Re: [PATCH v2 08/31] x86/virt/tdx: Configure TDX Module with optional TDX Connect feature

[Nikolay Borisov]

On 27.03.26 г. 18:01 ч., Xu Yilun wrote:
> TDX Module supports optional TDX features (e.g. TDX Connect & TDX Module
> Extensions) that won't be enabled by default. It extends TDH.SYS.CONFIG
> for host to choose to enable them on bootup.
>
> Call TDH.SYS.CONFIG with a new bitmap input parameter to specify which
> features to enable. The bitmap uses the same definitions as
> TDX_FEATURES0. But note not all bits in TDX_FEATURES0 are valid for
> configuration, e.g. TDX Module Extensions is a service that supports TDX
> Connect, it is implicitly enabled when TDX Connect is enabled. Setting
> TDX_FEATURES0_EXT in the bitmap has no effect.
>
> TDX Module advances the version of TDH.SYS.CONFIG for the change, so
> use the latest version (v1) for optional feature enabling. But
> supporting existing Modules which only support v0 is still necessary
> until they are deprecated, enumerate via TDX_FEATURES0 to decide which
> version to use.
>
> TDX Module updates global metadata when optional features are enabled.
> Host should update the cached tdx_sysinfo to reflect these changes.
>
> Co-developed-by: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxx>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxx>
> Signed-off-by: Xu Yilun <yilun.xu@xxxxxxxxxxxxxxx>
> ---
>   arch/x86/virt/vmx/tdx/tdx.h |  3 ++-
>   arch/x86/virt/vmx/tdx/tdx.c | 16 +++++++++++++++-
>   2 files changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
> index e5a9331df451..870bb75da3ba 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.h
> +++ b/arch/x86/virt/vmx/tdx/tdx.h
> @@ -58,7 +58,8 @@
>   #define TDH_PHYMEM_CACHE_WB		40
>   #define TDH_PHYMEM_PAGE_WBINVD		41
>   #define TDH_VP_WR			43
> -#define TDH_SYS_CONFIG			45
> +#define TDH_SYS_CONFIG_V0		45
> +#define TDH_SYS_CONFIG			SEAMCALL_LEAF_VER(TDH_SYS_CONFIG_V0, 1)

Since newer versions of tdx module apis are backwards compatible with 
older ones, and v0 are actually deprecated why have both definitions?


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