[PATCH 4/7] drm/apu: Add support of IOMMU

[Alexandre Bailon <abailon@baylibre.com>]

Some APU devices are behind an IOMMU.
For some of these devices, we can't use DMA API because
they use static addresses so we have to manually use
IOMMU API to correctly map the buffers.
This adds support of IOMMU.

Signed-off-by: Alexandre Bailon <abailon@baylibre.com>
Reviewed-by: Julien Stephan <jstephan@baylibre.com>
---
 drivers/gpu/drm/apu/apu_drv.c      |   4 +
 drivers/gpu/drm/apu/apu_gem.c      | 174 +++++++++++++++++++++++++++++
 drivers/gpu/drm/apu/apu_internal.h |  16 +++
 drivers/gpu/drm/apu/apu_sched.c    |  28 +++++
 include/uapi/drm/apu_drm.h         |  12 +-
 5 files changed, 233 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/apu/apu_drv.c b/drivers/gpu/drm/apu/apu_drv.c
index b6bd340b2bc8..a0dce785a02a 100644
--- a/drivers/gpu/drm/apu/apu_drv.c
+++ b/drivers/gpu/drm/apu/apu_drv.c
@@ -23,6 +23,10 @@ static const struct drm_ioctl_desc ioctls[] = {
 			  DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF_DRV(APU_GEM_DEQUEUE, ioctl_gem_dequeue,
 			  DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF_DRV(APU_GEM_IOMMU_MAP, ioctl_gem_iommu_map,
+			  DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF_DRV(APU_GEM_IOMMU_UNMAP, ioctl_gem_iommu_unmap,
+			  DRM_RENDER_ALLOW),
 };
 
 DEFINE_DRM_GEM_DMA_FOPS(apu_drm_ops);
diff --git a/drivers/gpu/drm/apu/apu_gem.c b/drivers/gpu/drm/apu/apu_gem.c
index 0e7b3b27942c..0a91363754c5 100644
--- a/drivers/gpu/drm/apu/apu_gem.c
+++ b/drivers/gpu/drm/apu/apu_gem.c
@@ -2,6 +2,9 @@
 //
 // Copyright 2020 BayLibre SAS
 
+#include <linux/iommu.h>
+#include <linux/iova.h>
+
 #include <drm/drm_gem_dma_helper.h>
 
 #include <uapi/drm/apu_drm.h>
@@ -42,6 +45,7 @@ int ioctl_gem_new(struct drm_device *dev, void *data,
 	 */
 	apu_obj->size = args->size;
 	apu_obj->offset = 0;
+	apu_obj->iommu_refcount = 0;
 	mutex_init(&apu_obj->mutex);
 
 	ret = drm_gem_handle_create(file_priv, gem_obj, &args->handle);
@@ -54,3 +58,173 @@ int ioctl_gem_new(struct drm_device *dev, void *data,
 
 	return 0;
 }
+
+void apu_bo_iommu_unmap(struct apu_drm *apu_drm, struct apu_gem_object *obj)
+{
+	int iova_pfn;
+	int i;
+
+	if (!obj->iommu_sgt)
+		return;
+
+	mutex_lock(&obj->mutex);
+	obj->iommu_refcount--;
+	if (obj->iommu_refcount) {
+		mutex_unlock(&obj->mutex);
+		return;
+	}
+
+	iova_pfn = PHYS_PFN(obj->iova);
+	for (i = 0; i < obj->iommu_sgt->nents; i++) {
+		iommu_unmap(apu_drm->domain, PFN_PHYS(iova_pfn),
+			    PAGE_ALIGN(obj->iommu_sgt->sgl[i].length));
+		iova_pfn += PHYS_PFN(PAGE_ALIGN(obj->iommu_sgt->sgl[i].length));
+	}
+
+	sg_free_table(obj->iommu_sgt);
+	kfree(obj->iommu_sgt);
+
+	free_iova(&apu_drm->iovad, PHYS_PFN(obj->iova));
+	mutex_unlock(&obj->mutex);
+}
+
+static struct sg_table *apu_get_sg_table(struct drm_gem_object *obj)
+{
+	if (obj->funcs)
+		return obj->funcs->get_sg_table(obj);
+	return NULL;
+}
+
+int apu_bo_iommu_map(struct apu_drm *apu_drm, struct drm_gem_object *obj)
+{
+	struct apu_gem_object *apu_obj = to_apu_bo(obj);
+	struct scatterlist *sgl;
+	phys_addr_t phys;
+	int total_buf_space;
+	int iova_pfn;
+	int iova;
+	int ret;
+	int i;
+
+	mutex_lock(&apu_obj->mutex);
+	apu_obj->iommu_refcount++;
+	if (apu_obj->iommu_refcount != 1) {
+		mutex_unlock(&apu_obj->mutex);
+		return 0;
+	}
+
+	apu_obj->iommu_sgt = apu_get_sg_table(obj);
+	if (IS_ERR(apu_obj->iommu_sgt)) {
+		mutex_unlock(&apu_obj->mutex);
+		return PTR_ERR(apu_obj->iommu_sgt);
+	}
+
+	total_buf_space = obj->size;
+	iova_pfn = alloc_iova_fast(&apu_drm->iovad,
+				   total_buf_space >> PAGE_SHIFT,
+				   apu_drm->iova_limit_pfn, true);
+	apu_obj->iova = PFN_PHYS(iova_pfn);
+
+	if (!iova_pfn) {
+		dev_err(apu_drm->dev, "Failed to allocate iova address\n");
+		mutex_unlock(&apu_obj->mutex);
+		return -ENOMEM;
+	}
+
+	iova = apu_obj->iova;
+	sgl = apu_obj->iommu_sgt->sgl;
+	for (i = 0; i < apu_obj->iommu_sgt->nents; i++) {
+		phys = page_to_phys(sg_page(&sgl[i]));
+		ret =
+		    iommu_map(apu_drm->domain, PFN_PHYS(iova_pfn), phys,
+			      PAGE_ALIGN(sgl[i].length), IOMMU_READ | IOMMU_WRITE,
+			      GFP_KERNEL);
+		if (ret) {
+			dev_err(apu_drm->dev, "Failed to iommu map\n");
+			free_iova(&apu_drm->iovad, iova_pfn);
+			mutex_unlock(&apu_obj->mutex);
+			return ret;
+		}
+		iova += sgl[i].offset + sgl[i].length;
+		iova_pfn += PHYS_PFN(PAGE_ALIGN(sgl[i].length));
+	}
+	mutex_unlock(&apu_obj->mutex);
+
+	return 0;
+}
+
+int ioctl_gem_iommu_map(struct drm_device *dev, void *data,
+			struct drm_file *file_priv)
+{
+	struct apu_drm *apu_drm = dev->dev_private;
+	struct drm_apu_gem_iommu_map *args = data;
+	struct drm_gem_object **bos;
+	void __user *bo_handles;
+	u64 *das;
+	int ret;
+	int i;
+
+	if (!apu_drm->domain)
+		return -ENODEV;
+
+	das = kvmalloc_array(args->bo_handle_count, sizeof(*das), GFP_KERNEL);
+	if (!das)
+		return -ENOMEM;
+
+	bo_handles = (void __user *)(uintptr_t) args->bo_handles;
+	ret = drm_gem_objects_lookup(file_priv, bo_handles,
+				     args->bo_handle_count, &bos);
+	if (ret) {
+		kvfree(das);
+		return ret;
+	}
+
+	for (i = 0; i < args->bo_handle_count; i++) {
+		ret = apu_bo_iommu_map(apu_drm, bos[i]);
+		if (ret) {
+			/* TODO: handle error */
+			break;
+		}
+		das[i] = to_apu_bo(bos[i])->iova + to_apu_bo(bos[i])->offset;
+	}
+
+	if (copy_to_user((void *)args->bo_device_addresses, das,
+			 args->bo_handle_count * sizeof(u64))) {
+		ret = -EFAULT;
+		DRM_DEBUG("Failed to copy device addresses\n");
+		goto out;
+	}
+
+out:
+	kvfree(das);
+	kvfree(bos);
+
+	return 0;
+}
+
+int ioctl_gem_iommu_unmap(struct drm_device *dev, void *data,
+			  struct drm_file *file_priv)
+{
+	struct apu_drm *apu_drm = dev->dev_private;
+	struct drm_apu_gem_iommu_map *args = data;
+	struct drm_gem_object **bos;
+	void __user *bo_handles;
+	int ret;
+	int i;
+
+	if (!apu_drm->domain)
+		return -ENODEV;
+
+	bo_handles = (void __user *)(uintptr_t) args->bo_handles;
+	ret = drm_gem_objects_lookup(file_priv, bo_handles,
+				     args->bo_handle_count, &bos);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < args->bo_handle_count; i++)
+		apu_bo_iommu_unmap(apu_drm, to_apu_bo(bos[i]));
+
+	kvfree(bos);
+
+	return 0;
+}
diff --git a/drivers/gpu/drm/apu/apu_internal.h b/drivers/gpu/drm/apu/apu_internal.h
index 021a3efdedf2..ea4183f3fb15 100644
--- a/drivers/gpu/drm/apu/apu_internal.h
+++ b/drivers/gpu/drm/apu/apu_internal.h
@@ -2,6 +2,9 @@
 #ifndef __APU_INTERNAL_H__
 #define __APU_INTERNAL_H__
 
+#include <linux/iommu.h>
+#include <linux/iova.h>
+
 #include <drm/drm_drv.h>
 #include <drm/drm_gem_dma_helper.h>
 #include <drm/gpu_scheduler.h>
@@ -9,7 +12,10 @@
 struct apu_gem_object {
 	struct drm_gem_dma_object base;
 	struct mutex mutex;
+	struct sg_table *iommu_sgt;
+	int iommu_refcount;
 	size_t size;
+	u32 iova;
 	u32 offset;
 };
 
@@ -35,6 +41,10 @@ struct apu_drm {
 	struct drm_device base;
 	struct device *dev;
 
+	struct iommu_domain *domain;
+	struct iova_domain iovad;
+	int iova_limit_pfn;
+
 	struct list_head cores;
 	struct list_head node;
 
@@ -165,12 +175,18 @@ struct apu_gem_object *to_apu_bo(struct drm_gem_object *obj);
 struct drm_gem_object *apu_gem_create_object(struct drm_device *dev,
 					     size_t size);
 
+int apu_bo_iommu_map(struct apu_drm *apu_drm, struct drm_gem_object *obj);
+void apu_bo_iommu_unmap(struct apu_drm *apu_drm, struct apu_gem_object *obj);
 int ioctl_gem_new(struct drm_device *dev, void *data,
 		  struct drm_file *file_priv);
 int ioctl_gem_user_new(struct drm_device *dev, void *data,
 		       struct drm_file *file_priv);
 struct dma_buf *apu_gem_prime_export(struct drm_gem_object *gem,
 				     int flags);
+int ioctl_gem_iommu_map(struct drm_device *dev, void *data,
+			struct drm_file *file_priv);
+int ioctl_gem_iommu_unmap(struct drm_device *dev, void *data,
+			  struct drm_file *file_priv);
 int ioctl_gem_queue(struct drm_device *dev, void *data,
 		    struct drm_file *file_priv);
 int ioctl_gem_dequeue(struct drm_device *dev, void *data,
diff --git a/drivers/gpu/drm/apu/apu_sched.c b/drivers/gpu/drm/apu/apu_sched.c
index 13b6fbd00bd8..716d4b7f2d55 100644
--- a/drivers/gpu/drm/apu/apu_sched.c
+++ b/drivers/gpu/drm/apu/apu_sched.c
@@ -117,6 +117,8 @@ static void apu_job_cleanup(struct kref *ref)
 			struct apu_gem_object *apu_obj;
 
 			apu_obj = to_apu_bo(job->bos[i]);
+			if (job->apu->domain)
+				apu_bo_iommu_unmap(job->apu, apu_obj);
 			drm_gem_object_put(job->bos[i]);
 		}
 
@@ -397,6 +399,7 @@ static int apu_lookup_bos(struct drm_device *dev, struct drm_file *file_priv,
 			  struct drm_apu_gem_queue *args, struct apu_job *job)
 {
 	void __user *bo_handles;
+	unsigned int i;
 	int ret;
 
 	job->bo_count = args->bo_handle_count;
@@ -413,6 +416,31 @@ static int apu_lookup_bos(struct drm_device *dev, struct drm_file *file_priv,
 	bo_handles = (void __user *)(uintptr_t) args->bo_handles;
 	ret = drm_gem_objects_lookup(file_priv, bo_handles,
 				     job->bo_count, &job->bos);
+	if (ret)
+		return ret;
+
+	if (!job->apu->domain)
+		return 0;
+
+	for (i = 0; i < job->bo_count; i++) {
+		ret = apu_bo_iommu_map(job->apu, job->bos[i]);
+		if (ret)
+			goto err_iommu_map;
+	}
+
+	return ret;
+
+err_iommu_map:
+	kvfree(job->implicit_fences);
+	for (i = 0; i < job->bo_count; i++) {
+		struct apu_gem_object *apu_obj;
+
+		apu_obj = to_apu_bo(job->bos[i]);
+		if (job->apu->domain)
+			apu_bo_iommu_unmap(job->apu, apu_obj);
+		drm_gem_object_put(job->bos[i]);
+	}
+	kvfree(job->bos);
 
 	return ret;
 }
diff --git a/include/uapi/drm/apu_drm.h b/include/uapi/drm/apu_drm.h
index c47000097040..0ecc739d8aed 100644
--- a/include/uapi/drm/apu_drm.h
+++ b/include/uapi/drm/apu_drm.h
@@ -41,6 +41,12 @@ struct drm_apu_gem_dequeue {
 	__u64 data;
 };
 
+struct drm_apu_gem_iommu_map {
+	__u64 bo_handles;
+	__u32 bo_handle_count;
+	__u64 bo_device_addresses;
+};
+
 struct apu_job_event {
 	struct drm_event base;
 	__u32 out_sync;
@@ -57,12 +63,16 @@ struct drm_apu_state {
 #define DRM_APU_GEM_NEW			0x01
 #define DRM_APU_GEM_QUEUE		0x02
 #define DRM_APU_GEM_DEQUEUE		0x03
-#define DRM_APU_NUM_IOCTLS		0x04
+#define DRM_APU_GEM_IOMMU_MAP		0x04
+#define DRM_APU_GEM_IOMMU_UNMAP		0x05
+#define DRM_APU_NUM_IOCTLS		0x06
 
 #define DRM_IOCTL_APU_STATE		DRM_IOWR(DRM_COMMAND_BASE + DRM_APU_STATE, struct drm_apu_state)
 #define DRM_IOCTL_APU_GEM_NEW		DRM_IOWR(DRM_COMMAND_BASE + DRM_APU_GEM_NEW, struct drm_apu_gem_new)
 #define DRM_IOCTL_APU_GEM_QUEUE		DRM_IOWR(DRM_COMMAND_BASE + DRM_APU_GEM_QUEUE, struct drm_apu_gem_queue)
 #define DRM_IOCTL_APU_GEM_DEQUEUE	DRM_IOWR(DRM_COMMAND_BASE + DRM_APU_GEM_DEQUEUE, struct drm_apu_gem_dequeue)
+#define DRM_IOCTL_APU_GEM_IOMMU_MAP	DRM_IOWR(DRM_COMMAND_BASE + DRM_APU_GEM_IOMMU_MAP, struct drm_apu_gem_iommu_map)
+#define DRM_IOCTL_APU_GEM_IOMMU_UNMAP	DRM_IOWR(DRM_COMMAND_BASE + DRM_APU_GEM_IOMMU_UNMAP, struct drm_apu_gem_iommu_map)
 
 #if defined(__cplusplus)
 }
-- 
2.39.2


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