Re: [XEN][PATCH 2/7] xen/domctl: introduce XEN_DOMCTL_CDF_is_32bits

[Jan Beulich <jbeulich@xxxxxxxx>]

On 31.07.2025 11:42, Grygorii Strashko wrote:
> --- a/xen/arch/arm/domain.c
> +++ b/xen/arch/arm/domain.c
> @@ -613,7 +613,8 @@ int arch_sanitise_domain_config(struct 
> xen_domctl_createdomain *config)
>      unsigned int flags_required = (XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap);
>      unsigned int flags_optional = (XEN_DOMCTL_CDF_iommu | 
> XEN_DOMCTL_CDF_vpmu |
>                                     XEN_DOMCTL_CDF_xs_domain |
> -                                   XEN_DOMCTL_CDF_trap_unmapped_accesses );
> +                                   XEN_DOMCTL_CDF_trap_unmapped_accesses |
> +                                   XEN_DOMCTL_CDF_is_32bits );
>      unsigned int sve_vl_bits = sve_decode_vl(config->arch.sve_vl);
>  
>      if ( (config->flags & ~flags_optional) != flags_required )
> @@ -711,6 +712,13 @@ int arch_domain_create(struct domain *d,
>  
>      BUILD_BUG_ON(GUEST_MAX_VCPUS < MAX_VIRT_CPUS);
>  
> +#ifdef CONFIG_ARM_64
> +    if ( d->options & XEN_DOMCTL_CDF_is_32bits )
> +        d->arch.type = DOMAIN_32BIT;
> +    else
> +        d->arch.type = DOMAIN_64BIT;
> +#endif
> +
>  #ifdef CONFIG_IOREQ_SERVER
>      ioreq_domain_init(d);
>  #endif

No adjustment to x86'es arch_sanitise_domain_config()? Until the new bit
is actually properly handled, I think its use will need rejecting.

> --- a/xen/include/public/domctl.h
> +++ b/xen/include/public/domctl.h
> @@ -68,9 +68,14 @@ struct xen_domctl_createdomain {
>  #define XEN_DOMCTL_CDF_vpmu           (1U << 7)
>  /* Should we trap guest accesses to unmapped addresses? */
>  #define XEN_DOMCTL_CDF_trap_unmapped_accesses  (1U << 8)
> +/*
> + * Is this domain running 32bit guest?
> + * Used for 64bits arches.
> + */
> +#define XEN_DOMCTL_CDF_is_32bits (1U << 9)

Please pad suitably, as is the case for XEN_DOMCTL_CDF_vpmu visible in
context. XEN_DOMCTL_CDF_trap_unmapped_accesses simply is too long to fit
that padding scheme.

Jan