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Peter Anvin" Subject: [PATCH v8 03/21] coco/tdx-host: Expose TDX module version Date: Mon, 27 Apr 2026 08:27:57 -0700 Message-ID: <20260427152854.101171-4-chao.gao@intel.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260427152854.101171-1-chao.gao@intel.com> References: <20260427152854.101171-1-chao.gao@intel.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit For TDX module updates, userspace needs to select compatible update versions based on the current module version. This design delegates module selection complexity to userspace because TDX module update policies are complex and version series are platform-specific. For example, the 1.5.x series is for certain platform generations, while the 2.0.x series is intended for others. And TDX module 1.5.x may be updated to 1.5.y but not to 1.5.y+1. Expose the TDX module version to userspace via sysfs to aid module selection. Since the TDX faux device will drive module updates, expose the version as its attribute. One bonus of exposing TDX module version via sysfs is: TDX module version information remains available even after dmesg logs are cleared. Define TDX_VERSION_FMT macro for the TDX version format since it will be used multiple times. Also convert an existing print statement to use it. == Background == The "faux device + device attribute" approach compares to other update mechanisms as follows: 1. AMD SEV leverages an existing PCI device for the PSP to expose metadata. TDX uses a faux device as it doesn't have PCI device in its architecture. 2. Microcode uses per-CPU virtual devices to report microcode revisions because CPUs can have different revisions. But, there is only a single TDX module, so exposing the TDX module version through a global TDX faux device is appropriate 3. ARM's CCA implementation isn't in-tree yet, but will likely follow a similar faux device approach, though it's unclear whether they need to expose firmware version information Signed-off-by: Chao Gao Reviewed-by: Binbin Wu Reviewed-by: Tony Lindgren Reviewed-by: Xu Yilun Reviewed-by: Kai Huang Reviewed-by: Kiryl Shutsemau (Meta) Reviewed-by: Xiaoyao Li Link: https://lore.kernel.org/all/2025073035-bulginess-rematch-b92e@gregkh/ # [1] --- .../ABI/testing/sysfs-devices-faux-tdx-host | 6 +++++ arch/x86/include/asm/tdx.h | 6 +++++ arch/x86/virt/vmx/tdx/tdx_global_metadata.c | 2 +- drivers/virt/coco/tdx-host/tdx-host.c | 26 ++++++++++++++++++- 4 files changed, 38 insertions(+), 2 deletions(-) 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..2cf682b65acf --- /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@lists.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, TDX module updates etc. diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h index 31e01ab8b01a..2afa8dde72e0 100644 --- a/arch/x86/include/asm/tdx.h +++ b/arch/x86/include/asm/tdx.h @@ -38,6 +38,12 @@ #include #include +/* + * TDX module and P-SEAMLDR version convention: "major.minor.update" + * (e.g., "1.5.08") with zero-padded two-digit update field. + */ +#define TDX_VERSION_FMT "%u.%u.%02u" + /* * Used by the #VE exception handler to gather the #VE exception * info from the TDX module. This is a software only structure diff --git a/arch/x86/virt/vmx/tdx/tdx_global_metadata.c b/arch/x86/virt/vmx/tdx/tdx_global_metadata.c index c7db393a9cfb..d54d4227990c 100644 --- a/arch/x86/virt/vmx/tdx/tdx_global_metadata.c +++ b/arch/x86/virt/vmx/tdx/tdx_global_metadata.c @@ -106,7 +106,7 @@ static __init int get_tdx_sys_info(struct tdx_sys_info *sysinfo) ret = ret ?: get_tdx_sys_info_version(&sysinfo->version); - pr_info("Module version: %u.%u.%02u\n", + pr_info("Module version: " TDX_VERSION_FMT "\n", sysinfo->version.major_version, sysinfo->version.minor_version, sysinfo->version.update_version); diff --git a/drivers/virt/coco/tdx-host/tdx-host.c b/drivers/virt/coco/tdx-host/tdx-host.c index c77885392b09..ef117a836b3a 100644 --- a/drivers/virt/coco/tdx-host/tdx-host.c +++ b/drivers/virt/coco/tdx-host/tdx-host.c @@ -8,6 +8,7 @@ #include #include #include +#include #include #include @@ -18,6 +19,29 @@ static const struct x86_cpu_id tdx_host_ids[] = { }; MODULE_DEVICE_TABLE(x86cpu, tdx_host_ids); +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, TDX_VERSION_FMT "\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 struct faux_device *fdev; static int __init tdx_host_init(void) @@ -25,7 +49,7 @@ static int __init tdx_host_init(void) if (!x86_match_cpu(tdx_host_ids) || !tdx_get_sysinfo()) 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; -- 2.47.1