The Intel VT-d hardware uses paging for DMA remapping. The minimum mapped window is a page size. The device drivers may map buffers not filling the whole IOMMU window. This allows the device to access to possibly unrelated memory and a malicious device could exploit this to perform DMA attacks. To address this, the Intel IOMMU driver will use bounce pages for those buffers which don't fill whole IOMMU pages.
Cc: Ashok Raj <ashok....@intel.com> Cc: Jacob Pan <jacob.jun....@linux.intel.com> Cc: Kevin Tian <kevin.t...@intel.com> Signed-off-by: Lu Baolu <baolu...@linux.intel.com> Tested-by: Xu Pengfei <pengfei...@intel.com> Tested-by: Mika Westerberg <mika.westerb...@intel.com> --- drivers/iommu/Kconfig | 2 + drivers/iommu/intel-iommu.c | 181 ++++++++++++++++++++++++++++++++++++ 2 files changed, 183 insertions(+) diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig index d7f2e09cbcf2..3baa418edc16 100644 --- a/drivers/iommu/Kconfig +++ b/drivers/iommu/Kconfig @@ -195,6 +195,8 @@ config INTEL_IOMMU select IOMMU_IOVA select NEED_DMA_MAP_STATE select DMAR_TABLE + select SWIOTLB + select IOMMU_BOUNCE_PAGE help DMA remapping (DMAR) devices support enables independent address translations for Direct Memory Access (DMA) from devices. diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index fcbbf8de07e7..9a60feeda313 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -44,6 +44,7 @@ #include <asm/irq_remapping.h> #include <asm/cacheflush.h> #include <asm/iommu.h> +#include <trace/events/intel_iommu.h> #include "irq_remapping.h" #include "intel-pasid.h" @@ -3745,6 +3746,183 @@ static const struct dma_map_ops intel_dma_ops = { .dma_supported = dma_direct_supported, }; +static dma_addr_t +bounce_map_single(struct device *dev, phys_addr_t paddr, size_t size, + enum dma_data_direction dir, unsigned long attrs, + u64 dma_mask) +{ + struct dmar_domain *domain; + struct intel_iommu *iommu; + unsigned long iova_pfn; + unsigned long nrpages; + dma_addr_t ret_addr; + + domain = find_domain(dev); + if (WARN_ON(dir == DMA_NONE || !domain)) + return DMA_MAPPING_ERROR; + + iommu = domain_get_iommu(domain); + nrpages = aligned_nrpages(0, size); + iova_pfn = intel_alloc_iova(dev, domain, + dma_to_mm_pfn(nrpages), dma_mask); + if (!iova_pfn) + return DMA_MAPPING_ERROR; + + ret_addr = iommu_bounce_map(dev, iova_pfn << PAGE_SHIFT, + paddr, size, dir, attrs); + if (ret_addr == DMA_MAPPING_ERROR) { + free_iova_fast(&domain->iovad, iova_pfn, dma_to_mm_pfn(nrpages)); + return DMA_MAPPING_ERROR; + } + + trace_bounce_map_single(dev, iova_pfn << PAGE_SHIFT, paddr, size); + + return ret_addr; +} + +static void +bounce_unmap_single(struct device *dev, dma_addr_t dev_addr, size_t size, + enum dma_data_direction dir, unsigned long attrs) +{ + struct dmar_domain *domain; + struct intel_iommu *iommu; + unsigned long iova_pfn; + unsigned long nrpages; + + domain = find_domain(dev); + if (WARN_ON(!domain)) + return; + + iommu_bounce_unmap(dev, dev_addr, size, dir, attrs); + trace_bounce_unmap_single(dev, dev_addr, size); + + iommu = domain_get_iommu(domain); + iova_pfn = IOVA_PFN(dev_addr); + nrpages = aligned_nrpages(0, size); + + iommu_flush_iotlb_psi(iommu, domain, + mm_to_dma_pfn(iova_pfn), nrpages, 0, 0); + free_iova_fast(&domain->iovad, iova_pfn, dma_to_mm_pfn(nrpages)); +} + +static dma_addr_t +bounce_map_page(struct device *dev, struct page *page, unsigned long offset, + size_t size, enum dma_data_direction dir, unsigned long attrs) +{ + return bounce_map_single(dev, page_to_phys(page) + offset, + size, dir, attrs, *dev->dma_mask); +} + +static dma_addr_t +bounce_map_resource(struct device *dev, phys_addr_t phys_addr, size_t size, + enum dma_data_direction dir, unsigned long attrs) +{ + return bounce_map_single(dev, phys_addr, size, + dir, attrs, *dev->dma_mask); +} + +static void +bounce_unmap_page(struct device *dev, dma_addr_t dev_addr, size_t size, + enum dma_data_direction dir, unsigned long attrs) +{ + bounce_unmap_single(dev, dev_addr, size, dir, attrs); +} + +static void +bounce_unmap_resource(struct device *dev, dma_addr_t dev_addr, size_t size, + enum dma_data_direction dir, unsigned long attrs) +{ + bounce_unmap_single(dev, dev_addr, size, dir, attrs); +} + +static void +bounce_unmap_sg(struct device *dev, struct scatterlist *sglist, int nelems, + enum dma_data_direction dir, unsigned long attrs) +{ + struct scatterlist *sg; + int i; + + for_each_sg(sglist, sg, nelems, i) + bounce_unmap_page(dev, sg->dma_address, + sg_dma_len(sg), dir, attrs); +} + +static int +bounce_map_sg(struct device *dev, struct scatterlist *sglist, int nelems, + enum dma_data_direction dir, unsigned long attrs) +{ + int i; + struct scatterlist *sg; + + for_each_sg(sglist, sg, nelems, i) { + sg->dma_address = bounce_map_page(dev, sg_page(sg), + sg->offset, sg->length, dir, attrs); + if (sg->dma_address == DMA_MAPPING_ERROR) + goto out_unmap; + sg_dma_len(sg) = sg->length; + } + + return nelems; + +out_unmap: + bounce_unmap_sg(dev, sglist, i, dir, attrs | DMA_ATTR_SKIP_CPU_SYNC); + return 0; +} + +static void +bounce_sync_single_for_cpu(struct device *dev, dma_addr_t addr, + size_t size, enum dma_data_direction dir) +{ + iommu_bounce_sync(dev, addr, size, dir, SYNC_FOR_CPU); +} + +static void +bounce_sync_single_for_device(struct device *dev, dma_addr_t addr, + size_t size, enum dma_data_direction dir) +{ + iommu_bounce_sync(dev, addr, size, dir, SYNC_FOR_DEVICE); +} + +static void +bounce_sync_sg_for_cpu(struct device *dev, struct scatterlist *sglist, + int nelems, enum dma_data_direction dir) +{ + struct scatterlist *sg; + int i; + + for_each_sg(sglist, sg, nelems, i) + iommu_bounce_sync(dev, sg_dma_address(sg), + sg_dma_len(sg), dir, SYNC_FOR_CPU); +} + +static void +bounce_sync_sg_for_device(struct device *dev, struct scatterlist *sglist, + int nelems, enum dma_data_direction dir) +{ + struct scatterlist *sg; + int i; + + for_each_sg(sglist, sg, nelems, i) + iommu_bounce_sync(dev, sg_dma_address(sg), + sg_dma_len(sg), dir, SYNC_FOR_DEVICE); +} + +static const struct dma_map_ops bounce_dma_ops = { + .alloc = intel_alloc_coherent, + .free = intel_free_coherent, + .map_sg = bounce_map_sg, + .unmap_sg = bounce_unmap_sg, + .map_page = bounce_map_page, + .unmap_page = bounce_unmap_page, + .sync_single_for_cpu = bounce_sync_single_for_cpu, + .sync_single_for_device = bounce_sync_single_for_device, + .sync_sg_for_cpu = bounce_sync_sg_for_cpu, + .sync_sg_for_device = bounce_sync_sg_for_device, + .map_resource = bounce_map_resource, + .unmap_resource = bounce_unmap_resource, + .dma_supported = dma_direct_supported, +}; + static inline int iommu_domain_cache_init(void) { int ret = 0; @@ -5304,6 +5482,9 @@ static int intel_iommu_add_device(struct device *dev) } } + if (device_needs_bounce(dev)) + set_dma_ops(dev, &bounce_dma_ops); + return 0; } -- 2.17.1