IOMMU Updates for Linux v3.8

A few new features this merge-window. The most important one is
 probably, that dma-debug now warns if a dma-handle is not checked with
 dma_mapping_error by the device driver. This requires minor changes to
 some architectures which make use of dma-debug. Most of these changes
 have the respective Acks by the Arch-Maintainers.
 Besides that there are updates to the AMD IOMMU driver for refactor the
 IOMMU-Groups support and to make sure it does not trigger a hardware
 erratum.
 The OMAP changes (for which I pulled in a branch from Tony Lindgren's
 tree) have a conflict in linux-next with the arm-soc tree. The conflict
 is in the file arch/arm/mach-omap2/clock44xx_data.c which is deleted in
 the arm-soc tree. It is safe to delete the file too so solve the
 conflict. Similar changes are done in the arm-soc tree in the common
 clock framework migration. A missing hunk from the patch in the IOMMU
 tree will be submitted as a seperate patch when the merge-window is
 closed.
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Merge tag 'iommu-updates-v3.8' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu

Pull IOMMU updates from Joerg Roedel:
 "A few new features this merge-window.  The most important one is
  probably, that dma-debug now warns if a dma-handle is not checked with
  dma_mapping_error by the device driver.  This requires minor changes
  to some architectures which make use of dma-debug.  Most of these
  changes have the respective Acks by the Arch-Maintainers.

  Besides that there are updates to the AMD IOMMU driver for refactor
  the IOMMU-Groups support and to make sure it does not trigger a
  hardware erratum.

  The OMAP changes (for which I pulled in a branch from Tony Lindgren's
  tree) have a conflict in linux-next with the arm-soc tree.  The
  conflict is in the file arch/arm/mach-omap2/clock44xx_data.c which is
  deleted in the arm-soc tree.  It is safe to delete the file too so
  solve the conflict.  Similar changes are done in the arm-soc tree in
  the common clock framework migration.  A missing hunk from the patch
  in the IOMMU tree will be submitted as a seperate patch when the
  merge-window is closed."

* tag 'iommu-updates-v3.8' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu: (29 commits)
  ARM: dma-mapping: support debug_dma_mapping_error
  ARM: OMAP4: hwmod data: ipu and dsp to use parent clocks instead of leaf clocks
  iommu/omap: Adapt to runtime pm
  iommu/omap: Migrate to hwmod framework
  iommu/omap: Keep mmu enabled when requested
  iommu/omap: Remove redundant clock handling on ISR
  iommu/amd: Remove obsolete comment
  iommu/amd: Don't use 512GB pages
  iommu/tegra: smmu: Move bus_set_iommu after probe for multi arch
  iommu/tegra: gart: Move bus_set_iommu after probe for multi arch
  iommu/tegra: smmu: Remove unnecessary PTC/TLB flush all
  tile: dma_debug: add debug_dma_mapping_error support
  sh: dma_debug: add debug_dma_mapping_error support
  powerpc: dma_debug: add debug_dma_mapping_error support
  mips: dma_debug: add debug_dma_mapping_error support
  microblaze: dma-mapping: support debug_dma_mapping_error
  ia64: dma_debug: add debug_dma_mapping_error support
  c6x: dma_debug: add debug_dma_mapping_error support
  ARM64: dma_debug: add debug_dma_mapping_error support
  intel-iommu: Prevent devices with RMRRs from being placed into SI Domain
  ...

Documentation/DMA-API-HOWTO.txt

@@ -468,11 +468,46 @@ To map a single region, you do:
 	size_t size = buffer->len;
 
 	dma_handle = dma_map_single(dev, addr, size, direction);
+	if (dma_mapping_error(dma_handle)) {
+		/*
+		 * reduce current DMA mapping usage,
+		 * delay and try again later or
+		 * reset driver.
+		 */
+		goto map_error_handling;
+	}
 
 and to unmap it:
 
 	dma_unmap_single(dev, dma_handle, size, direction);
 
+You should call dma_mapping_error() as dma_map_single() could fail and return
+error. Not all dma implementations support dma_mapping_error() interface.
+However, it is a good practice to call dma_mapping_error() interface, which
+will invoke the generic mapping error check interface. Doing so will ensure
+that the mapping code will work correctly on all dma implementations without
+any dependency on the specifics of the underlying implementation. Using the
+returned address without checking for errors could result in failures ranging
+from panics to silent data corruption. Couple of example of incorrect ways to
+check for errors that make assumptions about the underlying dma implementation
+are as follows and these are applicable to dma_map_page() as well.
+
+Incorrect example 1:
+	dma_addr_t dma_handle;
+
+	dma_handle = dma_map_single(dev, addr, size, direction);
+	if ((dma_handle & 0xffff != 0) || (dma_handle >= 0x1000000)) {
+		goto map_error;
+	}
+
+Incorrect example 2:
+	dma_addr_t dma_handle;
+
+	dma_handle = dma_map_single(dev, addr, size, direction);
+	if (dma_handle == DMA_ERROR_CODE) {
+		goto map_error;
+	}
+
 You should call dma_unmap_single when the DMA activity is finished, e.g.
 from the interrupt which told you that the DMA transfer is done.
 
@@ -489,6 +524,14 @@ Specifically:
 	size_t size = buffer->len;
 
 	dma_handle = dma_map_page(dev, page, offset, size, direction);
+	if (dma_mapping_error(dma_handle)) {
+		/*
+		 * reduce current DMA mapping usage,
+		 * delay and try again later or
+		 * reset driver.
+		 */
+		goto map_error_handling;
+	}
 
 	...
 
@@ -496,6 +539,12 @@ Specifically:
 
 Here, "offset" means byte offset within the given page.
 
+You should call dma_mapping_error() as dma_map_page() could fail and return
+error as outlined under the dma_map_single() discussion.
+
+You should call dma_unmap_page when the DMA activity is finished, e.g.
+from the interrupt which told you that the DMA transfer is done.
+
 With scatterlists, you map a region gathered from several regions by:
 
 	int i, count = dma_map_sg(dev, sglist, nents, direction);
@@ -578,6 +627,14 @@ to use the dma_sync_*() interfaces.
 		dma_addr_t mapping;
 
 		mapping = dma_map_single(cp->dev, buffer, len, DMA_FROM_DEVICE);
+		if (dma_mapping_error(dma_handle)) {
+			/*
+			 * reduce current DMA mapping usage,
+			 * delay and try again later or
+			 * reset driver.
+			 */
+			goto map_error_handling;
+		}
 
 		cp->rx_buf = buffer;
 		cp->rx_len = len;
@@ -658,6 +715,75 @@ failure can be determined by:
 		 * delay and try again later or
 		 * reset driver.
 		 */
+		goto map_error_handling;
+	}
+
+- unmap pages that are already mapped, when mapping error occurs in the middle
+  of a multiple page mapping attempt. These example are applicable to
+  dma_map_page() as well.
+
+Example 1:
+	dma_addr_t dma_handle1;
+	dma_addr_t dma_handle2;
+
+	dma_handle1 = dma_map_single(dev, addr, size, direction);
+	if (dma_mapping_error(dev, dma_handle1)) {
+		/*
+		 * reduce current DMA mapping usage,
+		 * delay and try again later or
+		 * reset driver.
+		 */
+		goto map_error_handling1;
+	}
+	dma_handle2 = dma_map_single(dev, addr, size, direction);
+	if (dma_mapping_error(dev, dma_handle2)) {
+		/*
+		 * reduce current DMA mapping usage,
+		 * delay and try again later or
+		 * reset driver.
+		 */
+		goto map_error_handling2;
+	}
+
+	...
+
+	map_error_handling2:
+		dma_unmap_single(dma_handle1);
+	map_error_handling1:
+
+Example 2: (if buffers are allocated a loop, unmap all mapped buffers when
+	    mapping error is detected in the middle)
+
+	dma_addr_t dma_addr;
+	dma_addr_t array[DMA_BUFFERS];
+	int save_index = 0;
+
+	for (i = 0; i < DMA_BUFFERS; i++) {
+
+		...
+
+		dma_addr = dma_map_single(dev, addr, size, direction);
+		if (dma_mapping_error(dev, dma_addr)) {
+			/*
+			 * reduce current DMA mapping usage,
+			 * delay and try again later or
+			 * reset driver.
+			 */
+			goto map_error_handling;
+		}
+		array[i].dma_addr = dma_addr;
+		save_index++;
+	}
+
+	...
+
+	map_error_handling:
+
+	for (i = 0; i < save_index; i++) {
+
+		...
+
+		dma_unmap_single(array[i].dma_addr);
 	}
 
 Networking drivers must call dev_kfree_skb to free the socket buffer

Documentation/DMA-API.txt

@@ -678,3 +678,15 @@ out of dma_debug_entries. These entries are preallocated at boot. The number
 of preallocated entries is defined per architecture. If it is too low for you
 boot with 'dma_debug_entries=<your_desired_number>' to overwrite the
 architectural default.
+
+void debug_dmap_mapping_error(struct device *dev, dma_addr_t dma_addr);
+
+dma-debug interface debug_dma_mapping_error() to debug drivers that fail
+to check dma mapping errors on addresses returned by dma_map_single() and
+dma_map_page() interfaces. This interface clears a flag set by
+debug_dma_map_page() to indicate that dma_mapping_error() has been called by
+the driver. When driver does unmap, debug_dma_unmap() checks the flag and if
+this flag is still set, prints warning message that includes call trace that
+leads up to the unmap. This interface can be called from dma_mapping_error()
+routines to enable dma mapping error check debugging.
+

arch/arm/include/asm/dma-mapping.h

@@ -91,6 +91,7 @@ static inline dma_addr_t virt_to_dma(struct device *dev, void *addr)
  */
 static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 {
+	debug_dma_mapping_error(dev, dma_addr);
 	return dma_addr == DMA_ERROR_CODE;
 }
 

arch/arm/mach-omap2/devices.c

@@ -226,7 +226,7 @@ static struct platform_device omap3isp_device = {
 };
 
 static struct omap_iommu_arch_data omap3_isp_iommu = {
-	.name = "isp",
+	.name = "mmu_isp",
 };
 
 int omap3_init_camera(struct isp_platform_data *pdata)

arch/arm/mach-omap2/omap-iommu.c

@@ -12,153 +12,60 @@
 
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/err.h>
+#include <linux/slab.h>
 
 #include <linux/platform_data/iommu-omap.h>
+#include <plat/omap_hwmod.h>
+#include <plat/omap_device.h>
 
-#include "soc.h"
+static int __init omap_iommu_dev_init(struct omap_hwmod *oh, void *unused)
-#include "common.h"
+{
+	struct platform_device *pdev;
+	struct iommu_platform_data *pdata;
+	struct omap_mmu_dev_attr *a = (struct omap_mmu_dev_attr *)oh->dev_attr;
+	static int i;
 
-struct iommu_device {
+	pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
-	resource_size_t base;
+	if (!pdata)
-	int irq;
+		return -ENOMEM;
-	struct iommu_platform_data pdata;
-	struct resource res[2];
-};
-static struct iommu_device *devices;
-static int num_iommu_devices;
 
-#ifdef CONFIG_ARCH_OMAP3
+	pdata->name = oh->name;
-static struct iommu_device omap3_devices[] = {
+	pdata->nr_tlb_entries = a->nr_tlb_entries;
-	{
+	pdata->da_start = a->da_start;
-		.base = 0x480bd400,
+	pdata->da_end = a->da_end;
-		.irq = 24 + OMAP_INTC_START,
-		.pdata = {
-			.name = "isp",
-			.nr_tlb_entries = 8,
-			.clk_name = "cam_ick",
-			.da_start = 0x0,
-			.da_end = 0xFFFFF000,
-		},
-	},
-#if defined(CONFIG_OMAP_IOMMU_IVA2)
-	{
-		.base = 0x5d000000,
-		.irq = 28 + OMAP_INTC_START,
-		.pdata = {
-			.name = "iva2",
-			.nr_tlb_entries = 32,
-			.clk_name = "iva2_ck",
-			.da_start = 0x11000000,
-			.da_end = 0xFFFFF000,
-		},
-	},
-#endif
-};
-#define NR_OMAP3_IOMMU_DEVICES ARRAY_SIZE(omap3_devices)
-static struct platform_device *omap3_iommu_pdev[NR_OMAP3_IOMMU_DEVICES];
-#else
-#define omap3_devices		NULL
-#define NR_OMAP3_IOMMU_DEVICES	0
-#define omap3_iommu_pdev	NULL
-#endif
 
-#ifdef CONFIG_ARCH_OMAP4
+	if (oh->rst_lines_cnt == 1) {
-static struct iommu_device omap4_devices[] = {
+		pdata->reset_name = oh->rst_lines->name;
-	{
+		pdata->assert_reset = omap_device_assert_hardreset;
-		.base = OMAP4_MMU1_BASE,
+		pdata->deassert_reset = omap_device_deassert_hardreset;
-		.irq = 100 + OMAP44XX_IRQ_GIC_START,
+	}
-		.pdata = {
-			.name = "ducati",
-			.nr_tlb_entries = 32,
-			.clk_name = "ipu_fck",
-			.da_start = 0x0,
-			.da_end = 0xFFFFF000,
-		},
-	},
-	{
-		.base = OMAP4_MMU2_BASE,
-		.irq = 28 + OMAP44XX_IRQ_GIC_START,
-		.pdata = {
-			.name = "tesla",
-			.nr_tlb_entries = 32,
-			.clk_name = "dsp_fck",
-			.da_start = 0x0,
-			.da_end = 0xFFFFF000,
-		},
-	},
-};
-#define NR_OMAP4_IOMMU_DEVICES ARRAY_SIZE(omap4_devices)
-static struct platform_device *omap4_iommu_pdev[NR_OMAP4_IOMMU_DEVICES];
-#else
-#define omap4_devices		NULL
-#define NR_OMAP4_IOMMU_DEVICES	0
-#define omap4_iommu_pdev	NULL
-#endif
 
-static struct platform_device **omap_iommu_pdev;
+	pdev = omap_device_build("omap-iommu", i, oh, pdata, sizeof(*pdata),
+				NULL, 0, 0);
+
+	kfree(pdata);
+
+	if (IS_ERR(pdev)) {
+		pr_err("%s: device build err: %ld\n", __func__, PTR_ERR(pdev));
+		return PTR_ERR(pdev);
+	}
+
+	i++;
+
+	return 0;
+}
 
 static int __init omap_iommu_init(void)
 {
-	int i, err;
+	return omap_hwmod_for_each_by_class("mmu", omap_iommu_dev_init, NULL);
-	struct resource res[] = {
-		{ .flags = IORESOURCE_MEM },
-		{ .flags = IORESOURCE_IRQ },
-	};
-
-	if (cpu_is_omap34xx()) {
-		devices = omap3_devices;
-		omap_iommu_pdev = omap3_iommu_pdev;
-		num_iommu_devices = NR_OMAP3_IOMMU_DEVICES;
-	} else if (cpu_is_omap44xx()) {
-		devices = omap4_devices;
-		omap_iommu_pdev = omap4_iommu_pdev;
-		num_iommu_devices = NR_OMAP4_IOMMU_DEVICES;
-	} else
-		return -ENODEV;
-
-	for (i = 0; i < num_iommu_devices; i++) {
-		struct platform_device *pdev;
-		const struct iommu_device *d = &devices[i];
-
-		pdev = platform_device_alloc("omap-iommu", i);
-		if (!pdev) {
-			err = -ENOMEM;
-			goto err_out;
-		}
-
-		res[0].start = d->base;
-		res[0].end = d->base + MMU_REG_SIZE - 1;
-		res[1].start = res[1].end = d->irq;
-
-		err = platform_device_add_resources(pdev, res,
-						    ARRAY_SIZE(res));
-		if (err)
-			goto err_out;
-		err = platform_device_add_data(pdev, &d->pdata,
-					       sizeof(d->pdata));
-		if (err)
-			goto err_out;
-		err = platform_device_add(pdev);
-		if (err)
-			goto err_out;
-		omap_iommu_pdev[i] = pdev;
-	}
-	return 0;
-
-err_out:
-	while (i--)
-		platform_device_put(omap_iommu_pdev[i]);
-	return err;
 }
 /* must be ready before omap3isp is probed */
 subsys_initcall(omap_iommu_init);
 
 static void __exit omap_iommu_exit(void)
 {
-	int i;
+	/* Do nothing */
-
-	for (i = 0; i < num_iommu_devices; i++)
-		platform_device_unregister(omap_iommu_pdev[i]);
 }
 module_exit(omap_iommu_exit);
 

arch/arm/mach-omap2/omap_hwmod_44xx_data.c

@@ -653,7 +653,7 @@ static struct omap_hwmod omap44xx_dsp_hwmod = {
 	.mpu_irqs	= omap44xx_dsp_irqs,
 	.rst_lines	= omap44xx_dsp_resets,
 	.rst_lines_cnt	= ARRAY_SIZE(omap44xx_dsp_resets),
-	.main_clk	= "dsp_fck",
+	.main_clk	= "dpll_iva_m4x2_ck",
 	.prcm = {
 		.omap4 = {
 			.clkctrl_offs = OMAP4_CM_TESLA_TESLA_CLKCTRL_OFFSET,
@@ -1679,7 +1679,7 @@ static struct omap_hwmod omap44xx_ipu_hwmod = {
 	.mpu_irqs	= omap44xx_ipu_irqs,
 	.rst_lines	= omap44xx_ipu_resets,
 	.rst_lines_cnt	= ARRAY_SIZE(omap44xx_ipu_resets),
-	.main_clk	= "ipu_fck",
+	.main_clk	= "ducati_clk_mux_ck",
 	.prcm = {
 		.omap4 = {
 			.clkctrl_offs = OMAP4_CM_DUCATI_DUCATI_CLKCTRL_OFFSET,

arch/arm64/include/asm/dma-mapping.h

@@ -50,6 +50,7 @@ static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dev_addr)
 static inline int dma_mapping_error(struct device *dev, dma_addr_t dev_addr)
 {
 	struct dma_map_ops *ops = get_dma_ops(dev);
+	debug_dma_mapping_error(dev, dev_addr);
 	return ops->mapping_error(dev, dev_addr);
 }
 

arch/c6x/include/asm/dma-mapping.h

@@ -32,6 +32,7 @@ static inline int dma_set_mask(struct device *dev, u64 dma_mask)
  */
 static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 {
+	debug_dma_mapping_error(dev, dma_addr);
 	return dma_addr == ~0;
 }
 

arch/ia64/include/asm/dma-mapping.h

@@ -58,6 +58,7 @@ static inline void dma_free_attrs(struct device *dev, size_t size,
 static inline int dma_mapping_error(struct device *dev, dma_addr_t daddr)
 {
 	struct dma_map_ops *ops = platform_dma_get_ops(dev);
+	debug_dma_mapping_error(dev, daddr);
 	return ops->mapping_error(dev, daddr);
 }
 

arch/microblaze/include/asm/dma-mapping.h

@@ -114,6 +114,8 @@ static inline void __dma_sync(unsigned long paddr,
 static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 {
 	struct dma_map_ops *ops = get_dma_ops(dev);
+
+	debug_dma_mapping_error(dev, dma_addr);
 	if (ops->mapping_error)
 		return ops->mapping_error(dev, dma_addr);
 

arch/mips/include/asm/dma-mapping.h

@@ -40,6 +40,8 @@ static inline int dma_supported(struct device *dev, u64 mask)
 static inline int dma_mapping_error(struct device *dev, u64 mask)
 {
 	struct dma_map_ops *ops = get_dma_ops(dev);
+
+	debug_dma_mapping_error(dev, mask);
 	return ops->mapping_error(dev, mask);
 }
 

arch/powerpc/include/asm/dma-mapping.h

@@ -172,6 +172,7 @@ static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 {
 	struct dma_map_ops *dma_ops = get_dma_ops(dev);
 
+	debug_dma_mapping_error(dev, dma_addr);
 	if (dma_ops->mapping_error)
 		return dma_ops->mapping_error(dev, dma_addr);
 

arch/sh/include/asm/dma-mapping.h

@@ -46,6 +46,7 @@ static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 {
 	struct dma_map_ops *ops = get_dma_ops(dev);
 
+	debug_dma_mapping_error(dev, dma_addr);
 	if (ops->mapping_error)
 		return ops->mapping_error(dev, dma_addr);
 

arch/sparc/include/asm/dma-mapping.h

@@ -59,6 +59,7 @@ static inline void dma_free_attrs(struct device *dev, size_t size,
 
 static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 {
+	debug_dma_mapping_error(dev, dma_addr);
 	return (dma_addr == DMA_ERROR_CODE);
 }
 

arch/tile/include/asm/dma-mapping.h

@@ -72,6 +72,7 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
 static inline int
 dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 {
+	debug_dma_mapping_error(dev, dma_addr);
 	return get_dma_ops(dev)->mapping_error(dev, dma_addr);
 }
 

arch/x86/include/asm/dma-mapping.h

@@ -47,6 +47,7 @@ static inline struct dma_map_ops *get_dma_ops(struct device *dev)
 static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 {
 	struct dma_map_ops *ops = get_dma_ops(dev);
+	debug_dma_mapping_error(dev, dma_addr);
 	if (ops->mapping_error)
 		return ops->mapping_error(dev, dma_addr);
 

drivers/iommu/amd_iommu.c

@@ -57,17 +57,9 @@
  * physically contiguous memory regions it is mapping into page sizes
  * that we support.
  *
- * Traditionally the IOMMU core just handed us the mappings directly,
+ * 512GB Pages are not supported due to a hardware bug
- * after making sure the size is an order of a 4KiB page and that the
- * mapping has natural alignment.
- *
- * To retain this behavior, we currently advertise that we support
- * all page sizes that are an order of 4KiB.
- *
- * If at some point we'd like to utilize the IOMMU core's new behavior,
- * we could change this to advertise the real page sizes we support.
  */
-#define AMD_IOMMU_PGSIZES	(~0xFFFUL)
+#define AMD_IOMMU_PGSIZES	((~0xFFFUL) & ~(2ULL << 38))
 
 static DEFINE_RWLOCK(amd_iommu_devtable_lock);
 
@@ -140,6 +132,9 @@ static void free_dev_data(struct iommu_dev_data *dev_data)
 	list_del(&dev_data->dev_data_list);
 	spin_unlock_irqrestore(&dev_data_list_lock, flags);
 
+	if (dev_data->group)
+		iommu_group_put(dev_data->group);
+
 	kfree(dev_data);
 }
 
@@ -274,13 +269,160 @@ static void swap_pci_ref(struct pci_dev **from, struct pci_dev *to)
 	*from = to;
 }
 
+static struct pci_bus *find_hosted_bus(struct pci_bus *bus)
+{
+	while (!bus->self) {
+		if (!pci_is_root_bus(bus))
+			bus = bus->parent;
+		else
+			return ERR_PTR(-ENODEV);
+	}
+
+	return bus;
+}
+
 #define REQ_ACS_FLAGS	(PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF)
 
+static struct pci_dev *get_isolation_root(struct pci_dev *pdev)
+{
+	struct pci_dev *dma_pdev = pdev;
+
+	/* Account for quirked devices */
+	swap_pci_ref(&dma_pdev, pci_get_dma_source(dma_pdev));
+
+	/*
+	 * If it's a multifunction device that does not support our
+	 * required ACS flags, add to the same group as function 0.
+	 */
+	if (dma_pdev->multifunction &&
+	    !pci_acs_enabled(dma_pdev, REQ_ACS_FLAGS))
+		swap_pci_ref(&dma_pdev,
+			     pci_get_slot(dma_pdev->bus,
+					  PCI_DEVFN(PCI_SLOT(dma_pdev->devfn),
+					  0)));
+
+	/*
+	 * Devices on the root bus go through the iommu.  If that's not us,
+	 * find the next upstream device and test ACS up to the root bus.
+	 * Finding the next device may require skipping virtual buses.
+	 */
+	while (!pci_is_root_bus(dma_pdev->bus)) {
+		struct pci_bus *bus = find_hosted_bus(dma_pdev->bus);
+		if (IS_ERR(bus))
+			break;
+
+		if (pci_acs_path_enabled(bus->self, NULL, REQ_ACS_FLAGS))
+			break;
+
+		swap_pci_ref(&dma_pdev, pci_dev_get(bus->self));
+	}
+
+	return dma_pdev;
+}
+
+static int use_pdev_iommu_group(struct pci_dev *pdev, struct device *dev)
+{
+	struct iommu_group *group = iommu_group_get(&pdev->dev);
+	int ret;
+
+	if (!group) {
+		group = iommu_group_alloc();
+		if (IS_ERR(group))
+			return PTR_ERR(group);
+
+		WARN_ON(&pdev->dev != dev);
+	}
+
+	ret = iommu_group_add_device(group, dev);
+	iommu_group_put(group);
+	return ret;
+}
+
+static int use_dev_data_iommu_group(struct iommu_dev_data *dev_data,
+				    struct device *dev)
+{
+	if (!dev_data->group) {
+		struct iommu_group *group = iommu_group_alloc();
+		if (IS_ERR(group))
+			return PTR_ERR(group);
+
+		dev_data->group = group;
+	}
+
+	return iommu_group_add_device(dev_data->group, dev);
+}
+
+static int init_iommu_group(struct device *dev)
+{
+	struct iommu_dev_data *dev_data;
+	struct iommu_group *group;
+	struct pci_dev *dma_pdev;
+	int ret;
+
+	group = iommu_group_get(dev);
+	if (group) {
+		iommu_group_put(group);
+		return 0;
+	}
+
+	dev_data = find_dev_data(get_device_id(dev));
+	if (!dev_data)
+		return -ENOMEM;
+
+	if (dev_data->alias_data) {
+		u16 alias;
+		struct pci_bus *bus;
+
+		if (dev_data->alias_data->group)
+			goto use_group;
+
+		/*
+		 * If the alias device exists, it's effectively just a first
+		 * level quirk for finding the DMA source.
+		 */
+		alias = amd_iommu_alias_table[dev_data->devid];
+		dma_pdev = pci_get_bus_and_slot(alias >> 8, alias & 0xff);
+		if (dma_pdev) {
+			dma_pdev = get_isolation_root(dma_pdev);
+			goto use_pdev;
+		}
+
+		/*
+		 * If the alias is virtual, try to find a parent device
+		 * and test whether the IOMMU group is actualy rooted above
+		 * the alias.  Be careful to also test the parent device if
+		 * we think the alias is the root of the group.
+		 */
+		bus = pci_find_bus(0, alias >> 8);
+		if (!bus)
+			goto use_group;
+
+		bus = find_hosted_bus(bus);
+		if (IS_ERR(bus) || !bus->self)
+			goto use_group;
+
+		dma_pdev = get_isolation_root(pci_dev_get(bus->self));
+		if (dma_pdev != bus->self || (dma_pdev->multifunction &&
+		    !pci_acs_enabled(dma_pdev, REQ_ACS_FLAGS)))
+			goto use_pdev;
+
+		pci_dev_put(dma_pdev);
+		goto use_group;
+	}
+
+	dma_pdev = get_isolation_root(pci_dev_get(to_pci_dev(dev)));
+use_pdev:
+	ret = use_pdev_iommu_group(dma_pdev, dev);
+	pci_dev_put(dma_pdev);
+	return ret;
+use_group:
+	return use_dev_data_iommu_group(dev_data->alias_data, dev);
+}
+
 static int iommu_init_device(struct device *dev)
 {
-	struct pci_dev *dma_pdev = NULL, *pdev = to_pci_dev(dev);
+	struct pci_dev *pdev = to_pci_dev(dev);
 	struct iommu_dev_data *dev_data;
-	struct iommu_group *group;
 	u16 alias;
 	int ret;
 
@@ -303,61 +445,9 @@ static int iommu_init_device(struct device *dev)
 			return -ENOTSUPP;
 		}
 		dev_data->alias_data = alias_data;
-
-		dma_pdev = pci_get_bus_and_slot(alias >> 8, alias & 0xff);
 	}
 
-	if (dma_pdev == NULL)
+	ret = init_iommu_group(dev);
-		dma_pdev = pci_dev_get(pdev);
-
-	/* Account for quirked devices */
-	swap_pci_ref(&dma_pdev, pci_get_dma_source(dma_pdev));
-
-	/*
-	 * If it's a multifunction device that does not support our
-	 * required ACS flags, add to the same group as function 0.
-	 */
-	if (dma_pdev->multifunction &&
-	    !pci_acs_enabled(dma_pdev, REQ_ACS_FLAGS))
-		swap_pci_ref(&dma_pdev,
-			     pci_get_slot(dma_pdev->bus,
-					  PCI_DEVFN(PCI_SLOT(dma_pdev->devfn),
-					  0)));
-
-	/*
-	 * Devices on the root bus go through the iommu.  If that's not us,
-	 * find the next upstream device and test ACS up to the root bus.
-	 * Finding the next device may require skipping virtual buses.
-	 */
-	while (!pci_is_root_bus(dma_pdev->bus)) {
-		struct pci_bus *bus = dma_pdev->bus;
-
-		while (!bus->self) {
-			if (!pci_is_root_bus(bus))
-				bus = bus->parent;
-			else
-				goto root_bus;
-		}
-
-		if (pci_acs_path_enabled(bus->self, NULL, REQ_ACS_FLAGS))
-			break;
-
-		swap_pci_ref(&dma_pdev, pci_dev_get(bus->self));
-	}
-
-root_bus:
-	group = iommu_group_get(&dma_pdev->dev);
-	pci_dev_put(dma_pdev);
-	if (!group) {
-		group = iommu_group_alloc();
-		if (IS_ERR(group))
-			return PTR_ERR(group);
-	}
-
-	ret = iommu_group_add_device(group, dev);
-
-	iommu_group_put(group);
-
 	if (ret)
 		return ret;
 

drivers/iommu/amd_iommu_types.h

@@ -426,6 +426,7 @@ struct iommu_dev_data {
 	struct iommu_dev_data *alias_data;/* The alias dev_data */
 	struct protection_domain *domain; /* Domain the device is bound to */
 	atomic_t bind;			  /* Domain attach reference count */
+	struct iommu_group *group;	  /* IOMMU group for virtual aliases */
 	u16 devid;			  /* PCI Device ID */
 	bool iommu_v2;			  /* Device can make use of IOMMUv2 */
 	bool passthrough;		  /* Default for device is pt_domain */

drivers/iommu/intel-iommu.c

@@ -2327,8 +2327,39 @@ static int domain_add_dev_info(struct dmar_domain *domain,
 	return 0;
 }
 
+static bool device_has_rmrr(struct pci_dev *dev)
+{
+	struct dmar_rmrr_unit *rmrr;
+	int i;
+
+	for_each_rmrr_units(rmrr) {
+		for (i = 0; i < rmrr->devices_cnt; i++) {
+			/*
+			 * Return TRUE if this RMRR contains the device that
+			 * is passed in.
+			 */
+			if (rmrr->devices[i] == dev)
+				return true;
+		}
+	}
+	return false;
+}
+
 static int iommu_should_identity_map(struct pci_dev *pdev, int startup)
 {
+
+	/*
+	 * We want to prevent any device associated with an RMRR from
+	 * getting placed into the SI Domain. This is done because
+	 * problems exist when devices are moved in and out of domains
+	 * and their respective RMRR info is lost. We exempt USB devices
+	 * from this process due to their usage of RMRRs that are known
+	 * to not be needed after BIOS hand-off to OS.
+	 */
+	if (device_has_rmrr(pdev) &&
+	    (pdev->class >> 8) != PCI_CLASS_SERIAL_USB)
+		return 0;
+
 	if ((iommu_identity_mapping & IDENTMAP_AZALIA) && IS_AZALIA(pdev))
 		return 1;
 

drivers/iommu/omap-iommu.c

@@ -16,13 +16,13 @@
 #include <linux/slab.h>
 #include <linux/interrupt.h>
 #include <linux/ioport.h>
-#include <linux/clk.h>
 #include <linux/platform_device.h>
 #include <linux/iommu.h>
 #include <linux/omap-iommu.h>
 #include <linux/mutex.h>
 #include <linux/spinlock.h>
 #include <linux/io.h>
+#include <linux/pm_runtime.h>
 
 #include <asm/cacheflush.h>
 
@@ -143,31 +143,44 @@ EXPORT_SYMBOL_GPL(omap_iommu_arch_version);
 static int iommu_enable(struct omap_iommu *obj)
 {
 	int err;
+	struct platform_device *pdev = to_platform_device(obj->dev);
+	struct iommu_platform_data *pdata = pdev->dev.platform_data;
 
-	if (!obj)
+	if (!obj || !pdata)
 		return -EINVAL;
 
 	if (!arch_iommu)
 		return -ENODEV;
 
-	clk_enable(obj->clk);
+	if (pdata->deassert_reset) {
+		err = pdata->deassert_reset(pdev, pdata->reset_name);
+		if (err) {
+			dev_err(obj->dev, "deassert_reset failed: %d\n", err);
+			return err;
+		}
+	}
+
+	pm_runtime_get_sync(obj->dev);
 
 	err = arch_iommu->enable(obj);
 
-	clk_disable(obj->clk);
 	return err;
 }
 
 static void iommu_disable(struct omap_iommu *obj)
 {
-	if (!obj)
+	struct platform_device *pdev = to_platform_device(obj->dev);
-		return;
+	struct iommu_platform_data *pdata = pdev->dev.platform_data;
 
-	clk_enable(obj->clk);
+	if (!obj || !pdata)
+		return;
 
 	arch_iommu->disable(obj);
 
-	clk_disable(obj->clk);
+	pm_runtime_put_sync(obj->dev);
+
+	if (pdata->assert_reset)
+		pdata->assert_reset(pdev, pdata->reset_name);
 }
 
 /*
@@ -290,7 +303,7 @@ static int load_iotlb_entry(struct omap_iommu *obj, struct iotlb_entry *e)
 	if (!obj || !obj->nr_tlb_entries || !e)
 		return -EINVAL;
 
-	clk_enable(obj->clk);
+	pm_runtime_get_sync(obj->dev);
 
 	iotlb_lock_get(obj, &l);
 	if (l.base == obj->nr_tlb_entries) {
@@ -320,7 +333,7 @@ static int load_iotlb_entry(struct omap_iommu *obj, struct iotlb_entry *e)
 
 	cr = iotlb_alloc_cr(obj, e);
 	if (IS_ERR(cr)) {
-		clk_disable(obj->clk);
+		pm_runtime_put_sync(obj->dev);
 		return PTR_ERR(cr);
 	}
 
@@ -334,7 +347,7 @@ static int load_iotlb_entry(struct omap_iommu *obj, struct iotlb_entry *e)
 		l.vict = l.base;
 	iotlb_lock_set(obj, &l);
 out:
-	clk_disable(obj->clk);
+	pm_runtime_put_sync(obj->dev);
 	return err;
 }
 
@@ -364,7 +377,7 @@ static void flush_iotlb_page(struct omap_iommu *obj, u32 da)
 	int i;
 	struct cr_regs cr;
 
-	clk_enable(obj->clk);
+	pm_runtime_get_sync(obj->dev);
 
 	for_each_iotlb_cr(obj, obj->nr_tlb_entries, i, cr) {
 		u32 start;
@@ -383,7 +396,7 @@ static void flush_iotlb_page(struct omap_iommu *obj, u32 da)
 			iommu_write_reg(obj, 1, MMU_FLUSH_ENTRY);
 		}
 	}
-	clk_disable(obj->clk);
+	pm_runtime_put_sync(obj->dev);
 
 	if (i == obj->nr_tlb_entries)
 		dev_dbg(obj->dev, "%s: no page for %08x\n", __func__, da);
@@ -397,7 +410,7 @@ static void flush_iotlb_all(struct omap_iommu *obj)
 {
 	struct iotlb_lock l;
 
-	clk_enable(obj->clk);
+	pm_runtime_get_sync(obj->dev);
 
 	l.base = 0;
 	l.vict = 0;
@@ -405,7 +418,7 @@ static void flush_iotlb_all(struct omap_iommu *obj)
 
 	iommu_write_reg(obj, 1, MMU_GFLUSH);
 
-	clk_disable(obj->clk);
+	pm_runtime_put_sync(obj->dev);
 }
 
 #if defined(CONFIG_OMAP_IOMMU_DEBUG) || defined(CONFIG_OMAP_IOMMU_DEBUG_MODULE)
@@ -415,11 +428,11 @@ ssize_t omap_iommu_dump_ctx(struct omap_iommu *obj, char *buf, ssize_t bytes)
 	if (!obj || !buf)
 		return -EINVAL;
 
-	clk_enable(obj->clk);
+	pm_runtime_get_sync(obj->dev);
 
 	bytes = arch_iommu->dump_ctx(obj, buf, bytes);
 
-	clk_disable(obj->clk);
+	pm_runtime_put_sync(obj->dev);
 
 	return bytes;
 }
@@ -433,7 +446,7 @@ __dump_tlb_entries(struct omap_iommu *obj, struct cr_regs *crs, int num)
 	struct cr_regs tmp;
 	struct cr_regs *p = crs;
 
-	clk_enable(obj->clk);
+	pm_runtime_get_sync(obj->dev);
 	iotlb_lock_get(obj, &saved);
 
 	for_each_iotlb_cr(obj, num, i, tmp) {
@@ -443,7 +456,7 @@ __dump_tlb_entries(struct omap_iommu *obj, struct cr_regs *crs, int num)
 	}
 
 	iotlb_lock_set(obj, &saved);
-	clk_disable(obj->clk);
+	pm_runtime_put_sync(obj->dev);
 
 	return  p - crs;
 }
@@ -807,9 +820,7 @@ static irqreturn_t iommu_fault_handler(int irq, void *data)
 	if (!obj->refcount)
 		return IRQ_NONE;
 
-	clk_enable(obj->clk);
 	errs = iommu_report_fault(obj, &da);
-	clk_disable(obj->clk);
 	if (errs == 0)
 		return IRQ_HANDLED;
 
@@ -931,17 +942,10 @@ static int __devinit omap_iommu_probe(struct platform_device *pdev)
 	struct resource *res;
 	struct iommu_platform_data *pdata = pdev->dev.platform_data;
 
-	if (pdev->num_resources != 2)
-		return -EINVAL;
-
 	obj = kzalloc(sizeof(*obj) + MMU_REG_SIZE, GFP_KERNEL);
 	if (!obj)
 		return -ENOMEM;
 
-	obj->clk = clk_get(&pdev->dev, pdata->clk_name);
-	if (IS_ERR(obj->clk))
-		goto err_clk;
-
 	obj->nr_tlb_entries = pdata->nr_tlb_entries;
 	obj->name = pdata->name;
 	obj->dev = &pdev->dev;
@@ -984,6 +988,9 @@ static int __devinit omap_iommu_probe(struct platform_device *pdev)
 		goto err_irq;
 	platform_set_drvdata(pdev, obj);
 
+	pm_runtime_irq_safe(obj->dev);
+	pm_runtime_enable(obj->dev);
+
 	dev_info(&pdev->dev, "%s registered\n", obj->name);
 	return 0;
 
@@ -992,8 +999,6 @@ err_irq:
 err_ioremap:
 	release_mem_region(res->start, resource_size(res));
 err_mem:
-	clk_put(obj->clk);
-err_clk:
 	kfree(obj);
 	return err;
 }
@@ -1014,7 +1019,8 @@ static int __devexit omap_iommu_remove(struct platform_device *pdev)
 	release_mem_region(res->start, resource_size(res));
 	iounmap(obj->regbase);
 
-	clk_put(obj->clk);
+	pm_runtime_disable(obj->dev);
+
 	dev_info(&pdev->dev, "%s removed\n", obj->name);
 	kfree(obj);
 	return 0;

drivers/iommu/omap-iommu.h

@@ -29,7 +29,6 @@ struct iotlb_entry {
 struct omap_iommu {
 	const char	*name;
 	struct module	*owner;
-	struct clk	*clk;
 	void __iomem	*regbase;
 	struct device	*dev;
 	void		*isr_priv;
@@ -116,8 +115,6 @@ static inline struct omap_iommu *dev_to_omap_iommu(struct device *dev)
  * MMU Register offsets
  */
 #define MMU_REVISION		0x00
-#define MMU_SYSCONFIG		0x10
-#define MMU_SYSSTATUS		0x14
 #define MMU_IRQSTATUS		0x18
 #define MMU_IRQENABLE		0x1c
 #define MMU_WALKING_ST		0x40

drivers/iommu/omap-iommu2.c

@@ -28,19 +28,6 @@
  */
 #define IOMMU_ARCH_VERSION	0x00000011
 
-/* SYSCONF */
-#define MMU_SYS_IDLE_SHIFT	3
-#define MMU_SYS_IDLE_FORCE	(0 << MMU_SYS_IDLE_SHIFT)
-#define MMU_SYS_IDLE_NONE	(1 << MMU_SYS_IDLE_SHIFT)
-#define MMU_SYS_IDLE_SMART	(2 << MMU_SYS_IDLE_SHIFT)
-#define MMU_SYS_IDLE_MASK	(3 << MMU_SYS_IDLE_SHIFT)
-
-#define MMU_SYS_SOFTRESET	(1 << 1)
-#define MMU_SYS_AUTOIDLE	1
-
-/* SYSSTATUS */
-#define MMU_SYS_RESETDONE	1
-
 /* IRQSTATUS & IRQENABLE */
 #define MMU_IRQ_MULTIHITFAULT	(1 << 4)
 #define MMU_IRQ_TABLEWALKFAULT	(1 << 3)
@@ -97,7 +84,6 @@ static void __iommu_set_twl(struct omap_iommu *obj, bool on)
 static int omap2_iommu_enable(struct omap_iommu *obj)
 {
 	u32 l, pa;
-	unsigned long timeout;
 
 	if (!obj->iopgd || !IS_ALIGNED((u32)obj->iopgd,  SZ_16K))
 		return -EINVAL;
@@ -106,29 +92,10 @@ static int omap2_iommu_enable(struct omap_iommu *obj)
 	if (!IS_ALIGNED(pa, SZ_16K))
 		return -EINVAL;
 
-	iommu_write_reg(obj, MMU_SYS_SOFTRESET, MMU_SYSCONFIG);
-
-	timeout = jiffies + msecs_to_jiffies(20);
-	do {
-		l = iommu_read_reg(obj, MMU_SYSSTATUS);
-		if (l & MMU_SYS_RESETDONE)
-			break;
-	} while (!time_after(jiffies, timeout));
-
-	if (!(l & MMU_SYS_RESETDONE)) {
-		dev_err(obj->dev, "can't take mmu out of reset\n");
-		return -ENODEV;
-	}
-
 	l = iommu_read_reg(obj, MMU_REVISION);
 	dev_info(obj->dev, "%s: version %d.%d\n", obj->name,
 		 (l >> 4) & 0xf, l & 0xf);
 
-	l = iommu_read_reg(obj, MMU_SYSCONFIG);
-	l &= ~MMU_SYS_IDLE_MASK;
-	l |= (MMU_SYS_IDLE_SMART | MMU_SYS_AUTOIDLE);
-	iommu_write_reg(obj, l, MMU_SYSCONFIG);
-
 	iommu_write_reg(obj, pa, MMU_TTB);
 
 	__iommu_set_twl(obj, true);
@@ -142,7 +109,6 @@ static void omap2_iommu_disable(struct omap_iommu *obj)
 
 	l &= ~MMU_CNTL_MASK;
 	iommu_write_reg(obj, l, MMU_CNTL);
-	iommu_write_reg(obj, MMU_SYS_IDLE_FORCE, MMU_SYSCONFIG);
 
 	dev_dbg(obj->dev, "%s is shutting down\n", obj->name);
 }
@@ -271,8 +237,6 @@ omap2_iommu_dump_ctx(struct omap_iommu *obj, char *buf, ssize_t len)
 	char *p = buf;
 
 	pr_reg(REVISION);
-	pr_reg(SYSCONFIG);
-	pr_reg(SYSSTATUS);
 	pr_reg(IRQSTATUS);
 	pr_reg(IRQENABLE);
 	pr_reg(WALKING_ST);

drivers/iommu/tegra-gart.c

@@ -398,6 +398,7 @@ static int tegra_gart_probe(struct platform_device *pdev)
 	do_gart_setup(gart, NULL);
 
 	gart_handle = gart;
+	bus_set_iommu(&platform_bus_type, &gart_iommu_ops);
 	return 0;
 
 fail:
@@ -450,7 +451,6 @@ static struct platform_driver tegra_gart_driver = {
 
 static int __devinit tegra_gart_init(void)
 {
-	bus_set_iommu(&platform_bus_type, &gart_iommu_ops);
 	return platform_driver_register(&tegra_gart_driver);
 }
 

drivers/iommu/tegra-smmu.c

@@ -694,10 +694,8 @@ static void __smmu_iommu_unmap(struct smmu_as *as, dma_addr_t iova)
 	*pte = _PTE_VACANT(iova);
 	FLUSH_CPU_DCACHE(pte, page, sizeof(*pte));
 	flush_ptc_and_tlb(as->smmu, as, iova, pte, page, 0);
-	if (!--(*count)) {
+	if (!--(*count))
 		free_ptbl(as, iova);
-		smmu_flush_regs(as->smmu, 0);
-	}
 }
 
 static void __smmu_iommu_map_pfn(struct smmu_as *as, dma_addr_t iova,
@@ -1232,6 +1230,7 @@ static int tegra_smmu_probe(struct platform_device *pdev)
 
 	smmu_debugfs_create(smmu);
 	smmu_handle = smmu;
+	bus_set_iommu(&platform_bus_type, &smmu_iommu_ops);
 	return 0;
 }
 
@@ -1276,7 +1275,6 @@ static struct platform_driver tegra_smmu_driver = {
 
 static int __devinit tegra_smmu_init(void)
 {
-	bus_set_iommu(&platform_bus_type, &smmu_iommu_ops);
 	return platform_driver_register(&tegra_smmu_driver);
 }
 

include/linux/dma-debug.h

@@ -39,6 +39,8 @@ extern void debug_dma_map_page(struct device *dev, struct page *page,
 			       int direction, dma_addr_t dma_addr,
 			       bool map_single);
 
+extern void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr);
+
 extern void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
 				 size_t size, int direction, bool map_single);
 
@@ -105,6 +107,11 @@ static inline void debug_dma_map_page(struct device *dev, struct page *page,
 {
 }
 
+static inline void debug_dma_mapping_error(struct device *dev,
+					  dma_addr_t dma_addr)
+{
+}
+
 static inline void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
 					size_t size, int direction,
 					bool map_single)

include/linux/platform_data/iommu-omap.h

@@ -10,6 +10,8 @@
  * published by the Free Software Foundation.
  */
 
+#include <linux/platform_device.h>
+
 #define MMU_REG_SIZE		256
 
 /**
@@ -42,8 +44,11 @@ struct omap_mmu_dev_attr {
 
 struct iommu_platform_data {
 	const char *name;
-	const char *clk_name;
+	const char *reset_name;
-	const int nr_tlb_entries;
+	int nr_tlb_entries;
 	u32 da_start;
 	u32 da_end;
+
+	int (*assert_reset)(struct platform_device *pdev, const char *name);
+	int (*deassert_reset)(struct platform_device *pdev, const char *name);
 };

lib/dma-debug.c

@@ -45,6 +45,12 @@ enum {
 	dma_debug_coherent,
 };
 
+enum map_err_types {
+	MAP_ERR_CHECK_NOT_APPLICABLE,
+	MAP_ERR_NOT_CHECKED,
+	MAP_ERR_CHECKED,
+};
+
 #define DMA_DEBUG_STACKTRACE_ENTRIES 5
 
 struct dma_debug_entry {
@@ -57,6 +63,7 @@ struct dma_debug_entry {
 	int              direction;
 	int		 sg_call_ents;
 	int		 sg_mapped_ents;
+	enum map_err_types  map_err_type;
 #ifdef CONFIG_STACKTRACE
 	struct		 stack_trace stacktrace;
 	unsigned long	 st_entries[DMA_DEBUG_STACKTRACE_ENTRIES];
@@ -114,6 +121,12 @@ static struct device_driver *current_driver                    __read_mostly;
 
 static DEFINE_RWLOCK(driver_name_lock);
 
+static const char *const maperr2str[] = {
+	[MAP_ERR_CHECK_NOT_APPLICABLE] = "dma map error check not applicable",
+	[MAP_ERR_NOT_CHECKED] = "dma map error not checked",
+	[MAP_ERR_CHECKED] = "dma map error checked",
+};
+
 static const char *type2name[4] = { "single", "page",
 				    "scather-gather", "coherent" };
 
@@ -376,11 +389,12 @@ void debug_dma_dump_mappings(struct device *dev)
 		list_for_each_entry(entry, &bucket->list, list) {
 			if (!dev || dev == entry->dev) {
 				dev_info(entry->dev,
-					 "%s idx %d P=%Lx D=%Lx L=%Lx %s\n",
+					 "%s idx %d P=%Lx D=%Lx L=%Lx %s %s\n",
 					 type2name[entry->type], idx,
 					 (unsigned long long)entry->paddr,
 					 entry->dev_addr, entry->size,
-					 dir2name[entry->direction]);
+					 dir2name[entry->direction],
+					 maperr2str[entry->map_err_type]);
 			}
 		}
 
@@ -844,16 +858,16 @@ static void check_unmap(struct dma_debug_entry *ref)
 	struct hash_bucket *bucket;
 	unsigned long flags;
 
-	if (dma_mapping_error(ref->dev, ref->dev_addr)) {
-		err_printk(ref->dev, NULL, "DMA-API: device driver tries "
-			   "to free an invalid DMA memory address\n");
-		return;
-	}
-
 	bucket = get_hash_bucket(ref, &flags);
 	entry = bucket_find_exact(bucket, ref);
 
 	if (!entry) {
+		if (dma_mapping_error(ref->dev, ref->dev_addr)) {
+			err_printk(ref->dev, NULL,
+				   "DMA-API: device driver tries "
+				   "to free an invalid DMA memory address\n");
+			return;
+		}
 		err_printk(ref->dev, NULL, "DMA-API: device driver tries "
 			   "to free DMA memory it has not allocated "
 			   "[device address=0x%016llx] [size=%llu bytes]\n",
@@ -910,6 +924,15 @@ static void check_unmap(struct dma_debug_entry *ref)
 			   dir2name[ref->direction]);
 	}
 
+	if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
+		err_printk(ref->dev, entry,
+			   "DMA-API: device driver failed to check map error"
+			   "[device address=0x%016llx] [size=%llu bytes] "
+			   "[mapped as %s]",
+			   ref->dev_addr, ref->size,
+			   type2name[entry->type]);
+	}
+
 	hash_bucket_del(entry);
 	dma_entry_free(entry);
 
@@ -1017,7 +1040,7 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
 	if (unlikely(global_disable))
 		return;
 
-	if (unlikely(dma_mapping_error(dev, dma_addr)))
+	if (dma_mapping_error(dev, dma_addr))
 		return;
 
 	entry = dma_entry_alloc();
@@ -1030,6 +1053,7 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
 	entry->dev_addr  = dma_addr;
 	entry->size      = size;
 	entry->direction = direction;
+	entry->map_err_type = MAP_ERR_NOT_CHECKED;
 
 	if (map_single)
 		entry->type = dma_debug_single;
@@ -1045,6 +1069,30 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
 }
 EXPORT_SYMBOL(debug_dma_map_page);
 
+void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
+{
+	struct dma_debug_entry ref;
+	struct dma_debug_entry *entry;
+	struct hash_bucket *bucket;
+	unsigned long flags;
+
+	if (unlikely(global_disable))
+		return;
+
+	ref.dev = dev;
+	ref.dev_addr = dma_addr;
+	bucket = get_hash_bucket(&ref, &flags);
+	entry = bucket_find_exact(bucket, &ref);
+
+	if (!entry)
+		goto out;
+
+	entry->map_err_type = MAP_ERR_CHECKED;
+out:
+	put_hash_bucket(bucket, &flags);
+}
+EXPORT_SYMBOL(debug_dma_mapping_error);
+
 void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
 			  size_t size, int direction, bool map_single)
 {