Re: [PATCH 40/70] x86/sev-es: Setup per-cpu GHCBs for the runtime handler

Tom Lendacky
2020-04-14T20:18:55Z

On 4/14/20 3:16 PM, Tom Lendacky wrote:
>
>
> On 4/14/20 3:12 PM, Dave Hansen wrote:
>> On 4/14/20 1:04 PM, Tom Lendacky wrote:
>>>> set_memory_decrypted needs to check the return value. I see it
>>>> consistently return ENOMEM. I've traced that back to split_large_page
>>>> in arch/x86/mm/pat/set_memory.c.
>>>
>>> At that point the guest won't be able to communicate with the
>>> hypervisor, too. Maybe we should BUG() here to terminate further
>>> processing?
>>
>> Escalating an -ENOMEM into a crashed kernel seems a bit extreme.
>> Granted, the guest may be in an unrecoverable state, but the host
>> doesn't need to be too.
>>
>
> The host wouldn't be. This only happens in a guest, so it would be just
> causing the guest kernel to panic early in the boot.

And I should add that it would only impact an SEV-ES guest.

Thanks,
Tom

>
> Thanks,
> Tom
>