Re: [PATCH 15/24] x86/mm: Allow flushing for future ASID switches

[Dave Hansen]

On 11/30/2017 10:55 AM, Peter Zijlstra wrote:
>> __flush_tlb() does a flushing CR3 write that flushes the current PCID.
>> If we need other PCIDs flushed, we have to do it via the
>> tlb_flush_shared_nonglobals() mechanism.
> But the thing is, you _cannot_ have PCID enabled in that branch.

Is there some hardware limitation that I'm missing?