On 20.06.2012, at 01:52, Benjamin Herrenschmidt wrote: > On Wed, 2012-06-20 at 01:30 +0200, Alexander Graf wrote: >>> We support the paravirtualized -M pseries in full emu as well, in which >>> case the hashed page table is handled by qemu itself who implements the >>> H_ENTER & co hypercalls. So it's very similar, except that qemu doesn't >>> have to ask the kernel to get a snapshot :-) >>> >>> So I can flush out the storage format and two stage process inside qemu, >>> and then bother with the kvm/kernel interface. >>> >>> Normal "bare metal" operation in qemu (or even KVM "PR") doesn't require >>> this as in that case the hash table is just a normal part of the guest >>> memory, it's only an issue when doing paravirtualized guest such as >>> pseries (aka PAPR). >> >> IIRC we still allocate it outside of normal guest memory, so you don't get >> the migration for free :). > > You haven't ready my post properly :-)
Ugh. Right. I haven't :). For Non-pseries VMs, the HTAB is always in guest RAM, so it's migrated automatically. Only pseries is special in keeping it outside. Alex