drm/msm: add support for non-IOMMU systems

Add a VRAM carveout that is used for systems which do not have an IOMMU.

The VRAM carveout uses CMA.  The arch code must setup a CMA pool for the
device (preferrably in highmem.. a 256m-512m VRAM pool in lowmem is not
cool).  The user can configure the VRAM pool size using msm.vram module
param.

Technically, the abstraction of IOMMU behind msm_mmu is not strictly
needed, but it simplifies the GEM code a bit, and will be useful later
when I add support for a2xx devices with GPUMMU, so I decided to keep
this part.

It appears to be possible to configure the GPU to restrict access to
addresses within the VRAM pool, but this is not done yet.  So for now
the GPU will refuse to load if there is no sort of mmu.  Once address
based limits are supported and tested to confirm that we aren't giving
the GPU access to arbitrary memory, this restriction can be lifted

Signed-off-by: Rob Clark <robdclark@gmail.com>

1 files changed, 89 insertions, 81 deletions

diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index e587d251c590..d8d60c969ac7 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -22,7 +22,45 @@
 #include "msm_drv.h"
 #include "msm_gem.h"
 #include "msm_gpu.h"
+#include "msm_mmu.h"
 
+static dma_addr_t physaddr(struct drm_gem_object *obj)
+{
+	struct msm_gem_object *msm_obj = to_msm_bo(obj);
+	struct msm_drm_private *priv = obj->dev->dev_private;
+	return (((dma_addr_t)msm_obj->vram_node->start) << PAGE_SHIFT) +
+			priv->vram.paddr;
+}
+
+/* allocate pages from VRAM carveout, used when no IOMMU: */
+static struct page **get_pages_vram(struct drm_gem_object *obj,
+		int npages)
+{
+	struct msm_gem_object *msm_obj = to_msm_bo(obj);
+	struct msm_drm_private *priv = obj->dev->dev_private;
+	dma_addr_t paddr;
+	struct page **p;
+	int ret, i;
+
+	p = drm_malloc_ab(npages, sizeof(struct page *));
+	if (!p)
+		return ERR_PTR(-ENOMEM);
+
+	ret = drm_mm_insert_node(&priv->vram.mm, msm_obj->vram_node,
+			npages, 0, DRM_MM_SEARCH_DEFAULT);
+	if (ret) {
+		drm_free_large(p);
+		return ERR_PTR(ret);
+	}
+
+	paddr = physaddr(obj);
+	for (i = 0; i < npages; i++) {
+		p[i] = phys_to_page(paddr);
+		paddr += PAGE_SIZE;
+	}
+
+	return p;
+}
 
 /* called with dev->struct_mutex held */
 static struct page **get_pages(struct drm_gem_object *obj)
@@ -31,9 +69,14 @@ static struct page **get_pages(struct drm_gem_object *obj)
 
 	if (!msm_obj->pages) {
 		struct drm_device *dev = obj->dev;
-		struct page **p = drm_gem_get_pages(obj, 0);
+		struct page **p;
 		int npages = obj->size >> PAGE_SHIFT;
 
+		if (iommu_present(&platform_bus_type))
+			p = drm_gem_get_pages(obj, 0);
+		else
+			p = get_pages_vram(obj, npages);
+
 		if (IS_ERR(p)) {
 			dev_err(dev->dev, "could not get pages: %ld\n",
 					PTR_ERR(p));
@@ -73,7 +116,11 @@ static void put_pages(struct drm_gem_object *obj)
 		sg_free_table(msm_obj->sgt);
 		kfree(msm_obj->sgt);
 
-		drm_gem_put_pages(obj, msm_obj->pages, true, false);
+		if (iommu_present(&platform_bus_type))
+			drm_gem_put_pages(obj, msm_obj->pages, true, false);
+		else
+			drm_mm_remove_node(msm_obj->vram_node);
+
 		msm_obj->pages = NULL;
 	}
 }
@@ -138,7 +185,6 @@ int msm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
 int msm_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	struct drm_gem_object *obj = vma->vm_private_data;
-	struct msm_gem_object *msm_obj = to_msm_bo(obj);
 	struct drm_device *dev = obj->dev;
 	struct page **pages;
 	unsigned long pfn;
@@ -163,7 +209,7 @@ int msm_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 	pgoff = ((unsigned long)vmf->virtual_address -
 			vma->vm_start) >> PAGE_SHIFT;
 
-	pfn = page_to_pfn(msm_obj->pages[pgoff]);
+	pfn = page_to_pfn(pages[pgoff]);
 
 	VERB("Inserting %p pfn %lx, pa %lx", vmf->virtual_address,
 			pfn, pfn << PAGE_SHIFT);
@@ -219,67 +265,6 @@ uint64_t msm_gem_mmap_offset(struct drm_gem_object *obj)
 	return offset;
 }
 
-/* helpers for dealing w/ iommu: */
-static int map_range(struct iommu_domain *domain, unsigned int iova,
-		struct sg_table *sgt, unsigned int len, int prot)
-{
-	struct scatterlist *sg;
-	unsigned int da = iova;
-	unsigned int i, j;
-	int ret;
-
-	if (!domain || !sgt)
-		return -EINVAL;
-
-	for_each_sg(sgt->sgl, sg, sgt->nents, i) {
-		u32 pa = sg_phys(sg) - sg->offset;
-		size_t bytes = sg->length + sg->offset;
-
-		VERB("map[%d]: %08x %08x(%x)", i, iova, pa, bytes);
-
-		ret = iommu_map(domain, da, pa, bytes, prot);
-		if (ret)
-			goto fail;
-
-		da += bytes;
-	}
-
-	return 0;
-
-fail:
-	da = iova;
-
-	for_each_sg(sgt->sgl, sg, i, j) {
-		size_t bytes = sg->length + sg->offset;
-		iommu_unmap(domain, da, bytes);
-		da += bytes;
-	}
-	return ret;
-}
-
-static void unmap_range(struct iommu_domain *domain, unsigned int iova,
-		struct sg_table *sgt, unsigned int len)
-{
-	struct scatterlist *sg;
-	unsigned int da = iova;
-	int i;
-
-	for_each_sg(sgt->sgl, sg, sgt->nents, i) {
-		size_t bytes = sg->length + sg->offset;
-		size_t unmapped;
-
-		unmapped = iommu_unmap(domain, da, bytes);
-		if (unmapped < bytes)
-			break;
-
-		VERB("unmap[%d]: %08x(%x)", i, iova, bytes);
-
-		BUG_ON(!IS_ALIGNED(bytes, PAGE_SIZE));
-
-		da += bytes;
-	}
-}
-
 /* should be called under struct_mutex.. although it can be called
  * from atomic context without struct_mutex to acquire an extra
  * iova ref if you know one is already held.
@@ -295,15 +280,20 @@ int msm_gem_get_iova_locked(struct drm_gem_object *obj, int id,
 
 	if (!msm_obj->domain[id].iova) {
 		struct msm_drm_private *priv = obj->dev->dev_private;
-		uint32_t offset = (uint32_t)mmap_offset(obj);
-		struct page **pages;
-		pages = get_pages(obj);
+		struct msm_mmu *mmu = priv->mmus[id];
+		struct page **pages = get_pages(obj);
+
 		if (IS_ERR(pages))
 			return PTR_ERR(pages);
-		// XXX ideally we would not map buffers writable when not needed...
-		ret = map_range(priv->iommus[id], offset, msm_obj->sgt,
-				obj->size, IOMMU_READ | IOMMU_WRITE);
-		msm_obj->domain[id].iova = offset;
+
+		if (iommu_present(&platform_bus_type)) {
+			uint32_t offset = (uint32_t)mmap_offset(obj);
+			ret = mmu->funcs->map(mmu, offset, msm_obj->sgt,
+					obj->size, IOMMU_READ | IOMMU_WRITE);
+			msm_obj->domain[id].iova = offset;
+		} else {
+			msm_obj->domain[id].iova = physaddr(obj);
+		}
 	}
 
 	if (!ret)
@@ -514,6 +504,7 @@ void msm_gem_describe_objects(struct list_head *list, struct seq_file *m)
 void msm_gem_free_object(struct drm_gem_object *obj)
 {
 	struct drm_device *dev = obj->dev;
+	struct msm_drm_private *priv = obj->dev->dev_private;
 	struct msm_gem_object *msm_obj = to_msm_bo(obj);
 	int id;
 
@@ -525,11 +516,10 @@ void msm_gem_free_object(struct drm_gem_object *obj)
 	list_del(&msm_obj->mm_list);
 
 	for (id = 0; id < ARRAY_SIZE(msm_obj->domain); id++) {
-		if (msm_obj->domain[id].iova) {
-			struct msm_drm_private *priv = obj->dev->dev_private;
+		struct msm_mmu *mmu = priv->mmus[id];
+		if (mmu && msm_obj->domain[id].iova) {
 			uint32_t offset = (uint32_t)mmap_offset(obj);
-			unmap_range(priv->iommus[id], offset,
-					msm_obj->sgt, obj->size);
+			mmu->funcs->unmap(mmu, offset, msm_obj->sgt, obj->size);
 		}
 	}
 
@@ -591,6 +581,7 @@ static int msm_gem_new_impl(struct drm_device *dev,
 {
 	struct msm_drm_private *priv = dev->dev_private;
 	struct msm_gem_object *msm_obj;
+	unsigned sz;
 
 	switch (flags & MSM_BO_CACHE_MASK) {
 	case MSM_BO_UNCACHED:
@@ -603,10 +594,17 @@ static int msm_gem_new_impl(struct drm_device *dev,
 		return -EINVAL;
 	}
 
-	msm_obj = kzalloc(sizeof(*msm_obj), GFP_KERNEL);
+	sz = sizeof(*msm_obj);
+	if (!iommu_present(&platform_bus_type))
+		sz += sizeof(struct drm_mm_node);
+
+	msm_obj = kzalloc(sz, GFP_KERNEL);
 	if (!msm_obj)
 		return -ENOMEM;
 
+	if (!iommu_present(&platform_bus_type))
+		msm_obj->vram_node = (void *)&msm_obj[1];
+
 	msm_obj->flags = flags;
 
 	msm_obj->resv = &msm_obj->_resv;
@@ -623,7 +621,7 @@ static int msm_gem_new_impl(struct drm_device *dev,
 struct drm_gem_object *msm_gem_new(struct drm_device *dev,
 		uint32_t size, uint32_t flags)
 {
-	struct drm_gem_object *obj;
+	struct drm_gem_object *obj = NULL;
 	int ret;
 
 	WARN_ON(!mutex_is_locked(&dev->struct_mutex));
@@ -634,9 +632,13 @@ struct drm_gem_object *msm_gem_new(struct drm_device *dev,
 	if (ret)
 		goto fail;
 
-	ret = drm_gem_object_init(dev, obj, size);
-	if (ret)
-		goto fail;
+	if (iommu_present(&platform_bus_type)) {
+		ret = drm_gem_object_init(dev, obj, size);
+		if (ret)
+			goto fail;
+	} else {
+		drm_gem_private_object_init(dev, obj, size);
+	}
 
 	return obj;
 
@@ -654,6 +656,12 @@ struct drm_gem_object *msm_gem_import(struct drm_device *dev,
 	struct drm_gem_object *obj;
 	int ret, npages;
 
+	/* if we don't have IOMMU, don't bother pretending we can import: */
+	if (!iommu_present(&platform_bus_type)) {
+		dev_err(dev->dev, "cannot import without IOMMU\n");
+		return ERR_PTR(-EINVAL);
+	}
+
 	size = PAGE_ALIGN(size);
 
 	ret = msm_gem_new_impl(dev, size, MSM_BO_WC, &obj);