Re: [RFC 6/7] iommu/vt-d: convert the intel iommu driver to the dma-iommu ops api

Tom Murphy
2019-05-05T17:03:02Z

On Sun, May 5, 2019 at 3:44 AM Lu Baolu <baolu.lu@linux.intel.com> wrote:
>
> Hi,
>
> On 5/4/19 9:23 PM, Tom Murphy wrote:
> > static int intel_iommu_add_device(struct device *dev)
> > {
> > + struct dmar_domain *dmar_domain;
> > + struct iommu_domain *domain;
> > struct intel_iommu *iommu;
> > struct iommu_group *group;
> > - struct iommu_domain *domain;
> > + dma_addr_t base;
> > u8 bus, devfn;
> >
> > iommu = device_to_iommu(dev, &bus, &devfn);
> > @@ -4871,9 +4514,12 @@ static int intel_iommu_add_device(struct device *dev)
> > if (IS_ERR(group))
> > return PTR_ERR(group);
> >
> > + base = IOVA_START_PFN << VTD_PAGE_SHIFT;
> > domain = iommu_get_domain_for_dev(dev);
> > + dmar_domain = to_dmar_domain(domain);
> > if (domain->type == IOMMU_DOMAIN_DMA)
> > - dev->dma_ops = &intel_dma_ops;
> > + iommu_setup_dma_ops(dev, base,
> > + __DOMAIN_MAX_ADDR(dmar_domain->gaw) - base);
>
> I didn't find the implementation of iommu_setup_dma_ops() in this
> series. Will the iova resource be initialized in this function?

Ah sorry, I should've mentioned this is based on the
http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/dma-iommu-ops.3
branch with the "iommu/vt-d: Delegate DMA domain to generic iommu" and
"iommu/amd: Convert the AMD iommu driver to the dma-iommu api" patch
sets applied.

>
> If so, will this block iommu_group_create_direct_mappings() which
> reserves and maps the reserved iova ranges.

The reserved regions will be reserved by the
iova_reserve_iommu_regions function instead:
( https://github.com/torvalds/linux/blob/6203838dec05352bc357625b1e9ba0a10d3bca35/drivers/iommu/dma-iommu.c#L238
)
iommu_setup_dma_ops calls iommu_dma_init_domain which calls
iova_reserve_iommu_regions.
iommu_group_create_direct_mappings will still execute normally but it
won't be able to call the intel_iommu_apply_resv_region function
because it's been removed in this patchset.
This shouldn't change any behavior and the same regions should be reserved.

>
> >
> > iommu_group_put(group);
> > return 0;
> > @@ -5002,19 +4648,6 @@ int intel_iommu_enable_pasid(struct intel_iommu *iommu, struct intel_svm_dev *sd
> > return ret;
> > }
> >
> > -static void intel_iommu_apply_resv_region(struct device *dev,
> > - struct iommu_domain *domain,
> > - struct iommu_resv_region *region)
> > -{
> > - struct dmar_domain *dmar_domain = to_dmar_domain(domain);
> > - unsigned long start, end;
> > -
> > - start = IOVA_PFN(region->start);
> > - end = IOVA_PFN(region->start + region->length - 1);
> > -
> > - WARN_ON_ONCE(!reserve_iova(&dmar_domain->iovad, start, end));
> > -}
> > -
> > struct intel_iommu *intel_svm_device_to_iommu(struct device *dev)
> > {
> > struct intel_iommu *iommu;
> > @@ -5050,13 +4683,13 @@ const struct iommu_ops intel_iommu_ops = {
> > .detach_dev = intel_iommu_detach_device,
> > .map = intel_iommu_map,
> > .unmap = intel_iommu_unmap,
> > + .flush_iotlb_all = iommu_flush_iova,
> > .flush_iotlb_range = intel_iommu_flush_iotlb_range,
> > .iova_to_phys = intel_iommu_iova_to_phys,
> > .add_device = intel_iommu_add_device,
> > .remove_device = intel_iommu_remove_device,
> > .get_resv_regions = intel_iommu_get_resv_regions,
> > .put_resv_regions = intel_iommu_put_resv_regions,
> > - .apply_resv_region = intel_iommu_apply_resv_region,
>
> With this removed, how will iommu_group_create_direct_mappings() work?
>
> Best regards,
> Lu Baolu