Re: swapping with MMU Notifiers V2

Andrea Arcangeli
2008-01-29T18:34:51Z

On Tue, Jan 29, 2008 at 08:05:20PM +0200, Avi Kivity wrote:
> If a hypervisor mandates (host virtual) == (guest physical), it would work.
> x86 still misses the dual-tagged tlb, so mmu notifiers are needed
> regardless. With s390, they have an additional offset parameter, so (host

Yep. NPT is certainly better given two levels are bad enough. The mmu
notifiers aren't really a performance problem unlike the three levels
would be (the bigger cost is likely the ipi for the tlb flushes on a
smp guest on smp host, and they cost nothing on up guest).

> virtual) == (guest physical) + offset, so qemu can coexist with the guest,
> and dual tagged tlb so that a host invalidate also evicts guest tlb
> entries.

Thanks!