Re: [RFC PATCH v2 5/6] PCI/TSM: Authenticate devices via platform TSM

From: Xu Yilun <yilun.xu@linux.intel.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Alexey Kardashevskiy <aik@amd.com>,
	linux-coco@lists.linux.dev, Wu Hao <hao.wu@intel.com>,
	Yilun Xu <yilun.xu@intel.com>, Lukas Wunner <lukas@wunner.de>,
	Samuel Ortiz <sameo@rivosinc.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	kevin.tian@intel.com, gregkh@linuxfoundation.org,
	linux-pci@vger.kernel.org
Subject: Re: [RFC PATCH v2 5/6] PCI/TSM: Authenticate devices via platform TSM
Date: Tue, 7 May 2024 16:46:29 +0800	[thread overview]
Message-ID: <ZjnqZRPaijFxO9rh@yilunxu-OptiPlex-7050> (raw)
In-Reply-To: <662c69eb6dbf1_b6e0294d1@dwillia2-mobl3.amr.corp.intel.com.notmuch>

> > > +
> > > +/* collect TSM capable devices to rendezvous with the tsm driver */
> > > +static DEFINE_XARRAY(pci_tsm_devs);
> > 
> > imho either this or pci_dev::tsm is enough but not necessarily both.
> 
> You mean:
> 
> s/pci_tsm_devs/tsm_devs/
> 
> ?

I don't think the concern is just a renaming. My understanding is, we
already have a struct pci_tsm embedded in struct pci_dev, we could loop
and find all TSM capable devices by:

	for_each_pci_dev(pdev) {
		if (pdev->tsm)
			pci_tsm_add/del(pdev);
	}

A dedicated list for TSM capable devices seems not necessary.

But my concern is about VFs.  VFs are as well TSM capable but not
applicable for tsm_ops->exec(TSM_EXEC_CONNECT), maybe not applicable
for tsm_ops->add() either.  One way to distinguish PF/VFs is we only
collect PFs in pci_tsm_devs, but all TSM capable devices have
valid pci_dev::tsm pointer.

TSM capable devices in Guest should not been collected in pci_tsm_devs
either.

Thanks,
Yilun