dma-mapping: bypass indirect calls for dma-direct

Avoid expensive indirect calls in the fast path DMA mapping operations by directly calling the dma_direct_* ops if we are using the directly mapped DMA operations. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Tested-by: Jesper Dangaard Brouer <brouer@redhat.com> Tested-by: Tony Luck <tony.luck@intel.com>
mariux64 · Dec 13, 2018 · 356da6d · 356da6d
1 parent 190d4e5
commit 356da6d
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Showing 20 changed files with 150 additions and 119 deletions.
diff --git a/arch/alpha/include/asm/dma-mapping.h b/arch/alpha/include/asm/dma-mapping.h
@@ -7,7 +7,7 @@ extern const struct dma_map_ops alpha_pci_ops;
 static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 {
 #ifdef CONFIG_ALPHA_JENSEN
-	return &dma_direct_ops;
+	return NULL;
 #else
 	return &alpha_pci_ops;
 #endif

diff --git a/arch/arc/mm/cache.c b/arch/arc/mm/cache.c
@@ -1280,7 +1280,7 @@ void __init arc_cache_init_master(void)
 	/*
 	 * In case of IOC (say IOC+SLC case), pointers above could still be set
 	 * but end up not being relevant as the first function in chain is not
-	 * called at all for @dma_direct_ops
+	 * called at all for devices using coherent DMA.
 	 *     arch_sync_dma_for_cpu() -> dma_cache_*() -> __dma_cache_*()
 	 */
 }

diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
@@ -18,7 +18,7 @@ extern const struct dma_map_ops arm_coherent_dma_ops;
 
 static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 {
-	return IS_ENABLED(CONFIG_MMU) ? &arm_dma_ops : &dma_direct_ops;
+	return IS_ENABLED(CONFIG_MMU) ? &arm_dma_ops : NULL;
 }
 
 #ifdef __arch_page_to_dma

diff --git a/arch/arm/mm/dma-mapping-nommu.c b/arch/arm/mm/dma-mapping-nommu.c
@@ -22,7 +22,7 @@
 #include "dma.h"
 
 /*
- *  dma_direct_ops is used if
+ *  The generic direct mapping code is used if
  *   - MMU/MPU is off
  *   - cpu is v7m w/o cache support
  *   - device is coherent
@@ -209,16 +209,9 @@ const struct dma_map_ops arm_nommu_dma_ops = {
 };
 EXPORT_SYMBOL(arm_nommu_dma_ops);
 
-static const struct dma_map_ops *arm_nommu_get_dma_map_ops(bool coherent)
-{
-	return coherent ? &dma_direct_ops : &arm_nommu_dma_ops;
-}
-
 void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 			const struct iommu_ops *iommu, bool coherent)
 {
-	const struct dma_map_ops *dma_ops;
-
 	if (IS_ENABLED(CONFIG_CPU_V7M)) {
 		/*
 		 * Cache support for v7m is optional, so can be treated as
@@ -234,7 +227,6 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 		dev->archdata.dma_coherent = (get_cr() & CR_M) ? coherent : true;
 	}
 
-	dma_ops = arm_nommu_get_dma_map_ops(dev->archdata.dma_coherent);
-
-	set_dma_ops(dev, dma_ops);
+	if (!dev->archdata.dma_coherent)
+		set_dma_ops(dev, &arm_nommu_dma_ops);
 }
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
@@ -462,9 +462,6 @@ static void __iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 			const struct iommu_ops *iommu, bool coherent)
 {
-	if (!dev->dma_ops)
-		dev->dma_ops = &dma_direct_ops;
-
 	dev->dma_coherent = coherent;
 	__iommu_setup_dma_ops(dev, dma_base, size, iommu);
 

diff --git a/arch/ia64/hp/common/hwsw_iommu.c b/arch/ia64/hp/common/hwsw_iommu.c
@@ -38,7 +38,7 @@ static inline int use_swiotlb(struct device *dev)
 const struct dma_map_ops *hwsw_dma_get_ops(struct device *dev)
 {
 	if (use_swiotlb(dev))
-		return &dma_direct_ops;
+		return NULL;
 	return &sba_dma_ops;
 }
 EXPORT_SYMBOL(hwsw_dma_get_ops);

diff --git a/arch/ia64/hp/common/sba_iommu.c b/arch/ia64/hp/common/sba_iommu.c
@@ -2078,7 +2078,7 @@ sba_init(void)
 	 * a successful kdump kernel boot is to use the swiotlb.
 	 */
 	if (is_kdump_kernel()) {
-		dma_ops = &dma_direct_ops;
+		dma_ops = NULL;
 		if (swiotlb_late_init_with_default_size(64 * (1<<20)) != 0)
 			panic("Unable to initialize software I/O TLB:"
 				  " Try machvec=dig boot option");
@@ -2100,7 +2100,7 @@ sba_init(void)
 		 * If we didn't find something sba_iommu can claim, we
 		 * need to setup the swiotlb and switch to the dig machvec.
 		 */
-		dma_ops = &dma_direct_ops;
+		dma_ops = NULL;
 		if (swiotlb_late_init_with_default_size(64 * (1<<20)) != 0)
 			panic("Unable to find SBA IOMMU or initialize "
 			      "software I/O TLB: Try machvec=dig boot option");

diff --git a/arch/ia64/kernel/dma-mapping.c b/arch/ia64/kernel/dma-mapping.c
@@ -36,7 +36,6 @@ long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr,
 
 void __init swiotlb_dma_init(void)
 {
-	dma_ops = &dma_direct_ops;
 	swiotlb_init(1);
 }
 #endif
diff --git a/arch/mips/include/asm/dma-mapping.h b/arch/mips/include/asm/dma-mapping.h
@@ -11,7 +11,7 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 #if defined(CONFIG_MACH_JAZZ)
 	return &jazz_dma_ops;
 #else
-	return &dma_direct_ops;
+	return NULL;
 #endif
 }
 

diff --git a/arch/parisc/kernel/setup.c b/arch/parisc/kernel/setup.c
@@ -99,10 +99,6 @@ void __init dma_ops_init(void)
 
 	case pcxl2:
 		pa7300lc_init();
-	case pcxl: /* falls through */
-	case pcxs:
-	case pcxt:
-		hppa_dma_ops = &dma_direct_ops;
 		break;
 	default:
 		break;

diff --git a/arch/sparc/include/asm/dma-mapping.h b/arch/sparc/include/asm/dma-mapping.h
@@ -12,11 +12,11 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 {
 #ifdef CONFIG_SPARC_LEON
 	if (sparc_cpu_model == sparc_leon)
-		return &dma_direct_ops;
+		return NULL;
 #endif
 #if defined(CONFIG_SPARC32) && defined(CONFIG_PCI)
 	if (bus == &pci_bus_type)
-		return &dma_direct_ops;
+		return NULL;
 #endif
 	return dma_ops;
 }

diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
@@ -17,7 +17,7 @@
 
 static bool disable_dac_quirk __read_mostly;
 
-const struct dma_map_ops *dma_ops = &dma_direct_ops;
+const struct dma_map_ops *dma_ops;
 EXPORT_SYMBOL(dma_ops);
 
 #ifdef CONFIG_IOMMU_DEBUG

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
@@ -581,7 +581,7 @@ static int vmw_dma_select_mode(struct vmw_private *dev_priv)
 
 	dev_priv->map_mode = vmw_dma_map_populate;
 
-	if (dma_ops->sync_single_for_cpu)
+	if (dma_ops && dma_ops->sync_single_for_cpu)
 		dev_priv->map_mode = vmw_dma_alloc_coherent;
 #ifdef CONFIG_SWIOTLB
 	if (swiotlb_nr_tbl() == 0)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
@@ -2184,7 +2184,7 @@ static int amd_iommu_add_device(struct device *dev)
 				dev_name(dev));
 
 		iommu_ignore_device(dev);
-		dev->dma_ops = &dma_direct_ops;
+		dev->dma_ops = NULL;
 		goto out;
 	}
 	init_iommu_group(dev);
@@ -2770,17 +2770,6 @@ int __init amd_iommu_init_dma_ops(void)
 	swiotlb        = (iommu_pass_through || sme_me_mask) ? 1 : 0;
 	iommu_detected = 1;
 
-	/*
-	 * In case we don't initialize SWIOTLB (actually the common case
-	 * when AMD IOMMU is enabled and SME is not active), make sure there
-	 * are global dma_ops set as a fall-back for devices not handled by
-	 * this driver (for example non-PCI devices). When SME is active,
-	 * make sure that swiotlb variable remains set so the global dma_ops
-	 * continue to be SWIOTLB.
-	 */
-	if (!swiotlb)
-		dma_ops = &dma_direct_ops;
-
 	if (amd_iommu_unmap_flush)
 		pr_info("AMD-Vi: IO/TLB flush on unmap enabled\n");
 	else

diff --git a/include/asm-generic/dma-mapping.h b/include/asm-generic/dma-mapping.h
@@ -4,7 +4,7 @@
 
 static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 {
-	return &dma_direct_ops;
+	return NULL;
 }
 
 #endif /* _ASM_GENERIC_DMA_MAPPING_H */
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
@@ -60,22 +60,5 @@ void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr,
 struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
 		dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs);
 void __dma_direct_free_pages(struct device *dev, size_t size, struct page *page);
-dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,
-		unsigned long offset, size_t size, enum dma_data_direction dir,
-		unsigned long attrs);
-void dma_direct_unmap_page(struct device *dev, dma_addr_t addr,
-		size_t size, enum dma_data_direction dir, unsigned long attrs);
-int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
-		enum dma_data_direction dir, unsigned long attrs);
-void dma_direct_unmap_sg(struct device *dev, struct scatterlist *sgl,
-		int nents, enum dma_data_direction dir, unsigned long attrs);
-void dma_direct_sync_single_for_device(struct device *dev,
-		dma_addr_t addr, size_t size, enum dma_data_direction dir);
-void dma_direct_sync_sg_for_device(struct device *dev,
-		struct scatterlist *sgl, int nents, enum dma_data_direction dir);
-void dma_direct_sync_single_for_cpu(struct device *dev,
-		dma_addr_t addr, size_t size, enum dma_data_direction dir);
-void dma_direct_sync_sg_for_cpu(struct device *dev,
-		struct scatterlist *sgl, int nents, enum dma_data_direction dir);
 int dma_direct_supported(struct device *dev, u64 mask);
 #endif /* _LINUX_DMA_DIRECT_H */