Re: [edk2-devel] [PATCH v10 1/4] OvmfPkg: Add memory acceptance event in AmdSevDxe

["Dionna Glaze" <dionnaglaze@google.com>]

>
> So, no memory is getting accepted. Questions below:
>
> - If no memory is getting accepted at all, should guest boot fail with
>    below errors?

No, the guest should not error. EBS should return success on the
second call and permit progress.

> - Why unaccepted memory not being set in my setup but works fine for
>    you? Does it require any other change?
>

We have an internal fork of EDK2 that we regularly rebase on top of
upstream, and we have our own hypervisor called Vanadium. So there's a
lot different. We don't have an easy way to test with upstream EDK2
and Qemu.
A recent import found incompatibilities with measured boot only in
SEV-SNP that we have disabled, but that's related to NVdata, which we
deal with differently in GCE due to the cloud IVARS service and our
allergy to SMM emulation. Should be unrelated.

I've looked over our OvmfPkg.patch that we maintain after every rebase
and most everything is related to our paravirtualized UEFI package
that eschews SMM to talk to Vanadium directly through either shared
memory or port I/O depending on whether the guest OS owns cr3 or not.

You've added a log for the if != unaccepted memory, but will you log
what status the function ultimately returns? And both the MapKey what
status CoreTerminateMemoryMap returns in DxeMain.c's
CoreExitBootServices? I'm wondering if maybe the EFI stub calling EBS
isn't calling GetMemoryMap to update the MapKey after the
invalid_param result that this semantics depends on. If the stub is
the Linux kernel's own stub, then it should be doing the right
thing...

> Thanks,
> Pankaj
>
> > 9. Return successfully (one would hope)
> >
> >> Accepting all memory^M
> >> Accepting all memory^M
> >> EFI stub: ERROR: exit_boot() failed!^M
> >> EFI stub: ERROR: efi_main() failed!^M
> >
> > This now does suggest that EBS is failing twice, since after the
> > supposed no-op of the second log, the EFI stub's exit_boot claims
> > failure. I can't reproduce this part. Would you try adding a log
> > within the acceptance loop inside the if that checks for unaccepted
> > memory? I'd be curious if the loop is indeed changing the map again,
> > despite my claims at idempotency.
> >
>
--
-Dionna Glaze, PhD (she/her)