Re: [PATCH v3 3/7] KVM: pfncache: Use RCU for readers instead of a rwlock

On Thu, 2026-08-06 at 11:11 -0700, Sean Christopherson wrote:
> 
> It's probably a slow path for all current users, but it definitely won't be a slow
> path for nested virtualization, because a refresh() will be required any time the
> GPA changes, i.e. any time the vCPU runs a different vmc{b,c}12.  

Those need caching anyway, FWIW. We need a pool of nested contexts
(including these GPCs), rather than throwing them away each some the L1
switches to a different L2.

> That's why I think we should treat GPCs that are strictly bound to a
> vCPU differently.

Yes. I wonder if it's reasonable to tie it to the GUEST_USES_PFN case;
they aren't *perfectly* correlated (maybe the steal one could be
considered to be in your category too)... but perhaps those are the
ones that *care*?




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