From: cross@spitfire.i.gajendra.net   
      
   In article , BGB   wrote:   
   >On 5/22/2023 3:10 PM, Dan Cross wrote:   
   >[snip]   
   >> L2PT's like the EPT and NPT are wins here; even in the nested   
   >> VM case, where we have to resort to shadow paging techniques, we   
   >> can handle L2 page faults in the top-level hypervisor.   
   >>   
   >   
   >But, if one uses SW TLB, then NPT (as a concept) has no reason to need   
   >to exist...   
      
   Yes, at great expense.   
      
   >> There's a reason soft-TLBs have basically disappeared.  :-)   
   >   
   >Probably depends some on how the software-managed TLB is implemented.   
      
   Not really; the design issues and the impact are both   
   well-known.  Think through how a nested guest (note, not a   
   nested page table, but a recursive instance of a hypervisor)   
   would be handled.   
      
   >In my case, TLB miss triggers an interrupt, and there is an "LDTLB"   
   >instruction which basically means "Take the TLBE from these two   
   >registers and shove it into the TLB at the appropriate place".   
      
   That's pretty much the way they all work, yes.   
      
   	- Dan C.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)