RE: [PATCH 2/6] VT-d: split domid map cleanup check into a function

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Jan Beulich <jbeulich@xxxxxxxx>
> Sent: Friday, November 12, 2021 5:48 PM
> 
> This logic will want invoking from elsewhere.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>

> 
> --- a/xen/drivers/passthrough/vtd/iommu.c
> +++ b/xen/drivers/passthrough/vtd/iommu.c
> @@ -157,6 +157,51 @@ static void cleanup_domid_map(struct dom
>      }
>  }
> 
> +static bool any_pdev_behind_iommu(const struct domain *d,
> +                                  const struct pci_dev *exclude,
> +                                  const struct vtd_iommu *iommu)
> +{
> +    const struct pci_dev *pdev;
> +
> +    for_each_pdev ( d, pdev )
> +    {
> +        const struct acpi_drhd_unit *drhd;
> +
> +        if ( pdev == exclude )
> +            continue;
> +
> +        drhd = acpi_find_matched_drhd_unit(pdev);
> +        if ( drhd && drhd->iommu == iommu )
> +            return true;
> +    }
> +
> +    return false;
> +}
> +
> +/*
> + * If no other devices under the same iommu owned by this domain,
> + * clear iommu in iommu_bitmap and clear domain_id in domid_bitmap.
> + */
> +static void check_cleanup_domid_map(struct domain *d,
> +                                    const struct pci_dev *exclude,
> +                                    struct vtd_iommu *iommu)
> +{
> +    bool found = any_pdev_behind_iommu(d, exclude, iommu);
> +
> +    /*
> +     * Hidden devices are associated with DomXEN but usable by the
> hardware
> +     * domain. Hence they need considering here as well.
> +     */
> +    if ( !found && is_hardware_domain(d) )
> +        found = any_pdev_behind_iommu(dom_xen, exclude, iommu);
> +
> +    if ( !found )
> +    {
> +        clear_bit(iommu->index, dom_iommu(d)->arch.vtd.iommu_bitmap);
> +        cleanup_domid_map(d, iommu);
> +    }
> +}
> +
>  static void sync_cache(const void *addr, unsigned int size)
>  {
>      static unsigned long clflush_size = 0;
> @@ -1675,27 +1720,6 @@ int domain_context_unmap_one(
>      return rc;
>  }
> 
> -static bool any_pdev_behind_iommu(const struct domain *d,
> -                                  const struct pci_dev *exclude,
> -                                  const struct vtd_iommu *iommu)
> -{
> -    const struct pci_dev *pdev;
> -
> -    for_each_pdev ( d, pdev )
> -    {
> -        const struct acpi_drhd_unit *drhd;
> -
> -        if ( pdev == exclude )
> -            continue;
> -
> -        drhd = acpi_find_matched_drhd_unit(pdev);
> -        if ( drhd && drhd->iommu == iommu )
> -            return true;
> -    }
> -
> -    return false;
> -}
> -
>  static int domain_context_unmap(struct domain *domain, u8 devfn,
>                                  struct pci_dev *pdev)
>  {
> @@ -1704,7 +1728,6 @@ static int domain_context_unmap(struct d
>      int ret;
>      uint16_t seg = pdev->seg;
>      uint8_t bus = pdev->bus, tmp_bus, tmp_devfn, secbus;
> -    bool found;
> 
>      switch ( pdev->type )
>      {
> @@ -1780,28 +1803,10 @@ static int domain_context_unmap(struct d
>          return -EINVAL;
>      }
> 
> -    if ( ret || QUARANTINE_SKIP(domain) || pdev->devfn != devfn )
> -        return ret;
> +    if ( !ret && !QUARANTINE_SKIP(domain) && pdev->devfn == devfn )
> +        check_cleanup_domid_map(domain, pdev, iommu);
> 
> -    /*
> -     * If no other devices under the same iommu owned by this domain,
> -     * clear iommu in iommu_bitmap and clear domain_id in domid_bitmap.
> -     */
> -    found = any_pdev_behind_iommu(domain, pdev, iommu);
> -    /*
> -     * Hidden devices are associated with DomXEN but usable by the
> hardware
> -     * domain. Hence they need considering here as well.
> -     */
> -    if ( !found && is_hardware_domain(domain) )
> -        found = any_pdev_behind_iommu(dom_xen, pdev, iommu);
> -
> -    if ( !found )
> -    {
> -        clear_bit(iommu->index, dom_iommu(domain)-
> >arch.vtd.iommu_bitmap);
> -        cleanup_domid_map(domain, iommu);
> -    }
> -
> -    return 0;
> +    return ret;
>  }
> 
>  static void iommu_clear_root_pgtable(struct domain *d)