Re: [PATCH v4] x86: make Viridian support optional

[Jan Beulich <jbeulich@xxxxxxxx>]

On 19.09.2025 18:31, Grygorii Strashko wrote:
> --- a/xen/arch/x86/hvm/Kconfig
> +++ b/xen/arch/x86/hvm/Kconfig
> @@ -62,6 +62,17 @@ config ALTP2M
>  
>         If unsure, stay with defaults.
>  
> +config VIRIDIAN
> +     bool "Hyper-V enlightenments for guests" if EXPERT
> +     depends on AMD_SVM || INTEL_VMX

Looks like either there was a misunderstanding, or I wasn't clear enough.
Here the dependency should strictly be HVM. If anything, the dependency
above could appear for HVM (but as said, as of now it's deliberately not
there).

> @@ -1136,6 +1136,9 @@ static int cf_check viridian_load_domain_ctxt(
>      struct viridian_domain *vd = d->arch.hvm.viridian;
>      struct hvm_viridian_domain_context ctxt;
>  
> +    if ( !is_viridian_domain(d) )
> +        return 0;
> +
>      if ( hvm_load_entry_zeroextend(VIRIDIAN_DOMAIN, h, &ctxt) != 0 )
>          return -EINVAL;
>  
> @@ -1172,6 +1175,9 @@ static int cf_check viridian_load_vcpu_ctxt(
>      struct vcpu *v;
>      struct hvm_viridian_vcpu_context ctxt;
>  
> +    if ( !is_viridian_domain(d) )
> +        return 0;

I don't think we should let these go through, but rather flag an error.
And perhaps an intentionally exotic one (e.g. EILSEQ or something yet
more "odd").

Jan