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Commit c8847387 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Treat stolen memory as DMA addresses 



The conversion of stolen to use phys_addr_t (from essentially u32)
sparked an interesting discussion. We treat stolen memory as only
accessible from the GPU (the DMA device) - an attempt to use it from the
CPU will generate a MCE on gen6 onwards, although it is in theory a
physical address that can be dereferenced from the CPU as demonstrated
by earlier generations. As such, using phys_addr_t has the wrong
connotations and as we pass the address into the DMA device via
dma_addr_t (through the scatterlists used to program the GTT entries),
we should treat it as dma_addr_t throughout.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170127165531.28135-1-chris@chris-wilson.co.uk


Reviewed-by: default avatarPaulo Zanoni <paulo.r.zanoni@intel.com>
parent 4703b047

drivers/gpu/drm/i915/i915_drv.h

+1 −1
Original line number Diff line number Diff line
@@ -1461,7 +1461,7 @@ struct i915_gem_mm { 
	struct work_struct free_work;



	/** Usable portion of the GTT for GEM */

	phys_addr_t stolen_base; /* limited to low memory (32-bit) */

	dma_addr_t stolen_base; /* limited to low memory (32-bit) */



	/** PPGTT used for aliasing the PPGTT with the GTT */

	struct i915_hw_ppgtt *aliasing_ppgtt;

drivers/gpu/drm/i915/i915_gem_stolen.c

+18 −18
Original line number Diff line number Diff line
@@ -79,12 +79,12 @@ void i915_gem_stolen_remove_node(struct drm_i915_private *dev_priv, 
	mutex_unlock(&dev_priv->mm.stolen_lock);

}



static phys_addr_t i915_stolen_to_physical(struct drm_i915_private *dev_priv)

static dma_addr_t i915_stolen_to_dma(struct drm_i915_private *dev_priv)

{

	struct pci_dev *pdev = dev_priv->drm.pdev;

	struct i915_ggtt *ggtt = &dev_priv->ggtt;

	struct resource *r;

	phys_addr_t base;

	dma_addr_t base;



	/* Almost universally we can find the Graphics Base of Stolen Memory

	 * at register BSM (0x5c) in the igfx configuration space. On a few
@@ -196,7 +196,7 @@ static phys_addr_t i915_stolen_to_physical(struct drm_i915_private *dev_priv) 
	if (INTEL_GEN(dev_priv) <= 4 &&

	    !IS_G33(dev_priv) && !IS_PINEVIEW(dev_priv) && !IS_G4X(dev_priv)) {

		struct {

			phys_addr_t start, end;

			dma_addr_t start, end;

		} stolen[2] = {

			{ .start = base, .end = base + ggtt->stolen_size, },

			{ .start = base, .end = base + ggtt->stolen_size, },
@@ -228,12 +228,12 @@ static phys_addr_t i915_stolen_to_physical(struct drm_i915_private *dev_priv) 


		if (stolen[0].start != stolen[1].start ||

		    stolen[0].end != stolen[1].end) {

			phys_addr_t end = base + ggtt->stolen_size - 1;

			dma_addr_t end = base + ggtt->stolen_size - 1;



			DRM_DEBUG_KMS("GTT within stolen memory at 0x%llx-0x%llx\n",

				      (unsigned long long)ggtt_start,

				      (unsigned long long)ggtt_end - 1);

			DRM_DEBUG_KMS("Stolen memory adjusted to %pa - %pa\n",

			DRM_DEBUG_KMS("Stolen memory adjusted to %pad - %pad\n",

				      &base, &end);

		}

	}
@@ -263,9 +263,9 @@ static phys_addr_t i915_stolen_to_physical(struct drm_i915_private *dev_priv) 
		 * range. Apparently this works.

		 */

		if (r == NULL && !IS_GEN3(dev_priv)) {

			phys_addr_t end = base + ggtt->stolen_size;

			dma_addr_t end = base + ggtt->stolen_size;



			DRM_ERROR("conflict detected with stolen region: [%pa - %pa]\n",

			DRM_ERROR("conflict detected with stolen region: [%pad - %pad]\n",

				  &base, &end);

			base = 0;

		}
@@ -285,13 +285,13 @@ void i915_gem_cleanup_stolen(struct drm_device *dev) 
}



static void g4x_get_stolen_reserved(struct drm_i915_private *dev_priv,

				    phys_addr_t *base, u32 *size)

				    dma_addr_t *base, u32 *size)

{

	struct i915_ggtt *ggtt = &dev_priv->ggtt;

	uint32_t reg_val = I915_READ(IS_GM45(dev_priv) ?

				     CTG_STOLEN_RESERVED :

				     ELK_STOLEN_RESERVED);

	phys_addr_t stolen_top = dev_priv->mm.stolen_base + ggtt->stolen_size;

	dma_addr_t stolen_top = dev_priv->mm.stolen_base + ggtt->stolen_size;



	*base = (reg_val & G4X_STOLEN_RESERVED_ADDR2_MASK) << 16;
@@ -308,7 +308,7 @@ static void g4x_get_stolen_reserved(struct drm_i915_private *dev_priv, 
}



static void gen6_get_stolen_reserved(struct drm_i915_private *dev_priv,

				     phys_addr_t *base, u32 *size)

				     dma_addr_t *base, u32 *size)

{

	uint32_t reg_val = I915_READ(GEN6_STOLEN_RESERVED);
@@ -334,7 +334,7 @@ static void gen6_get_stolen_reserved(struct drm_i915_private *dev_priv, 
}



static void gen7_get_stolen_reserved(struct drm_i915_private *dev_priv,

				     phys_addr_t *base, u32 *size)

				     dma_addr_t *base, u32 *size)

{

	uint32_t reg_val = I915_READ(GEN6_STOLEN_RESERVED);
@@ -354,7 +354,7 @@ static void gen7_get_stolen_reserved(struct drm_i915_private *dev_priv, 
}



static void chv_get_stolen_reserved(struct drm_i915_private *dev_priv,

				    phys_addr_t *base, u32 *size)

				    dma_addr_t *base, u32 *size)

{

	uint32_t reg_val = I915_READ(GEN6_STOLEN_RESERVED);
@@ -380,11 +380,11 @@ static void chv_get_stolen_reserved(struct drm_i915_private *dev_priv, 
}



static void bdw_get_stolen_reserved(struct drm_i915_private *dev_priv,

				    phys_addr_t *base, u32 *size)

				    dma_addr_t *base, u32 *size)

{

	struct i915_ggtt *ggtt = &dev_priv->ggtt;

	uint32_t reg_val = I915_READ(GEN6_STOLEN_RESERVED);

	phys_addr_t stolen_top;

	dma_addr_t stolen_top;



	stolen_top = dev_priv->mm.stolen_base + ggtt->stolen_size;
@@ -403,7 +403,7 @@ static void bdw_get_stolen_reserved(struct drm_i915_private *dev_priv, 
int i915_gem_init_stolen(struct drm_i915_private *dev_priv)

{

	struct i915_ggtt *ggtt = &dev_priv->ggtt;

	phys_addr_t reserved_base, stolen_top;

	dma_addr_t reserved_base, stolen_top;

	u32 reserved_total, reserved_size;

	u32 stolen_usable_start;
@@ -419,7 +419,7 @@ int i915_gem_init_stolen(struct drm_i915_private *dev_priv) 
	if (ggtt->stolen_size == 0)

		return 0;



	dev_priv->mm.stolen_base = i915_stolen_to_physical(dev_priv);

	dev_priv->mm.stolen_base = i915_stolen_to_dma(dev_priv);

	if (dev_priv->mm.stolen_base == 0)

		return 0;
@@ -468,8 +468,8 @@ int i915_gem_init_stolen(struct drm_i915_private *dev_priv) 


	if (reserved_base < dev_priv->mm.stolen_base ||

	    reserved_base + reserved_size > stolen_top) {

		phys_addr_t reserved_top = reserved_base + reserved_size;

		DRM_DEBUG_KMS("Stolen reserved area [%pa - %pa] outside stolen memory [%pa - %pa]\n",

		dma_addr_t reserved_top = reserved_base + reserved_size;

		DRM_DEBUG_KMS("Stolen reserved area [%pad - %pad] outside stolen memory [%pad - %pad]\n",

			      &reserved_base, &reserved_top,

			      &dev_priv->mm.stolen_base, &stolen_top);

		return 0;