Re: [PATCH v7 9/9] iommu/dma: Reserve any RMR regions associated with a dev

[Jon Nettleton <jon@solid-run.com>]

On Fri, Oct 8, 2021 at 3:10 PM Robin Murphy <robin.murphy@arm.com> wrote:
>
> On 2021-08-05 09:07, Shameer Kolothum wrote:
> > Get ACPI IORT RMR regions associated with a dev reserved
> > so that there is a unity mapping for them in SMMU.
>
> This feels like most of it belongs in the IORT code rather than
> iommu-dma (which should save the temporary list copy as well).

See previous comment.  The original intent was for device-tree to also
be able to use these mechanisms to create RMR's and support them
in the SMMU.

-Jon

>
> Robin.
>
> > Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> > ---
> >   drivers/iommu/dma-iommu.c | 56 +++++++++++++++++++++++++++++++++++----
> >   1 file changed, 51 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> > index 1b6e27475279..c1ae0c3d4b33 100644
> > --- a/drivers/iommu/dma-iommu.c
> > +++ b/drivers/iommu/dma-iommu.c
> > @@ -207,22 +207,68 @@ void iommu_dma_put_rmrs(struct fwnode_handle *iommu_fwnode,
> >   }
> >   EXPORT_SYMBOL(iommu_dma_put_rmrs);
> >
> > +static bool iommu_dma_dev_has_rmr(struct iommu_fwspec *fwspec,
> > +                               struct iommu_resv_region *e)
> > +{
> > +     int i;
> > +
> > +     for (i = 0; i < fwspec->num_ids; i++) {
> > +             if (e->fw_data.rmr.sid == fwspec->ids[i])
> > +                     return true;
> > +     }
> > +
> > +     return false;
> > +}
> > +
> > +static void iommu_dma_get_rmr_resv_regions(struct device *dev,
> > +                                        struct list_head *list)
> > +{
> > +     struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
> > +     struct list_head rmr_list;
> > +     struct iommu_resv_region *rmr, *tmp;
> > +
> > +     INIT_LIST_HEAD(&rmr_list);
> > +     if (iommu_dma_get_rmrs(fwspec->iommu_fwnode, &rmr_list))
> > +             return;
> > +
> > +     if (dev_is_pci(dev)) {
> > +             struct pci_dev *pdev = to_pci_dev(dev);
> > +             struct pci_host_bridge *host = pci_find_host_bridge(pdev->bus);
> > +
> > +             if (!host->preserve_config)
> > +                     return;
> > +     }
> > +
> > +     list_for_each_entry_safe(rmr, tmp, &rmr_list, list) {
> > +             if (!iommu_dma_dev_has_rmr(fwspec, rmr))
> > +                     continue;
> > +
> > +             /* Remove from iommu RMR list and add to dev resv_regions */
> > +             list_del_init(&rmr->list);
> > +             list_add_tail(&rmr->list, list);
> > +     }
> > +
> > +     iommu_dma_put_rmrs(fwspec->iommu_fwnode, &rmr_list);
> > +}
> > +
> >   /**
> >    * iommu_dma_get_resv_regions - Reserved region driver helper
> >    * @dev: Device from iommu_get_resv_regions()
> >    * @list: Reserved region list from iommu_get_resv_regions()
> >    *
> >    * IOMMU drivers can use this to implement their .get_resv_regions callback
> > - * for general non-IOMMU-specific reservations. Currently, this covers GICv3
> > - * ITS region reservation on ACPI based ARM platforms that may require HW MSI
> > - * reservation.
> > + * for general non-IOMMU-specific reservations. Currently this covers,
> > + *  -GICv3 ITS region reservation on ACPI based ARM platforms that may
> > + *   require HW MSI reservation.
> > + *  -Any ACPI IORT RMR memory range reservations (IORT spec rev E.b)
> >    */
> >   void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list)
> >   {
> >
> > -     if (!is_of_node(dev_iommu_fwspec_get(dev)->iommu_fwnode))
> > +     if (!is_of_node(dev_iommu_fwspec_get(dev)->iommu_fwnode)) {
> >               iort_iommu_msi_get_resv_regions(dev, list);
> > -
> > +             iommu_dma_get_rmr_resv_regions(dev, list);
> > +     }
> >   }
> >   EXPORT_SYMBOL(iommu_dma_get_resv_regions);
> >
> >