Re: [PATCH v1] x86: make Viridian support optional

[Jan Beulich <jbeulich@xxxxxxxx>]

On 17.03.2025 08:19, Sergiy Kibrik wrote:
> --- a/xen/arch/x86/Kconfig
> +++ b/xen/arch/x86/Kconfig
> @@ -348,6 +348,11 @@ config HYPERV_GUEST
>  
>  endif
>  
> +config HVM_VIRIDIAN
> +     bool "Viridian enlightenments support" if EXPERT
> +     depends on HVM
> +     default y

Imo the prompt wants to include "guest", somewhat along the lines of what
Alejandro has also said.

> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -695,9 +695,12 @@ int hvm_domain_initialise(struct domain *d,
>      if ( hvm_tsc_scaling_supported )
>          d->arch.hvm.tsc_scaling_ratio = hvm_default_tsc_scaling_ratio;
>  
> -    rc = viridian_domain_init(d);
> -    if ( rc )
> -        goto fail2;
> +    if ( is_viridian_domain(d) )
> +    {
> +        rc = viridian_domain_init(d);
> +        if ( rc )
> +            goto fail2;
> +    }
>  
>      rc = alternative_call(hvm_funcs.domain_initialise, d);
>      if ( rc != 0 )
> @@ -733,7 +736,8 @@ void hvm_domain_relinquish_resources(struct domain *d)
>      if ( hvm_funcs.nhvm_domain_relinquish_resources )
>          alternative_vcall(hvm_funcs.nhvm_domain_relinquish_resources, d);
>  
> -    viridian_domain_deinit(d);
> +    if ( is_viridian_domain(d) )
> +        viridian_domain_deinit(d);
>  
>      ioreq_server_destroy_all(d);
>  
> @@ -1637,9 +1641,12 @@ int hvm_vcpu_initialise(struct vcpu *v)
>           && (rc = nestedhvm_vcpu_initialise(v)) < 0 ) /* teardown: 
> nestedhvm_vcpu_destroy */
>          goto fail5;
>  
> -    rc = viridian_vcpu_init(v);
> -    if ( rc )
> -        goto fail6;
> +    if ( is_viridian_domain(v->domain) )

Like you do further up, please also use "d" here and ...

> @@ -1669,13 +1676,15 @@ int hvm_vcpu_initialise(struct vcpu *v)
>   fail2:
>      hvm_vcpu_cacheattr_destroy(v);
>   fail1:
> -    viridian_vcpu_deinit(v);
> +    if ( is_viridian_domain(v->domain) )

... here.

> --- a/xen/arch/x86/hvm/vlapic.c
> +++ b/xen/arch/x86/hvm/vlapic.c
> @@ -426,7 +426,8 @@ void vlapic_EOI_set(struct vlapic *vlapic)
>       * priority vector and then recurse to handle the lower priority
>       * vector.
>       */
> -    bool missed_eoi = viridian_apic_assist_completed(v);
> +    bool missed_eoi = has_viridian_apic_assist(v->domain) ?
> +                          viridian_apic_assist_completed(v) : false;

    bool missed_eoi = has_viridian_apic_assist(v->domain) &&
                      viridian_apic_assist_completed(v);

?

> --- a/xen/arch/x86/include/asm/hvm/domain.h
> +++ b/xen/arch/x86/include/asm/hvm/domain.h
> @@ -110,9 +110,9 @@ struct hvm_domain {
>  
>      /* hypervisor intercepted msix table */
>      struct list_head       msixtbl_list;
> -
> +#ifdef CONFIG_HVM_VIRIDIAN
>      struct viridian_domain *viridian;
> -
> +#endif
>      /*
>       * TSC value that VCPUs use to calculate their tsc_offset value.
>       * Used during initialization and save/restore.

Why would the blank lines need to go away?

> --- a/xen/arch/x86/include/asm/hvm/hvm.h
> +++ b/xen/arch/x86/include/asm/hvm/hvm.h
> @@ -507,7 +507,8 @@ hvm_get_cpl(struct vcpu *v)
>      (has_hvm_params(d) ? (d)->arch.hvm.params[HVM_PARAM_VIRIDIAN] : 0)
>  
>  #define is_viridian_domain(d) \
> -    (is_hvm_domain(d) && (viridian_feature_mask(d) & HVMPV_base_freq))
> +    (is_hvm_domain(d) && IS_ENABLED(CONFIG_HVM_VIRIDIAN) && \
> +                         (viridian_feature_mask(d) & HVMPV_base_freq))

May I suggest to put IS_ENABLED() first? And to adjust (reduce) indentation
on the 2nd line?

> --- a/xen/arch/x86/include/asm/hvm/vcpu.h
> +++ b/xen/arch/x86/include/asm/hvm/vcpu.h
> @@ -171,8 +171,9 @@ struct hvm_vcpu {
>  
>      /* Pending hw/sw interrupt (.vector = -1 means nothing pending). */
>      struct x86_event     inject_event;
> -
> +#ifdef CONFIG_HVM_VIRIDIAN
>      struct viridian_vcpu *viridian;
> +#endif
>  };

Again, not need for the blank line to go away.

Jan