Re: [Xen-devel] [PATCH v6 02/10] x86/hvm/domain: remove the 'hap_enabled' flag

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 16/08/2019 18:19, Paul Durrant wrote:
> The hap_enabled() macro can determine whether the feature is available
> using the domain 'options'; there is no need for a separate flag.
>
> NOTE: Furthermore, by extending sanitiziing of the domain 'options', the

s/ii/i/

> diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
> index 9a6eb89ddc..bc0db03387 100644
> --- a/xen/arch/x86/domain.c
> +++ b/xen/arch/x86/domain.c
> @@ -460,6 +460,12 @@ int arch_sanitise_domain_config(struct 
> xen_domctl_createdomain *config)
>          return -EINVAL;
>      }
>  
> +    if ( (config->flags & XEN_DOMCTL_CDF_hap) && !hvm_hap_supported() )
> +    {
> +        dprintk(XENLOG_INFO, "HAP enabled but not supported\n");

s/enabled/requested/

> diff --git a/xen/common/domain.c b/xen/common/domain.c
> index 744b572195..6109623730 100644
> --- a/xen/common/domain.c
> +++ b/xen/common/domain.c
> @@ -313,6 +313,13 @@ static int sanitise_domain_config(struct 
> xen_domctl_createdomain *config)
>          return -EINVAL;
>      }
>  
> +    if ( !(config->flags & XEN_DOMCTL_CDF_hvm_guest) &&
> +         (config->flags & XEN_DOMCTL_CDF_hap) )
> +    {
> +        dprintk(XENLOG_INFO, "HAP enabled for non-HVM guest\n");

Again, I think 'requested' would be better here.

> diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
> index 2e6e0d3488..07a64947ed 100644
> --- a/xen/include/xen/sched.h
> +++ b/xen/include/xen/sched.h
> @@ -954,6 +954,12 @@ static inline bool is_hvm_vcpu(const struct vcpu *v)
>      return is_hvm_domain(v->domain);
>  }
>  
> +static inline bool hap_enabled(const struct domain *d)
> +{
> +    return IS_ENABLED(CONFIG_HVM) && /* necessary for pv shim build */
> +        evaluate_nospec(d->options & XEN_DOMCTL_CDF_hap);

I'm not sure how helpful this comment is.  What should be here however
is a note saying that this logic depends on domain_create() rejecting
!HVM  and HAP.

All can be adjusted on commit if there are no other concerns.

~Andrew

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