Re: [PATCH v2 08/19] PCI/TSM: Add "evidence" support

[Dan Williams <dan.j.williams@intel.com>]

Xu Yilun wrote:
> > +void pci_tsm_init_evidence(struct pci_tsm_evidence *evidence, int slot,
> > +			   enum hash_algo digest_algo)
> > +{
> > +	evidence->slot = slot;
> > +	evidence->generation = 1;
> > +	evidence->digest_algo = digest_algo;
> > +	init_rwsem(&evidence->lock);
> 
> IIUC, this function is for link tsm driver, is it?

It is meant to be generic for both, and an "optional" support
library for the low-level TSM drivers.

- Host PCI/TSM evidence interface collects the blobs
- Guest PCI/TSM evidence interface retrieves the digests via private TSM
  GHCI
- Some infrastructure (either arch specific GHCI or new common GHCI)
  pushes the blobs from Host to Guest so that guest PCI/TSM evidence
gathering can also get the blobs.

> But in the following patch, devsec tsm would consume
> pci_tsm_mmio_alloc() which uses evidence->lock. So my solution is to
> initialize the lock on tsm construction.

So I did flub the "->evidence == 0" check, and yes initializing the lock
by default looks like the right answer to that problem.