Re: [PATCH v7 11/22] x86/virt/seamldr: Shut down the current TDX module

[Chao Gao <chao.gao@intel.com>]

On Sat, Apr 11, 2026 at 09:35:32AM +0800, Edgecombe, Rick P wrote:
>On Tue, 2026-03-31 at 05:41 -0700, Chao Gao wrote:
>> The first step of TDX module updates is shutting down the current TDX
>> Module. This step also packs state information that needs to be
>> preserved across updates as handoff data, which will be consumed by the
>> updated module. The handoff data is stored internally in the SEAM range
>> and is hidden from the kernel.
>> 
>> To ensure a successful update, the new module must be able to consume
>> the handoff data generated by the old module. Since handoff data layout
>> may change between modules, the handoff data is versioned. Each module
>> has a native handoff version and provides backward support for several
>> older versions.
>> 
>> The complete handoff versioning protocol is complex as it supports both
>> module upgrades and downgrades. See details in Intel® Trust Domain
>> Extensions (Intel® TDX) Module Base Architecture Specification, Chapter
>> "Handoff Versioning".
>> 
>> Ideally, the kernel needs to retrieve the handoff versions supported by
>> the current module and the new module and select a version supported by
>> both. But, since this implementation chooses to only support module
>> upgrades, simply request the current module to generate handoff data
>> using its highest supported version, expecting that the new module will
>> likely support it.
>
>I feel like somewhere it's missing what this patch does. It explains the
>reasoning for the handoff version selection, but nothing about implement
>"MODULE_UPDATE_SHUTDOWN" or anything like that.

Yes. How about:

Retrieve the module's handoff version from TDX global metadata and add an
update step to shut down the module. Module shutdown has global effect, so
it only needs to run on one CPU.