Re: [PATCH v9 05/23] coco/tdx-host: Expose TDX module version

[Chao Gao]

On Fri, May 15, 2026 at 09:53:59AM -0700, Dave Hansen wrote:
>On 5/13/26 08:09, Chao Gao wrote:
>> 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.
>
>I'm not sure exactly what a "version series" is.

By "version series" I meant release lines such as 1.5.x, 2.0.x, and
3.0.x, but that is not clear from the changelog.

>Do you need to say more
>than that the policy is complex?

I will tighten it up and just say that the update policy is complex.

>
>> 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.
>
>That's not much of an example, IMNHO. How about:
>
>	For example, the 1.5.x series runs on Sapphire Rapids but not
>	Granite Rapids, which needs 2.0.x. Updates are also constrained
>	by version distance, so a 1.5.6 module might permit updates to
>	1.5.7 but not to 1.5.20.

Yes, that is much better than my version.

>
>> 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.
>
>I honestly wouldn't even mention this bit. You don't need a bonus.

Sure, I will drop that part.

>
>> +++ b/Documentation/ABI/testing/sysfs-devices-faux-tdx-host
>> @@ -0,0 +1,6 @@
>> +What:		/sys/devices/faux/tdx_host/version
>> +Contact:	linux-coco@xxxxxxxxxxxxxxx
>> +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.
>
>The "etc." is silly. Just zap it.
>
>Description:	(RO) Report the version of the loaded TDX module.
>		Formatted as "major.minor.update". Used by TDX module
>		update tooling. Example: "1.2.03"
>
>That's at least a wee bit of warning to folks about the leading 0 so if
>they are parsing it they are a wee bit careful with it.

Thanks, this wording is much better and more concise.