Re: [Xen-devel] Re: One potential issue of shadow fault emulation

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 24/12/07 18:27, "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx> wrote:

>> That will disable the VMX TPR optimization too -- the p2m lookup needs
>> to return this magic page when the shadow propagation code looks it up
>> but not when other callers look it up.  Maybe the existing scheme for
>> mapping MMIO pages directly would do; mark the page as direct MMIO
>> instead of as RAM?  Otherwise at least one of the shadow propagation
>> code and the emulator needs to special-case the vlapic page.
> 
> There are quite a few users of gfn-to-mfn functionality and only one of them
> wants the magic page. So I think it'd be cleaner to push the vlapic check a
> bit deeper than just the shadow emulation callbacks.

I should have read your email a bit more closely -- fixing this via the
typed p2m table in 3.2 would be neat. Or even not including the magic page
in the p2m at all and explicitly special-casing inside the shadow
propagation code would be okay.

 -- Keir



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