[PATCH v5 11/17] drm/tegra: Add IOMMU support

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From: Thierry Reding <treding@xxxxxxxxxx>

When an IOMMU device is available on the platform bus, allocate an IOMMU
domain and attach the display controllers to it. The display controllers
can then scan out non-contiguous buffers by mapping them through the
IOMMU.

Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
---
Changes in v5:
- fix PRIME export of physically non-contiguous buffers
- refactor and fix error cleanup paths
- fix checking for failed allocations
- fix build warnings on 64-bit

Changes in v4:
- error out if IOMMU attachment fails

Changes in v3:
- create write-combined mappings for mmap()
- keep non-IOMMU fallback path working
- no longer rely on iommu_attach()

Changes in v2:
- don't pass GFP_KERNEL to drm_gem_get_pages()

 drivers/gpu/drm/tegra/dc.c  |  17 +++
 drivers/gpu/drm/tegra/drm.c |  18 +++
 drivers/gpu/drm/tegra/drm.h |   5 +
 drivers/gpu/drm/tegra/fb.c  |  16 ++-
 drivers/gpu/drm/tegra/gem.c | 277 ++++++++++++++++++++++++++++++++++++++------
 drivers/gpu/drm/tegra/gem.h |   6 +
 6 files changed, 302 insertions(+), 37 deletions(-)

diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
index 4da366a4d78a..a1e7962ccbe2 100644
--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -9,6 +9,7 @@
 
 #include <linux/clk.h>
 #include <linux/debugfs.h>
+#include <linux/iommu.h>
 #include <linux/reset.h>
 
 #include <soc/tegra/pmc.h>
@@ -1287,6 +1288,17 @@ static int tegra_dc_init(struct host1x_client *client)
 	struct tegra_drm *tegra = drm->dev_private;
 	int err;
 
+	if (tegra->domain) {
+		err = iommu_attach_device(tegra->domain, dc->dev);
+		if (err < 0) {
+			dev_err(dc->dev, "failed to attach to domain: %d\n",
+				err);
+			return err;
+		}
+
+		dc->domain = tegra->domain;
+	}
+
 	drm_crtc_init(drm, &dc->base, &tegra_crtc_funcs);
 	drm_mode_crtc_set_gamma_size(&dc->base, 256);
 	drm_crtc_helper_add(&dc->base, &tegra_crtc_helper_funcs);
@@ -1344,6 +1356,11 @@ static int tegra_dc_exit(struct host1x_client *client)
 		return err;
 	}
 
+	if (dc->domain) {
+		iommu_detach_device(dc->domain, dc->dev);
+		dc->domain = NULL;
+	}
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index 59736bb810cd..ce5123c2c3c5 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -8,6 +8,7 @@
  */
 
 #include <linux/host1x.h>
+#include <linux/iommu.h>
 
 #include "drm.h"
 #include "gem.h"
@@ -33,6 +34,17 @@ static int tegra_drm_load(struct drm_device *drm, unsigned long flags)
 	if (!tegra)
 		return -ENOMEM;
 
+	if (iommu_present(&platform_bus_type)) {
+		tegra->domain = iommu_domain_alloc(&platform_bus_type);
+		if (IS_ERR(tegra->domain)) {
+			kfree(tegra);
+			return PTR_ERR(tegra->domain);
+		}
+
+		DRM_DEBUG("IOMMU context initialized\n");
+		drm_mm_init(&tegra->mm, 0, SZ_2G);
+	}
+
 	mutex_init(&tegra->clients_lock);
 	INIT_LIST_HEAD(&tegra->clients);
 	drm->dev_private = tegra;
@@ -71,6 +83,7 @@ static int tegra_drm_load(struct drm_device *drm, unsigned long flags)
 static int tegra_drm_unload(struct drm_device *drm)
 {
 	struct host1x_device *device = to_host1x_device(drm->dev);
+	struct tegra_drm *tegra = drm->dev_private;
 	int err;
 
 	drm_kms_helper_poll_fini(drm);
@@ -82,6 +95,11 @@ static int tegra_drm_unload(struct drm_device *drm)
 	if (err < 0)
 		return err;
 
+	if (tegra->domain) {
+		iommu_domain_free(tegra->domain);
+		drm_mm_takedown(&tegra->mm);
+	}
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/tegra/drm.h b/drivers/gpu/drm/tegra/drm.h
index b994c017971d..2fdae404e719 100644
--- a/drivers/gpu/drm/tegra/drm.h
+++ b/drivers/gpu/drm/tegra/drm.h
@@ -39,6 +39,9 @@ struct tegra_fbdev {
 struct tegra_drm {
 	struct drm_device *drm;
 
+	struct iommu_domain *domain;
+	struct drm_mm mm;
+
 	struct mutex clients_lock;
 	struct list_head clients;
 
@@ -121,6 +124,8 @@ struct tegra_dc {
 	struct drm_pending_vblank_event *event;
 
 	const struct tegra_dc_soc_info *soc;
+
+	struct iommu_domain *domain;
 };
 
 static inline struct tegra_dc *
diff --git a/drivers/gpu/drm/tegra/fb.c b/drivers/gpu/drm/tegra/fb.c
index 3513d12d5aa1..c5fa3c4b2ed5 100644
--- a/drivers/gpu/drm/tegra/fb.c
+++ b/drivers/gpu/drm/tegra/fb.c
@@ -65,8 +65,12 @@ static void tegra_fb_destroy(struct drm_framebuffer *framebuffer)
 	for (i = 0; i < fb->num_planes; i++) {
 		struct tegra_bo *bo = fb->planes[i];
 
-		if (bo)
+		if (bo) {
+			if (bo->pages && bo->vaddr)
+				vunmap(bo->vaddr);
+
 			drm_gem_object_unreference_unlocked(&bo->gem);
+		}
 	}
 
 	drm_framebuffer_cleanup(framebuffer);
@@ -254,6 +258,16 @@ static int tegra_fbdev_probe(struct drm_fb_helper *helper,
 	offset = info->var.xoffset * bytes_per_pixel +
 		 info->var.yoffset * fb->pitches[0];
 
+	if (bo->pages) {
+		bo->vaddr = vmap(bo->pages, bo->num_pages, VM_MAP,
+				 pgprot_writecombine(PAGE_KERNEL));
+		if (!bo->vaddr) {
+			dev_err(drm->dev, "failed to vmap() framebuffer\n");
+			err = -ENOMEM;
+			goto destroy;
+		}
+	}
+
 	drm->mode_config.fb_base = (resource_size_t)bo->paddr;
 	info->screen_base = (void __iomem *)bo->vaddr + offset;
 	info->screen_size = size;
diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c
index b513df33f17a..8b1095d05c58 100644
--- a/drivers/gpu/drm/tegra/gem.c
+++ b/drivers/gpu/drm/tegra/gem.c
@@ -14,6 +14,7 @@
  */
 
 #include <linux/dma-buf.h>
+#include <linux/iommu.h>
 #include <drm/tegra_drm.h>
 
 #include "drm.h"
@@ -91,6 +92,88 @@ static const struct host1x_bo_ops tegra_bo_ops = {
 	.kunmap = tegra_bo_kunmap,
 };
 
+/*
+ * A generic iommu_map_sg() function is being reviewed and will hopefully be
+ * merged soon. At that point this function can be dropped in favour of the
+ * one provided by the IOMMU API.
+ */
+static ssize_t __iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
+			      struct scatterlist *sg, unsigned int nents,
+			      int prot)
+{
+	struct scatterlist *s;
+	size_t offset = 0;
+	unsigned int i;
+	int err;
+
+	for_each_sg(sg, s, nents, i) {
+		phys_addr_t phys = page_to_phys(sg_page(s));
+		size_t length = s->offset + s->length;
+
+		err = iommu_map(domain, iova + offset, phys, length, prot);
+		if (err < 0) {
+			iommu_unmap(domain, iova, offset);
+			return err;
+		}
+
+		offset += length;
+	}
+
+	return offset;
+}
+
+static int tegra_bo_iommu_map(struct tegra_drm *tegra, struct tegra_bo *bo)
+{
+	int prot = IOMMU_READ | IOMMU_WRITE;
+	ssize_t err;
+
+	if (bo->mm)
+		return -EBUSY;
+
+	bo->mm = kzalloc(sizeof(*bo->mm), GFP_KERNEL);
+	if (!bo->mm)
+		return -ENOMEM;
+
+	err = drm_mm_insert_node_generic(&tegra->mm, bo->mm, bo->gem.size,
+					 PAGE_SIZE, 0, 0, 0);
+	if (err < 0) {
+		dev_err(tegra->drm->dev, "out of I/O virtual memory: %zd\n",
+			err);
+		goto free;
+	}
+
+	bo->paddr = bo->mm->start;
+
+	err = __iommu_map_sg(tegra->domain, bo->paddr, bo->sgt->sgl,
+			     bo->sgt->nents, prot);
+	if (err < 0) {
+		dev_err(tegra->drm->dev, "failed to map buffer: %zd\n", err);
+		goto remove;
+	}
+
+	bo->size = err;
+
+	return 0;
+
+remove:
+	drm_mm_remove_node(bo->mm);
+free:
+	kfree(bo->mm);
+	return err;
+}
+
+static int tegra_bo_iommu_unmap(struct tegra_drm *tegra, struct tegra_bo *bo)
+{
+	if (!bo->mm)
+		return 0;
+
+	iommu_unmap(tegra->domain, bo->paddr, bo->size);
+	drm_mm_remove_node(bo->mm);
+	kfree(bo->mm);
+
+	return 0;
+}
+
 static struct tegra_bo *tegra_bo_alloc_object(struct drm_device *drm,
 					      size_t size)
 {
@@ -121,9 +204,64 @@ free:
 	return ERR_PTR(err);
 }
 
-static void tegra_bo_destroy(struct drm_device *drm, struct tegra_bo *bo)
+static void tegra_bo_free(struct drm_device *drm, struct tegra_bo *bo)
 {
-	dma_free_writecombine(drm->dev, bo->gem.size, bo->vaddr, bo->paddr);
+	if (bo->pages) {
+		drm_gem_put_pages(&bo->gem, bo->pages, true, true);
+		sg_free_table(bo->sgt);
+		kfree(bo->sgt);
+	} else {
+		dma_free_writecombine(drm->dev, bo->gem.size, bo->vaddr,
+				      bo->paddr);
+	}
+}
+
+static int tegra_bo_get_pages(struct drm_device *drm, struct tegra_bo *bo,
+			      size_t size)
+{
+	bo->pages = drm_gem_get_pages(&bo->gem);
+	if (IS_ERR(bo->pages))
+		return PTR_ERR(bo->pages);
+
+	bo->num_pages = size >> PAGE_SHIFT;
+
+	bo->sgt = drm_prime_pages_to_sg(bo->pages, bo->num_pages);
+	if (IS_ERR(bo->sgt)) {
+		drm_gem_put_pages(&bo->gem, bo->pages, false, false);
+		return PTR_ERR(bo->sgt);
+	}
+
+	return 0;
+}
+
+static int tegra_bo_alloc(struct drm_device *drm, struct tegra_bo *bo,
+			  size_t size)
+{
+	struct tegra_drm *tegra = drm->dev_private;
+	int err;
+
+	if (tegra->domain) {
+		err = tegra_bo_get_pages(drm, bo, size);
+		if (err < 0)
+			return err;
+
+		err = tegra_bo_iommu_map(tegra, bo);
+		if (err < 0) {
+			tegra_bo_free(drm, bo);
+			return err;
+		}
+	} else {
+		bo->vaddr = dma_alloc_writecombine(drm->dev, size, &bo->paddr,
+						   GFP_KERNEL | __GFP_NOWARN);
+		if (!bo->vaddr) {
+			dev_err(drm->dev,
+				"failed to allocate buffer of size %zu\n",
+				size);
+			return -ENOMEM;
+		}
+	}
+
+	return 0;
 }
 
 struct tegra_bo *tegra_bo_create(struct drm_device *drm, unsigned int size,
@@ -136,14 +274,9 @@ struct tegra_bo *tegra_bo_create(struct drm_device *drm, unsigned int size,
 	if (IS_ERR(bo))
 		return bo;
 
-	bo->vaddr = dma_alloc_writecombine(drm->dev, size, &bo->paddr,
-					   GFP_KERNEL | __GFP_NOWARN);
-	if (!bo->vaddr) {
-		dev_err(drm->dev, "failed to allocate buffer with size %u\n",
-			size);
-		err = -ENOMEM;
-		goto err_dma;
-	}
+	err = tegra_bo_alloc(drm, bo, size);
+	if (err < 0)
+		goto release;
 
 	if (flags & DRM_TEGRA_GEM_CREATE_TILED)
 		bo->tiling.mode = TEGRA_BO_TILING_MODE_TILED;
@@ -153,13 +286,9 @@ struct tegra_bo *tegra_bo_create(struct drm_device *drm, unsigned int size,
 
 	return bo;
 
-err_mmap:
+release:
 	drm_gem_object_release(&bo->gem);
-err_init:
-	tegra_bo_destroy(drm, bo);
-err_dma:
 	kfree(bo);
-
 	return ERR_PTR(err);
 }
 
@@ -190,6 +319,7 @@ struct tegra_bo *tegra_bo_create_with_handle(struct drm_file *file,
 static struct tegra_bo *tegra_bo_import(struct drm_device *drm,
 					struct dma_buf *buf)
 {
+	struct tegra_drm *tegra = drm->dev_private;
 	struct dma_buf_attachment *attach;
 	struct tegra_bo *bo;
 	int err;
@@ -217,12 +347,19 @@ static struct tegra_bo *tegra_bo_import(struct drm_device *drm,
 		goto detach;
 	}
 
-	if (bo->sgt->nents > 1) {
-		err = -EINVAL;
-		goto detach;
+	if (tegra->domain) {
+		err = tegra_bo_iommu_map(tegra, bo);
+		if (err < 0)
+			goto detach;
+	} else {
+		if (bo->sgt->nents > 1) {
+			err = -EINVAL;
+			goto detach;
+		}
+
+		bo->paddr = sg_dma_address(bo->sgt->sgl);
 	}
 
-	bo->paddr = sg_dma_address(bo->sgt->sgl);
 	bo->gem.import_attach = attach;
 
 	return bo;
@@ -241,14 +378,18 @@ free:
 
 void tegra_bo_free_object(struct drm_gem_object *gem)
 {
+	struct tegra_drm *tegra = gem->dev->dev_private;
 	struct tegra_bo *bo = to_tegra_bo(gem);
 
+	if (tegra->domain)
+		tegra_bo_iommu_unmap(tegra, bo);
+
 	if (gem->import_attach) {
 		dma_buf_unmap_attachment(gem->import_attach, bo->sgt,
 					 DMA_TO_DEVICE);
 		drm_prime_gem_destroy(gem, NULL);
 	} else {
-		tegra_bo_destroy(gem->dev, bo);
+		tegra_bo_free(gem->dev, bo);
 	}
 
 	drm_gem_object_release(gem);
@@ -303,14 +444,44 @@ int tegra_bo_dumb_map_offset(struct drm_file *file, struct drm_device *drm,
 	return 0;
 }
 
+static int tegra_bo_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct drm_gem_object *gem = vma->vm_private_data;
+	struct tegra_bo *bo = to_tegra_bo(gem);
+	struct page *page;
+	pgoff_t offset;
+	int err;
+
+	if (!bo->pages)
+		return VM_FAULT_SIGBUS;
+
+	offset = ((unsigned long)vmf->virtual_address - vma->vm_start) >> PAGE_SHIFT;
+	page = bo->pages[offset];
+
+	err = vm_insert_page(vma, (unsigned long)vmf->virtual_address, page);
+	switch (err) {
+	case -EAGAIN:
+	case 0:
+	case -ERESTARTSYS:
+	case -EINTR:
+	case -EBUSY:
+		return VM_FAULT_NOPAGE;
+
+	case -ENOMEM:
+		return VM_FAULT_OOM;
+	}
+
+	return VM_FAULT_SIGBUS;
+}
+
 const struct vm_operations_struct tegra_bo_vm_ops = {
+	.fault = tegra_bo_fault,
 	.open = drm_gem_vm_open,
 	.close = drm_gem_vm_close,
 };
 
 int tegra_drm_mmap(struct file *file, struct vm_area_struct *vma)
 {
-	unsigned long vm_pgoff = vma->vm_pgoff;
 	struct drm_gem_object *gem;
 	struct tegra_bo *bo;
 	int ret;
@@ -322,17 +493,28 @@ int tegra_drm_mmap(struct file *file, struct vm_area_struct *vma)
 	gem = vma->vm_private_data;
 	bo = to_tegra_bo(gem);
 
-	vma->vm_flags &= ~VM_PFNMAP;
-	vma->vm_pgoff = 0;
+	if (!bo->pages) {
+		unsigned long vm_pgoff = vma->vm_pgoff;
 
-	ret = dma_mmap_writecombine(gem->dev->dev, vma, bo->vaddr, bo->paddr,
-				    gem->size);
-	if (ret) {
-		drm_gem_vm_close(vma);
-		return ret;
-	}
+		vma->vm_flags &= ~VM_PFNMAP;
+		vma->vm_pgoff = 0;
 
-	vma->vm_pgoff = vm_pgoff;
+		ret = dma_mmap_writecombine(gem->dev->dev, vma, bo->vaddr,
+					    bo->paddr, gem->size);
+		if (ret) {
+			drm_gem_vm_close(vma);
+			return ret;
+		}
+
+		vma->vm_pgoff = vm_pgoff;
+	} else {
+		pgprot_t prot = vm_get_page_prot(vma->vm_flags);
+
+		vma->vm_flags |= VM_MIXEDMAP;
+		vma->vm_flags &= ~VM_PFNMAP;
+
+		vma->vm_page_prot = pgprot_writecombine(prot);
+	}
 
 	return 0;
 }
@@ -349,21 +531,44 @@ tegra_gem_prime_map_dma_buf(struct dma_buf_attachment *attach,
 	if (!sgt)
 		return NULL;
 
-	if (sg_alloc_table(sgt, 1, GFP_KERNEL)) {
-		kfree(sgt);
-		return NULL;
-	}
+	if (bo->pages) {
+		struct scatterlist *sg;
+		unsigned int i;
+
+		if (sg_alloc_table(sgt, bo->num_pages, GFP_KERNEL))
+			goto free;
 
-	sg_dma_address(sgt->sgl) = bo->paddr;
-	sg_dma_len(sgt->sgl) = gem->size;
+		for_each_sg(sgt->sgl, sg, bo->num_pages, i)
+			sg_set_page(sg, bo->pages[i], PAGE_SIZE, 0);
+
+		if (dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir) == 0)
+			goto free;
+	} else {
+		if (sg_alloc_table(sgt, 1, GFP_KERNEL))
+			goto free;
+
+		sg_dma_address(sgt->sgl) = bo->paddr;
+		sg_dma_len(sgt->sgl) = gem->size;
+	}
 
 	return sgt;
+
+free:
+	sg_free_table(sgt);
+	kfree(sgt);
+	return NULL;
 }
 
 static void tegra_gem_prime_unmap_dma_buf(struct dma_buf_attachment *attach,
 					  struct sg_table *sgt,
 					  enum dma_data_direction dir)
 {
+	struct drm_gem_object *gem = attach->dmabuf->priv;
+	struct tegra_bo *bo = to_tegra_bo(gem);
+
+	if (bo->pages)
+		dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir);
+
 	sg_free_table(sgt);
 	kfree(sgt);
 }
diff --git a/drivers/gpu/drm/tegra/gem.h b/drivers/gpu/drm/tegra/gem.h
index 6538b56780c2..3dd4165f812a 100644
--- a/drivers/gpu/drm/tegra/gem.h
+++ b/drivers/gpu/drm/tegra/gem.h
@@ -38,6 +38,12 @@ struct tegra_bo {
 	dma_addr_t paddr;
 	void *vaddr;
 
+	struct drm_mm_node *mm;
+	unsigned long num_pages;
+	struct page **pages;
+	/* size of IOMMU mapping */
+	size_t size;
+
 	struct tegra_bo_tiling tiling;
 };
 
-- 
2.1.2

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