drm/vgem: virtual GEM provider (v4)drm-next-todo

In addition's to Adam's requirements below, I would like to use VGEM to
help support dma-buf development. VGEM is without quirks and makes both
development and debug of other importers and exporters substantially
easier.

v2:
Use fault based mmap instead of do_mmap

v3:
Drop the getparam
use the dumb bo interface

v4:
cleanup some bits that aren't needed, file private, misc methods,
change get_pages to return earlier if pages already, free dev private.
fix checkpatch warnings

[From Adam Jackson, RFCv1]
This is about as minimal of a virtual GEM service as possible.  My plan
is to use this with non-native-3D hardware for buffer sharing between X
and DRI.

The current drisw winsys assumes an unmodified X server, which means
it's hopelessly inefficient for both the push direction of SwapBuffers/
DrawPixels and the pull direction of GLX_EXT_texture_from_pixmap.  I'm
still working through the details of what the xserver support will look
like, but in broad strokes it's "use vgem for CreatePixmap and
optionally the shadowfb".

Obviously alpha quality, mostly looking for feedback on the approach or
any glaring bugs.  Eventually I'd like to see solutions for sharing gem
objects between drm devices and/or the dma_buf API, but that's a ways
down the road.

[RFCv1]
Signed-off-by: Adam Jackson <ajax@redhat.com>
[RFCv2]
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

5 files changed, 419 insertions, 0 deletions

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index e354bc0b052a..22ee088ab011 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -179,6 +179,14 @@ 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/vmwgfx/Kconfig"
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index c20da5bda355..f49f32f02249 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -38,6 +38,7 @@ 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_GMA500) += gma500/
diff --git a/drivers/gpu/drm/vgem/Makefile b/drivers/gpu/drm/vgem/Makefile
new file mode 100644
index 000000000000..3f4c7b842028
--- /dev/null
+++ b/drivers/gpu/drm/vgem/Makefile
@@ -0,0 +1,4 @@
+ccflags-y := -Iinclude/drm
+vgem-y := vgem_drv.o
+
+obj-$(CONFIG_DRM_VGEM)	+= vgem.o
diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
new file mode 100644
index 000000000000..588e8959fbef
--- /dev/null
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -0,0 +1,358 @@
+/*
+ * Copyright 2011 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
+ * 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 "drmP.h"
+#include "drm.h"
+#include <linux/module.h>
+#include <linux/ramfs.h>
+#include <linux/shmem_fs.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
+
+static int vgem_load(struct drm_device *dev, unsigned long flags)
+{
+	struct drm_vgem_private *dev_priv;
+
+	dev_priv = kzalloc(sizeof(*dev_priv), GFP_KERNEL);
+	if (!dev_priv)
+		return -ENOMEM;
+
+	dev->dev_private = dev_priv;
+	dev_priv->dev = dev;
+
+	return 0;
+}
+
+static int vgem_unload(struct drm_device *dev)
+{
+	kfree(dev->dev_private);
+	return 0;
+}
+
+static int vgem_gem_init_object(struct drm_gem_object *obj)
+{
+	return 0;
+}
+
+void vgem_gem_put_pages(struct drm_vgem_gem_object *obj)
+{
+	int num_pages = obj->base.size / PAGE_SIZE;
+	int i;
+
+	for (i = 0; i < num_pages; i++) {
+		if (obj->pages[i] == NULL)
+			break;
+		page_cache_release(obj->pages[i]);
+	}
+
+	drm_free_large(obj->pages);
+	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);
+
+	if (obj)
+		drm_gem_free_mmap_offset(obj);
+
+	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 address_space *mapping;
+	gfp_t gfpmask = __GFP_NORETRY | __GFP_NOWARN;
+	int num_pages, i, ret = 0;
+
+	if (obj->pages)
+		return 0;
+
+	num_pages = obj->base.size / PAGE_SIZE;
+
+	obj->pages = drm_malloc_ab(num_pages, sizeof(struct page *));
+	if (obj->pages == NULL)
+		return -ENOMEM;
+
+	mapping = obj->base.filp->f_path.dentry->d_inode->i_mapping;
+	gfpmask |= mapping_gfp_mask(mapping);
+
+	for (i = 0; i < num_pages; i++) {
+		struct page *page;
+		page = shmem_read_mapping_page_gfp(mapping, i, gfpmask);
+		if (IS_ERR(page)) {
+			ret = PTR_ERR(page);
+			goto err_out;
+		}
+		obj->pages[i] = page;
+	}
+
+	return ret;
+
+err_out:
+	vgem_gem_put_pages(obj);
+	return ret;
+}
+
+static int vgem_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct drm_vgem_gem_object *obj = to_vgem_bo(vma->vm_private_data);
+	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 = obj->base.size / PAGE_SIZE;
+
+	if (WARN_ON(page_offset > num_pages))
+		return VM_FAULT_SIGBUS;
+
+	ret = vgem_gem_get_pages(obj);
+	if (ret)
+		return ret;
+
+	ret = vm_insert_page(vma, (unsigned long)vmf->virtual_address,
+			     obj->pages[page_offset]);
+
+	/* Pretty dumb handler for now */
+	switch (ret) {
+	case 0:
+	case -ERESTARTSYS:
+	case -EINTR:
+		return VM_FAULT_NOPAGE;
+	default:
+		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_create_mmap_offset(gem_object);
+	if (err)
+		goto mmap_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_free_mmap_offset(gem_object);
+
+mmap_out:
+	drm_gem_object_release(gem_object);
+
+out:
+	kfree(gem_object);
+
+	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;
+
+	size = args->height * args->width * args->bpp;
+
+	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 = size;
+	args->pitch = args->width;
+
+	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)
+{
+	struct drm_gem_object *obj;
+
+	obj = drm_gem_object_lookup(dev, file, handle);
+	if (!obj)
+		return -ENOENT;
+
+	obj->filp->private_data = obj;
+
+	BUG_ON(!obj->map_list.map);
+
+	*offset = (uint64_t)obj->map_list.hash.key << PAGE_SHIFT;
+
+	drm_gem_object_unreference_unlocked(obj);
+
+	return 0;
+}
+
+static const struct file_operations vgem_driver_fops = {
+	.owner		= THIS_MODULE,
+	.open		= drm_open,
+	.mmap		= drm_gem_mmap,
+	.poll		= drm_poll,
+	.read		= drm_read,
+	.unlocked_ioctl = drm_ioctl,
+	.release	= drm_release,
+	.fasync		= drm_fasync,
+	.llseek		= noop_llseek,
+};
+
+static struct drm_driver vgem_driver = {
+	.driver_features	= DRIVER_BUS_PLATFORM | DRIVER_GEM,
+	.load			= vgem_load,
+	.unload			= vgem_unload,
+
+	.gem_init_object	= vgem_gem_init_object,
+	.gem_free_object	= vgem_gem_free_object,
+	.gem_vm_ops		= &vgem_gem_vm_ops,
+
+	.fops			= &vgem_driver_fops,
+
+	.dumb_create		= vgem_gem_dumb_create,
+	.dumb_map_offset	= vgem_gem_dumb_map,
+
+	.name	= DRIVER_NAME,
+	.desc	= DRIVER_DESC,
+	.date	= DRIVER_DATE,
+	.major	= DRIVER_MAJOR,
+	.minor	= DRIVER_MINOR,
+};
+
+static int vgem_platform_probe(struct platform_device *pdev)
+{
+	return drm_platform_init(&vgem_driver, pdev);
+}
+
+static int vgem_platform_remove(struct platform_device *pdev)
+{
+	drm_platform_exit(&vgem_driver, pdev);
+	return 0;
+}
+
+static struct platform_driver vgem_platform_driver = {
+	.probe		= vgem_platform_probe,
+	.remove		= __devexit_p(vgem_platform_remove),
+	.driver		= {
+		.owner	= THIS_MODULE,
+		.name	= DRIVER_NAME,
+	},
+};
+
+static struct platform_device *vgem_device;
+
+static int __init vgem_init(void)
+{
+	int ret;
+
+	ret = platform_driver_register(&vgem_platform_driver);
+	if (ret)
+		return ret;
+
+	vgem_device = platform_device_alloc("vgem", -1);
+	if (!vgem_device) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ret = platform_device_add(vgem_device);
+	if (!ret)
+		return 0;
+
+out:
+	platform_device_put(vgem_device);
+	platform_driver_unregister(&vgem_platform_driver);
+
+	return ret;
+}
+
+static void __exit vgem_exit(void)
+{
+	platform_device_unregister(vgem_device);
+	platform_driver_unregister(&vgem_platform_driver);
+}
+
+module_init(vgem_init);
+module_exit(vgem_exit);
+
+MODULE_AUTHOR("Red Hat, Inc.");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL and additional rights");
diff --git a/drivers/gpu/drm/vgem/vgem_drv.h b/drivers/gpu/drm/vgem/vgem_drv.h
new file mode 100644
index 000000000000..2502de8c32b9
--- /dev/null
+++ b/drivers/gpu/drm/vgem/vgem_drv.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright © 2012 Intel Corporation
+ *
+ * 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 "drmP.h"
+#include <linux/types.h>
+
+struct drm_vgem_private {
+	struct drm_device *dev;
+};
+
+#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;
+};
+
+/* 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);
+
+#endif