Re: [PATCH 5/8] x86/clear_page: add clear_page_uncached()

[Borislav Petkov]

On Wed, Oct 14, 2020 at 08:21:57PM -0700, Ankur Arora wrote:
> Also, if we did extend clear_page() to take the page-size as parameter
> we still might not have enough information (ex. a 4K or a 2MB page that
> clear_page() sees could be part of a GUP of a much larger extent) to
> decide whether to go uncached or not.

clear_page* assumes 4K. All of the lowlevel asm variants do. So adding
the size there won't bring you a whole lot.

So you'd need to devise this whole thing differently. Perhaps have a
clear_pages() helper which decides based on size what to do: uncached
clearing or the clear_page() as is now in a loop.

Looking at the callsites would give you a better idea I'd say.

Thx.

-- 
Regards/Gruss,
    Boris.

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