drm/vgem: implement virtual GEM

This patch implements the virtual GEM driver with PRIME sharing which
allows vgem to import a gem object from other drivers for the purpose
of mmap-ing them to userspace. The mmap is done using the mmap
operation exported by other drivers.

v2: remove platform_device and do not attach to dma bufs
v3: use drm helpers for get/put pages
v4: correct dumb create pitch

Reviewed-by: Rob Clark <robdclark@gmail.com> (v3)
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org> (v3)
Signed-off-by: NAdam Jackson <ajax@redhat.com>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NZach Reizner <zachr@google.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

drivers/gpu/drm/Kconfig

@@ -165,6 +165,15 @@ config DRM_SAVAGE
 	  Choose this option if you have a Savage3D/4/SuperSavage/Pro/Twister
 	  chipset. If M is selected the module will be called savage.
 
+config DRM_VGEM
+	tristate "Virtual GEM provider"
+	depends on DRM
+	help
+	  Choose this option to get a virtual graphics memory manager,
+	  as used by Mesa's software renderer for enhanced performance.
+	  If M is selected the module will be called vgem.
+
+
 source "drivers/gpu/drm/exynos/Kconfig"
 
 source "drivers/gpu/drm/rockchip/Kconfig"

drivers/gpu/drm/Makefile

@@ -48,6 +48,7 @@ obj-$(CONFIG_DRM_SIS)   += sis/
 obj-$(CONFIG_DRM_SAVAGE)+= savage/
 obj-$(CONFIG_DRM_VMWGFX)+= vmwgfx/
 obj-$(CONFIG_DRM_VIA)	+=via/
+obj-$(CONFIG_DRM_VGEM)	+= vgem/
 obj-$(CONFIG_DRM_NOUVEAU) +=nouveau/
 obj-$(CONFIG_DRM_EXYNOS) +=exynos/
 obj-$(CONFIG_DRM_ROCKCHIP) +=rockchip/

drivers/gpu/drm/vgem/Makefile

+ccflags-y := -Iinclude/drm
+vgem-y := vgem_drv.o vgem_dma_buf.o
+
+obj-$(CONFIG_DRM_VGEM)	+= vgem.o

drivers/gpu/drm/vgem/vgem_dma_buf.c

+/*
+ * Copyright © 2012 Intel Corporation
+ * Copyright © 2014 The Chromium OS Authors
+ *
+ * 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:
+ *    Ben Widawsky <ben@bwidawsk.net>
+ *
+ */
+
+#include <linux/dma-buf.h>
+#include "vgem_drv.h"
+
+struct sg_table *vgem_gem_prime_get_sg_table(struct drm_gem_object *gobj)
+{
+	struct drm_vgem_gem_object *obj = to_vgem_bo(gobj);
+	BUG_ON(obj->pages == NULL);
+
+	return drm_prime_pages_to_sg(obj->pages, obj->base.size / PAGE_SIZE);
+}
+
+int vgem_gem_prime_pin(struct drm_gem_object *gobj)
+{
+	struct drm_vgem_gem_object *obj = to_vgem_bo(gobj);
+	return vgem_gem_get_pages(obj);
+}
+
+void vgem_gem_prime_unpin(struct drm_gem_object *gobj)
+{
+	struct drm_vgem_gem_object *obj = to_vgem_bo(gobj);
+	vgem_gem_put_pages(obj);
+}
+
+void *vgem_gem_prime_vmap(struct drm_gem_object *gobj)
+{
+	struct drm_vgem_gem_object *obj = to_vgem_bo(gobj);
+	BUG_ON(obj->pages == NULL);
+
+	return vmap(obj->pages, obj->base.size / PAGE_SIZE, 0, PAGE_KERNEL);
+}
+
+void vgem_gem_prime_vunmap(struct drm_gem_object *obj, void *vaddr)
+{
+	vunmap(vaddr);
+}
+
+struct drm_gem_object *vgem_gem_prime_import(struct drm_device *dev,
+					     struct dma_buf *dma_buf)
+{
+	struct drm_vgem_gem_object *obj = NULL;
+	int ret;
+
+	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
+	if (obj == NULL) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+
+	ret = drm_gem_object_init(dev, &obj->base, dma_buf->size);
+	if (ret) {
+		ret = -ENOMEM;
+		goto fail_free;
+	}
+
+	get_dma_buf(dma_buf);
+
+	obj->base.dma_buf = dma_buf;
+	obj->use_dma_buf = true;
+
+	return &obj->base;
+
+fail_free:
+	kfree(obj);
+fail:
+	return ERR_PTR(ret);
+}

drivers/gpu/drm/vgem/vgem_drv.c

+/*
+ * Copyright 2011 Red Hat, Inc.
+ * Copyright © 2014 The Chromium OS Authors
+ *
+ * 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
+ * on the rights to use, copy, modify, merge, publish, distribute, sub
+ * license, and/or sell copies of the Software, and to permit persons to whom
+ * them 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 MERCHANTIBILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS 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:
+ *	Adam Jackson <ajax@redhat.com>
+ *	Ben Widawsky <ben@bwidawsk.net>
+ */
+
+/**
+ * This is vgem, a (non-hardware-backed) GEM service.  This is used by Mesa's
+ * software renderer and the X server for efficient buffer sharing.
+ */
+
+#include <linux/module.h>
+#include <linux/ramfs.h>
+#include <linux/shmem_fs.h>
+#include <linux/dma-buf.h>
+#include "vgem_drv.h"
+
+#define DRIVER_NAME	"vgem"
+#define DRIVER_DESC	"Virtual GEM provider"
+#define DRIVER_DATE	"20120112"
+#define DRIVER_MAJOR	1
+#define DRIVER_MINOR	0
+
+void vgem_gem_put_pages(struct drm_vgem_gem_object *obj)
+{
+	drm_gem_put_pages(&obj->base, obj->pages, false, false);
+	obj->pages = NULL;
+}
+
+static void vgem_gem_free_object(struct drm_gem_object *obj)
+{
+	struct drm_vgem_gem_object *vgem_obj = to_vgem_bo(obj);
+
+	drm_gem_free_mmap_offset(obj);
+
+	if (vgem_obj->use_dma_buf && obj->dma_buf) {
+		dma_buf_put(obj->dma_buf);
+		obj->dma_buf = NULL;
+	}
+
+	drm_gem_object_release(obj);
+
+	if (vgem_obj->pages)
+		vgem_gem_put_pages(vgem_obj);
+
+	vgem_obj->pages = NULL;
+
+	kfree(vgem_obj);
+}
+
+int vgem_gem_get_pages(struct drm_vgem_gem_object *obj)
+{
+	struct page **pages;
+
+	if (obj->pages || obj->use_dma_buf)
+		return 0;
+
+	pages = drm_gem_get_pages(&obj->base);
+	if (IS_ERR(pages)) {
+		return PTR_ERR(pages);
+	}
+
+	obj->pages = pages;
+
+	return 0;
+}
+
+static int vgem_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct drm_vgem_gem_object *obj = vma->vm_private_data;
+	struct drm_device *dev = obj->base.dev;
+	loff_t num_pages;
+	pgoff_t page_offset;
+	int ret;
+
+	/* We don't use vmf->pgoff since that has the fake offset */
+	page_offset = ((unsigned long)vmf->virtual_address - vma->vm_start) >>
+		PAGE_SHIFT;
+
+	num_pages = DIV_ROUND_UP(obj->base.size, PAGE_SIZE);
+
+	if (page_offset > num_pages)
+		return VM_FAULT_SIGBUS;
+
+	mutex_lock(&dev->struct_mutex);
+
+	ret = vm_insert_page(vma, (unsigned long)vmf->virtual_address,
+			     obj->pages[page_offset]);
+
+	mutex_unlock(&dev->struct_mutex);
+	switch (ret) {
+	case 0:
+		return VM_FAULT_NOPAGE;
+	case -ENOMEM:
+		return VM_FAULT_OOM;
+	case -EBUSY:
+		return VM_FAULT_RETRY;
+	case -EFAULT:
+	case -EINVAL:
+		return VM_FAULT_SIGBUS;
+	default:
+		WARN_ON(1);
+		return VM_FAULT_SIGBUS;
+	}
+}
+
+static struct vm_operations_struct vgem_gem_vm_ops = {
+	.fault = vgem_gem_fault,
+	.open = drm_gem_vm_open,
+	.close = drm_gem_vm_close,
+};
+
+/* ioctls */
+
+static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
+					      struct drm_file *file,
+					      unsigned int *handle,
+					      unsigned long size)
+{
+	struct drm_vgem_gem_object *obj;
+	struct drm_gem_object *gem_object;
+	int err;
+
+	size = roundup(size, PAGE_SIZE);
+
+	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
+	if (!obj)
+		return ERR_PTR(-ENOMEM);
+
+	gem_object = &obj->base;
+
+	err = drm_gem_object_init(dev, gem_object, size);
+	if (err)
+		goto out;
+
+	err = drm_gem_handle_create(file, gem_object, handle);
+	if (err)
+		goto handle_out;
+
+	drm_gem_object_unreference_unlocked(gem_object);
+
+	return gem_object;
+
+handle_out:
+	drm_gem_object_release(gem_object);
+out:
+	kfree(obj);
+	return ERR_PTR(err);
+}
+
+static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
+				struct drm_mode_create_dumb *args)
+{
+	struct drm_gem_object *gem_object;
+	uint64_t size;
+	uint64_t pitch = args->width * DIV_ROUND_UP(args->bpp, 8);
+
+	size = args->height * pitch;
+	if (size == 0)
+		return -EINVAL;
+
+	gem_object = vgem_gem_create(dev, file, &args->handle, size);
+
+	if (IS_ERR(gem_object)) {
+		DRM_DEBUG_DRIVER("object creation failed\n");
+		return PTR_ERR(gem_object);
+	}
+
+	args->size = gem_object->size;
+	args->pitch = pitch;
+
+	DRM_DEBUG_DRIVER("Created object of size %lld\n", size);
+
+	return 0;
+}
+
+int vgem_gem_dumb_map(struct drm_file *file, struct drm_device *dev,
+		      uint32_t handle, uint64_t *offset)
+{
+	int ret = 0;
+	struct drm_gem_object *obj;
+
+	mutex_lock(&dev->struct_mutex);
+	obj = drm_gem_object_lookup(dev, file, handle);
+	if (!obj) {
+		ret = -ENOENT;
+		goto unlock;
+	}
+
+	if (!drm_vma_node_has_offset(&obj->vma_node)) {
+		ret = drm_gem_create_mmap_offset(obj);
+		if (ret)
+			goto unref;
+	}
+
+	BUG_ON(!obj->filp);
+
+	obj->filp->private_data = obj;
+
+	ret = vgem_gem_get_pages(to_vgem_bo(obj));
+	if (ret)
+		goto fail_get_pages;
+
+	*offset = drm_vma_node_offset_addr(&obj->vma_node);
+
+	goto unref;
+
+fail_get_pages:
+	drm_gem_free_mmap_offset(obj);
+unref:
+	drm_gem_object_unreference(obj);
+unlock:
+	mutex_unlock(&dev->struct_mutex);
+	return ret;
+}
+
+int vgem_drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+	struct drm_file *priv = filp->private_data;
+	struct drm_device *dev = priv->minor->dev;
+	struct drm_vma_offset_node *node;
+	struct drm_gem_object *obj;
+	struct drm_vgem_gem_object *vgem_obj;
+	int ret = 0;
+
+	mutex_lock(&dev->struct_mutex);
+
+	node = drm_vma_offset_exact_lookup(dev->vma_offset_manager,
+					   vma->vm_pgoff,
+					   vma_pages(vma));
+	if (!node) {
+		ret = -EINVAL;
+		goto out_unlock;
+	} else if (!drm_vma_node_is_allowed(node, filp)) {
+		ret = -EACCES;
+		goto out_unlock;
+	}
+
+	obj = container_of(node, struct drm_gem_object, vma_node);
+
+	vgem_obj = to_vgem_bo(obj);
+
+	if (obj->dma_buf && vgem_obj->use_dma_buf) {
+		ret = dma_buf_mmap(obj->dma_buf, vma, 0);
+		goto out_unlock;
+	}
+
+	if (!obj->dev->driver->gem_vm_ops) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	vma->vm_flags |= VM_IO | VM_MIXEDMAP | VM_DONTEXPAND | VM_DONTDUMP;
+	vma->vm_ops = obj->dev->driver->gem_vm_ops;
+	vma->vm_private_data = vgem_obj;
+	vma->vm_page_prot =
+		pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
+
+	mutex_unlock(&dev->struct_mutex);
+	drm_gem_vm_open(vma);
+	return ret;
+
+out_unlock:
+	mutex_unlock(&dev->struct_mutex);
+
+	return ret;
+}
+
+
+static struct drm_ioctl_desc vgem_ioctls[] = {
+};
+
+static const struct file_operations vgem_driver_fops = {
+	.owner		= THIS_MODULE,
+	.open		= drm_open,
+	.mmap		= vgem_drm_gem_mmap,
+	.poll		= drm_poll,
+	.read		= drm_read,
+	.unlocked_ioctl = drm_ioctl,
+	.release	= drm_release,
+};
+
+static struct drm_driver vgem_driver = {
+	.driver_features		= DRIVER_GEM | DRIVER_PRIME,
+	.gem_free_object		= vgem_gem_free_object,
+	.gem_vm_ops			= &vgem_gem_vm_ops,
+	.ioctls				= vgem_ioctls,
+	.fops				= &vgem_driver_fops,
+	.dumb_create			= vgem_gem_dumb_create,
+	.dumb_map_offset		= vgem_gem_dumb_map,
+	.prime_handle_to_fd		= drm_gem_prime_handle_to_fd,
+	.prime_fd_to_handle		= drm_gem_prime_fd_to_handle,
+	.gem_prime_export		= drm_gem_prime_export,
+	.gem_prime_import		= vgem_gem_prime_import,
+	.gem_prime_pin			= vgem_gem_prime_pin,
+	.gem_prime_unpin		= vgem_gem_prime_unpin,
+	.gem_prime_get_sg_table		= vgem_gem_prime_get_sg_table,
+	.gem_prime_vmap			= vgem_gem_prime_vmap,
+	.gem_prime_vunmap		= vgem_gem_prime_vunmap,
+	.name	= DRIVER_NAME,
+	.desc	= DRIVER_DESC,
+	.date	= DRIVER_DATE,
+	.major	= DRIVER_MAJOR,
+	.minor	= DRIVER_MINOR,
+};
+
+struct drm_device *vgem_device;
+
+static int __init vgem_init(void)
+{
+	int ret;
+
+	vgem_device = drm_dev_alloc(&vgem_driver, NULL);
+	if (!vgem_device) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ret  = drm_dev_register(vgem_device, 0);
+
+	if (ret)
+		goto out_unref;
+
+	return 0;
+
+out_unref:
+	drm_dev_unref(vgem_device);
+out:
+	return ret;
+}
+
+static void __exit vgem_exit(void)
+{
+	drm_dev_unregister(vgem_device);
+	drm_dev_unref(vgem_device);
+}
+
+module_init(vgem_init);
+module_exit(vgem_exit);
+
+MODULE_AUTHOR("Red Hat, Inc.");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL and additional rights");

drivers/gpu/drm/vgem/vgem_drv.h

+/*
+ * Copyright © 2012 Intel Corporation
+ * Copyright © 2014 The Chromium OS Authors
+ *
+ * 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:
+ *    Ben Widawsky <ben@bwidawsk.net>
+ *
+ */
+
+#ifndef _VGEM_DRV_H_
+#define _VGEM_DRV_H_
+
+#include <drm/drmP.h>
+#include <drm/drm_gem.h>
+
+#define to_vgem_bo(x) container_of(x, struct drm_vgem_gem_object, base)
+struct drm_vgem_gem_object {
+	struct drm_gem_object base;
+	struct page **pages;
+	bool use_dma_buf;
+};
+
+/* vgem_drv.c */
+extern void vgem_gem_put_pages(struct drm_vgem_gem_object *obj);
+extern int vgem_gem_get_pages(struct drm_vgem_gem_object *obj);
+
+/* vgem_dma_buf.c */
+extern struct sg_table *vgem_gem_prime_get_sg_table(
+			struct drm_gem_object *gobj);
+extern int vgem_gem_prime_pin(struct drm_gem_object *gobj);
+extern void vgem_gem_prime_unpin(struct drm_gem_object *gobj);
+extern void *vgem_gem_prime_vmap(struct drm_gem_object *gobj);
+extern void vgem_gem_prime_vunmap(struct drm_gem_object *obj, void *vaddr);
+extern struct drm_gem_object *vgem_gem_prime_import(struct drm_device *dev,
+						    struct dma_buf *dma_buf);
+
+
+#endif