Re: [Xen-devel] [PATCH RFC v12 14/21] pvh: read_descriptor for PVH guests.

[George Dunlap <george.dunlap@xxxxxxxxxxxxx>]

On 13/09/13 17:25, George Dunlap wrote:
> This is in preparation for enabling emulated privops for PVH guests.
>
> This one unfortunately has a bit more of an impedance mismatch:
>
> * For PV, the selector is hard-coded in by passing #name in the
>    #define.  For PVH, we have to do a switch statement.
>
> * For PV, given the desrciptor, it can read the resulting base, limit,
>    &c directly; for PVH, we have to read the values currently loaded in the 
> vmcs.
>
> This leads to a rather awkward construct where we *both* read the
> descriptor, *and* specify a selector, and introduce an intermediate function,
> read_descriptor_sel.
>
> Unfortunately, without introducing a rather pointless switch()
> statement to the PV path similar to the one in the PVH path, there's
> no way to make this less awkward.
If anyone has any clever ideas about this one, feel free to chime in...

 -George


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