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
  ...

2 files changed, 138 insertions, 0 deletions

diff --git a/Documentation/DMA-API-HOWTO.txt b/Documentation/DMA-API-HOWTO.txt
index a0b6250add79..4a4fb295ceef 100644
--- a/Documentation/DMA-API-HOWTO.txt
+++ b/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
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index 66bd97a95f10..78a6c569d204 100644
--- a/Documentation/DMA-API.txt
+++ b/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.
+