[PATCH v1 1/8] docs: documentation and schema for the new TPM Proxy device

[Daniel Henrique Barboza]

On 5/11/20 8:50 AM, Daniel Henrique Barboza wrote:
> 
> 
> On 5/11/20 8:28 AM, Daniel P. Berrangé wrote:
>> On Mon, May 11, 2020 at 08:26:53AM -0300, Daniel Henrique Barboza wrote:
>>>
>>>
>>> On 5/11/20 6:57 AM, Daniel P. Berrangé wrote:
>>>> On Mon, May 11, 2020 at 11:22:57AM +1000, David Gibson wrote:
>>> [...]
[...]
>>
>> Currently libvirt only allows a single <tpm>, but we can trivially
>> lift that restriction to allow multiple if desired too.
> 
> I don't believe it'll be necessary. Since it's only this TPM Proxy device that
> can coexist with other TPMs, my idea is to do what I did here in this series,
> but instead of creating a new device type I'll re-use the existing TPM device
> in a 'tpmproxy' pointer in the domain for this case.
> 
> I'll still thinking about whether a new backend type is warranted or not. For
> this PPC64 case alone it'll be simpler to just add a new 'model' called
> 'spapr-tpm'-proxy' for the existing TPM passthrough type. Creating a new
> backend type makes it easier to add other TPM Proxy devices when other archs
> implement it though.

Update: I tried it out the new "backend" approach and didn't enjoy the results.
It ended up replicating a large amount of existing cgroup/dac/selinux code that
handles the existing "passthrough" backend and, all said and done, it didn't alleviate
that much the parsing/format XML logic comparing to the alternative.

I chose then to go to the simpler route - adding a new 'passthrough' model called
'spapr-tpm-proxy'. This will not scale well if/when more TPM proxies devices are
added in the future, but we can cross that bridge when we come to it.


DHB


> 
> 
> 
> Thanks,
> 
> DHB
> 
> 
>>
>> Regards,
>> Daniel
>>