Re: [PATCH 2/4] x86/tdx: Use ReportFatalError to report missing SEPT_VE_DISABLE

Dave Hansen
2022-12-12T16:43:01Z

On 12/12/22 08:37, Sathyanarayanan Kuppuswamy wrote:
> On 12/12/22 8:10 AM, Dave Hansen wrote:
>> On 12/9/22 12:51, Sathyanarayanan Kuppuswamy wrote:
>>>>>> + while (1) {
>>>>>> + __tdx_hypercall(&args, 0);
>>>>>> + }
>>>>> Instead of an infinite loop, I'm wondering if the guest should panic after
>>>>> retrying for few times.
>>>> Hm. What difference would it make?
>>> IIUC, the goal of this patch is to report the fatal error to VMM and panic.
>>> But, if VMM does not terminate the guest as we expect, rather than trying
>>> continuously, isn't it better to panic ourselves? That way the behavior
>>> will be similar to what we have currently.
>> What does "panic ourselves" mean exactly? What is the current behavior
>> which that would match?
> I meant directly calling panic(). Before this patch, if the SEPT VE DISABLE
> attribute was not set, we would call panic(). In this patch, we try to report
> the error to VMM and wait for it to terminate the guest in the same case.
> But after reporting the error, if VMM does not terminate the guest as expected,
> I thought instead of retrying continuously, we can call panic() directly after
> some retries.

Could you explain how panic() is better than retrying?

You might also want to go look at the original changelog for this patch.