linux-kernel - RE: [PATCH Part2 v6 09/49] x86/fault: Add support to handle the RMP fault for user address

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Date:   Sat, 03 Sep 2022 08:31:09 +0000
From:   Boris Petkov <bp@...en8.de>
To:     "Kalra, Ashish" <Ashish.Kalra@....com>
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Subject: RE: [PATCH Part2 v6 09/49] x86/fault: Add support to handle the RMP fault for user address

On September 3, 2022 6:57:51 AM UTC, "Kalra, Ashish" <Ashish.Kalra@....com> wrote:
>[AMD Official Use Only - General]
>
>So essentially we want to map the faulting address to a RMP entry, considering the fact that a 2M host hugepage can be mapped as 
>4K RMP table entries and 1G host hugepage can be mapped as 2M RMP table entries.

So something's seriously confusing or missing here because if you fault on a 2M host page and the underlying RMP entries are 4K then you can use pte_index().

If the host page is 1G and the underlying RMP entries are 2M, pmd_index() should work here too.

But this piecemeal back'n'forth doesn't seem to resolve this so I'd like to ask you pls to sit down, take your time and give a detailed example of the two possible cases and what the difference is between pte_/pmd_index and your way. Feel free to add actual debug output and paste it here.

Thanks.

-- 
Sent from a small device: formatting sux and brevity is inevitable.