At 8k per TLB (for 64-bit host or target), 8 or more modes
make the TLBs bigger than 64k, and some RISC TCG backends do
not like that. On the affected hosts, cut the TLB size in
half---there is still a measurable speedup on PPC with the
next patch.
Backports commit 1de29aef17a7d70dbc04a7fe51e18942e3ebe313 from qemu
Add a MemTxAttrs field to the IOTLB, and allow target-specific
code to set it via a new tlb_set_page_with_attrs() function;
pass the attributes through to the device when making IO accesses.
Backports commit fadc1cbe85c6b032d5842ec0d19d209f50fcb375 from qemu
Make the CPU iotlb a structure rather than a plain hwaddr;
this will allow us to add transaction attributes to it.
Backports commit e469b22ffda40188954fafaf6e3308f58d50f8f8 from qemu