Re: [PATCH 2/2] tpm: add backend for mssim

[Stefan Berger <stefanb@linux.ibm.com>]

On 12/16/22 05:27, Daniel P. Berrangé wrote:
> On Thu, Dec 15, 2022 at 03:53:43PM -0500, Stefan Berger wrote:
>>
>>
>> On 12/15/22 15:30, James Bottomley wrote:
>>> On Thu, 2022-12-15 at 15:22 -0500, Stefan Berger wrote:
>>>> On 12/15/22 15:07, James Bottomley wrote:
>>> [...]
>>>>> don't really have much interest in the migration use case, but I
>>>>> knew it should work like the passthrough case, so that's what I
>>>>> tested.
>>>>
>>>> I think your device needs to block migrations since it doesn't handle
>>>> all migration scenarios correctly.
>>>
>>> Passthrough doesn't block migrations either, presumably because it can
>>> also be made to work if you know what you're doing.  I might not be
>>
>> Don't compare it to passthrough, compare it to swtpm. It should
>> have at least the same features as swtpm or be better, otherwise
>> I don't see why we need to have the backend device in the upstream
>> repo.
> 
> James has explained multiple times that mssim is a beneficial
> thing to support, given that it is the reference implementation
> of TPM2. Requiring the same or greater features than swtpm is
> an unreasonable thing to demand.

Nevertheless it needs documentation and has to handle migration scenarios either via a blocker or it has to handle them all correctly. Since it's supposed to be a TPM running remote you had asked for TLS support iirc.

   Stefan

> 
> With regards,
> Daniel