Pass the physical address of our BIOS reserved stolen memory to the dma
mapper so we convert it into a proper dma_addr_t and track access with
the iommu.

Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/gem/i915_gem_stolen.c | 21 ++++++++++++++++++++-
 drivers/gpu/drm/i915/i915_drv.h            |  5 +++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c 
b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
index 0be5e8683337..ecb4ee6ac19d 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
@@ -162,6 +162,11 @@ static void i915_gem_cleanup_stolen(struct 
drm_i915_private *i915)
        if (!drm_mm_initialized(&i915->mm.stolen))
                return;
 
+       dma_unmap_resource(i915->drm.dev,
+                          i915->dsm_dma, resource_size(&i915->dsm),
+                          DMA_BIDIRECTIONAL,
+                          DMA_ATTR_NO_WARN);
+
        drm_mm_takedown(&i915->mm.stolen);
 }
 
@@ -489,6 +494,19 @@ static int i915_gem_init_stolen(struct drm_i915_private 
*i915)
        i915->stolen_usable_size =
                resource_size(&i915->dsm) - reserved_total;
 
+       i915->dsm_dma =
+               dma_map_resource(i915->drm.dev,
+                                i915->dsm.start, resource_size(&i915->dsm),
+                                DMA_BIDIRECTIONAL,
+                                DMA_ATTR_NO_KERNEL_MAPPING |
+                                DMA_ATTR_SKIP_CPU_SYNC);
+       if (dma_mapping_error(i915->drm.dev, i915->dsm_dma)) {
+               drm_err(&i915->drm,
+                       "Failed to map stolen memory %pR for use with DMA\n",
+                       &i915->dsm);
+               return 0; /* bail; continue to load the driver without stolen */
+       }
+
        /* Basic memrange allocator for stolen space. */
        drm_mm_init(&i915->mm.stolen, 0, i915->stolen_usable_size);
 
@@ -504,6 +522,7 @@ i915_pages_create_for_stolen(struct drm_device *dev,
        struct scatterlist *sg;
 
        GEM_BUG_ON(range_overflows(offset, size, resource_size(&i915->dsm)));
+       GEM_BUG_ON(dma_mapping_error(dev->dev, i915->dsm_dma));
 
        /* We hide that we have no struct page backing our stolen object
         * by wrapping the contiguous physical allocation with a fake
@@ -523,7 +542,7 @@ i915_pages_create_for_stolen(struct drm_device *dev,
        sg->offset = 0;
        sg->length = size;
 
-       sg_dma_address(sg) = (dma_addr_t)i915->dsm.start + offset;
+       sg_dma_address(sg) = i915->dsm_dma + offset;
        sg_dma_len(sg) = size;
 
        return st;
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 9c2672c56cc1..44972eda7fb8 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -836,6 +836,11 @@ struct drm_i915_private {
         */
        struct resource dsm_reserved;
 
+       /**
+        * dma-mapping of the Data Stolen Memory.
+        */
+       dma_addr_t dsm_dma;
+
        /*
         * Stolen memory is segmented in hardware with different portions
         * offlimits to certain functions.
-- 
2.20.1

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