Re: [Xen-devel] [PATCH v9 3/6] sysctl / libxl: report whether IOMMU/HAP page table sharing is supported

[Jan Beulich <jbeulich@xxxxxxxx>]

On 12.09.2019 13:17, Paul Durrant wrote:
> --- a/xen/arch/arm/sysctl.c
> +++ b/xen/arch/arm/sysctl.c
> @@ -15,6 +15,9 @@
>  void arch_do_physinfo(struct xen_sysctl_physinfo *pi)
>  {
>      pi->capabilities |= XEN_SYSCTL_PHYSCAP_hvm | XEN_SYSCTL_PHYSCAP_hap;
> +
> +    if ( iommu_enabled && iommu_hap_pt_share )
> +        pi->capabilities |= XEN_SYSCTL_PHYSCAP_iommu_hap_pt_share;
>  }

I think this should be done in common code.

> --- a/xen/arch/x86/sysctl.c
> +++ b/xen/arch/x86/sysctl.c
> @@ -164,7 +164,12 @@ void arch_do_physinfo(struct xen_sysctl_physinfo *pi)
>      if ( IS_ENABLED(CONFIG_PV) )
>          pi->capabilities |= XEN_SYSCTL_PHYSCAP_pv;
>      if ( hvm_hap_supported() )
> +    {
>          pi->capabilities |= XEN_SYSCTL_PHYSCAP_hap;
> +
> +        if ( iommu_enabled && iommu_hap_pt_share )
> +            pi->capabilities |= XEN_SYSCTL_PHYSCAP_iommu_hap_pt_share;
> +    }
>  }

And if it's important to not have the bit set when !hvm_hap_supported(),
then iommu_hap_pt_share should be cleared in __init code in this case.

Jan

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