Re: [PATCH v5 04/22] x86/virt/seamldr: Introduce a wrapper for P-SEAMLDR SEAMCALLs

[Xiaoyao Li]

On 3/15/2026 9:58 PM, Chao Gao wrote:
> The TDX architecture uses the "SEAMCALL" instruction to communicate with
> SEAM mode software. Right now, the only SEAM mode software that the kernel
> communicates with is the TDX module. But, there is actually another
> component that runs in SEAM mode but it is separate from the TDX module:
> the persistent SEAM loader or "P-SEAMLDR". Right now, the only component
> that communicates with it is the BIOS which loads the TDX module itself at
> boot. But, to support updating the TDX module, the kernel now needs to be
> able to talk to it.
>
> P-SEAMLDR SEAMCALLs differ from TDX module SEAMCALLs in areas such as
> concurrency requirements. Add a P-SEAMLDR wrapper to handle these
> differences and prepare for implementing concrete functions.
>
> Note that unlike P-SEAMLDR, there is also a non-persistent SEAM loader
> ("NP-SEAMLDR"). This is an authenticated code module (ACM) that is not
> callable at runtime. Only BIOS launches it to load P-SEAMLDR at boot;
> the kernel does not need to interact with it for runtime update.
>
> For details of P-SEAMLDR SEAMCALLs, see Intel® Trust Domain CPU
> Architectural Extensions, Revision 343754-002, Chapter 2.3 "INSTRUCTION
> SET REFERENCE".

SDM started to contain SEAMCALL definitions. How about just dropping 
this paragraph to avoid people from reading the old doc?

...

> +static __maybe_unused int seamldr_call(u64 fn, struct tdx_module_args *args)
> +{
> +	guard(raw_spinlock)(&seamldr_lock);
> +	return seamcall_prerr(fn, args);

How about adding the reason of why choosing seamcall_prerr() instead of 
seamcall_prerr_ret() in the changelog?