Re: [PATCH RFC 3/3] tsm: Add TVM Measurement Sample Code

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Sat, 2024-09-07 at 23:56 -0500, Cedric Xing wrote:
> This sample kernel module demonstrates how to make MRs accessible to
> user mode
> through TSM.
> 
> Once loaded, this module registers a virtual measurement provider
> with the TSM
> core and will result in the directory tree below.
> 
> /sys/kernel/tsm/
> └── measurement-example
>     ├── config_mr
>     ├── full_report
>     ├── report_digest
>     ├── rtmr0
>     │   ├── append_event
>     │   ├── digest
>     │   ├── event_log
>     │   └── hash_algo
>     ├── rtmr1
>     │   ├── append_event
>     │   ├── digest
>     │   ├── event_log
>     │   └── hash_algo
>     ├── static_mr
>     └── user_data

I'm not sure this is the best structure to apply to logs with multiple
banks (hash algorithms).  There needs to be a way to get the same
registers measurement for each bank, but the log should sit above that
(appending should extend all active banks)

How about

/sys/kernel/tsm/
└──<measurement type>
   ├──reg0
   │   ├── <log format>
   │   │   ├── append_event
   │   │   └── event_log
   │   ├── <hash algo>  
   │  ...  └── digest
   ...

That way it supports multiple log formats (would be the job of the log
extender to ensure compatibility) and multiple banks.

James