Andrea Arcangeli wrote: > On Tue, Jan 29, 2008 at 05:35:34PM +0100, Carsten Otte wrote: > >> Avi Kivity wrote: >> >>> Every arch except s390 needs it. An ugly #ifndef >>> CONFIG_KVM_HARDWARE_TLB_SYNC is preferred to duplicating the code. >>> >> BTW, from reading AMDs spec I don't expect NPT to need this vehicle >> > > By your conclusion I suppose you thought NPT maps guest physical to > host virtual. If it was the case the cpu would to walk three layer of > pagetables (each layer is an arrow): guest virtual -> guest physical > -> host virtual -> host physical. Instead it's just guest virtual -> > guest physical -> host physical. Or even less for shadow: guest > virtual -> host physical, which is why shadow should be faster for > number crunching still (and definitely slower for dbms). >
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 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. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
