Re: [XEN][PATCH v8] x86: make Viridian support optional

[Grygorii Strashko <grygorii_strashko@xxxxxxxx>]

Hi Jan,

On 20.11.25 10:50, Jan Beulich wrote:
> (adding v8 tag to subject)
>
> On 19.11.2025 20:32, Grygorii Strashko wrote:
> > From: Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx>
> >
> > Add config option VIRIDIAN that covers viridian code within HVM.
> > Calls to viridian functions guarded by is_viridian_domain() and related macros.
> > Having this option may be beneficial by reducing code footprint for systems
> > that are not using Hyper-V.
> >
> > [grygorii_strashko@xxxxxxxx: fixed NULL pointer deref in
> > viridian_save_domain_ctxt(); stub viridian_vcpu/domain_init/deinit()]
> > Signed-off-by: Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx>
> > Signed-off-by: Grygorii Strashko <grygorii_strashko@xxxxxxxx>
> > Reviewed-by: Jason Andryuk <jason.andryuk@xxxxxxx>
> As before - this R-b likely would need dropping, ...
>
> > ---
> > changes in v8:
> > - drop checks from viridian_load_vcpu/domain_ctxt()
> > - drop check "value != 0" in HVM_PARAM_VIRIDIAN handler, laways return
> >    -ENODEV for VIRIDIAN=n
> ... when more than just cosmetic changes are made. Jason, please can you
> indicate whether it's fine to retain?
Sorry, I'll be more careful with tags.

> > --- a/xen/arch/x86/hvm/Makefile
> > +++ b/xen/arch/x86/hvm/Makefile
> > @@ -1,6 +1,6 @@
> >   obj-$(CONFIG_AMD_SVM) += svm/
> >   obj-$(CONFIG_INTEL_VMX) += vmx/
> > -obj-y += viridian/
> > +obj-$(CONFIG_VIRIDIAN) += viridian/
> When committing, I'll likely take the liberty to also move the altered line
> up, to restore proper alphabetical sorting here.
>
> > --- a/xen/arch/x86/include/asm/hvm/viridian.h
> > +++ b/xen/arch/x86/include/asm/hvm/viridian.h
> > @@ -86,11 +86,26 @@ viridian_hypercall(struct cpu_user_regs *regs);
> >   void viridian_time_domain_freeze(const struct domain *d);
> >   void viridian_time_domain_thaw(const struct domain *d);
> >   
> > +#if defined(CONFIG_VIRIDIAN)
> Similarly I'm likely going to take the liberty and change this to #ifdef,
> just like you have it elsewhere.
I'm ok with mentioned adjustments.

> Preferably with the adjustments:
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Thank you.

--
Best regards,
-grygorii