[PATCH 08/33] powerpc/dma: handle iommu bypass in dma_iommu_ops

Christoph Hellwig
2018-10-09T13:29:03Z

Add a new iommu_bypass flag to struct dev_archdata so that the dma_iommu
implementation can handle the direct mapping transparently instead of
switiching ops around. Setting of this flag is controlled by new
pci_controller_ops method.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
arch/powerpc/include/asm/device.h | 5 ++
arch/powerpc/include/asm/dma-mapping.h | 7 +++
arch/powerpc/include/asm/pci-bridge.h | 2 +
arch/powerpc/kernel/dma-iommu.c | 70 +++++++++++++++++++++++---
arch/powerpc/kernel/dma.c | 17 +++----
5 files changed, 85 insertions(+), 16 deletions(-)

diff --git a/arch/powerpc/include/asm/device.h b/arch/powerpc/include/asm/device.h
index 0245bfcaac32..1aa53318b4bc 100644
--- a/arch/powerpc/include/asm/device.h
+++ b/arch/powerpc/include/asm/device.h
@@ -19,6 +19,11 @@ struct iommu_table;
* drivers/macintosh/macio_asic.c
*/
struct dev_archdata {
+ /*
+ * Set to %true if the dma_iommu_ops are requested to use a direct
+ * window instead of dynamically mapping memory.
+ */
+ bool iommu_bypass : 1;
/*
* These two used to be a union. However, with the hybrid ops we need
* both so here we store both a DMA offset for direct mappings and
diff --git a/arch/powerpc/include/asm/dma-mapping.h b/arch/powerpc/include/asm/dma-mapping.h
index dacd0f93f2b2..27283eb68c50 100644
--- a/arch/powerpc/include/asm/dma-mapping.h
+++ b/arch/powerpc/include/asm/dma-mapping.h
@@ -29,6 +29,13 @@ extern int dma_nommu_mmap_coherent(struct device *dev,
struct vm_area_struct *vma,
void *cpu_addr, dma_addr_t handle,
size_t size, unsigned long attrs);
+int dma_nommu_map_sg(struct device *dev, struct scatterlist *sgl,
+ int nents, enum dma_data_direction direction,
+ unsigned long attrs);
+dma_addr_t dma_nommu_map_page(struct device *dev, struct page *page,
+ unsigned long offset, size_t size,
+ enum dma_data_direction dir, unsigned long attrs);
+int dma_nommu_dma_supported(struct device *dev, u64 mask);

#ifdef CONFIG_NOT_COHERENT_CACHE
/*
diff --git a/arch/powerpc/include/asm/pci-bridge.h b/arch/powerpc/include/asm/pci-bridge.h
index 94d449031b18..5c7a1e7ffc8a 100644
--- a/arch/powerpc/include/asm/pci-bridge.h
+++ b/arch/powerpc/include/asm/pci-bridge.h
@@ -19,6 +19,8 @@ struct device_node;
struct pci_controller_ops {
void (*dma_dev_setup)(struct pci_dev *pdev);
void (*dma_bus_setup)(struct pci_bus *bus);
+ bool (*iommu_bypass_supported)(struct pci_dev *pdev,
+ u64 mask);

int (*probe_mode)(struct pci_bus *bus);

diff --git a/arch/powerpc/kernel/dma-iommu.c b/arch/powerpc/kernel/dma-iommu.c
index 0613278abf9f..c865e15ad024 100644
--- a/arch/powerpc/kernel/dma-iommu.c
+++ b/arch/powerpc/kernel/dma-iommu.c
@@ -6,12 +6,30 @@
* busses using the iommu infrastructure
*/

+#include <linux/dma-direct.h>
+#include <linux/pci.h>
#include <asm/iommu.h>

/*
* Generic iommu implementation
*/

+/*
+ * The coherent mask may be smaller than the real mask, check if we can
+ * really use a direct window.
+ */
+static inline bool dma_iommu_alloc_bypass(struct device *dev)
+{
+ return dev->archdata.iommu_bypass &&
+ dma_nommu_dma_supported(dev, dev->coherent_dma_mask);
+}
+
+static inline bool dma_iommu_map_bypass(struct device *dev,
+ unsigned long attrs)
+{
+ return dev->archdata.iommu_bypass;
+}
+
/* Allocates a contiguous real buffer and creates mappings over it.
* Returns the virtual address of the buffer and sets dma_handle
* to the dma address (mapping) of the first page.
@@ -20,6 +38,9 @@ static void *dma_iommu_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t flag,
unsigned long attrs)
{
+ if (dma_iommu_alloc_bypass(dev))
+ return __dma_nommu_alloc_coherent(dev, size, dma_handle, flag,
+ attrs);
return iommu_alloc_coherent(dev, get_iommu_table_base(dev), size,
dma_handle, dev->coherent_dma_mask, flag,
dev_to_node(dev));
@@ -29,7 +50,11 @@ static void dma_iommu_free_coherent(struct device *dev, size_t size,
void *vaddr, dma_addr_t dma_handle,
unsigned long attrs)
{
- iommu_free_coherent(get_iommu_table_base(dev), size, vaddr, dma_handle);
+ if (dma_iommu_alloc_bypass(dev))
+ __dma_nommu_free_coherent(dev, size, vaddr, dma_handle, attrs);
+ else
+ iommu_free_coherent(get_iommu_table_base(dev), size, vaddr,
+ dma_handle);
}

/* Creates TCEs for a user provided buffer. The user buffer must be
@@ -42,6 +67,9 @@ static dma_addr_t dma_iommu_map_page(struct device *dev, struct page *page,
enum dma_data_direction direction,
unsigned long attrs)
{
+ if (dma_iommu_map_bypass(dev, attrs))
+ return dma_nommu_map_page(dev, page, offset, size, direction,
+ attrs);
return iommu_map_page(dev, get_iommu_table_base(dev), page, offset,
size, device_to_mask(dev), direction, attrs);
}
@@ -51,8 +79,9 @@ static void dma_iommu_unmap_page(struct device *dev, dma_addr_t dma_handle,
size_t size, enum dma_data_direction direction,
unsigned long attrs)
{
- iommu_unmap_page(get_iommu_table_base(dev), dma_handle, size, direction,
- attrs);
+ if (!dma_iommu_map_bypass(dev, attrs))
+ iommu_unmap_page(get_iommu_table_base(dev), dma_handle, size,
+ direction, attrs);
}

@@ -60,6 +89,8 @@ static int dma_iommu_map_sg(struct device *dev, struct scatterlist *sglist,
int nelems, enum dma_data_direction direction,
unsigned long attrs)
{
+ if (dma_iommu_map_bypass(dev, attrs))
+ return dma_nommu_map_sg(dev, sglist, nelems, direction, attrs);
return ppc_iommu_map_sg(dev, get_iommu_table_base(dev), sglist, nelems,
device_to_mask(dev), direction, attrs);
}
@@ -68,10 +99,20 @@ static void dma_iommu_unmap_sg(struct device *dev, struct scatterlist *sglist,
int nelems, enum dma_data_direction direction,
unsigned long attrs)
{
- ppc_iommu_unmap_sg(get_iommu_table_base(dev), sglist, nelems,
+ if (!dma_iommu_map_bypass(dev, attrs))
+ ppc_iommu_unmap_sg(get_iommu_table_base(dev), sglist, nelems,
direction, attrs);
}

+static bool dma_iommu_bypass_supported(struct device *dev, u64 mask)
+{
+ struct pci_dev *pdev = to_pci_dev(dev);
+ struct pci_controller *phb = pci_bus_to_host(pdev->bus);
+
+ return phb->controller_ops.iommu_bypass_supported &&
+ phb->controller_ops.iommu_bypass_supported(pdev, mask);
+}
+
/* We support DMA to/from any memory page via the iommu */
int dma_iommu_dma_supported(struct device *dev, u64 mask)
{
@@ -83,22 +124,39 @@ int dma_iommu_dma_supported(struct device *dev, u64 mask)
return 0;
}

+ if (dev_is_pci(dev) && dma_iommu_bypass_supported(dev, mask)) {
+ dev->archdata.iommu_bypass = true;
+ dev_dbg(dev, "iommu: 64-bit OK, using fixed ops\n");
+ return 1;
+ }
+
if (tbl->it_offset > (mask >> tbl->it_page_shift)) {
dev_info(dev, "Warning: IOMMU offset too big for device mask\n");
dev_info(dev, "mask: 0x%08llx, table offset: 0x%08lx\n",
mask, tbl->it_offset << tbl->it_page_shift);
return 0;
- } else
- return 1;
+ }
+
+ dev_dbg(dev, "iommu: not 64-bit, using default ops\n");
+ dev->archdata.iommu_bypass = false;
+ return 1;
}

u64 dma_iommu_get_required_mask(struct device *dev)
{
struct iommu_table *tbl = get_iommu_table_base(dev);
u64 mask;
+
if (!tbl)
return 0;

+ if (dev_is_pci(dev)) {
+ u64 bypass_mask = dma_direct_get_required_mask(dev);
+
+ if (dma_iommu_bypass_supported(dev, bypass_mask))
+ return bypass_mask;
+ }
+
mask = 1ULL < (fls_long(tbl->it_offset + tbl->it_size) - 1);
mask += mask - 1;

diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
index 7078d72baec2..716b7eab3ee7 100644
--- a/arch/powerpc/kernel/dma.c
+++ b/arch/powerpc/kernel/dma.c
@@ -40,7 +40,7 @@ static u64 __maybe_unused get_pfn_limit(struct device *dev)
return pfn;
}

-static int dma_nommu_dma_supported(struct device *dev, u64 mask)
+int dma_nommu_dma_supported(struct device *dev, u64 mask)
{
#ifdef CONFIG_PPC64
u64 limit = get_dma_offset(dev) + (memblock_end_of_DRAM() - 1);
@@ -177,9 +177,9 @@ int dma_nommu_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
vma->vm_page_prot);
}

-static int dma_nommu_map_sg(struct device *dev, struct scatterlist *sgl,
- int nents, enum dma_data_direction direction,
- unsigned long attrs)
+int dma_nommu_map_sg(struct device *dev, struct scatterlist *sgl,
+ int nents, enum dma_data_direction direction,
+ unsigned long attrs)
{
struct scatterlist *sg;
int i;
@@ -209,12 +209,9 @@ static u64 dma_nommu_get_required_mask(struct device *dev)
return mask;
}

-static inline dma_addr_t dma_nommu_map_page(struct device *dev,
- struct page *page,
- unsigned long offset,
- size_t size,
- enum dma_data_direction dir,
- unsigned long attrs)
+dma_addr_t dma_nommu_map_page(struct device *dev, struct page *page,
+ unsigned long offset, size_t size,
+ enum dma_data_direction dir, unsigned long attrs)
{
if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
__dma_sync_page(page, offset, size, dir);
--
2.19.0