Re: [PATCH v3 06/13] samples/devsec: Introduce a PCI device-security bus + endpoint sample

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

On Thu, 15 May 2025 22:47:25 -0700
Dan Williams <dan.j.williams@intel.com> wrote:

> Establish just enough emulated PCI infrastructure to register a sample
> TSM (platform security manager) driver and have it discover an IDE + TEE
> (link encryption + device-interface security protocol (TDISP)) capable
> device.
> 
> Use the existing a CONFIG_PCI_BRIDGE_EMUL to emulate an IDE capable root
> port, and open code the emulation of an endpoint device via simulated
> configuration cycle responses.
> 
> The devsec_tsm driver responds to the PCI core TSM operations as if it
> successfully exercised the given interface security protocol message.
> 
> The devsec_bus and devsec_tsm drivers can be loaded in either order to
> reflect cases like SEV-TIO where the TSM is PCI-device firmware, and
> cases like TDX Connect where the TSM is a software agent running on the
> host CPU.
> 
> Follow-on patches add common code for TSM managed IDE establishment. For
> now, just successfully complete setup and teardown of the DSM (device
> security manager) context as a building block for management of TDI
> (trusted device interface) instances.
> 
>  # modprobe devsec_bus
>     devsec_bus devsec_bus: PCI host bridge to bus 10000:00
>     pci_bus 10000:00: root bus resource [bus 00-01]
>     pci_bus 10000:00: root bus resource [mem 0xf000000000-0xffffffffff 64bit]
>     pci 10000:00:00.0: [8086:7075] type 01 class 0x060400 PCIe Root Port
>     pci 10000:00:00.0: PCI bridge to [bus 00]
>     pci 10000:00:00.0:   bridge window [io  0x0000-0x0fff]
>     pci 10000:00:00.0:   bridge window [mem 0x00000000-0x000fffff]
>     pci 10000:00:00.0:   bridge window [mem 0x00000000-0x000fffff 64bit pref]
>     pci 10000:00:00.0: bridge configuration invalid ([bus 00-00]), reconfiguring
>     pci 10000:01:00.0: [8086:ffff] type 00 class 0x000000 PCIe Endpoint
>     pci 10000:01:00.0: BAR 0 [mem 0xf000000000-0xf0001fffff 64bit pref]
>     pci_doe_abort: pci 10000:01:00.0: DOE: [100] Issuing Abort
>     pci_doe_cache_protocols: pci 10000:01:00.0: DOE: [100] Found protocol 0 vid: 1 prot: 1
>     pci 10000:01:00.0: disabling ASPM on pre-1.1 PCIe device.  You can enable it with 'pcie_aspm=force'
>     pci 10000:00:00.0: PCI bridge to [bus 01]
>     pci_bus 10000:01: busn_res: [bus 01] end is updated to 01
>  # modprobe devsec_tsm
>     devsec_tsm_pci_probe: pci 10000:01:00.0: devsec: tsm enabled
>     __pci_tsm_init: pci 10000:01:00.0: TSM: Device security capabilities detected ( ide tee ), TSM attach
> 
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: Lukas Wunner <lukas@wunner.de>
> Cc: Samuel Ortiz <sameo@rivosinc.com>
> Cc: Alexey Kardashevskiy <aik@amd.com>
> Cc: Xu Yilun <yilun.xu@linux.intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Interesting bit of emulation.  Only real question I have
is whether you can switch from platform devices to faux bus?



> diff --git a/samples/devsec/tsm.c b/samples/devsec/tsm.c
> new file mode 100644
> index 000000000000..7a8d33dc54c6
> --- /dev/null
> +++ b/samples/devsec/tsm.c
> @@ -0,0 +1,143 @@

> +static const struct pci_tsm_ops devsec_pci_ops = {
> +	.probe = devsec_tsm_pci_probe,
> +	.remove = devsec_tsm_pci_remove,
> +	.connect = devsec_tsm_connect,
> +	.disconnect = devsec_tsm_disconnect,
> +};
> +
> +static void devsec_tsm_remove(void *tsm_core)
> +{
> +	tsm_unregister(tsm_core);
> +}
> +
> +static int devsec_tsm_probe(struct platform_device *pdev)
> +{
> +	struct tsm_core_dev *tsm_core;
> +
> +	tsm_core = tsm_register(&pdev->dev, NULL, &devsec_pci_ops);
> +	if (IS_ERR(tsm_core))
> +		return PTR_ERR(tsm_core);
> +
> +	return devm_add_action_or_reset(&pdev->dev, devsec_tsm_remove,
> +					tsm_core);
> +}
> +
> +static struct platform_driver devsec_tsm_driver = {
> +	.driver = {
> +		.name = "devsec_tsm",
> +	},
> +};
> +
> +static struct platform_device *devsec_tsm;
> +
> +static int __init devsec_tsm_init(void)
> +{

Could this use the faux bus stuff or does it need to be a platform
device for some reason?  That support may well have crossed with this work.


> +	struct platform_device_info devsec_tsm_info = {
> +		.name = "devsec_tsm",
> +		.id = -1,
> +	};
> +	int rc;
> +
> +	devsec_tsm = platform_device_register_full(&devsec_tsm_info);
> +	if (IS_ERR(devsec_tsm))
> +		return PTR_ERR(devsec_tsm);
> +
> +	rc = platform_driver_probe(&devsec_tsm_driver, devsec_tsm_probe);
> +	if (rc)
> +		platform_device_unregister(devsec_tsm);
> +	return rc;
> +}
> +module_init(devsec_tsm_init);
> +
> +static void __exit devsec_tsm_exit(void)
> +{
> +	platform_driver_unregister(&devsec_tsm_driver);
> +	platform_device_unregister(devsec_tsm);
> +}
> +module_exit(devsec_tsm_exit);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Device Security Sample Infrastructure: Platform TSM Driver");