Re: [PATCH v6 04/11] swiotlb: Map the buffer if it was unmapped by XPFO

[Christoph Hellwig]

> -     if (PageHighMem(pfn_to_page(pfn))) {
> +     if (PageHighMem(page) || xpfo_page_is_unmapped(page)) {

Please don't sprinkle xpfo details over various bits of code.

Just add a helper with a descriptive name, e.g.

page_is_unmapped()

that also includes the highmem case, as that will easily document
what this check is doing.