Re: [RFC PATCH 14/15] x86/virt/tdx: Embed version info in SEAMCALL leaf function definitions

[Xu Yilun]

On Fri, Jun 12, 2026 at 08:47:26AM +0300, Adrian Hunter wrote:
> On 22/05/2026 06:41, Xu Yilun wrote:
> > Embed version information in SEAMCALL leaf function definitions rather
> > than let the caller open code them. For now, only TDH.VP.INIT is
> > involved.
> 
> > @@ -31,7 +44,7 @@
> >  #define TDH_VP_CREATE			10
> >  #define TDH_MNG_KEY_FREEID		20
> >  #define TDH_MNG_INIT			21
> > -#define TDH_VP_INIT			22
> > +#define TDH_VP_INIT			SEAMCALL_LEAF_VER(22, 1)
> 
> FWIW I find the macro a bit ugly, and hiding the version number in
> the leaf number macro a little counter-intuitive compared with setting
> it at the call site.  It anyway needs some explanation at the call site.

We actually discussed about this and realized we don't need to keep
version. This is because:

  1. Newer version SEAMCALLs are always compatible with older ones.
  2. System security requires us to stop using an older TDX module when
     there is a newer one. So don't try to support an older TDX module
     which doesn't understand newer version SEAMCALLs.

https://lore.kernel.org/all/ca331aa3-6304-4e07-9ed9-94dc69726382@xxxxxxxxx/

> 
> > @@ -2217,8 +2217,8 @@ u64 tdh_vp_init(struct tdx_vp *vp, u64 initial_rcx, u32 x2apicid)
> >  		.r8 = x2apicid,
> >  	};
> >  
> > -	/* apicid requires version == 1. */
> > -	return seamcall(TDH_VP_INIT | (1ULL << TDX_VERSION_SHIFT), &args);
> > +	/* apicid requires version == 1. See TDH_VP_INIT definition.*/
> > +	return seamcall(TDH_VP_INIT, &args);
> 
> Now the reader has to go look at TDH_VP_INIT.

mm.. I think I should just delete the comment.