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

[Lu Baolu]

Hi,

On 5/6/19 1:03 AM, Tom Murphy wrote:
> On Sun, May 5, 2019 at 3:44 AM Lu Baolu<baolu.lu@xxxxxxxxxxxxxxx>  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.

Okay, I understand it now. Thanks for the explanation.

Best regards,
Lu Baolu