[PATCH -fixes] drm/vmwgfx: Improve on IOMMU detection

[Thomas Hellstrom]

instead of relying on intel_iommu_enabled, use the fact that the
dma_map:ops::map_page != dma_direct_map_page.

Signed-off-by: Thomas Hellstrom <thellstrom at vmware.com>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_drv.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
index 3e2bcff34032..77f422cd18ab 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
@@ -26,6 +26,7 @@
  **************************************************************************/
 #include <linux/module.h>
 #include <linux/console.h>
+#include <linux/dma-mapping.h>
 
 #include <drm/drmP.h>
 #include "vmwgfx_drv.h"
@@ -34,7 +35,6 @@
 #include <drm/ttm/ttm_placement.h>
 #include <drm/ttm/ttm_bo_driver.h>
 #include <drm/ttm/ttm_module.h>
-#include <linux/intel-iommu.h>
 
 #define VMWGFX_DRIVER_DESC "Linux drm driver for VMware graphics devices"
 #define VMWGFX_CHIP_SVGAII 0
@@ -545,6 +545,20 @@ static void vmw_get_initial_size(struct vmw_private *dev_priv)
 	dev_priv->initial_height = height;
 }
 
+/**
+ * vmw_assume_iommu - Figure out whether coherent dma-remapping might be
+ * taking place.
+ * @dev: Pointer to the struct drm_device.
+ *
+ * Return: true if iommu present, false otherwise.
+ */
+static bool vmw_assume_iommu(struct drm_device *dev)
+{
+	const struct dma_map_ops *ops = get_dma_ops(dev->dev);
+
+	return !dma_is_direct(ops) && ops->map_page != dma_direct_map_page;
+}
+
 /**
  * vmw_dma_select_mode - Determine how DMA mappings should be set up for this
  * system.
@@ -568,7 +582,7 @@ static int vmw_dma_select_mode(struct vmw_private *dev_priv)
 
 	if (vmw_force_coherent)
 		dev_priv->map_mode = vmw_dma_alloc_coherent;
-	else if (intel_iommu_enabled)
+	else if (vmw_assume_iommu(dev_priv->dev))
 		dev_priv->map_mode = vmw_dma_map_populate;
 	else if (!vmw_force_iommu)
 		dev_priv->map_mode = vmw_dma_phys;
@@ -601,7 +615,7 @@ static int vmw_dma_masks(struct vmw_private *dev_priv)
 {
 	struct drm_device *dev = dev_priv->dev;
 
-	if (intel_iommu_enabled &&
+	if (vmw_assume_iommu(dev) &&
 	    (sizeof(unsigned long) == 4 || vmw_restrict_dma_mask)) {
 		DRM_INFO("Restricting DMA addresses to 44 bits.\n");
 		return dma_set_mask(dev->dev, DMA_BIT_MASK(44));
-- 
2.19.0.rc1