Re: [PATCH 04/12] Nested Virtualization: core

[Christoph Egger <Christoph.Egger@amd.com>]

On Thursday 06 January 2011 18:33:56 Dong, Eddie wrote:
> >> This is overcomplicated. Static table should serve this much simple
> >> and efficient.
> >
> > The logic to select the right static table will be still needed. I am
> > not sure if removing the _xmalloc() call simplifies this part a lot.
>
> It will be much simple. You don't need the nestedhvm_vcpu_iomap_get/put
> api, nor the refcnt.
>
> The thing more important is policy: If you are in favoring of memory size
> or simplicity. If it is for memory size, then you should only allocate 2
> io_bitmap pages for VMX.
>
> > I appreciate opinions from other people on this.
>
> Besides, ideally we should implement per guest io bitmap page, by reusing
> L1 guest io_bitmap + write protection of the page table. At least for both
> Xen & KVM, the io bitmap is not modified at runtime once it is initialized.
> The readibility can be improved & the memory page can be saved. We only
> need 2 bits per L1 guest.
>
> But if we want simplicity, I am ok too, however the current patch doesn't
> fit for either of the goal.

I think, I need to excuse. Now that I did the change in my local tree
I have to mention that did not realize that I can remove the put function
completely. This in fact is a simplification.

Christoph


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