Re: [Xen-devel] Re: [PATCH 12/13] Nested Virtualization: vram

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

At 16:36 +0100 on 13 Sep (1284395780), Christoph Egger wrote:
> On Monday 13 September 2010 15:50:40 Tim Deegan wrote:
> > OK.  That's certainly confusing.  I think the fix is to have all the
> > outward-facing interfaces to the p2m code always operate on the host
> > (L1->L0) p2m.  None of their callers would know what to do with an L2
> > pfn anyway.  Only code that explicitly asks for it (e.g. the NPF
> > handler) should see the L2->L0 p2m.
> 
> The instruction emulator also must see the L2 -> L0 p2m
> - to be more precise it is __hvm_copy() that fetches the
> instruction - in order to be able to emulate instructions
> for the L2 guest the L1 guest does not intercept.

It needs to be able to fetch from virtual addresses; if we make
paging_gva_to_gfn always return an N1 pfn then that should just work.
Does the instruction emulator need to read N2 pfns for anything else?

Tim.

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, XenServer Engineering
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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