Re: Single memory slot

[Anthony Liguori <anthony@codemonkey.ws>]

Avi Kivity wrote:
> One way to improve the gfn_to_pfn() memslot search is to register just 
> one slot.  This can only work on 64-bit, since even the smallest 
> guests need 4GB of physical address space.  Apart from speeding up 
> gfn_to_page(), it would also speed up mmio which must iterate over all 
> slots, so a lookup cache cannot help.
>
> This would require quite a bunch of changes:
> - modify gfn_to_pfn() to fail gracefully if the page is in the slot 
> but unmapped (hole handling)
> - modify qemu to reserve the guest physical address space

It could potentially speed up qemu quite a lot too as we would return to 
a model where host va == fixed address + guest pa.  That makes things 
like stl_phys/ldl_phys trivial.

Regards,

Anthony Liguori