microcode or the kernel is running in a hypervisor

[Andrew Cooper]

On 11/04/2024 3:48 pm, Xi Ruoyao wrote:
> On Thu, 2024-04-11 at 07:44 -0700, Dave Hansen wrote:
>> I agree that it sounds weird.  It _is_ weird that systems running under
>> hypervisors aren't affected.  But that's all it is: a weird bug.  The
>> documentation is correct.
> Yes, these hardware issues are just weird to me...
>

I have no inside knowledge here, but this isn't surprising to me.

VPID tags are unique to VMX operation.  At a guess, VMXON reconfigures
the tagging in the TLB to include VPID (and EPTP tags for that matter),
and works around the buggy selection for which PCIDs to drop.

~Andrew