Hi Dan On Sat, Oct 07, 2017 at 08:45:00PM -0700, Dan Williams wrote: > Add a dma-mapping api helper to retrieve the generic iommu_domain for a device. > The motivation for this interface is making RDMA transfers to DAX mappings > safe. If the DAX file's block map changes we need to be to reliably stop > accesses to blocks that have been freed or re-assigned to a new file. With the > iommu_domain and a callback from the DAX filesystem the kernel can safely > revoke access to a DMA device. The process that performed the RDMA memory > registration is also notified of this revocation event, but the kernel can not > otherwise be in the position of waiting for userspace to quiesce the device. > > Since PMEM+DAX is currently only enabled for x86, we only update the x86 > iommu drivers. > > Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> > Cc: Robin Murphy <robin.murphy@xxxxxxx> > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > Cc: Joerg Roedel <joro@xxxxxxxxxx> > Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx> > Cc: Ashok Raj <ashok.raj@xxxxxxxxx> > Cc: Jan Kara <jack@xxxxxxx> > Cc: Jeff Moyer <jmoyer@xxxxxxxxxx> > Cc: Christoph Hellwig <hch@xxxxxx> > Cc: Dave Chinner <david@xxxxxxxxxxxxx> > Cc: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx> > Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> > Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> > --- > Changes since v7: > * retrieve the iommu_domain so that we can later pass the results of > dma_map_* to iommu_unmap() in advance of the actual dma_unmap_*. > > drivers/base/dma-mapping.c | 10 ++++++++++ > drivers/iommu/amd_iommu.c | 10 ++++++++++ > drivers/iommu/intel-iommu.c | 15 +++++++++++++++ > include/linux/dma-mapping.h | 3 +++ > 4 files changed, 38 insertions(+) > > diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c > index e584eddef0a7..fdb9764f95a4 100644 > --- a/drivers/base/dma-mapping.c > +++ b/drivers/base/dma-mapping.c > @@ -369,3 +369,13 @@ void dma_deconfigure(struct device *dev) > of_dma_deconfigure(dev); > acpi_dma_deconfigure(dev); > } > + > +struct iommu_domain *dma_get_iommu_domain(struct device *dev) > +{ > + const struct dma_map_ops *ops = get_dma_ops(dev); > + > + if (ops && ops->get_iommu) > + return ops->get_iommu(dev); > + return NULL; > +} > +EXPORT_SYMBOL(dma_get_iommu_domain); > diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c > index 51f8215877f5..c8e1a45af182 100644 > --- a/drivers/iommu/amd_iommu.c > +++ b/drivers/iommu/amd_iommu.c > @@ -2271,6 +2271,15 @@ static struct protection_domain *get_domain(struct device *dev) > return domain; > } > > +static struct iommu_domain *amd_dma_get_iommu(struct device *dev) Minor: Do you want to keep the naming consistent.. amd_dma_get_domain() vs get_iommu? > +{ > + struct protection_domain *domain = get_domain(dev); > + > + if (IS_ERR(domain)) > + return NULL; > + return &domain->domain; > +} > + > static void update_device_table(struct protection_domain *domain) > { > struct iommu_dev_data *dev_data; > @@ -2689,6 +2698,7 @@ static const struct dma_map_ops amd_iommu_dma_ops = { > .unmap_sg = unmap_sg, > .dma_supported = amd_iommu_dma_supported, > .mapping_error = amd_iommu_mapping_error, > + .get_iommu = amd_dma_get_iommu, ditto for here and other places below: > }; > > static int init_reserved_iova_ranges(void) > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > index 6784a05dd6b2..f3f4939cebad 100644 > --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -3578,6 +3578,20 @@ static int iommu_no_mapping(struct device *dev) > return 0; > } > > +static struct iommu_domain *intel_dma_get_iommu(struct device *dev) > +{ > + struct dmar_domain *domain; > + > + if (iommu_no_mapping(dev)) > + return NULL; > + > + domain = get_valid_domain_for_dev(dev); > + if (!domain) > + return NULL; > + > + return &domain->domain; > +} > + > static dma_addr_t __intel_map_single(struct device *dev, phys_addr_t paddr, > size_t size, int dir, u64 dma_mask) > { > @@ -3872,6 +3886,7 @@ const struct dma_map_ops intel_dma_ops = { > .map_page = intel_map_page, > .unmap_page = intel_unmap_page, > .mapping_error = intel_mapping_error, > + .get_iommu = intel_dma_get_iommu, > #ifdef CONFIG_X86 > .dma_supported = x86_dma_supported, > #endif > diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h > index 29ce9815da87..aa62df1d0d72 100644 > --- a/include/linux/dma-mapping.h > +++ b/include/linux/dma-mapping.h > @@ -128,6 +128,7 @@ struct dma_map_ops { > enum dma_data_direction dir); > int (*mapping_error)(struct device *dev, dma_addr_t dma_addr); > int (*dma_supported)(struct device *dev, u64 mask); > + struct iommu_domain *(*get_iommu)(struct device *dev); > #ifdef ARCH_HAS_DMA_GET_REQUIRED_MASK > u64 (*get_required_mask)(struct device *dev); > #endif > @@ -221,6 +222,8 @@ static inline const struct dma_map_ops *get_dma_ops(struct device *dev) > } > #endif > > +extern struct iommu_domain *dma_get_iommu_domain(struct device *dev); > + > static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr, > size_t size, > enum dma_data_direction dir, > -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html