virtio: Guest->Snabb address cache optimization
virtio: Guest->Snabb address cache optimization

Check the cache (most recently used memory region) explicitly before
entering the loop. This is to help keep LuaJIT "on trace" for the
fast-path case.

fhanik/snabbswitch,dpino/snabb,snabbco/snabb,alexandergall/snabbswitch,snabbnfv-goodies/snabbswitch,dpino/snabb,javierguerragiraldez/snabbswitch,Igalia/snabbswitch,heryii/snabb,alexandergall/snabbswitch,hb9cwp/snabbswitch,Igalia/snabb,hb9cwp/snabbswitch,dpino/snabb,lukego/snabb,justincormack/snabbswitch,pirate/snabbswitch,fhanik/snabbswitch,snabbnfv-goodies/snabbswitch,Igalia/snabb,pavel-odintsov/snabbswitch,alexandergall/snabbswitch,javierguerragiraldez/snabbswitch,andywingo/snabbswitch,kbara/snabb,aperezdc/snabbswitch,eugeneia/snabb,lukego/snabb,snabbco/snabb,mixflowtech/logsensor,alexandergall/snabbswitch,snabbco/snabb,Igalia/snabbswitch,eugeneia/snabb,heryii/snabb,wingo/snabbswitch,snabbco/snabb,eugeneia/snabbswitch,andywingo/snabbswitch,lukego/snabb,dpino/snabbswitch,dpino/snabbswitch,Igalia/snabb,heryii/snabb,kbara/snabb,plajjan/snabbswitch,kbara/snabb,lukego/snabbswitch,wingo/snabb,eugeneia/snabb,plajjan/snabbswitch,hb9cwp/snabbswitch,eugeneia/snabb,kbara/snabb,snabbco/snabb,heryii/snabb,aperezdc/snabbswitch,xdel/snabbswitch,dpino/snabb,virtualopensystems/snabbswitch,plajjan/snabbswitch,dpino/snabbswitch,justincormack/snabbswitch,wingo/snabb,virtualopensystems/snabbswitch,dwdm/snabbswitch,alexandergall/snabbswitch,snabbnfv-goodies/snabbswitch,Igalia/snabb,wingo/snabbswitch,dwdm/snabbswitch,lukego/snabbswitch,lukego/snabbswitch,snabbco/snabb,kbara/snabb,andywingo/snabbswitch,eugeneia/snabbswitch,justincormack/snabbswitch,eugeneia/snabb,justincormack/snabbswitch,hb9cwp/snabbswitch,heryii/snabb,mixflowtech/logsensor,lukego/snabb,mixflowtech/logsensor,Igalia/snabb,eugeneia/snabbswitch,Igalia/snabb,SnabbCo/snabbswitch,Igalia/snabbswitch,kellabyte/snabbswitch,Igalia/snabbswitch,Igalia/snabbswitch,dpino/snabb,alexandergall/snabbswitch,xdel/snabbswitch,kbara/snabb,SnabbCo/snabbswitch,xdel/snabbswitch,SnabbCo/snabbswitch,SnabbCo/snabbswitch,pavel-odintsov/snabbswitch,wingo/snabb,andywingo/snabbswitch,alexandergall/snabbswitch,heryii/snabb,dpino/snabbswitch,dwdm/snabbswitch,snabbco/snabb,wingo/snabbswitch,pavel-odintsov/snabbswitch,dpino/snabb,eugeneia/snabb,mixflowtech/logsensor,virtualopensystems/snabbswitch,mixflowtech/logsensor,pirate/snabbswitch,wingo/snabbswitch,eugeneia/snabb,plajjan/snabbswitch,kellabyte/snabbswitch,javierguerragiraldez/snabbswitch,dpino/snabb,pirate/snabbswitch,alexandergall/snabbswitch,aperezdc/snabbswitch,wingo/snabb,fhanik/snabbswitch,lukego/snabbswitch,Igalia/snabb,wingo/snabb,Igalia/snabb,snabbnfv-goodies/snabbswitch,kellabyte/snabbswitch,wingo/snabb,eugeneia/snabbswitch,snabbco/snabb,eugeneia/snabb,aperezdc/snabbswitch