illumos gate

Can you share which of the MSRs it's emulating or not emulating as expected there? I would have expected them not to emulate any of them and behave closer to qemu. I assume this is in a nitro specific instance?

The issue is that it advertises support for the PPIN and shows it as unlocked, but attempts to enable it don't stick. This is not specific to Nitro (I've not tested Nitro).

OK. I'd be curious to understand more as the on_fault/no_fault logic in the CMI MSR code should cause us to return with no value, in that case, but clearly something's going wrong. If you have more details to share, I'd appreciate it as then I can potentially prototype a fix.

Here is the fix that we've been using: https://code.illumos.org/c/illumos-gate/+/679

So I agree double checking things is useful and in the face of a bunch of hypervisor games we should do anyways. But we do want to figure out why the on_fault/no_fault isn't working. Because the way this should work is that the rdmsr should be checked and eventually indicate that the cmi operation should fail which would return NULL.