By adding idte, we are now able to expose the DAT-enhancement facility
to our guest. Also, properly simulate and expose the local-tlb-clearing
facility.
To improve the TLB flushing, we will have to remember each used table (or
at least a hash!) for each tlb entry, just like real HW does.
This allows me to start an upstream kernel (having also the mvcos patch
applied) compiled for z9 using:
qemu-system-s390x ... -cpu qemu,mvcos=on,stfle=on,ldisp=on,ldisphp=on,\
eimm=on,stckf=on,csst=on,csst2=on,ginste=on,\
exrl=on,dateh=on,ltlbc=on
Linux will detect the DAT-enhancement facility and use idte+cspg.
v1 -> v2:
- Allow to enable the DAT-enhancement facility.
- Fix wrong register in idte.
- Simply set m4 to zero in case local-tlb-clearing is not enabled.