Re: [PATCH v4 13/24] x86/virt/seamldr: Shut down the current TDX module

[Xu Yilun]

On Thu, Feb 12, 2026 at 06:35:16AM -0800, 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, Revision
> 348549-007, Chapter 4.5.3 "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 the Linux kernel only supports 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.
> 
> Note that only one CPU needs to call the TDX Module's shutdown API.
> 
> Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
> Reviewed-by: Tony Lindgren <tony.lindgren@xxxxxxxxxxxxxxx>

Reviewed-by: Xu Yilun <yilun.xu@xxxxxxxxxxxxxxx>