Re: [PATCH v5 17/22] x86/virt/tdx: Avoid updates during update-sensitive operations

[Kiryl Shutsemau <kas@kernel.org>]

On Sun, Mar 15, 2026 at 06:58:37AM -0700, Chao Gao wrote:
> diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
> index b3a7301e77c6..4c4f7acd4044 100644
> --- a/arch/x86/include/asm/tdx.h
> +++ b/arch/x86/include/asm/tdx.h
> @@ -26,11 +26,18 @@
>  #define TDX_SEAMCALL_GP			(TDX_SW_ERROR | X86_TRAP_GP)
>  #define TDX_SEAMCALL_UD			(TDX_SW_ERROR | X86_TRAP_UD)
>  
> +#define TDX_SEAMCALL_STATUS_MASK		0xFFFFFFFF00000000ULL
> +
>  /*
>   * TDX module SEAMCALL leaf function error codes
>   */
> -#define TDX_SUCCESS		0ULL
> -#define TDX_RND_NO_ENTROPY	0x8000020300000000ULL
> +#define TDX_SUCCESS			0ULL
> +#define TDX_RND_NO_ENTROPY		0x8000020300000000ULL
> +#define TDX_UPDATE_COMPAT_SENSITIVE	0x8000051200000000ULL

This competes with other patchset[1].

[1] https://lore.kernel.org/all/20260307010358.819645-1-rick.p.edgecombe@intel.com

> @@ -1189,9 +1192,21 @@ int tdx_module_shutdown(void)
>  	 * modules as new modules likely have higher handoff version.
>  	 */
>  	args.rcx = tdx_sysinfo.handoff.module_hv;
> -	ret = seamcall_prerr(TDH_SYS_SHUTDOWN, &args);
> -	if (ret)
> -		return ret;
> +
> +	if (tdx_supports_update_compatibility(&tdx_sysinfo))
> +		args.rcx |= TDX_SYS_SHUTDOWN_AVOID_COMPAT_SENSITIVE;

Hm. So what happens if the module doesn't support it? We just ignore
problem?

Maybe we should just block updates on such modules?

-- 
  Kiryl Shutsemau / Kirill A. Shutemov