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Subject[PATCH 1/2] dma-iommu: fix swiotlb SKIP_CPU_SYNC and arch sync
Date
From: David Stevens <stevensd@chromium.org>

Make map_swiotlb and unmap_swiotlb only for mapping, and consistently
use sync_single_for and sync_sg_for functions for swiotlb sync and arch
sync. This ensures that the same code path is responsible for syncing
regardless of whether or not SKIP_CPU_SYNC is set. In the process, fix
various places where the original physical address and swiotlb tlb_addr
are mixed up:
- Make sync_sg functions call sync_single functions for untrusted
devices, so they use tlb_addr when checking is_swiotlb_buffer and
when doing arch sync if necessary.
- Use tlb_addr for arch sync in map_page if necessary.
- In map_sg, map before syncing so that arch sync can target the
bounce buffer if necessary.
- Pass SKIP_CPU_SYNC to swiotlb map and unmap to avoid double syncing
the swiotlb. This had previously only happened in the unmap_page
case, but is now necessary for all swiotlb cases.

Fixes: 82612d66d51d ("iommu: Allow the dma-iommu api to use bounce buffers")
Signed-off-by: David Stevens <stevensd@chromium.org>
---
drivers/iommu/dma-iommu.c | 82 ++++++++++++++++++++++++---------------
1 file changed, 51 insertions(+), 31 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 7bcdd1205535..24d1042cd052 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -505,7 +505,8 @@ static void __iommu_dma_unmap_swiotlb(struct device *dev, dma_addr_t dma_addr,
__iommu_dma_unmap(dev, dma_addr, size);

if (unlikely(is_swiotlb_buffer(phys)))
- swiotlb_tbl_unmap_single(dev, phys, size, dir, attrs);
+ swiotlb_tbl_unmap_single(dev, phys, size, dir,
+ attrs | DMA_ATTR_SKIP_CPU_SYNC);
}

static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys,
@@ -536,7 +537,8 @@ static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys,

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)
+ enum dma_data_direction dir, unsigned long attrs,
+ phys_addr_t *adj_phys)
{
int prot = dma_info_to_prot(dir, coherent, attrs);
struct iommu_domain *domain = iommu_get_dma_domain(dev);
@@ -555,7 +557,8 @@ static dma_addr_t __iommu_dma_map_swiotlb(struct device *dev, phys_addr_t phys,
iova_offset(iovad, phys | org_size)) {
aligned_size = iova_align(iovad, org_size);
phys = swiotlb_tbl_map_single(dev, phys, org_size,
- aligned_size, dir, attrs);
+ aligned_size, dir,
+ attrs | DMA_ATTR_SKIP_CPU_SYNC);

if (phys == DMA_MAPPING_ERROR)
return DMA_MAPPING_ERROR;
@@ -573,6 +576,8 @@ static dma_addr_t __iommu_dma_map_swiotlb(struct device *dev, phys_addr_t phys,

memset(padding_start, 0, padding_size);
}
+ if (adj_phys)
+ *adj_phys = phys;

iova = __iommu_dma_map(dev, phys, aligned_size, prot, dma_mask);
if (iova == DMA_MAPPING_ERROR && is_swiotlb_buffer(phys))
@@ -785,15 +790,17 @@ static void iommu_dma_sync_single_for_cpu(struct device *dev,
swiotlb_sync_single_for_cpu(dev, phys, size, dir);
}

-static void iommu_dma_sync_single_for_device(struct device *dev,
- dma_addr_t dma_handle, size_t size, enum dma_data_direction dir)
+static void __iommu_dma_sync_single_for_device(struct device *dev,
+ dma_addr_t dma_handle, size_t size,
+ enum dma_data_direction dir, phys_addr_t phys)
{
- phys_addr_t phys;
-
if (dev_is_dma_coherent(dev) && !dev_is_untrusted(dev))
return;

- phys = iommu_iova_to_phys(iommu_get_dma_domain(dev), dma_handle);
+ if (phys == 0)
+ phys = iommu_iova_to_phys(iommu_get_dma_domain(dev),
+ dma_handle);
+
if (is_swiotlb_buffer(phys))
swiotlb_sync_single_for_device(dev, phys, size, dir);

@@ -801,6 +808,12 @@ static void iommu_dma_sync_single_for_device(struct device *dev,
arch_sync_dma_for_device(phys, size, dir);
}

+static void iommu_dma_sync_single_for_device(struct device *dev,
+ dma_addr_t dma_handle, size_t size, enum dma_data_direction dir)
+{
+ __iommu_dma_sync_single_for_device(dev, dma_handle, size, dir, 0);
+}
+
static void iommu_dma_sync_sg_for_cpu(struct device *dev,
struct scatterlist *sgl, int nelems,
enum dma_data_direction dir)
@@ -811,14 +824,13 @@ static void iommu_dma_sync_sg_for_cpu(struct device *dev,
if (dev_is_dma_coherent(dev) && !dev_is_untrusted(dev))
return;

- for_each_sg(sgl, sg, nelems, i) {
- if (!dev_is_dma_coherent(dev))
+ if (dev_is_untrusted(dev))
+ for_each_sg(sgl, sg, nelems, i)
+ iommu_dma_sync_single_for_cpu(dev, sg_dma_address(sg),
+ sg->length, dir);
+ else
+ for_each_sg(sgl, sg, nelems, i)
arch_sync_dma_for_cpu(sg_phys(sg), sg->length, dir);
-
- if (is_swiotlb_buffer(sg_phys(sg)))
- swiotlb_sync_single_for_cpu(dev, sg_phys(sg),
- sg->length, dir);
- }
}

static void iommu_dma_sync_sg_for_device(struct device *dev,
@@ -831,29 +843,30 @@ static void iommu_dma_sync_sg_for_device(struct device *dev,
if (dev_is_dma_coherent(dev) && !dev_is_untrusted(dev))
return;

- for_each_sg(sgl, sg, nelems, i) {
- if (is_swiotlb_buffer(sg_phys(sg)))
- swiotlb_sync_single_for_device(dev, sg_phys(sg),
- sg->length, dir);
-
- if (!dev_is_dma_coherent(dev))
+ if (dev_is_untrusted(dev))
+ for_each_sg(sgl, sg, nelems, i)
+ __iommu_dma_sync_single_for_device(dev,
+ sg_dma_address(sg),
+ sg->length, dir, 0);
+ else
+ for_each_sg(sgl, sg, nelems, i)
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,
unsigned long offset, size_t size, enum dma_data_direction dir,
unsigned long attrs)
{
- phys_addr_t phys = page_to_phys(page) + offset;
+ phys_addr_t phys = page_to_phys(page) + offset, adj_phys;
bool coherent = dev_is_dma_coherent(dev);
dma_addr_t dma_handle;

- 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 = __iommu_dma_map_swiotlb(dev, phys, size,
+ dma_get_mask(dev), coherent, dir, attrs, &adj_phys);
+ if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
dma_handle != DMA_MAPPING_ERROR)
- arch_sync_dma_for_device(phys, size, dir);
+ __iommu_dma_sync_single_for_device(dev, dma_handle, size,
+ dir, adj_phys);
return dma_handle;
}

@@ -960,7 +973,7 @@ static int iommu_dma_map_sg_swiotlb(struct device *dev, struct scatterlist *sg,
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);
+ dev_is_dma_coherent(dev), dir, attrs, NULL);
if (sg_dma_address(s) == DMA_MAPPING_ERROR)
goto out_unmap;
sg_dma_len(s) = s->length;
@@ -991,17 +1004,24 @@ static int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
dma_addr_t iova;
size_t iova_len = 0;
unsigned long mask = dma_get_seg_boundary(dev);
- int i;
+ int i, early_mapped = 0;

if (static_branch_unlikely(&iommu_deferred_attach_enabled) &&
iommu_deferred_attach(dev, domain))
return 0;

+ if (dev_is_untrusted(dev)) {
+ early_mapped = iommu_dma_map_sg_swiotlb(dev, sg, nents,
+ dir, attrs);
+ if (!early_mapped)
+ return 0;
+ }
+
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);
+ if (early_mapped)
+ return early_mapped;

/*
* Work out how much IOVA space we need, and align the segments to
--
2.32.0.93.g670b81a890-goog
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