Re: [Xen-devel] [PATCH v5 3/8] iommu: make iommu_inclusive_mapping a suboption of dom0-iommu

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 14.08.18 at 15:43, <roger.pau@xxxxxxxxxx> wrote:
> --- a/xen/drivers/passthrough/vtd/iommu.c
> +++ b/xen/drivers/passthrough/vtd/iommu.c
> @@ -1304,11 +1304,9 @@ static void __hwdom_init intel_iommu_hwdom_init(struct 
> domain *d)
>  {
>      struct acpi_drhd_unit *drhd;
>  
> -    if ( !iommu_hwdom_passthrough && is_pv_domain(d) )
> -    {
> -        /* Set up 1:1 page table for hardware domain. */
> -        vtd_set_hwdom_mapping(d);
> -    }
> +    /* Inclusive mappings are enabled by default on Intel hardware for PV. */
> +    if ( iommu_hwdom_inclusive == -1 )
> +        iommu_hwdom_inclusive = is_pv_domain(d);

Hmm, I didn't notice this before, but there's an issue here for the
late-hwdom case: What if Dom0 and the actual hardware domain
differ in their PV-ness? I think you need to keep it at -1 here and
take the still -1 value into account in arch_iommu_hwdom_init().
iommu_hwdom_init() then also should not override it.

Jan



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