Re: [PATCH v10 11/41] KVM: guest_memfd: Ensure pages are not in use before conversion

On Thu, 2026-08-13 at 11:51 -0700, Ackerley Tng wrote:

"Edgecombe, Rick P" [off-list ref] writes:

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On Tue, 2026-08-11 at 10:35 -0700, Ackerley Tng wrote:

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Would like to see what Sean thinks of this. Either way, is it okay to
follow up after conversions lands?

Let's see what Sean thinks of this :)
I raised this because the issue was encountered by one TDX's stress
selftest.

Which stress selftest is this? I can try running this on my side too.

We have some selftests that are built on the basic TDX selftests. One just
hammers the MMU stuff with a bunch of zaps and also weird stuff from the guest.
It was eventually too much work to try to keep the internal enhancements rebased

Would like all the comments we can get on TDX selftests v14 [1]!

I think we had a few. Let me try to round up some more folks.

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nicely so we actually just run an old branch's TDX selftests against newer
kernels. So the branch is a bit of a pile, and not really suitable for sharing.
We plan to clean it and upstream it when the path clears. So it would really
help to get those basic ones upstream. We remain happy to help, so please let us
know.

I guess at this point I'm hoping y'all and Sean are okay that this
conversions series merges, and we let this stress test failure be
handled later. I'll be around to fix things :)

I'd say the line of sight to fixing this would be when the KVM MMU only
gets PFNs (and no pages at all) from guest_memfd.

Hmm, I think we shouldn't upstream a uABI that we don't have line of sight to
making robust. So it would be good to settle this thread at least.

I'd point to Yan for what side of that line this is on, as she has been
following this stuff much more to me.