Re: [PATCH v19 007/130] x86/virt/tdx: Export SEAMCALL functions

Edgecombe, Rick P
2024-04-23T00:28:13Z

On Mon, 2024-04-22 at 12:50 -0700, Sean Christopherson wrote:
> The kernel already does panic() if TDCALL itself fails,
>
>   static inline void tdcall(u64 fn, struct tdx_module_args *args)
>   {
>         if (__tdcall_ret(fn, args))
>                 panic("TDCALL %lld failed (Buggy TDX module!)\n", fn);
>   }
>
>   /* Called from __tdx_hypercall() for unrecoverable failure */
>   noinstr void __noreturn __tdx_hypercall_failed(void)
>   {
>         instrumentation_begin();
>         panic("TDVMCALL failed. TDX module bug?");
>   }
>
> it's just doesn in C code via panic(), not in asm via a bare ud2.

Hmm, I didn't realize. It looks like today some calls do and some don't. I don't
mean to reopen old debates. Just surprised that these are able to bring down the
system. Which funnily enough connects back to the original issue of the patch:
whether they are safe to export for module use.