Re: [PATCH] x86/mm/cpa: Warn if set_memory_XXcrypted() fails

[Edgecombe, Rick P]

On Wed, 2023-10-25 at 13:03 -0500, Tom Lendacky wrote:
> 
> Reviewed-by: Tom Lendacky <thomas.lendacky@xxxxxxx>

Thanks!
> > 
> 
> Under SEV, when making a page private/encrypted and the hypervisor
> does 
> not assign the page to the guest (encrypted), but says it did, then
> when 
> SEV tries to perform the PVALIDATE in the enc_status_change_finish()
> call, 
> a nested page fault (#NPF) will be generated and exit to the
> hypervisor. 
> Until the hypervisor assigns the page to the guest, the guest will
> not be 
> able to make forward progress in regards to updating or using that
> page.

Yea, mismatches between guest page tables and EPT/NPT can be trouble
for TDX as well.

> 
> And if the hypervisor returns an error when changing the page state,
> then, 
> yes, the guest will terminate.

I guess those callbacks could be changed to return an error after all
these fixes then, if you want.