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

[Xu Yilun]

On Tue, Mar 31, 2026 at 01:38:16PM +0300, Nikolay Borisov wrote:
> 
> 
> 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?

No, for this TDH_SYS_CONFIG SEAMCALL, the situation is different. There
is no public TDX Module release yet to support TDH_SYS_CONFIG_V1. So I
can't say v0 is deprecated.

> 
> 
> <snip>