linux-kernel - [PATCH v2 2/3] coco/tdx-host: Expose TDX Module version

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Message-ID: <20260105074350.98564-3-chao.gao@intel.com>
Date: Sun,  4 Jan 2026 23:43:45 -0800
From: Chao Gao <chao.gao@...el.com>
To: x86@...nel.org,
	linux-coco@...ts.linux.dev,
	kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: vishal.l.verma@...el.com,
	kai.huang@...el.com,
	dan.j.williams@...el.com,
	yilun.xu@...ux.intel.com,
	vannapurve@...gle.com,
	Chao Gao <chao.gao@...el.com>,
	Kiryl Shutsemau <kas@...nel.org>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Rick Edgecombe <rick.p.edgecombe@...el.com>
Subject: [PATCH v2 2/3] coco/tdx-host: Expose TDX Module version

Currently there is no way to know the TDX Module version from the
userspace. Such information is always helpful for bug reporting or
debugging.

With the tdx-host device in place, expose the TDX Module version as
a device attribute via sysfs.

Signed-off-by: Chao Gao <chao.gao@...el.com>
---
v2: 
 - No need to update MAINTAINERS to include sysfs-devices-faux-tdx-host
   explicitly (Kirill)

 .../ABI/testing/sysfs-devices-faux-tdx-host   |  6 +++++
 drivers/virt/coco/tdx-host/tdx-host.c         | 26 ++++++++++++++++++-
 2 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/ABI/testing/sysfs-devices-faux-tdx-host

diff --git a/Documentation/ABI/testing/sysfs-devices-faux-tdx-host b/Documentation/ABI/testing/sysfs-devices-faux-tdx-host
new file mode 100644
index 000000000000..35ef21f53c2e
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-faux-tdx-host
@@ -0,0 +1,6 @@
+What:		/sys/devices/faux/tdx_host/version
+Contact:	linux-coco@...ts.linux.dev
+Description:	(RO) Report the version of the loaded TDX Module. The TDX Module
+		version is formatted as x.y.z, where "x" is the major version,
+		"y" is the minor version and "z" is the update version. Versions
+		are used for bug reporting, TD-Preserving updates and etc.
diff --git a/drivers/virt/coco/tdx-host/tdx-host.c b/drivers/virt/coco/tdx-host/tdx-host.c
index ced1c980dc6f..2883c6638faf 100644
--- a/drivers/virt/coco/tdx-host/tdx-host.c
+++ b/drivers/virt/coco/tdx-host/tdx-host.c
@@ -9,6 +9,7 @@
 #include <linux/mod_devicetable.h>
 #include <linux/device/faux.h>
 #include <asm/cpu_device_id.h>
+#include <asm/tdx.h>
 
 static const struct x86_cpu_id tdx_host_ids[] = {
 	X86_MATCH_FEATURE(X86_FEATURE_TDX_HOST_PLATFORM, NULL),
@@ -18,12 +19,35 @@ MODULE_DEVICE_TABLE(x86cpu, tdx_host_ids);
 
 static struct faux_device *fdev;
 
+static ssize_t version_show(struct device *dev, struct device_attribute *attr,
+			    char *buf)
+{
+	const struct tdx_sys_info *tdx_sysinfo = tdx_get_sysinfo();
+	const struct tdx_sys_info_version *ver;
+
+	if (!tdx_sysinfo)
+		return -ENXIO;
+
+	ver = &tdx_sysinfo->version;
+
+	return sysfs_emit(buf, "%u.%u.%02u\n", ver->major_version,
+					       ver->minor_version,
+					       ver->update_version);
+}
+static DEVICE_ATTR_RO(version);
+
+static struct attribute *tdx_host_attrs[] = {
+	&dev_attr_version.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(tdx_host);
+
 static int __init tdx_host_init(void)
 {
 	if (!x86_match_cpu(tdx_host_ids))
 		return -ENODEV;
 
-	fdev = faux_device_create(KBUILD_MODNAME, NULL, NULL);
+	fdev = faux_device_create_with_groups(KBUILD_MODNAME, NULL, NULL, tdx_host_groups);
 	if (!fdev)
 		return -ENODEV;
 
-- 
2.47.3