Re: [PATCH 01/16] KVM: MMU: pass unadulterated gpa to direct_page_fault

[Sean Christopherson]

On Sat, Aug 07, 2021, Paolo Bonzini wrote:
> Do not bother removing the low bits of the gpa.  This masking dates back
> to the very first commit of KVM but it is unnecessary---or even
> problematic, because the gpa is later used to fill in the MMIO page cache.

I don't disagree with the code change, but I don't see how stripping the offset
can be problematic for the MMIO page cache.  I assume you're referring to
handle_abnormal_pfn() -> vcpu_cache_mmio_info().  The "gva" is masked with
PAGE_MASK, i.e. the offset is stripped anyways.  And fundamentally, that cache
is tied to the granularity of the memslots, tracking the offset would be wrong.