> From: Jan Beulich <jbeul...@suse.com>
> Sent: Friday, November 12, 2021 5:48 PM
>
> Merely setting bit 0 in the bitmap is insufficient, as then Dom0 will
> still have DID 0 allocated to it, because of the zero-filling of
> domid_map[]. Set slot 0 to DOMID_INVALID to keep DID 0 from getting
> used.
>
> Fixes: b9c20c78789f ("VT-d: per-iommu domain-id")
> Signed-off-by: Jan Beulich <jbeul...@suse.com>
Reviewed-by: Kevin Tian <kevin.t...@intel.com>
>
> --- a/xen/drivers/passthrough/vtd/iommu.c
> +++ b/xen/drivers/passthrough/vtd/iommu.c
> @@ -1257,16 +1257,19 @@ int __init iommu_alloc(struct acpi_drhd_
> if ( !iommu->domid_bitmap )
> return -ENOMEM;
>
> + iommu->domid_map = xzalloc_array(u16, nr_dom);
> + if ( !iommu->domid_map )
> + return -ENOMEM;
> +
> /*
> - * if Caching mode is set, then invalid translations are tagged with
> - * domain id 0, Hence reserve bit 0 for it
> + * If Caching mode is set, then invalid translations are tagged with
> + * domain id 0. Hence reserve bit/slot 0.
> */
> if ( cap_caching_mode(iommu->cap) )
> + {
> + iommu->domid_map[0] = DOMID_INVALID;
> __set_bit(0, iommu->domid_bitmap);
> -
> - iommu->domid_map = xzalloc_array(u16, nr_dom);
> - if ( !iommu->domid_map )
> - return -ENOMEM;
> + }
>
> return 0;
> }
