Date:   Thu,  3 Jan 2019 18:13:11 -0800
From:   rkir@...gle.com
To:     gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org, Roman Kiryanov <rkir@...gle.com>
Subject: [PATCH] drivers: misc: goldfish_address_space: add a driver

From: Roman Kiryanov <rkir@...gle.com>

A driver for the Goldfish Android emulator that occupies
address space to use it with the memory sharing device
on the QEMU side. The memory sharding device allocates
subranges and populate them with actual RAM.
This allows sharing host's memory with the guest.

Signed-off-by: Roman Kiryanov <rkir@...gle.com>
---
 drivers/misc/Kconfig                          |   9 +
 drivers/misc/Makefile                         |   1 +
 drivers/misc/goldfish_address_space.c         | 742 ++++++++++++++++++
 .../linux/goldfish/goldfish_address_space.h   |  27 +
 4 files changed, 779 insertions(+)
 create mode 100644 drivers/misc/goldfish_address_space.c
 create mode 100644 include/uapi/linux/goldfish/goldfish_address_space.h

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index f417b06e11c5..66518bbe4217 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -521,6 +521,15 @@ config PVPANIC
 	  a paravirtualized device provided by QEMU; it lets a virtual machine
 	  (guest) communicate panic events to the host.
 
+config GOLDFISH_ADDRESS_SPACE
+	tristate "A Goldfish driver that talks to the memory sharing device in QEMU"
+	depends on PCI
+	depends on GOLDFISH
+	help
+	  A Goldfish driver that allocates address space ranges in the guest to
+	  populate them later in the host. This allows sharing host's memory
+	  with the guest.
+
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
 source "drivers/misc/cb710/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index e39ccbbc1b3a..11c9f9d7d3a1 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -59,3 +59,4 @@ obj-$(CONFIG_PCI_ENDPOINT_TEST)	+= pci_endpoint_test.o
 obj-$(CONFIG_OCXL)		+= ocxl/
 obj-y				+= cardreader/
 obj-$(CONFIG_PVPANIC)   	+= pvpanic.o
+obj-$(CONFIG_GOLDFISH_ADDRESS_SPACE) += goldfish_address_space.o
diff --git a/drivers/misc/goldfish_address_space.c b/drivers/misc/goldfish_address_space.c
new file mode 100644
index 000000000000..3605adcdaf2e
--- /dev/null
+++ b/drivers/misc/goldfish_address_space.c
@@ -0,0 +1,742 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/wait.h>
+#include <linux/fs.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+#include <linux/miscdevice.h>
+
+#include <linux/device.h>
+#include <linux/pci_regs.h>
+#include <linux/pci_ids.h>
+#include <linux/pci.h>
+
+#include <uapi/linux/goldfish/goldfish_address_space.h>
+
+MODULE_DESCRIPTION("A driver for the Goldfish Android emulator that occupies "
+		   "address space to use it with the memory sharing device "
+		   "on the QEMU side. The memory sharding device allocates "
+		   "subranges and populate them with actual RAM. "
+		   "This allows sharing host's memory with the guest.");
+MODULE_AUTHOR("Roman Kiryanov <rkir@...gle.com>");
+MODULE_LICENSE("GPL v2");
+
+enum as_register_id {
+	AS_REGISTER_COMMAND = 0,
+	AS_REGISTER_STATUS = 4,
+	AS_REGISTER_GUEST_PAGE_SIZE = 8,
+	AS_REGISTER_BLOCK_SIZE_LOW = 12,
+	AS_REGISTER_BLOCK_SIZE_HIGH = 16,
+	AS_REGISTER_BLOCK_OFFSET_LOW = 20,
+	AS_REGISTER_BLOCK_OFFSET_HIGH = 24,
+};
+
+enum as_command_id {
+	AS_COMMAND_ALLOCATE_BLOCK = 1,
+	AS_COMMAND_DEALLOCATE_BLOCK = 2,
+};
+
+#define AS_PCI_VENDOR_ID	0x607D
+#define AS_PCI_DEVICE_ID	0xF153
+#define AS_MAGIC_U32		(AS_PCI_VENDOR_ID << 16 | AS_PCI_DEVICE_ID)
+#define AS_ALLOCATED_BLOCKS_INITIAL_CAPACITY 32
+
+enum as_pci_bar_id {
+	AS_PCI_CONTROL_BAR_ID = 0,
+	AS_PCI_AREA_BAR_ID = 1,
+};
+
+struct as_driver_state;
+
+struct as_device_state {
+	u32	magic;
+
+	struct miscdevice	miscdevice;
+	struct pci_dev		*dev;
+	struct as_driver_state	*driver_state;
+
+	void __iomem		*io_registers;
+
+	void			*address_area;	/* to claim the address space */
+
+	/* physical address to allocate from */
+	unsigned long		address_area_phys_address;
+
+	struct mutex		registers_lock;	/* protects registers */
+
+	wait_queue_head_t	wake_queue;	/* to wait for the hardware */
+
+	int			hw_done;	/* to say hw is done */
+};
+
+struct as_driver_state {
+	struct as_device_state *device_state;
+	struct pci_driver pci;
+};
+
+struct as_block {
+	u64 offset;
+	u64 size;
+};
+
+struct as_allocated_blocks {
+	struct as_device_state *state;
+
+	struct as_block *blocks;  /* a dynamic array of allocated blocks */
+	int blocks_size;
+	int blocks_capacity;
+	struct mutex blocks_lock; /* protects operations with blocks */
+};
+
+static void __iomem *as_register_address(void __iomem *base,
+					 int offset)
+{
+	return ((char __iomem *)base) + offset;
+}
+
+static void as_write_register(void __iomem *registers,
+			      int offset,
+			      u32 value)
+{
+	writel(value, as_register_address(registers, offset));
+}
+
+static u32 as_read_register(void __iomem *registers, int offset)
+{
+	return readl(as_register_address(registers, offset));
+}
+
+static int
+as_talk_to_hardware(struct as_device_state *state, enum as_command_id cmd)
+{
+	state->hw_done = 0;
+	as_write_register(state->io_registers, AS_REGISTER_COMMAND, cmd);
+	wait_event(state->wake_queue, state->hw_done);
+	return -as_read_register(state->io_registers,
+				 AS_REGISTER_STATUS);
+}
+
+static long
+as_ioctl_allocate_block_locked_impl(struct as_device_state *state,
+				    u64 *size, u64 *offset)
+{
+	long res;
+
+	as_write_register(state->io_registers,
+			  AS_REGISTER_BLOCK_SIZE_LOW,
+			  lower_32_bits(*size));
+	as_write_register(state->io_registers,
+			  AS_REGISTER_BLOCK_SIZE_HIGH,
+			  upper_32_bits(*size));
+
+	res = as_talk_to_hardware(state, AS_COMMAND_ALLOCATE_BLOCK);
+	if (!res) {
+		u64 low = as_read_register(state->io_registers,
+					   AS_REGISTER_BLOCK_OFFSET_LOW);
+		u64 high = as_read_register(state->io_registers,
+					    AS_REGISTER_BLOCK_OFFSET_HIGH);
+		*offset = low | (high << 32);
+
+		low = as_read_register(state->io_registers,
+				       AS_REGISTER_BLOCK_SIZE_LOW);
+		high = as_read_register(state->io_registers,
+					AS_REGISTER_BLOCK_SIZE_HIGH);
+		*size = low | (high << 32);
+	}
+
+	return res;
+}
+
+static long
+as_ioctl_unallocate_block_locked_impl(struct as_device_state *state, u64 offset)
+{
+	as_write_register(state->io_registers,
+			  AS_REGISTER_BLOCK_OFFSET_LOW,
+			  lower_32_bits(offset));
+	as_write_register(state->io_registers,
+			  AS_REGISTER_BLOCK_OFFSET_HIGH,
+			  upper_32_bits(offset));
+
+	return as_talk_to_hardware(state, AS_COMMAND_DEALLOCATE_BLOCK);
+}
+
+static int as_blocks_grow_capacity(int old_capacity)
+{
+	WARN_ON(old_capacity < 0);
+
+	return old_capacity + old_capacity;
+}
+
+static int
+as_blocks_insert(struct as_allocated_blocks *allocated_blocks,
+		 u64 offset,
+		 u64 size)
+{
+	int blocks_size;
+
+	if (mutex_lock_interruptible(&allocated_blocks->blocks_lock))
+		return -ERESTARTSYS;
+
+	blocks_size = allocated_blocks->blocks_size;
+
+	WARN_ON(allocated_blocks->blocks_capacity < 1);
+	WARN_ON(allocated_blocks->blocks_capacity <
+		allocated_blocks->blocks_size);
+	WARN_ON(!allocated_blocks->blocks);
+
+	if (allocated_blocks->blocks_capacity == blocks_size) {
+		int new_capacity =
+			as_blocks_grow_capacity(
+				allocated_blocks->blocks_capacity);
+		struct as_block *new_blocks =
+			kcalloc(new_capacity,
+				sizeof(allocated_blocks->blocks[0]),
+				GFP_KERNEL);
+
+		if (!new_blocks) {
+			mutex_unlock(&allocated_blocks->blocks_lock);
+			return -ENOMEM;
+		}
+
+		memcpy(new_blocks, allocated_blocks->blocks,
+		       blocks_size * sizeof(allocated_blocks->blocks[0]));
+
+		kfree(allocated_blocks->blocks);
+		allocated_blocks->blocks = new_blocks;
+		allocated_blocks->blocks_capacity = new_capacity;
+	}
+
+	WARN_ON(blocks_size >= allocated_blocks->blocks_capacity);
+
+	allocated_blocks->blocks[blocks_size] =
+		(struct as_block){ .offset = offset, .size = size };
+	allocated_blocks->blocks_size = blocks_size + 1;
+
+	mutex_unlock(&allocated_blocks->blocks_lock);
+	return 0;
+}
+
+static int
+as_blocks_remove(struct as_allocated_blocks *allocated_blocks, u64 offset)
+{
+	long res = -ENXIO;
+	struct as_block *blocks;
+	int blocks_size;
+	int i;
+
+	if (mutex_lock_interruptible(&allocated_blocks->blocks_lock))
+		return -ERESTARTSYS;
+
+	blocks = allocated_blocks->blocks;
+	WARN_ON(!blocks);
+
+	blocks_size = allocated_blocks->blocks_size;
+	WARN_ON(blocks_size < 0);
+
+	for (i = 0; i < blocks_size; ++i) {
+		if (offset == blocks[i].offset) {
+			int last = blocks_size - 1;
+
+			if (last > i)
+				blocks[i] = blocks[last];
+
+			--allocated_blocks->blocks_size;
+			res = 0;
+			break;
+		}
+	}
+
+	mutex_unlock(&allocated_blocks->blocks_lock);
+	return res;
+}
+
+static int
+as_blocks_check_if_mine(struct as_allocated_blocks *allocated_blocks,
+			u64 offset,
+			u64 size)
+{
+	int res = -ENXIO;
+	struct as_block *block;
+	int blocks_size;
+
+	if (mutex_lock_interruptible(&allocated_blocks->blocks_lock))
+		return -ERESTARTSYS;
+
+	block = allocated_blocks->blocks;
+	WARN_ON(!block);
+
+	blocks_size = allocated_blocks->blocks_size;
+	WARN_ON(blocks_size < 0);
+
+	for (; blocks_size > 0; --blocks_size, ++block) {
+		if (block->offset == offset) {
+			res = (block->size >= size) ? 0 : -EPERM;
+			break;
+		}
+	}
+
+	mutex_unlock(&allocated_blocks->blocks_lock);
+	return res;
+}
+
+static int as_open(struct inode *inode, struct file *filp)
+{
+	struct as_allocated_blocks *allocated_blocks;
+
+	allocated_blocks = kzalloc(sizeof(*allocated_blocks), GFP_KERNEL);
+	if (!allocated_blocks)
+		return -ENOMEM;
+
+	allocated_blocks->state =
+		container_of(filp->private_data,
+			     struct as_device_state,
+			     miscdevice);
+
+	allocated_blocks->blocks =
+		kcalloc(AS_ALLOCATED_BLOCKS_INITIAL_CAPACITY,
+			sizeof(allocated_blocks->blocks[0]),
+			GFP_KERNEL);
+	if (!allocated_blocks->blocks) {
+		kfree(allocated_blocks);
+		return -ENOMEM;
+	}
+
+	allocated_blocks->blocks_size = 0;
+	allocated_blocks->blocks_capacity =
+		AS_ALLOCATED_BLOCKS_INITIAL_CAPACITY;
+	mutex_init(&allocated_blocks->blocks_lock);
+
+	filp->private_data = allocated_blocks;
+	return 0;
+}
+
+static int as_release(struct inode *inode, struct file *filp)
+{
+	struct as_allocated_blocks *allocated_blocks = filp->private_data;
+	struct as_device_state *state;
+	int blocks_size;
+	int i;
+
+	WARN_ON(!allocated_blocks);
+	WARN_ON(!allocated_blocks->state);
+	WARN_ON(!allocated_blocks->blocks);
+	WARN_ON(allocated_blocks->blocks_size < 0);
+
+	state = allocated_blocks->state;
+	blocks_size = allocated_blocks->blocks_size;
+
+	if (mutex_lock_interruptible(&state->registers_lock))
+		return -ERESTARTSYS;
+
+	for (i = 0; i < blocks_size; ++i) {
+		WARN_ON(as_ioctl_unallocate_block_locked_impl(
+			state, allocated_blocks->blocks[i].offset));
+	}
+
+	mutex_unlock(&state->registers_lock);
+
+	kfree(allocated_blocks->blocks);
+	kfree(allocated_blocks);
+	return 0;
+}
+
+static int as_mmap_impl(struct as_device_state *state,
+			size_t size,
+			struct vm_area_struct *vma)
+{
+	unsigned long pfn = (state->address_area_phys_address >> PAGE_SHIFT) +
+		vma->vm_pgoff;
+
+	return remap_pfn_range(vma,
+			       vma->vm_start,
+			       pfn,
+			       size,
+			       vma->vm_page_prot);
+}
+
+static int as_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+	struct as_allocated_blocks *allocated_blocks = filp->private_data;
+	size_t size = PAGE_ALIGN(vma->vm_end - vma->vm_start);
+	int res;
+
+	WARN_ON(!allocated_blocks);
+
+	res = as_blocks_check_if_mine(allocated_blocks,
+				      vma->vm_pgoff << PAGE_SHIFT,
+				      size);
+
+	if (res)
+		return res;
+	else
+		return as_mmap_impl(allocated_blocks->state, size, vma);
+}
+
+static long as_ioctl_allocate_block_impl(
+	struct as_device_state *state,
+	struct goldfish_address_space_allocate_block *request)
+{
+	long res;
+
+	if (mutex_lock_interruptible(&state->registers_lock))
+		return -ERESTARTSYS;
+
+	res = as_ioctl_allocate_block_locked_impl(state,
+						  &request->size,
+						  &request->offset);
+	if (!res) {
+		request->phys_addr =
+			state->address_area_phys_address + request->offset;
+	}
+
+	mutex_unlock(&state->registers_lock);
+	return res;
+}
+
+static void
+as_ioctl_unallocate_block_impl(struct as_device_state *state, u64 offset)
+{
+	mutex_lock(&state->registers_lock);
+	WARN_ON(as_ioctl_unallocate_block_locked_impl(state, offset));
+	mutex_unlock(&state->registers_lock);
+}
+
+static long
+as_ioctl_allocate_block(struct as_allocated_blocks *allocated_blocks,
+			void __user *ptr)
+{
+	long res;
+	struct as_device_state *state = allocated_blocks->state;
+	struct goldfish_address_space_allocate_block request;
+
+	if (copy_from_user(&request, ptr, sizeof(request)))
+		return -EFAULT;
+
+	res = as_ioctl_allocate_block_impl(state, &request);
+	if (!res) {
+		res = as_blocks_insert(allocated_blocks,
+				       request.offset,
+				       request.size);
+
+		if (res) {
+			as_ioctl_unallocate_block_impl(state, request.offset);
+		} else if (copy_to_user(ptr, &request, sizeof(request))) {
+			as_ioctl_unallocate_block_impl(state, request.offset);
+			res = -EFAULT;
+		}
+	}
+
+	return res;
+}
+
+static long
+as_ioctl_unallocate_block(struct as_allocated_blocks *allocated_blocks,
+			  void __user *ptr)
+{
+	long res;
+	u64 offset;
+
+	if (copy_from_user(&offset, ptr, sizeof(offset)))
+		return -EFAULT;
+
+	res = as_blocks_remove(allocated_blocks, offset);
+	if (!res)
+		as_ioctl_unallocate_block_impl(allocated_blocks->state, offset);
+
+	return res;
+}
+
+static long as_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+	struct as_allocated_blocks *allocated_blocks = filp->private_data;
+
+	switch (cmd) {
+	case GOLDFISH_ADDRESS_SPACE_IOCTL_ALLOCATE_BLOCK:
+		return as_ioctl_allocate_block(allocated_blocks,
+					       (void __user *)arg);
+
+	case GOLDFISH_ADDRESS_SPACE_IOCTL_DEALLOCATE_BLOCK:
+		return as_ioctl_unallocate_block(allocated_blocks,
+						 (void __user *)arg);
+
+	default:
+		return -ENOTTY;
+	}
+}
+
+static const struct file_operations userspace_file_operations = {
+	.owner = THIS_MODULE,
+	.open = as_open,
+	.release = as_release,
+	.mmap = as_mmap,
+	.unlocked_ioctl = as_ioctl,
+	.compat_ioctl = as_ioctl,
+};
+
+static void __iomem __must_check *ioremap_pci_bar(struct pci_dev *dev,
+						  int bar_id)
+{
+	void __iomem *io;
+	unsigned long size = pci_resource_len(dev, bar_id);
+
+	if (!size)
+		return IOMEM_ERR_PTR(-ENXIO);
+
+	io = ioremap(pci_resource_start(dev, bar_id), size);
+	if (!io)
+		return IOMEM_ERR_PTR(-ENOMEM);
+
+	return io;
+}
+
+static void __must_check *memremap_pci_bar(struct pci_dev *dev,
+					   int bar_id,
+					   unsigned long flags)
+{
+	void *mem;
+	unsigned long size = pci_resource_len(dev, bar_id);
+
+	if (!size)
+		return ERR_PTR(-ENXIO);
+
+	mem = memremap(pci_resource_start(dev, bar_id), size, flags);
+	if (!mem)
+		return ERR_PTR(-ENOMEM);
+
+	return mem;
+}
+
+static void as_clear_device(struct as_device_state *state)
+{
+	struct as_driver_state *driver_state = state->driver_state;
+
+	WARN_ON(!driver_state->device_state);
+	driver_state->device_state = NULL;
+}
+
+static irqreturn_t __must_check as_interrupt_impl(struct as_device_state *state)
+{
+	state->hw_done = 1;
+	wake_up_interruptible(&state->wake_queue);
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t as_interrupt(int irq, void *dev_id)
+{
+	struct as_device_state *state = dev_id;
+
+	return (state->magic == AS_MAGIC_U32)
+		? as_interrupt_impl(state) : IRQ_NONE;
+}
+
+static void fill_miscdevice(struct miscdevice *miscdev)
+{
+	memset(miscdev, 0, sizeof(*miscdev));
+
+	miscdev->minor = MISC_DYNAMIC_MINOR;
+	miscdev->name = GOLDFISH_ADDRESS_SPACE_DEVICE_NAME;
+	miscdev->fops = &userspace_file_operations;
+}
+
+static int __must_check
+create_as_device(struct pci_dev *dev,
+		 const struct pci_device_id *id,
+		 struct as_driver_state *driver_state)
+{
+	int res;
+	struct as_device_state *state;
+
+	state = kzalloc(sizeof(*state), GFP_KERNEL);
+	if (!state)
+		return -ENOMEM;
+
+	res = pci_request_region(dev,
+				 AS_PCI_CONTROL_BAR_ID,
+				 "Address space control");
+	if (res) {
+		pr_err("(bn 0x%X, sn 0x%X) failed to allocate PCI resource for BAR%d",
+		       dev->bus->number,
+		       dev->devfn,
+		       AS_PCI_CONTROL_BAR_ID);
+		goto out_free_device_state;
+	}
+
+	res = pci_request_region(dev,
+				 AS_PCI_AREA_BAR_ID,
+				 "Address space area");
+	if (res) {
+		pr_err("(bn 0x%X, sn 0x%X) failed to allocate PCI resource for BAR%d",
+		       dev->bus->number,
+		       dev->devfn,
+		       AS_PCI_AREA_BAR_ID);
+		goto out_release_control_bar;
+	}
+
+	fill_miscdevice(&state->miscdevice);
+	res = misc_register(&state->miscdevice);
+	if (res)
+		goto out_release_area_bar;
+
+	state->io_registers = ioremap_pci_bar(dev,
+					      AS_PCI_CONTROL_BAR_ID);
+	if (IS_ERR(state->io_registers)) {
+		res = PTR_ERR(state->io_registers);
+		goto out_misc_deregister;
+	}
+
+	state->address_area = memremap_pci_bar(dev,
+					       AS_PCI_AREA_BAR_ID,
+					       MEMREMAP_WB);
+	if (IS_ERR(state->address_area)) {
+		res = PTR_ERR(state->address_area);
+		goto out_iounmap;
+	}
+
+	state->address_area_phys_address =
+		pci_resource_start(dev, AS_PCI_AREA_BAR_ID);
+
+	res = request_irq(dev->irq,
+			  as_interrupt, IRQF_SHARED,
+			  KBUILD_MODNAME, state);
+	if (res)
+		goto out_memunmap;
+
+	as_write_register(state->io_registers,
+			  AS_REGISTER_GUEST_PAGE_SIZE,
+			  PAGE_SIZE);
+
+	state->magic = AS_MAGIC_U32;
+	state->dev = dev;
+	state->driver_state = driver_state;
+	mutex_init(&state->registers_lock);
+	init_waitqueue_head(&state->wake_queue);
+
+	driver_state->device_state = state;
+
+	pci_set_drvdata(dev, state);
+	return 0;
+
+out_memunmap:
+	memunmap(state->address_area);
+out_iounmap:
+	iounmap(state->io_registers);
+out_misc_deregister:
+	misc_deregister(&state->miscdevice);
+out_release_area_bar:
+	pci_release_region(dev, AS_PCI_AREA_BAR_ID);
+out_release_control_bar:
+	pci_release_region(dev, AS_PCI_CONTROL_BAR_ID);
+out_free_device_state:
+	kzfree(state);
+
+	return res;
+}
+
+static void as_destroy_device(struct as_device_state *state)
+{
+	as_clear_device(state);
+	free_irq(state->dev->irq, state);
+	memunmap(state->address_area);
+	iounmap(state->io_registers);
+	misc_deregister(&state->miscdevice);
+	pci_release_region(state->dev, AS_PCI_AREA_BAR_ID);
+	pci_release_region(state->dev, AS_PCI_CONTROL_BAR_ID);
+	kfree(state);
+}
+
+static int __must_check as_pci_probe_impl(struct pci_dev *dev,
+					  const struct pci_device_id *id,
+					  struct as_driver_state *driver_state)
+{
+	int res;
+	u8 hardware_revision;
+
+	res = pci_enable_device(dev);
+	if (res)
+		return res;
+
+	res = pci_read_config_byte(dev, PCI_REVISION_ID, &hardware_revision);
+	if (res)
+		goto out_disable_pci;
+
+	switch (hardware_revision) {
+	case 1:
+		res = create_as_device(dev, id, driver_state);
+		break;
+
+	default:
+		res = -ENODEV;
+		goto out_disable_pci;
+	}
+
+	return 0;
+
+out_disable_pci:
+	pci_disable_device(dev);
+
+	return res;
+}
+
+static void as_pci_remove(struct pci_dev *dev)
+{
+	struct as_device_state *state = pci_get_drvdata(dev);
+
+	as_destroy_device(state);
+	pci_disable_device(dev);
+}
+
+static const struct pci_device_id as_pci_tbl[] = {
+	{ PCI_DEVICE(AS_PCI_VENDOR_ID, AS_PCI_DEVICE_ID), },
+	{ }
+};
+MODULE_DEVICE_TABLE(pci, as_pci_tbl);
+
+static int as_pci_probe(struct pci_dev *dev, const struct pci_device_id *id);
+
+static void __init fill_pci_driver(struct pci_driver *pci)
+{
+	pci->name = GOLDFISH_ADDRESS_SPACE_DEVICE_NAME;
+	pci->id_table = as_pci_tbl;
+	pci->probe = &as_pci_probe;
+	pci->remove = &as_pci_remove;
+	pci->shutdown = &as_pci_remove;
+}
+
+static int __must_check __init init_as_impl(struct as_driver_state *state)
+{
+	state->device_state = NULL;
+	fill_pci_driver(&state->pci);
+
+	return pci_register_driver(&state->pci);
+}
+
+static void __exit exit_as_impl(struct as_driver_state *state)
+{
+	WARN_ON(state->device_state);
+
+	pci_unregister_driver(&state->pci);
+}
+
+static struct as_driver_state g_driver_state;
+
+static int as_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
+{
+	return as_pci_probe_impl(dev, id, &g_driver_state);
+}
+
+static int __init init_address_space(void)
+{
+	memset(&g_driver_state, 0, sizeof(g_driver_state));
+	return init_as_impl(&g_driver_state);
+}
+
+static void __exit exit_address_space(void)
+{
+	exit_as_impl(&g_driver_state);
+}
+
+module_init(init_address_space);
+module_exit(exit_address_space);
diff --git a/include/uapi/linux/goldfish/goldfish_address_space.h b/include/uapi/linux/goldfish/goldfish_address_space.h
new file mode 100644
index 000000000000..b1d11f95a4e1
--- /dev/null
+++ b/include/uapi/linux/goldfish/goldfish_address_space.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef UAPI_GOLDFISH_ADDRESS_SPACE_H
+#define UAPI_GOLDFISH_ADDRESS_SPACE_H
+
+#include <linux/types.h>
+
+#define GOLDFISH_ADDRESS_SPACE_DEVICE_NAME	"goldfish_address_space"
+
+struct goldfish_address_space_allocate_block {
+	__u64 size;
+	__u64 offset;
+	__u64 phys_addr;
+};
+
+#define GOLDFISH_ADDRESS_SPACE_IOCTL_MAGIC	'G'
+
+#define GOLDFISH_ADDRESS_SPACE_IOCTL_OP(OP, T)	\
+	_IOWR(GOLDFISH_ADDRESS_SPACE_IOCTL_MAGIC, OP, T)
+
+#define GOLDFISH_ADDRESS_SPACE_IOCTL_ALLOCATE_BLOCK \
+	GOLDFISH_ADDRESS_SPACE_IOCTL_OP(10, \
+		struct goldfish_address_space_allocate_block)
+
+#define GOLDFISH_ADDRESS_SPACE_IOCTL_DEALLOCATE_BLOCK \
+	GOLDFISH_ADDRESS_SPACE_IOCTL_OP(11, __u64)
+
+#endif /* UAPI_GOLDFISH_ADDRESS_SPACE_H */
-- 
2.20.1.415.g653613c723-goog

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