i915: add dmabuf/prime buffer sharing support.

This adds handle->fd and fd->handle support to i915, this is to allow
for offloading of rendering in one direction and outputs in the other.

v2 from Daniel Vetter:
- fixup conflicts with the prepare/finish gtt prep work.
- implement ppgtt binding support.

Note that we have squat i-g-t testcoverage for any of the lifetime and
access rules dma_buf/prime support brings along. And there are quite a
few intricate situations here.

Also note that the integration with the existing code is a bit
hackish, especially around get_gtt_pages and put_gtt_pages. It imo
would be easier with the prep code from Chris Wilson's unbound series,
but that is for 3.6.

Also note that I didn't bother to put the new prepare/finish gtt hooks
to good use by moving the dma_buf_map/unmap_attachment calls in there
(like we've originally planned for).

Last but not least this patch is only compile-tested, but I've changed
very little compared to Dave Airlie's version. So there's a decent
chance v2 on drm-next works as well as v1 on 3.4-rc.

v3: Right when I've hit sent I've noticed that I've screwed up one
obj->sg_list (for dmar support) and obj->sg_table (for prime support)
disdinction. We should be able to merge these 2 paths, but that's
material for another patch.

v4: fix the error reporting bugs pointed out by ickle.

v5: fix another error, and stop non-gtt mmaps on shared objects
stop pread/pwrite on imported objects, add fake kmap
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/Makefile

@@ -38,7 +38,8 @@ i915-y := i915_drv.o i915_dma.o i915_irq.o \
 	  dvo_ch7017.o \
 	  dvo_ivch.o \
 	  dvo_tfp410.o \
-	  dvo_sil164.o
+	  dvo_sil164.o \
+	  i915_gem_dmabuf.o
 
 i915-$(CONFIG_COMPAT)   += i915_ioc32.o
 

drivers/gpu/drm/i915/i915_drv.c

@@ -1039,7 +1039,7 @@ static struct drm_driver driver = {
 	 */
 	.driver_features =
 	    DRIVER_USE_AGP | DRIVER_REQUIRE_AGP | /* DRIVER_USE_MTRR |*/
-	    DRIVER_HAVE_IRQ | DRIVER_IRQ_SHARED | DRIVER_GEM,
+	    DRIVER_HAVE_IRQ | DRIVER_IRQ_SHARED | DRIVER_GEM | DRIVER_PRIME,
 	.load = i915_driver_load,
 	.unload = i915_driver_unload,
 	.open = i915_driver_open,
@@ -1062,6 +1062,12 @@ static struct drm_driver driver = {
 	.gem_init_object = i915_gem_init_object,
 	.gem_free_object = i915_gem_free_object,
 	.gem_vm_ops = &i915_gem_vm_ops,
+
+	.prime_handle_to_fd = drm_gem_prime_handle_to_fd,
+	.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
+	.gem_prime_export = i915_gem_prime_export,
+	.gem_prime_import = i915_gem_prime_import,
+
 	.dumb_create = i915_gem_dumb_create,
 	.dumb_map_offset = i915_gem_mmap_gtt,
 	.dumb_destroy = i915_gem_dumb_destroy,

drivers/gpu/drm/i915/i915_drv.h

@@ -940,6 +940,8 @@ struct drm_i915_gem_object {
 	struct scatterlist *sg_list;
 	int num_sg;
 
+	/* prime dma-buf support */
+	struct sg_table *sg_table;
 	/**
 	 * Used for performing relocations during execbuffer insertion.
 	 */
@@ -1245,6 +1247,8 @@ int __must_check i915_gem_object_unbind(struct drm_i915_gem_object *obj);
 void i915_gem_release_mmap(struct drm_i915_gem_object *obj);
 void i915_gem_lastclose(struct drm_device *dev);
 
+int i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj,
+				  gfp_t gfpmask);
 int __must_check i915_mutex_lock_interruptible(struct drm_device *dev);
 int __must_check i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj);
 int i915_gem_object_sync(struct drm_i915_gem_object *obj,
@@ -1342,6 +1346,13 @@ i915_gem_get_unfenced_gtt_alignment(struct drm_device *dev,
 int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
 				    enum i915_cache_level cache_level);
 
+struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev,
+				struct dma_buf *dma_buf);
+
+struct dma_buf *i915_gem_prime_export(struct drm_device *dev,
+				struct drm_gem_object *gem_obj, int flags);
+
+
 /* i915_gem_gtt.c */
 int __must_check i915_gem_init_aliasing_ppgtt(struct drm_device *dev);
 void i915_gem_cleanup_aliasing_ppgtt(struct drm_device *dev);

drivers/gpu/drm/i915/i915_gem.c

@@ -35,6 +35,7 @@
 #include <linux/slab.h>
 #include <linux/swap.h>
 #include <linux/pci.h>
+#include <linux/dma-buf.h>
 
 static __must_check int i915_gem_object_flush_gpu_write_domain(struct drm_i915_gem_object *obj);
 static void i915_gem_object_flush_gtt_write_domain(struct drm_i915_gem_object *obj);
@@ -538,6 +539,14 @@ i915_gem_pread_ioctl(struct drm_device *dev, void *data,
 		goto out;
 	}
 
+	/* prime objects have no backing filp to GEM pread/pwrite
+	 * pages from.
+	 */
+	if (!obj->base.filp) {
+		ret = -EINVAL;
+		goto out;
+	}
+
 	trace_i915_gem_object_pread(obj, args->offset, args->size);
 
 	ret = i915_gem_shmem_pread(dev, obj, args, file);
@@ -880,6 +889,14 @@ i915_gem_pwrite_ioctl(struct drm_device *dev, void *data,
 		goto out;
 	}
 
+	/* prime objects have no backing filp to GEM pread/pwrite
+	 * pages from.
+	 */
+	if (!obj->base.filp) {
+		ret = -EINVAL;
+		goto out;
+	}
+
 	trace_i915_gem_object_pwrite(obj, args->offset, args->size);
 
 	ret = -EFAULT;
@@ -1021,6 +1038,14 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
 	if (obj == NULL)
 		return -ENOENT;
 
+	/* prime objects have no backing filp to GEM mmap
+	 * pages from.
+	 */
+	if (!obj->filp) {
+		drm_gem_object_unreference_unlocked(obj);
+		return -EINVAL;
+	}
+
 	addr = vm_mmap(obj->filp, 0, args->size,
 		       PROT_READ | PROT_WRITE, MAP_SHARED,
 		       args->offset);
@@ -1302,8 +1327,7 @@ i915_gem_mmap_gtt_ioctl(struct drm_device *dev, void *data,
 	return i915_gem_mmap_gtt(file, dev, args->handle, &args->offset);
 }
 
-
-static int
+int
 i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj,
 			      gfp_t gfpmask)
 {
@@ -1312,6 +1336,9 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj,
 	struct inode *inode;
 	struct page *page;
 
+	if (obj->pages || obj->sg_table)
+		return 0;
+
 	/* Get the list of pages out of our struct file.  They'll be pinned
 	 * at this point until we release them.
 	 */
@@ -1353,6 +1380,9 @@ i915_gem_object_put_pages_gtt(struct drm_i915_gem_object *obj)
 	int page_count = obj->base.size / PAGE_SIZE;
 	int i;
 
+	if (!obj->pages)
+		return;
+
 	BUG_ON(obj->madv == __I915_MADV_PURGED);
 
 	if (i915_gem_object_needs_bit17_swizzle(obj))
@@ -3327,6 +3357,9 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj)
 
 	trace_i915_gem_object_destroy(obj);
 
+	if (gem_obj->import_attach)
+		drm_prime_gem_destroy(gem_obj, obj->sg_table);
+
 	if (obj->phys_obj)
 		i915_gem_detach_phys_object(dev, obj);
 

drivers/gpu/drm/i915/i915_gem_dmabuf.c

+/*
+ * Copyright 2012 Red Hat Inc
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Authors:
+ *	Dave Airlie <airlied@redhat.com>
+ */
+#include "drmP.h"
+#include "i915_drv.h"
+#include <linux/dma-buf.h>
+
+struct sg_table *i915_gem_map_dma_buf(struct dma_buf_attachment *attachment,
+				      enum dma_data_direction dir)
+{
+	struct drm_i915_gem_object *obj = attachment->dmabuf->priv;
+	struct drm_device *dev = obj->base.dev;
+	int npages = obj->base.size / PAGE_SIZE;
+	struct sg_table *sg = NULL;
+	int ret;
+	int nents;
+
+	ret = i915_mutex_lock_interruptible(dev);
+	if (ret)
+		return ERR_PTR(ret);
+
+	if (!obj->pages) {
+		ret = i915_gem_object_get_pages_gtt(obj, __GFP_NORETRY | __GFP_NOWARN);
+		if (ret)
+			goto out;
+	}
+
+	/* link the pages into an SG then map the sg */
+	sg = drm_prime_pages_to_sg(obj->pages, npages);
+	nents = dma_map_sg(attachment->dev, sg->sgl, sg->nents, dir);
+out:
+	mutex_unlock(&dev->struct_mutex);
+	return sg;
+}
+
+void i915_gem_unmap_dma_buf(struct dma_buf_attachment *attachment,
+			    struct sg_table *sg, enum dma_data_direction dir)
+{
+	dma_unmap_sg(attachment->dev, sg->sgl, sg->nents, dir);
+	sg_free_table(sg);
+	kfree(sg);
+}
+
+void i915_gem_dmabuf_release(struct dma_buf *dma_buf)
+{
+	struct drm_i915_gem_object *obj = dma_buf->priv;
+
+	if (obj->base.export_dma_buf == dma_buf) {
+		/* drop the reference on the export fd holds */
+		obj->base.export_dma_buf = NULL;
+		drm_gem_object_unreference_unlocked(&obj->base);
+	}
+}
+
+static void *i915_gem_dmabuf_kmap_atomic(struct dma_buf *dma_buf, unsigned long page_num)
+{
+	return NULL;
+}
+
+static void i915_gem_dmabuf_kunmap_atomic(struct dma_buf *dma_buf, unsigned long page_num, void *addr)
+{
+
+}
+static void *i915_gem_dmabuf_kmap(struct dma_buf *dma_buf, unsigned long page_num)
+{
+	return NULL;
+}
+
+static void i915_gem_dmabuf_kunmap(struct dma_buf *dma_buf, unsigned long page_num, void *addr)
+{
+
+}
+
+struct dma_buf_ops i915_dmabuf_ops =  {
+	.map_dma_buf = i915_gem_map_dma_buf,
+	.unmap_dma_buf = i915_gem_unmap_dma_buf,
+	.release = i915_gem_dmabuf_release,
+	.kmap = i915_gem_dmabuf_kmap,
+	.kmap_atomic = i915_gem_dmabuf_kmap_atomic,
+	.kunmap = i915_gem_dmabuf_kunmap,
+	.kunmap_atomic = i915_gem_dmabuf_kunmap_atomic,
+};
+
+struct dma_buf *i915_gem_prime_export(struct drm_device *dev,
+				struct drm_gem_object *gem_obj, int flags)
+{
+	struct drm_i915_gem_object *obj = to_intel_bo(gem_obj);
+
+	return dma_buf_export(obj, &i915_dmabuf_ops,
+						  obj->base.size, 0600);
+}
+
+struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev,
+				struct dma_buf *dma_buf)
+{
+	struct dma_buf_attachment *attach;
+	struct sg_table *sg;
+	struct drm_i915_gem_object *obj;
+	int npages;
+	int size;
+	int ret;
+
+	/* is this one of own objects? */
+	if (dma_buf->ops == &i915_dmabuf_ops) {
+		obj = dma_buf->priv;
+		/* is it from our device? */
+		if (obj->base.dev == dev) {
+			drm_gem_object_reference(&obj->base);
+			return &obj->base;
+		}
+	}
+
+	/* need to attach */
+	attach = dma_buf_attach(dma_buf, dev->dev);
+	if (IS_ERR(attach))
+		return ERR_CAST(attach);
+
+	sg = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
+	if (IS_ERR(sg)) {
+		ret = PTR_ERR(sg);
+		goto fail_detach;
+	}
+
+	size = dma_buf->size;
+	npages = size / PAGE_SIZE;
+
+	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
+	if (obj == NULL) {
+		ret = -ENOMEM;
+		goto fail_unmap;
+	}
+
+	ret = drm_gem_private_object_init(dev, &obj->base, size);
+	if (ret) {
+		kfree(obj);
+		goto fail_unmap;
+	}
+
+	obj->sg_table = sg;
+	obj->base.import_attach = attach;
+
+	return &obj->base;
+
+fail_unmap:
+	dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
+fail_detach:
+	dma_buf_detach(dma_buf, attach);
+	return ERR_PTR(ret);
+}

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -267,7 +267,13 @@ void i915_ppgtt_bind_object(struct i915_hw_ppgtt *ppgtt,
 		BUG();
 	}
 
-	if (dev_priv->mm.gtt->needs_dmar) {
+	if (obj->sg_table) {
+		i915_ppgtt_insert_sg_entries(ppgtt,
+					     obj->sg_table->sgl,
+					     obj->sg_table->nents,
+					     obj->gtt_space->start >> PAGE_SHIFT,
+					     pte_flags);
+	} else if (dev_priv->mm.gtt->needs_dmar) {
 		BUG_ON(!obj->sg_list);
 
 		i915_ppgtt_insert_sg_entries(ppgtt,
@@ -371,7 +377,12 @@ void i915_gem_gtt_bind_object(struct drm_i915_gem_object *obj,
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	unsigned int agp_type = cache_level_to_agp_type(dev, cache_level);
 
-	if (dev_priv->mm.gtt->needs_dmar) {
+	if (obj->sg_table) {
+		intel_gtt_insert_sg_entries(obj->sg_table->sgl,
+					    obj->sg_table->nents,
+					    obj->gtt_space->start >> PAGE_SHIFT,
+					    agp_type);
+	} else if (dev_priv->mm.gtt->needs_dmar) {
 		BUG_ON(!obj->sg_list);
 
 		intel_gtt_insert_sg_entries(obj->sg_list,