Retrieve page table information from the data cache

[MikeIsAStar]

Thanks to @mkwcat for identifying the problematic code.

[Pokechu22]

Does this change affect any games? It seems like an accuracy improvement (based on ppc_750cl.pdf, section 5.4.5 Page Table Search Operation/page 207, list entry 2, which says "PTE reads [...] are considered cacheable", though it doesn't explicitly say that they can be read from the cache, just that they are "placed in the cache", which seems a bit odd). Even if it doesn't fix anything it's probably worth merging as such.

I think it'd be easier to change TranslatePageAddress to:

  template <const XCheckTLBFlag flag>
  TranslateAddressResult TranslatePageAddress(const EffectiveAddress address, bool* wi);

than to add ReadFromHardwareRuntime, as TranslatePageAddress is only called from TranslateAddress which already has flag as a template parameter.

[MikeIsAStar]

Does this change affect any games?

Despite not being a game, MKW-SP will crash on launch when the Enable Write-Back Cache (slow) option is enabled without this patch.

[Pokechu22]

I see that it does do something with page table entries without data cache flushes so this does seem like a reasonable change for that purpose. (The website's features list mentions adding security features to protect against exploits against custom files or the networking code, which is probably what this is for, though I haven't looked at in detail. So, as long as real hardware doesn't need the data cache flushes, it should be fine. If real hardware does need data cache flushes then I don't think it would work properly as a security feature...)

[MikeIsAStar]

So, as long as real hardware doesn't need the data cache flushes, it should be fine.

I can confirm that this is the case.

[Pokechu22]

I haven't tested this, but it looks good to me.