[RFC PATCH v1 3/3] docs: ABI: testing: Add documentation about TDX

[Alexey Gladkov <legion@kernel.org>]

From: "Alexey Gladkov (Intel)" <legion@kernel.org>

Document the new testing ABI of TDX module. Currently, there is no
reliable user interface within the guest as well as on the host system.

Signed-off-by: Alexey Gladkov (Intel) <legion@kernel.org>
---
 .../ABI/testing/sysfs-hypervisor-tdx          | 50 +++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-hypervisor-tdx

diff --git a/Documentation/ABI/testing/sysfs-hypervisor-tdx b/Documentation/ABI/testing/sysfs-hypervisor-tdx
new file mode 100644
index 000000000000..5ee33cdc59ef
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-hypervisor-tdx
@@ -0,0 +1,50 @@
+What:		/sys/hypervisor/tdx/version/major
+Date:		March 2025
+KernelVersion:	v6.15
+Contact:	linux-coco@lists.linux.dev
+Description:	(RO) Report the major version of the loaded TDX module.
+
+What:		/sys/hypervisor/tdx/version/minor
+Date:		March 2025
+KernelVersion:	v6.15
+Contact:	linux-coco@lists.linux.dev
+Description:	(RO) Report the major version of the loaded TDX module.
+
+What:		/sys/hypervisor/tdx/version/update
+Date:		March 2025
+KernelVersion:	v6.15
+Contact:	linux-coco@lists.linux.dev
+Description:	(RO) Report the update version of the loaded TDX module.
+		Not available on the guest side.
+
+What:		/sys/hypervisor/tdx/properties/build_num
+Date:		March 2025
+KernelVersion:	v6.15
+Contact:	linux-coco@lists.linux.dev
+Description:	(RO) Reports the build number of the loaded TDX module.
+		Not available on the guest side.
+
+What:		/sys/hypervisor/tdx/properties/build_date
+Date:		March 2025
+KernelVersion:	v6.15
+Contact:	linux-coco@lists.linux.dev
+Description:	(RO) Reports the build data of loaded TDX module in yyyymmdd
+		BCD format (each digit occupies 4 bits).
+		Not available on the guest side.
+
+What:		/sys/hypervisor/tdx/properties/features0
+Date:		March 2025
+KernelVersion:	v6.15
+Contact:	linux-coco@lists.linux.dev
+Description:	(RO) Reports the features supported by the loaded TDX module in
+		hex format. Enumerates TDX features:
+
+			=========   ===================================
+			Bit 0       TD Migration
+			Bit 1       TD Preserving
+			Bit 2       Service TD
+			Bit 3       TDG.VP.RD/WR
+			Bit 4       Relaxed mem management concurrency
+			Bits 63:5   Reserved, set to 0
+			=========   ===================================
+
-- 
2.48.1