platform/x86: Add Intel Software Defined Silicon driver

Intel Software Defined Silicon (SDSi) is a post manufacturing mechanism for
activating additional silicon features. Features are enabled through a
license activation process.  The SDSi driver provides a per socket, sysfs
attribute interface for applications to perform 3 main provisioning
functions:

1. Provision an Authentication Key Certificate (AKC), a key written to
   internal NVRAM that is used to authenticate a capability specific
   activation payload.

2. Provision a Capability Activation Payload (CAP), a token authenticated
   using the AKC and applied to the CPU configuration to activate a new
   feature.

3. Read the SDSi State Certificate, containing the CPU configuration
   state.

The operations perform function specific mailbox commands that forward the
requests to SDSi hardware to perform authentication of the payloads and
enable the silicon configuration (to be made available after power
cycling).

The SDSi device itself is enumerated as an auxiliary device from the
intel_vsec driver and as such has a build dependency on CONFIG_INTEL_VSEC.

Link: https://github.com/intel/intel-sdsi
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Reviewed-by: Mark Gross <markgross@kernel.org>

Documentation/ABI/testing/sysfs-driver-intel_sdsi

@@ -0,0 +1,77 @@
+What:		/sys/bus/auxiliary/devices/intel_vsec.sdsi.X
+Date:		Dec 2021
+KernelVersion:	5.17
+Contact:	"David E. Box" <david.e.box@linux.intel.com>
+Description:
+		This directory contains interface files for accessing Intel
+		Software Defined Silicon (SDSi) features on a CPU. X
+		represents the socket instance (though not the socket ID).
+		The socket ID is determined by reading the registers file
+		and decoding it per the specification.
+
+		Some files communicate with SDSi hardware through a mailbox.
+		Should the operation fail, one of the following error codes
+		may be returned:
+
+		Error Code	Cause
+	        ----------	-----
+	        EIO		General mailbox failure. Log may indicate cause.
+	        EBUSY		Mailbox is owned by another agent.
+	        EPERM		SDSI capability is not enabled in hardware.
+	        EPROTO		Failure in mailbox protocol detected by driver.
+				See log for details.
+	        EOVERFLOW	For provision commands, the size of the data
+				exceeds what may be written.
+	        ESPIPE		Seeking is not allowed.
+	        ETIMEDOUT	Failure to complete mailbox transaction in time.
+
+What:		/sys/bus/auxiliary/devices/intel_vsec.sdsi.X/guid
+Date:		Dec 2021
+KernelVersion:	5.17
+Contact:	"David E. Box" <david.e.box@linux.intel.com>
+Description:
+		(RO) The GUID for the registers file. The GUID identifies
+		the layout of the registers file in this directory.
+		Information about the register layouts for a particular GUID
+		is available at http://github.com/intel/intel-sdsi
+
+What:		/sys/bus/auxiliary/devices/intel_vsec.sdsi.X/registers
+Date:		Dec 2021
+KernelVersion:	5.17
+Contact:	"David E. Box" <david.e.box@linux.intel.com>
+Description:
+		(RO) Contains information needed by applications to provision
+		a CPU and monitor status information. The layout of this file
+		is determined by the GUID in this directory. Information about
+		the layout for a particular GUID is available at
+		http://github.com/intel/intel-sdsi
+
+What:		/sys/bus/auxiliary/devices/intel_vsec.sdsi.X/provision_akc
+Date:		Dec 2021
+KernelVersion:	5.17
+Contact:	"David E. Box" <david.e.box@linux.intel.com>
+Description:
+		(WO) Used to write an Authentication Key Certificate (AKC) to
+		the SDSi NVRAM for the CPU. The AKC is used to authenticate a
+		Capability Activation Payload. Mailbox command.
+
+What:		/sys/bus/auxiliary/devices/intel_vsec.sdsi.X/provision_cap
+Date:		Dec 2021
+KernelVersion:	5.17
+Contact:	"David E. Box" <david.e.box@linux.intel.com>
+Description:
+		(WO) Used to write a Capability Activation Payload (CAP) to the
+		SDSi NVRAM for the CPU. CAPs are used to activate a given CPU
+		feature. A CAP is validated by SDSi hardware using a previously
+		provisioned AKC file. Upon successful authentication, the CPU
+		configuration is updated. A cold reboot is required to fully
+		activate the feature. Mailbox command.
+
+What:		/sys/bus/auxiliary/devices/intel_vsec.sdsi.X/state_certificate
+Date:		Dec 2021
+KernelVersion:	5.17
+Contact:	"David E. Box" <david.e.box@linux.intel.com>
+Description:
+		(RO) Used to read back the current State Certificate for the CPU
+		from SDSi hardware. The State Certificate contains information
+		about the current licenses on the CPU. Mailbox command.

MAINTAINERS

@@ -9772,6 +9772,11 @@ S:	Maintained
 F:	arch/x86/include/asm/intel_scu_ipc.h
 F:	drivers/platform/x86/intel_scu_*
 
+INTEL SDSI DRIVER
+M:	David E. Box <david.e.box@linux.intel.com>
+S:	Supported
+F:	drivers/platform/x86/intel/sdsi.c
+
 INTEL SKYLAKE INT3472 ACPI DEVICE DRIVER
 M:	Daniel Scally <djrscally@gmail.com>
 S:	Maintained

drivers/platform/x86/intel/Kconfig

@@ -147,6 +147,18 @@ config INTEL_RST
 	  firmware will copy the memory contents back to RAM and resume the OS
 	  as usual.
 
+config INTEL_SDSI
+	tristate "Intel Software Defined Silicon Driver"
+	depends on INTEL_VSEC
+	depends on X86_64
+	help
+	  This driver enables access to the Intel Software Defined Silicon
+	  interface used to provision silicon features with an authentication
+	  certificate and capability license.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called intel_sdsi.
+
 config INTEL_SMARTCONNECT
 	tristate "Intel Smart Connect disabling driver"
 	depends on ACPI

drivers/platform/x86/intel/Makefile

@@ -26,6 +26,8 @@ intel_int0002_vgpio-y			:= int0002_vgpio.o
 obj-$(CONFIG_INTEL_INT0002_VGPIO)	+= intel_int0002_vgpio.o
 intel_oaktrail-y			:= oaktrail.o
 obj-$(CONFIG_INTEL_OAKTRAIL)		+= intel_oaktrail.o
+intel_sdsi-y				:= sdsi.o
+obj-$(CONFIG_INTEL_SDSI)		+= intel_sdsi.o
 intel_vsec-y				:= vsec.o
 obj-$(CONFIG_INTEL_VSEC)		+= intel_vsec.o