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Subject[PATCH v3 3/6] iommu: Allow the dma-iommu api to use bounce buffers
Date
From: Tom Murphy <murphyt7@tcd.ie>

Allow the dma-iommu api to use bounce buffers for untrusted devices.
This is a copy of the intel bounce buffer code.

Signed-off-by: Tom Murphy <murphyt7@tcd.ie>
Co-developed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
drivers/iommu/dma-iommu.c | 163 +++++++++++++++++++++++++++++++++++---
1 file changed, 150 insertions(+), 13 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index d06411bd5e08..1a1da22e5a5e 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -21,9 +21,11 @@
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/pci.h>
+#include <linux/swiotlb.h>
#include <linux/scatterlist.h>
#include <linux/vmalloc.h>
#include <linux/crash_dump.h>
+#include <linux/dma-direct.h>

struct iommu_dma_msi_page {
struct list_head list;
@@ -498,6 +500,31 @@ static void __iommu_dma_unmap(struct device *dev, dma_addr_t dma_addr,
iommu_dma_free_iova(cookie, dma_addr, size, iotlb_gather.freelist);
}

+static void __iommu_dma_unmap_swiotlb(struct device *dev, dma_addr_t dma_addr,
+ size_t size, enum dma_data_direction dir,
+ unsigned long attrs)
+{
+ struct iommu_domain *domain = iommu_get_dma_domain(dev);
+ struct iommu_dma_cookie *cookie = domain->iova_cookie;
+ struct iova_domain *iovad = &cookie->iovad;
+ phys_addr_t phys;
+
+ phys = iommu_iova_to_phys(domain, dma_addr);
+ if (WARN_ON(!phys))
+ return;
+
+ __iommu_dma_unmap(dev, dma_addr, size);
+
+ if (unlikely(is_swiotlb_buffer(phys)))
+ swiotlb_tbl_unmap_single(dev, phys, size,
+ iova_align(iovad, size), dir, attrs);
+}
+
+static bool dev_is_untrusted(struct device *dev)
+{
+ return dev_is_pci(dev) && to_pci_dev(dev)->untrusted;
+}
+
static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys,
size_t size, int prot, u64 dma_mask)
{
@@ -523,6 +550,55 @@ static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys,
return iova + iova_off;
}

+static dma_addr_t __iommu_dma_map_swiotlb(struct device *dev, phys_addr_t phys,
+ size_t org_size, dma_addr_t dma_mask, bool coherent,
+ enum dma_data_direction dir, unsigned long attrs)
+{
+ int prot = dma_info_to_prot(dir, coherent, attrs);
+ struct iommu_domain *domain = iommu_get_dma_domain(dev);
+ struct iommu_dma_cookie *cookie = domain->iova_cookie;
+ struct iova_domain *iovad = &cookie->iovad;
+ size_t aligned_size = org_size;
+ void *padding_start;
+ size_t padding_size;
+ dma_addr_t iova;
+
+ /*
+ * If both the physical buffer start address and size are
+ * page aligned, we don't need to use a bounce page.
+ */
+ if (IS_ENABLED(CONFIG_SWIOTLB) && dev_is_untrusted(dev) &&
+ iova_offset(iovad, phys | org_size)) {
+ aligned_size = iova_align(iovad, org_size);
+ phys = swiotlb_tbl_map_single(dev,
+ __phys_to_dma(dev, io_tlb_start),
+ phys, org_size, aligned_size, dir, attrs);
+
+ if (phys == DMA_MAPPING_ERROR)
+ return DMA_MAPPING_ERROR;
+
+ /* Cleanup the padding area. */
+ padding_start = phys_to_virt(phys);
+ padding_size = aligned_size;
+
+ if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
+ (dir == DMA_TO_DEVICE ||
+ dir == DMA_BIDIRECTIONAL)) {
+ padding_start += org_size;
+ padding_size -= org_size;
+ }
+
+ memset(padding_start, 0, padding_size);
+ }
+
+ iova = __iommu_dma_map(dev, phys, aligned_size, prot, dma_mask);
+ if ((iova == DMA_MAPPING_ERROR) && is_swiotlb_buffer(phys))
+ swiotlb_tbl_unmap_single(dev, phys, org_size,
+ aligned_size, dir, attrs);
+
+ return iova;
+}
+
static void __iommu_dma_free_pages(struct page **pages, int count)
{
while (count--)
@@ -698,11 +774,15 @@ static void iommu_dma_sync_single_for_cpu(struct device *dev,
{
phys_addr_t phys;

- if (dev_is_dma_coherent(dev))
+ if (dev_is_dma_coherent(dev) && !dev_is_untrusted(dev))
return;

phys = iommu_iova_to_phys(iommu_get_dma_domain(dev), dma_handle);
- arch_sync_dma_for_cpu(phys, size, dir);
+ if (!dev_is_dma_coherent(dev))
+ arch_sync_dma_for_cpu(phys, size, dir);
+
+ if (is_swiotlb_buffer(phys))
+ swiotlb_tbl_sync_single(dev, phys, size, dir, SYNC_FOR_CPU);
}

static void iommu_dma_sync_single_for_device(struct device *dev,
@@ -710,11 +790,15 @@ static void iommu_dma_sync_single_for_device(struct device *dev,
{
phys_addr_t phys;

- if (dev_is_dma_coherent(dev))
+ if (dev_is_dma_coherent(dev) && !dev_is_untrusted(dev))
return;

phys = iommu_iova_to_phys(iommu_get_dma_domain(dev), dma_handle);
- arch_sync_dma_for_device(phys, size, dir);
+ if (is_swiotlb_buffer(phys))
+ swiotlb_tbl_sync_single(dev, phys, size, dir, SYNC_FOR_DEVICE);
+
+ if (!dev_is_dma_coherent(dev))
+ arch_sync_dma_for_device(phys, size, dir);
}

static void iommu_dma_sync_sg_for_cpu(struct device *dev,
@@ -724,11 +808,17 @@ static void iommu_dma_sync_sg_for_cpu(struct device *dev,
struct scatterlist *sg;
int i;

- if (dev_is_dma_coherent(dev))
+ if (dev_is_dma_coherent(dev) && !dev_is_untrusted(dev))
return;

- for_each_sg(sgl, sg, nelems, i)
- arch_sync_dma_for_cpu(sg_phys(sg), sg->length, dir);
+ for_each_sg(sgl, sg, nelems, i) {
+ if (!dev_is_dma_coherent(dev))
+ arch_sync_dma_for_cpu(sg_phys(sg), sg->length, dir);
+
+ if (is_swiotlb_buffer(sg_phys(sg)))
+ swiotlb_tbl_sync_single(dev, sg_phys(sg), sg->length,
+ dir, SYNC_FOR_CPU);
+ }
}

static void iommu_dma_sync_sg_for_device(struct device *dev,
@@ -738,11 +828,17 @@ static void iommu_dma_sync_sg_for_device(struct device *dev,
struct scatterlist *sg;
int i;

- if (dev_is_dma_coherent(dev))
+ if (dev_is_dma_coherent(dev) && !dev_is_untrusted(dev))
return;

- for_each_sg(sgl, sg, nelems, i)
- arch_sync_dma_for_device(sg_phys(sg), sg->length, dir);
+ for_each_sg(sgl, sg, nelems, i) {
+ if (is_swiotlb_buffer(sg_phys(sg)))
+ swiotlb_tbl_sync_single(dev, sg_phys(sg), sg->length,
+ dir, SYNC_FOR_DEVICE);
+
+ if (!dev_is_dma_coherent(dev))
+ arch_sync_dma_for_device(sg_phys(sg), sg->length, dir);
+ }
}

static dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
@@ -751,10 +847,10 @@ static dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
{
phys_addr_t phys = page_to_phys(page) + offset;
bool coherent = dev_is_dma_coherent(dev);
- int prot = dma_info_to_prot(dir, coherent, attrs);
dma_addr_t dma_handle;

- dma_handle = __iommu_dma_map(dev, phys, size, prot, dma_get_mask(dev));
+ dma_handle = __iommu_dma_map_swiotlb(dev, phys, size, dma_get_mask(dev),
+ coherent, dir, attrs);
if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
dma_handle != DMA_MAPPING_ERROR)
arch_sync_dma_for_device(phys, size, dir);
@@ -766,7 +862,7 @@ static void iommu_dma_unmap_page(struct device *dev, dma_addr_t dma_handle,
{
if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
iommu_dma_sync_single_for_cpu(dev, dma_handle, size, dir);
- __iommu_dma_unmap(dev, dma_handle, size);
+ __iommu_dma_unmap_swiotlb(dev, dma_handle, size, dir, attrs);
}

/*
@@ -844,6 +940,39 @@ static void __invalidate_sg(struct scatterlist *sg, int nents)
}
}

+static void iommu_dma_unmap_sg_swiotlb(struct device *dev, struct scatterlist *sg,
+ int nents, enum dma_data_direction dir, unsigned long attrs)
+{
+ struct scatterlist *s;
+ int i;
+
+ for_each_sg(sg, s, nents, i)
+ __iommu_dma_unmap_swiotlb(dev, sg_dma_address(s),
+ sg_dma_len(s), dir, attrs);
+}
+
+static int iommu_dma_map_sg_swiotlb(struct device *dev, struct scatterlist *sg,
+ int nents, enum dma_data_direction dir, unsigned long attrs)
+{
+ struct scatterlist *s;
+ int i;
+
+ for_each_sg(sg, s, nents, i) {
+ sg_dma_address(s) = __iommu_dma_map_swiotlb(dev, sg_phys(s),
+ s->length, dma_get_mask(dev),
+ dev_is_dma_coherent(dev), dir, attrs);
+ if (sg_dma_address(s) == DMA_MAPPING_ERROR)
+ goto out_unmap;
+ sg_dma_len(s) = s->length;
+ }
+
+ return nents;
+
+out_unmap:
+ iommu_dma_unmap_sg_swiotlb(dev, sg, i, dir, attrs | DMA_ATTR_SKIP_CPU_SYNC);
+ return 0;
+}
+
/*
* The DMA API client is passing in a scatterlist which could describe
* any old buffer layout, but the IOMMU API requires everything to be
@@ -870,6 +999,9 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
iommu_dma_sync_sg_for_device(dev, sg, nents, dir);

+ if (dev_is_untrusted(dev))
+ return iommu_dma_map_sg_swiotlb(dev, sg, nents, dir, attrs);
+
/*
* Work out how much IOVA space we need, and align the segments to
* IOVA granules for the IOMMU driver to handle. With some clever
@@ -939,6 +1071,11 @@ static void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
iommu_dma_sync_sg_for_cpu(dev, sg, nents, dir);

+ if (dev_is_untrusted(dev)) {
+ iommu_dma_unmap_sg_swiotlb(dev, sg, nents, dir, attrs);
+ return;
+ }
+
/*
* The scatterlist segments are mapped into a single
* contiguous IOVA allocation, so this is incredibly easy.
--
2.17.1
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