Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

14 files changed, 9730 insertions, 0 deletions

diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
new file mode 100644
index 000000000..7b41130d3
--- /dev/null
+++ b/drivers/virtio/Kconfig
@@ -0,0 +1,142 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config VIRTIO
+	tristate
+	help
+	  This option is selected by any driver which implements the virtio
+	  bus, such as CONFIG_VIRTIO_PCI, CONFIG_VIRTIO_MMIO, CONFIG_RPMSG
+	  or CONFIG_S390_GUEST.
+
+config ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
+	bool
+	help
+	  This option is selected if the architecture may need to enforce
+	  VIRTIO_F_ACCESS_PLATFORM
+
+menuconfig VIRTIO_MENU
+	bool "Virtio drivers"
+	default y
+
+if VIRTIO_MENU
+
+config VIRTIO_PCI
+	tristate "PCI driver for virtio devices"
+	depends on PCI
+	select VIRTIO
+	help
+	  This driver provides support for virtio based paravirtual device
+	  drivers over PCI.  This requires that your VMM has appropriate PCI
+	  virtio backends.  Most QEMU based VMMs should support these devices
+	  (like KVM or Xen).
+
+	  If unsure, say M.
+
+config VIRTIO_PCI_LEGACY
+	bool "Support for legacy virtio draft 0.9.X and older devices"
+	default y
+	depends on VIRTIO_PCI
+	help
+          Virtio PCI Card 0.9.X Draft (circa 2014) and older device support.
+
+	  This option enables building a transitional driver, supporting
+	  both devices conforming to Virtio 1 specification, and legacy devices.
+	  If disabled, you get a slightly smaller, non-transitional driver,
+	  with no legacy compatibility.
+
+          So look out into your driveway.  Do you have a flying car?  If
+          so, you can happily disable this option and virtio will not
+          break.  Otherwise, leave it set.  Unless you're testing what
+          life will be like in The Future.
+
+	  If unsure, say Y.
+
+config VIRTIO_VDPA
+	tristate "vDPA driver for virtio devices"
+	depends on VDPA
+	select VIRTIO
+	help
+	  This driver provides support for virtio based paravirtual
+	  device driver over vDPA bus. For this to be useful, you need
+	  an appropriate vDPA device implementation that operates on a
+	  physical device to allow the datapath of virtio to be
+	  offloaded to hardware.
+
+	  If unsure, say M.
+
+config VIRTIO_PMEM
+	tristate "Support for virtio pmem driver"
+	depends on VIRTIO
+	depends on LIBNVDIMM
+	help
+	  This driver provides access to virtio-pmem devices, storage devices
+	  that are mapped into the physical address space - similar to NVDIMMs
+	   - with a virtio-based flushing interface.
+
+	  If unsure, say Y.
+
+config VIRTIO_BALLOON
+	tristate "Virtio balloon driver"
+	depends on VIRTIO
+	select MEMORY_BALLOON
+	select PAGE_REPORTING
+	help
+	 This driver supports increasing and decreasing the amount
+	 of memory within a KVM guest.
+
+	 If unsure, say M.
+
+config VIRTIO_MEM
+	tristate "Virtio mem driver"
+	default m
+	depends on X86_64
+	depends on VIRTIO
+	depends on MEMORY_HOTPLUG_SPARSE
+	depends on MEMORY_HOTREMOVE
+	depends on CONTIG_ALLOC
+	help
+	 This driver provides access to virtio-mem paravirtualized memory
+	 devices, allowing to hotplug and hotunplug memory.
+
+	 This driver was only tested under x86-64, but should theoretically
+	 work on all architectures that support memory hotplug and hotremove.
+
+	 If unsure, say M.
+
+config VIRTIO_INPUT
+	tristate "Virtio input driver"
+	depends on VIRTIO
+	depends on INPUT
+	help
+	 This driver supports virtio input devices such as
+	 keyboards, mice and tablets.
+
+	 If unsure, say M.
+
+config VIRTIO_MMIO
+	tristate "Platform bus driver for memory mapped virtio devices"
+	depends on HAS_IOMEM && HAS_DMA
+	select VIRTIO
+	help
+	 This drivers provides support for memory mapped virtio
+	 platform device driver.
+
+ 	 If unsure, say N.
+
+config VIRTIO_MMIO_CMDLINE_DEVICES
+	bool "Memory mapped virtio devices parameter parsing"
+	depends on VIRTIO_MMIO
+	help
+	 Allow virtio-mmio devices instantiation via the kernel command line
+	 or module parameters. Be aware that using incorrect parameters (base
+	 address in particular) can crash your system - you have been warned.
+	 See Documentation/admin-guide/kernel-parameters.rst for details.
+
+	 If unsure, say 'N'.
+
+config VIRTIO_DMA_SHARED_BUFFER
+	tristate
+	depends on DMA_SHARED_BUFFER
+	help
+	 This option adds a flavor of dma buffers that are backed by
+	 virtio resources.
+
+endif # VIRTIO_MENU
diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
new file mode 100644
index 000000000..591e6f72a
--- /dev/null
+++ b/drivers/virtio/Makefile
@@ -0,0 +1,11 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_VIRTIO) += virtio.o virtio_ring.o
+obj-$(CONFIG_VIRTIO_MMIO) += virtio_mmio.o
+obj-$(CONFIG_VIRTIO_PCI) += virtio_pci.o
+virtio_pci-y := virtio_pci_modern.o virtio_pci_common.o
+virtio_pci-$(CONFIG_VIRTIO_PCI_LEGACY) += virtio_pci_legacy.o
+obj-$(CONFIG_VIRTIO_BALLOON) += virtio_balloon.o
+obj-$(CONFIG_VIRTIO_INPUT) += virtio_input.o
+obj-$(CONFIG_VIRTIO_VDPA) += virtio_vdpa.o
+obj-$(CONFIG_VIRTIO_MEM) += virtio_mem.o
+obj-$(CONFIG_VIRTIO_DMA_SHARED_BUFFER) += virtio_dma_buf.o
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
new file mode 100644
index 000000000..441bc0578
--- /dev/null
+++ b/drivers/virtio/virtio.c
@@ -0,0 +1,484 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/virtio.h>
+#include <linux/spinlock.h>
+#include <linux/virtio_config.h>
+#include <linux/module.h>
+#include <linux/idr.h>
+#include <uapi/linux/virtio_ids.h>
+
+/* Unique numbering for virtio devices. */
+static DEFINE_IDA(virtio_index_ida);
+
+static ssize_t device_show(struct device *_d,
+			   struct device_attribute *attr, char *buf)
+{
+	struct virtio_device *dev = dev_to_virtio(_d);
+	return sprintf(buf, "0x%04x\n", dev->id.device);
+}
+static DEVICE_ATTR_RO(device);
+
+static ssize_t vendor_show(struct device *_d,
+			   struct device_attribute *attr, char *buf)
+{
+	struct virtio_device *dev = dev_to_virtio(_d);
+	return sprintf(buf, "0x%04x\n", dev->id.vendor);
+}
+static DEVICE_ATTR_RO(vendor);
+
+static ssize_t status_show(struct device *_d,
+			   struct device_attribute *attr, char *buf)
+{
+	struct virtio_device *dev = dev_to_virtio(_d);
+	return sprintf(buf, "0x%08x\n", dev->config->get_status(dev));
+}
+static DEVICE_ATTR_RO(status);
+
+static ssize_t modalias_show(struct device *_d,
+			     struct device_attribute *attr, char *buf)
+{
+	struct virtio_device *dev = dev_to_virtio(_d);
+	return sprintf(buf, "virtio:d%08Xv%08X\n",
+		       dev->id.device, dev->id.vendor);
+}
+static DEVICE_ATTR_RO(modalias);
+
+static ssize_t features_show(struct device *_d,
+			     struct device_attribute *attr, char *buf)
+{
+	struct virtio_device *dev = dev_to_virtio(_d);
+	unsigned int i;
+	ssize_t len = 0;
+
+	/* We actually represent this as a bitstring, as it could be
+	 * arbitrary length in future. */
+	for (i = 0; i < sizeof(dev->features)*8; i++)
+		len += sprintf(buf+len, "%c",
+			       __virtio_test_bit(dev, i) ? '1' : '0');
+	len += sprintf(buf+len, "\n");
+	return len;
+}
+static DEVICE_ATTR_RO(features);
+
+static struct attribute *virtio_dev_attrs[] = {
+	&dev_attr_device.attr,
+	&dev_attr_vendor.attr,
+	&dev_attr_status.attr,
+	&dev_attr_modalias.attr,
+	&dev_attr_features.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(virtio_dev);
+
+static inline int virtio_id_match(const struct virtio_device *dev,
+				  const struct virtio_device_id *id)
+{
+	if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID)
+		return 0;
+
+	return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor;
+}
+
+/* This looks through all the IDs a driver claims to support.  If any of them
+ * match, we return 1 and the kernel will call virtio_dev_probe(). */
+static int virtio_dev_match(struct device *_dv, struct device_driver *_dr)
+{
+	unsigned int i;
+	struct virtio_device *dev = dev_to_virtio(_dv);
+	const struct virtio_device_id *ids;
+
+	ids = drv_to_virtio(_dr)->id_table;
+	for (i = 0; ids[i].device; i++)
+		if (virtio_id_match(dev, &ids[i]))
+			return 1;
+	return 0;
+}
+
+static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env)
+{
+	struct virtio_device *dev = dev_to_virtio(_dv);
+
+	return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X",
+			      dev->id.device, dev->id.vendor);
+}
+
+void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
+					 unsigned int fbit)
+{
+	unsigned int i;
+	struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);
+
+	for (i = 0; i < drv->feature_table_size; i++)
+		if (drv->feature_table[i] == fbit)
+			return;
+
+	if (drv->feature_table_legacy) {
+		for (i = 0; i < drv->feature_table_size_legacy; i++)
+			if (drv->feature_table_legacy[i] == fbit)
+				return;
+	}
+
+	BUG();
+}
+EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
+
+static void __virtio_config_changed(struct virtio_device *dev)
+{
+	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
+
+	if (!dev->config_enabled)
+		dev->config_change_pending = true;
+	else if (drv && drv->config_changed)
+		drv->config_changed(dev);
+}
+
+void virtio_config_changed(struct virtio_device *dev)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->config_lock, flags);
+	__virtio_config_changed(dev);
+	spin_unlock_irqrestore(&dev->config_lock, flags);
+}
+EXPORT_SYMBOL_GPL(virtio_config_changed);
+
+void virtio_config_disable(struct virtio_device *dev)
+{
+	spin_lock_irq(&dev->config_lock);
+	dev->config_enabled = false;
+	spin_unlock_irq(&dev->config_lock);
+}
+EXPORT_SYMBOL_GPL(virtio_config_disable);
+
+void virtio_config_enable(struct virtio_device *dev)
+{
+	spin_lock_irq(&dev->config_lock);
+	dev->config_enabled = true;
+	if (dev->config_change_pending)
+		__virtio_config_changed(dev);
+	dev->config_change_pending = false;
+	spin_unlock_irq(&dev->config_lock);
+}
+EXPORT_SYMBOL_GPL(virtio_config_enable);
+
+void virtio_add_status(struct virtio_device *dev, unsigned int status)
+{
+	might_sleep();
+	dev->config->set_status(dev, dev->config->get_status(dev) | status);
+}
+EXPORT_SYMBOL_GPL(virtio_add_status);
+
+/* Do some validation, then set FEATURES_OK */
+static int virtio_features_ok(struct virtio_device *dev)
+{
+	unsigned status;
+	int ret;
+
+	might_sleep();
+
+	ret = arch_has_restricted_virtio_memory_access();
+	if (ret) {
+		if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
+			dev_warn(&dev->dev,
+				 "device must provide VIRTIO_F_VERSION_1\n");
+			return -ENODEV;
+		}
+
+		if (!virtio_has_feature(dev, VIRTIO_F_ACCESS_PLATFORM)) {
+			dev_warn(&dev->dev,
+				 "device must provide VIRTIO_F_ACCESS_PLATFORM\n");
+			return -ENODEV;
+		}
+	}
+
+	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1))
+		return 0;
+
+	virtio_add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
+	status = dev->config->get_status(dev);
+	if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
+		dev_err(&dev->dev, "virtio: device refuses features: %x\n",
+			status);
+		return -ENODEV;
+	}
+	return 0;
+}
+
+static int virtio_dev_probe(struct device *_d)
+{
+	int err, i;
+	struct virtio_device *dev = dev_to_virtio(_d);
+	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
+	u64 device_features;
+	u64 driver_features;
+	u64 driver_features_legacy;
+
+	/* We have a driver! */
+	virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
+
+	/* Figure out what features the device supports. */
+	device_features = dev->config->get_features(dev);
+
+	/* Figure out what features the driver supports. */
+	driver_features = 0;
+	for (i = 0; i < drv->feature_table_size; i++) {
+		unsigned int f = drv->feature_table[i];
+		BUG_ON(f >= 64);
+		driver_features |= (1ULL << f);
+	}
+
+	/* Some drivers have a separate feature table for virtio v1.0 */
+	if (drv->feature_table_legacy) {
+		driver_features_legacy = 0;
+		for (i = 0; i < drv->feature_table_size_legacy; i++) {
+			unsigned int f = drv->feature_table_legacy[i];
+			BUG_ON(f >= 64);
+			driver_features_legacy |= (1ULL << f);
+		}
+	} else {
+		driver_features_legacy = driver_features;
+	}
+
+	if (device_features & (1ULL << VIRTIO_F_VERSION_1))
+		dev->features = driver_features & device_features;
+	else
+		dev->features = driver_features_legacy & device_features;
+
+	/* Transport features always preserved to pass to finalize_features. */
+	for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
+		if (device_features & (1ULL << i))
+			__virtio_set_bit(dev, i);
+
+	err = dev->config->finalize_features(dev);
+	if (err)
+		goto err;
+
+	if (drv->validate) {
+		u64 features = dev->features;
+
+		err = drv->validate(dev);
+		if (err)
+			goto err;
+
+		/* Did validation change any features? Then write them again. */
+		if (features != dev->features) {
+			err = dev->config->finalize_features(dev);
+			if (err)
+				goto err;
+		}
+	}
+
+	err = virtio_features_ok(dev);
+	if (err)
+		goto err;
+
+	err = drv->probe(dev);
+	if (err)
+		goto err;
+
+	/* If probe didn't do it, mark device DRIVER_OK ourselves. */
+	if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
+		virtio_device_ready(dev);
+
+	if (drv->scan)
+		drv->scan(dev);
+
+	virtio_config_enable(dev);
+
+	return 0;
+err:
+	virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
+	return err;
+
+}
+
+static int virtio_dev_remove(struct device *_d)
+{
+	struct virtio_device *dev = dev_to_virtio(_d);
+	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
+
+	virtio_config_disable(dev);
+
+	drv->remove(dev);
+
+	/* Driver should have reset device. */
+	WARN_ON_ONCE(dev->config->get_status(dev));
+
+	/* Acknowledge the device's existence again. */
+	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
+	return 0;
+}
+
+static struct bus_type virtio_bus = {
+	.name  = "virtio",
+	.match = virtio_dev_match,
+	.dev_groups = virtio_dev_groups,
+	.uevent = virtio_uevent,
+	.probe = virtio_dev_probe,
+	.remove = virtio_dev_remove,
+};
+
+int register_virtio_driver(struct virtio_driver *driver)
+{
+	/* Catch this early. */
+	BUG_ON(driver->feature_table_size && !driver->feature_table);
+	driver->driver.bus = &virtio_bus;
+	return driver_register(&driver->driver);
+}
+EXPORT_SYMBOL_GPL(register_virtio_driver);
+
+void unregister_virtio_driver(struct virtio_driver *driver)
+{
+	driver_unregister(&driver->driver);
+}
+EXPORT_SYMBOL_GPL(unregister_virtio_driver);
+
+/**
+ * register_virtio_device - register virtio device
+ * @dev        : virtio device to be registered
+ *
+ * On error, the caller must call put_device on &@dev->dev (and not kfree),
+ * as another code path may have obtained a reference to @dev.
+ *
+ * Returns: 0 on suceess, -error on failure
+ */
+int register_virtio_device(struct virtio_device *dev)
+{
+	int err;
+
+	dev->dev.bus = &virtio_bus;
+	device_initialize(&dev->dev);
+
+	/* Assign a unique device index and hence name. */
+	err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
+	if (err < 0)
+		goto out;
+
+	dev->index = err;
+	dev_set_name(&dev->dev, "virtio%u", dev->index);
+
+	spin_lock_init(&dev->config_lock);
+	dev->config_enabled = false;
+	dev->config_change_pending = false;
+
+	/* We always start by resetting the device, in case a previous
+	 * driver messed it up.  This also tests that code path a little. */
+	dev->config->reset(dev);
+
+	/* Acknowledge that we've seen the device. */
+	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
+
+	INIT_LIST_HEAD(&dev->vqs);
+	spin_lock_init(&dev->vqs_list_lock);
+
+	/*
+	 * device_add() causes the bus infrastructure to look for a matching
+	 * driver.
+	 */
+	err = device_add(&dev->dev);
+	if (err)
+		ida_simple_remove(&virtio_index_ida, dev->index);
+out:
+	if (err)
+		virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
+	return err;
+}
+EXPORT_SYMBOL_GPL(register_virtio_device);
+
+bool is_virtio_device(struct device *dev)
+{
+	return dev->bus == &virtio_bus;
+}
+EXPORT_SYMBOL_GPL(is_virtio_device);
+
+void unregister_virtio_device(struct virtio_device *dev)
+{
+	int index = dev->index; /* save for after device release */
+
+	device_unregister(&dev->dev);
+	ida_simple_remove(&virtio_index_ida, index);
+}
+EXPORT_SYMBOL_GPL(unregister_virtio_device);
+
+#ifdef CONFIG_PM_SLEEP
+int virtio_device_freeze(struct virtio_device *dev)
+{
+	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
+
+	virtio_config_disable(dev);
+
+	dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
+
+	if (drv && drv->freeze)
+		return drv->freeze(dev);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_device_freeze);
+
+int virtio_device_restore(struct virtio_device *dev)
+{
+	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
+	int ret;
+
+	/* We always start by resetting the device, in case a previous
+	 * driver messed it up. */
+	dev->config->reset(dev);
+
+	/* Acknowledge that we've seen the device. */
+	virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
+
+	/* Maybe driver failed before freeze.
+	 * Restore the failed status, for debugging. */
+	if (dev->failed)
+		virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
+
+	if (!drv)
+		return 0;
+
+	/* We have a driver! */
+	virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
+
+	ret = dev->config->finalize_features(dev);
+	if (ret)
+		goto err;
+
+	ret = virtio_features_ok(dev);
+	if (ret)
+		goto err;
+
+	if (drv->restore) {
+		ret = drv->restore(dev);
+		if (ret)
+			goto err;
+	}
+
+	/* Finally, tell the device we're all set */
+	virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
+
+	virtio_config_enable(dev);
+
+	return 0;
+
+err:
+	virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(virtio_device_restore);
+#endif
+
+static int virtio_init(void)
+{
+	if (bus_register(&virtio_bus) != 0)
+		panic("virtio bus registration failed");
+	return 0;
+}
+
+static void __exit virtio_exit(void)
+{
+	bus_unregister(&virtio_bus);
+	ida_destroy(&virtio_index_ida);
+}
+core_initcall(virtio_init);
+module_exit(virtio_exit);
+
+MODULE_LICENSE("GPL");
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
new file mode 100644
index 000000000..935ea2f3d
--- /dev/null
+++ b/drivers/virtio/virtio_balloon.c
@@ -0,0 +1,1160 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Virtio balloon implementation, inspired by Dor Laor and Marcelo
+ * Tosatti's implementations.
+ *
+ *  Copyright 2008 Rusty Russell IBM Corporation
+ */
+
+#include <linux/virtio.h>
+#include <linux/virtio_balloon.h>
+#include <linux/swap.h>
+#include <linux/workqueue.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/balloon_compaction.h>
+#include <linux/oom.h>
+#include <linux/wait.h>
+#include <linux/mm.h>
+#include <linux/mount.h>
+#include <linux/magic.h>
+#include <linux/pseudo_fs.h>
+#include <linux/page_reporting.h>
+
+/*
+ * Balloon device works in 4K page units.  So each page is pointed to by
+ * multiple balloon pages.  All memory counters in this driver are in balloon
+ * page units.
+ */
+#define VIRTIO_BALLOON_PAGES_PER_PAGE (unsigned)(PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT)
+#define VIRTIO_BALLOON_ARRAY_PFNS_MAX 256
+/* Maximum number of (4k) pages to deflate on OOM notifications. */
+#define VIRTIO_BALLOON_OOM_NR_PAGES 256
+#define VIRTIO_BALLOON_OOM_NOTIFY_PRIORITY 80
+
+#define VIRTIO_BALLOON_FREE_PAGE_ALLOC_FLAG (__GFP_NORETRY | __GFP_NOWARN | \
+					     __GFP_NOMEMALLOC)
+/* The order of free page blocks to report to host */
+#define VIRTIO_BALLOON_HINT_BLOCK_ORDER (MAX_ORDER - 1)
+/* The size of a free page block in bytes */
+#define VIRTIO_BALLOON_HINT_BLOCK_BYTES \
+	(1 << (VIRTIO_BALLOON_HINT_BLOCK_ORDER + PAGE_SHIFT))
+#define VIRTIO_BALLOON_HINT_BLOCK_PAGES (1 << VIRTIO_BALLOON_HINT_BLOCK_ORDER)
+
+#ifdef CONFIG_BALLOON_COMPACTION
+static struct vfsmount *balloon_mnt;
+#endif
+
+enum virtio_balloon_vq {
+	VIRTIO_BALLOON_VQ_INFLATE,
+	VIRTIO_BALLOON_VQ_DEFLATE,
+	VIRTIO_BALLOON_VQ_STATS,
+	VIRTIO_BALLOON_VQ_FREE_PAGE,
+	VIRTIO_BALLOON_VQ_REPORTING,
+	VIRTIO_BALLOON_VQ_MAX
+};
+
+enum virtio_balloon_config_read {
+	VIRTIO_BALLOON_CONFIG_READ_CMD_ID = 0,
+};
+
+struct virtio_balloon {
+	struct virtio_device *vdev;
+	struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq;
+
+	/* Balloon's own wq for cpu-intensive work items */
+	struct workqueue_struct *balloon_wq;
+	/* The free page reporting work item submitted to the balloon wq */
+	struct work_struct report_free_page_work;
+
+	/* The balloon servicing is delegated to a freezable workqueue. */
+	struct work_struct update_balloon_stats_work;
+	struct work_struct update_balloon_size_work;
+
+	/* Prevent updating balloon when it is being canceled. */
+	spinlock_t stop_update_lock;
+	bool stop_update;
+	/* Bitmap to indicate if reading the related config fields are needed */
+	unsigned long config_read_bitmap;
+
+	/* The list of allocated free pages, waiting to be given back to mm */
+	struct list_head free_page_list;
+	spinlock_t free_page_list_lock;
+	/* The number of free page blocks on the above list */
+	unsigned long num_free_page_blocks;
+	/*
+	 * The cmd id received from host.
+	 * Read it via virtio_balloon_cmd_id_received to get the latest value
+	 * sent from host.
+	 */
+	u32 cmd_id_received_cache;
+	/* The cmd id that is actively in use */
+	__virtio32 cmd_id_active;
+	/* Buffer to store the stop sign */
+	__virtio32 cmd_id_stop;
+
+	/* Waiting for host to ack the pages we released. */
+	wait_queue_head_t acked;
+
+	/* Number of balloon pages we've told the Host we're not using. */
+	unsigned int num_pages;
+	/*
+	 * The pages we've told the Host we're not using are enqueued
+	 * at vb_dev_info->pages list.
+	 * Each page on this list adds VIRTIO_BALLOON_PAGES_PER_PAGE
+	 * to num_pages above.
+	 */
+	struct balloon_dev_info vb_dev_info;
+
+	/* Synchronize access/update to this struct virtio_balloon elements */
+	struct mutex balloon_lock;
+
+	/* The array of pfns we tell the Host about. */
+	unsigned int num_pfns;
+	__virtio32 pfns[VIRTIO_BALLOON_ARRAY_PFNS_MAX];
+
+	/* Memory statistics */
+	struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
+
+	/* Shrinker to return free pages - VIRTIO_BALLOON_F_FREE_PAGE_HINT */
+	struct shrinker shrinker;
+
+	/* OOM notifier to deflate on OOM - VIRTIO_BALLOON_F_DEFLATE_ON_OOM */
+	struct notifier_block oom_nb;
+
+	/* Free page reporting device */
+	struct virtqueue *reporting_vq;
+	struct page_reporting_dev_info pr_dev_info;
+};
+
+static const struct virtio_device_id id_table[] = {
+	{ VIRTIO_ID_BALLOON, VIRTIO_DEV_ANY_ID },
+	{ 0 },
+};
+
+static u32 page_to_balloon_pfn(struct page *page)
+{
+	unsigned long pfn = page_to_pfn(page);
+
+	BUILD_BUG_ON(PAGE_SHIFT < VIRTIO_BALLOON_PFN_SHIFT);
+	/* Convert pfn from Linux page size to balloon page size. */
+	return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE;
+}
+
+static void balloon_ack(struct virtqueue *vq)
+{
+	struct virtio_balloon *vb = vq->vdev->priv;
+
+	wake_up(&vb->acked);
+}
+
+static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq)
+{
+	struct scatterlist sg;
+	unsigned int len;
+
+	sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns);
+
+	/* We should always be able to add one buffer to an empty queue. */
+	virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
+	virtqueue_kick(vq);
+
+	/* When host has read buffer, this completes via balloon_ack */
+	wait_event(vb->acked, virtqueue_get_buf(vq, &len));
+
+}
+
+static int virtballoon_free_page_report(struct page_reporting_dev_info *pr_dev_info,
+				   struct scatterlist *sg, unsigned int nents)
+{
+	struct virtio_balloon *vb =
+		container_of(pr_dev_info, struct virtio_balloon, pr_dev_info);
+	struct virtqueue *vq = vb->reporting_vq;
+	unsigned int unused, err;
+
+	/* We should always be able to add these buffers to an empty queue. */
+	err = virtqueue_add_inbuf(vq, sg, nents, vb, GFP_NOWAIT | __GFP_NOWARN);
+
+	/*
+	 * In the extremely unlikely case that something has occurred and we
+	 * are able to trigger an error we will simply display a warning
+	 * and exit without actually processing the pages.
+	 */
+	if (WARN_ON_ONCE(err))
+		return err;
+
+	virtqueue_kick(vq);
+
+	/* When host has read buffer, this completes via balloon_ack */
+	wait_event(vb->acked, virtqueue_get_buf(vq, &unused));
+
+	return 0;
+}
+
+static void set_page_pfns(struct virtio_balloon *vb,
+			  __virtio32 pfns[], struct page *page)
+{
+	unsigned int i;
+
+	BUILD_BUG_ON(VIRTIO_BALLOON_PAGES_PER_PAGE > VIRTIO_BALLOON_ARRAY_PFNS_MAX);
+
+	/*
+	 * Set balloon pfns pointing at this page.
+	 * Note that the first pfn points at start of the page.
+	 */
+	for (i = 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE; i++)
+		pfns[i] = cpu_to_virtio32(vb->vdev,
+					  page_to_balloon_pfn(page) + i);
+}
+
+static unsigned fill_balloon(struct virtio_balloon *vb, size_t num)
+{
+	unsigned num_allocated_pages;
+	unsigned num_pfns;
+	struct page *page;
+	LIST_HEAD(pages);
+
+	/* We can only do one array worth at a time. */
+	num = min(num, ARRAY_SIZE(vb->pfns));
+
+	for (num_pfns = 0; num_pfns < num;
+	     num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
+		struct page *page = balloon_page_alloc();
+
+		if (!page) {
+			dev_info_ratelimited(&vb->vdev->dev,
+					     "Out of puff! Can't get %u pages\n",
+					     VIRTIO_BALLOON_PAGES_PER_PAGE);
+			/* Sleep for at least 1/5 of a second before retry. */
+			msleep(200);
+			break;
+		}
+
+		balloon_page_push(&pages, page);
+	}
+
+	mutex_lock(&vb->balloon_lock);
+
+	vb->num_pfns = 0;
+
+	while ((page = balloon_page_pop(&pages))) {
+		balloon_page_enqueue(&vb->vb_dev_info, page);
+
+		set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
+		vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE;
+		if (!virtio_has_feature(vb->vdev,
+					VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
+			adjust_managed_page_count(page, -1);
+		vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE;
+	}
+
+	num_allocated_pages = vb->num_pfns;
+	/* Did we get any? */
+	if (vb->num_pfns != 0)
+		tell_host(vb, vb->inflate_vq);
+	mutex_unlock(&vb->balloon_lock);
+
+	return num_allocated_pages;
+}
+
+static void release_pages_balloon(struct virtio_balloon *vb,
+				 struct list_head *pages)
+{
+	struct page *page, *next;
+
+	list_for_each_entry_safe(page, next, pages, lru) {
+		if (!virtio_has_feature(vb->vdev,
+					VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
+			adjust_managed_page_count(page, 1);
+		list_del(&page->lru);
+		put_page(page); /* balloon reference */
+	}
+}
+
+static unsigned leak_balloon(struct virtio_balloon *vb, size_t num)
+{
+	unsigned num_freed_pages;
+	struct page *page;
+	struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
+	LIST_HEAD(pages);
+
+	/* We can only do one array worth at a time. */
+	num = min(num, ARRAY_SIZE(vb->pfns));
+
+	mutex_lock(&vb->balloon_lock);
+	/* We can't release more pages than taken */
+	num = min(num, (size_t)vb->num_pages);
+	for (vb->num_pfns = 0; vb->num_pfns < num;
+	     vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
+		page = balloon_page_dequeue(vb_dev_info);
+		if (!page)
+			break;
+		set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
+		list_add(&page->lru, &pages);
+		vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE;
+	}
+
+	num_freed_pages = vb->num_pfns;
+	/*
+	 * Note that if
+	 * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST);
+	 * is true, we *have* to do it in this order
+	 */
+	if (vb->num_pfns != 0)
+		tell_host(vb, vb->deflate_vq);
+	release_pages_balloon(vb, &pages);
+	mutex_unlock(&vb->balloon_lock);
+	return num_freed_pages;
+}
+
+static inline void update_stat(struct virtio_balloon *vb, int idx,
+			       u16 tag, u64 val)
+{
+	BUG_ON(idx >= VIRTIO_BALLOON_S_NR);
+	vb->stats[idx].tag = cpu_to_virtio16(vb->vdev, tag);
+	vb->stats[idx].val = cpu_to_virtio64(vb->vdev, val);
+}
+
+#define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT)
+
+static unsigned int update_balloon_stats(struct virtio_balloon *vb)
+{
+	unsigned long events[NR_VM_EVENT_ITEMS];
+	struct sysinfo i;
+	unsigned int idx = 0;
+	long available;
+	unsigned long caches;
+
+	all_vm_events(events);
+	si_meminfo(&i);
+
+	available = si_mem_available();
+	caches = global_node_page_state(NR_FILE_PAGES);
+
+#ifdef CONFIG_VM_EVENT_COUNTERS
+	update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
+				pages_to_bytes(events[PSWPIN]));
+	update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT,
+				pages_to_bytes(events[PSWPOUT]));
+	update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]);
+	update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]);
+#ifdef CONFIG_HUGETLB_PAGE
+	update_stat(vb, idx++, VIRTIO_BALLOON_S_HTLB_PGALLOC,
+		    events[HTLB_BUDDY_PGALLOC]);
+	update_stat(vb, idx++, VIRTIO_BALLOON_S_HTLB_PGFAIL,
+		    events[HTLB_BUDDY_PGALLOC_FAIL]);
+#endif
+#endif
+	update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
+				pages_to_bytes(i.freeram));
+	update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT,
+				pages_to_bytes(i.totalram));
+	update_stat(vb, idx++, VIRTIO_BALLOON_S_AVAIL,
+				pages_to_bytes(available));
+	update_stat(vb, idx++, VIRTIO_BALLOON_S_CACHES,
+				pages_to_bytes(caches));
+
+	return idx;
+}
+
+/*
+ * While most virtqueues communicate guest-initiated requests to the hypervisor,
+ * the stats queue operates in reverse.  The driver initializes the virtqueue
+ * with a single buffer.  From that point forward, all conversations consist of
+ * a hypervisor request (a call to this function) which directs us to refill
+ * the virtqueue with a fresh stats buffer.  Since stats collection can sleep,
+ * we delegate the job to a freezable workqueue that will do the actual work via
+ * stats_handle_request().
+ */
+static void stats_request(struct virtqueue *vq)
+{
+	struct virtio_balloon *vb = vq->vdev->priv;
+
+	spin_lock(&vb->stop_update_lock);
+	if (!vb->stop_update)
+		queue_work(system_freezable_wq, &vb->update_balloon_stats_work);
+	spin_unlock(&vb->stop_update_lock);
+}
+
+static void stats_handle_request(struct virtio_balloon *vb)
+{
+	struct virtqueue *vq;
+	struct scatterlist sg;
+	unsigned int len, num_stats;
+
+	num_stats = update_balloon_stats(vb);
+
+	vq = vb->stats_vq;
+	if (!virtqueue_get_buf(vq, &len))
+		return;
+	sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats);
+	virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
+	virtqueue_kick(vq);
+}
+
+static inline s64 towards_target(struct virtio_balloon *vb)
+{
+	s64 target;
+	u32 num_pages;
+
+	/* Legacy balloon config space is LE, unlike all other devices. */
+	virtio_cread_le(vb->vdev, struct virtio_balloon_config, num_pages,
+			&num_pages);
+
+	/*
+	 * Aligned up to guest page size to avoid inflating and deflating
+	 * balloon endlessly.
+	 */
+	target = ALIGN(num_pages, VIRTIO_BALLOON_PAGES_PER_PAGE);
+	return target - vb->num_pages;
+}
+
+/* Gives back @num_to_return blocks of free pages to mm. */
+static unsigned long return_free_pages_to_mm(struct virtio_balloon *vb,
+					     unsigned long num_to_return)
+{
+	struct page *page;
+	unsigned long num_returned;
+
+	spin_lock_irq(&vb->free_page_list_lock);
+	for (num_returned = 0; num_returned < num_to_return; num_returned++) {
+		page = balloon_page_pop(&vb->free_page_list);
+		if (!page)
+			break;
+		free_pages((unsigned long)page_address(page),
+			   VIRTIO_BALLOON_HINT_BLOCK_ORDER);
+	}
+	vb->num_free_page_blocks -= num_returned;
+	spin_unlock_irq(&vb->free_page_list_lock);
+
+	return num_returned;
+}
+
+static void virtio_balloon_queue_free_page_work(struct virtio_balloon *vb)
+{
+	if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
+		return;
+
+	/* No need to queue the work if the bit was already set. */
+	if (test_and_set_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,
+			     &vb->config_read_bitmap))
+		return;
+
+	queue_work(vb->balloon_wq, &vb->report_free_page_work);
+}
+
+static void virtballoon_changed(struct virtio_device *vdev)
+{
+	struct virtio_balloon *vb = vdev->priv;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vb->stop_update_lock, flags);
+	if (!vb->stop_update) {
+		queue_work(system_freezable_wq,
+			   &vb->update_balloon_size_work);
+		virtio_balloon_queue_free_page_work(vb);
+	}
+	spin_unlock_irqrestore(&vb->stop_update_lock, flags);
+}
+
+static void update_balloon_size(struct virtio_balloon *vb)
+{
+	u32 actual = vb->num_pages;
+
+	/* Legacy balloon config space is LE, unlike all other devices. */
+	virtio_cwrite_le(vb->vdev, struct virtio_balloon_config, actual,
+			 &actual);
+}
+
+static void update_balloon_stats_func(struct work_struct *work)
+{
+	struct virtio_balloon *vb;
+
+	vb = container_of(work, struct virtio_balloon,
+			  update_balloon_stats_work);
+	stats_handle_request(vb);
+}
+
+static void update_balloon_size_func(struct work_struct *work)
+{
+	struct virtio_balloon *vb;
+	s64 diff;
+
+	vb = container_of(work, struct virtio_balloon,
+			  update_balloon_size_work);
+	diff = towards_target(vb);
+
+	if (!diff)
+		return;
+
+	if (diff > 0)
+		diff -= fill_balloon(vb, diff);
+	else
+		diff += leak_balloon(vb, -diff);
+	update_balloon_size(vb);
+
+	if (diff)
+		queue_work(system_freezable_wq, work);
+}
+
+static int init_vqs(struct virtio_balloon *vb)
+{
+	struct virtqueue *vqs[VIRTIO_BALLOON_VQ_MAX];
+	vq_callback_t *callbacks[VIRTIO_BALLOON_VQ_MAX];
+	const char *names[VIRTIO_BALLOON_VQ_MAX];
+	int err;
+
+	/*
+	 * Inflateq and deflateq are used unconditionally. The names[]
+	 * will be NULL if the related feature is not enabled, which will
+	 * cause no allocation for the corresponding virtqueue in find_vqs.
+	 */
+	callbacks[VIRTIO_BALLOON_VQ_INFLATE] = balloon_ack;
+	names[VIRTIO_BALLOON_VQ_INFLATE] = "inflate";
+	callbacks[VIRTIO_BALLOON_VQ_DEFLATE] = balloon_ack;
+	names[VIRTIO_BALLOON_VQ_DEFLATE] = "deflate";
+	callbacks[VIRTIO_BALLOON_VQ_STATS] = NULL;
+	names[VIRTIO_BALLOON_VQ_STATS] = NULL;
+	callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
+	names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
+	names[VIRTIO_BALLOON_VQ_REPORTING] = NULL;
+
+	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
+		names[VIRTIO_BALLOON_VQ_STATS] = "stats";
+		callbacks[VIRTIO_BALLOON_VQ_STATS] = stats_request;
+	}
+
+	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
+		names[VIRTIO_BALLOON_VQ_FREE_PAGE] = "free_page_vq";
+		callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
+	}
+
+	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) {
+		names[VIRTIO_BALLOON_VQ_REPORTING] = "reporting_vq";
+		callbacks[VIRTIO_BALLOON_VQ_REPORTING] = balloon_ack;
+	}
+
+	err = vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX,
+					 vqs, callbacks, names, NULL, NULL);
+	if (err)
+		return err;
+
+	vb->inflate_vq = vqs[VIRTIO_BALLOON_VQ_INFLATE];
+	vb->deflate_vq = vqs[VIRTIO_BALLOON_VQ_DEFLATE];
+	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
+		struct scatterlist sg;
+		unsigned int num_stats;
+		vb->stats_vq = vqs[VIRTIO_BALLOON_VQ_STATS];
+
+		/*
+		 * Prime this virtqueue with one buffer so the hypervisor can
+		 * use it to signal us later (it can't be broken yet!).
+		 */
+		num_stats = update_balloon_stats(vb);
+
+		sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats);
+		err = virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb,
+					   GFP_KERNEL);
+		if (err) {
+			dev_warn(&vb->vdev->dev, "%s: add stat_vq failed\n",
+				 __func__);
+			return err;
+		}
+		virtqueue_kick(vb->stats_vq);
+	}
+
+	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
+		vb->free_page_vq = vqs[VIRTIO_BALLOON_VQ_FREE_PAGE];
+
+	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING))
+		vb->reporting_vq = vqs[VIRTIO_BALLOON_VQ_REPORTING];
+
+	return 0;
+}
+
+static u32 virtio_balloon_cmd_id_received(struct virtio_balloon *vb)
+{
+	if (test_and_clear_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,
+			       &vb->config_read_bitmap)) {
+		/* Legacy balloon config space is LE, unlike all other devices. */
+		virtio_cread_le(vb->vdev, struct virtio_balloon_config,
+				free_page_hint_cmd_id,
+				&vb->cmd_id_received_cache);
+	}
+
+	return vb->cmd_id_received_cache;
+}
+
+static int send_cmd_id_start(struct virtio_balloon *vb)
+{
+	struct scatterlist sg;
+	struct virtqueue *vq = vb->free_page_vq;
+	int err, unused;
+
+	/* Detach all the used buffers from the vq */
+	while (virtqueue_get_buf(vq, &unused))
+		;
+
+	vb->cmd_id_active = cpu_to_virtio32(vb->vdev,
+					virtio_balloon_cmd_id_received(vb));
+	sg_init_one(&sg, &vb->cmd_id_active, sizeof(vb->cmd_id_active));
+	err = virtqueue_add_outbuf(vq, &sg, 1, &vb->cmd_id_active, GFP_KERNEL);
+	if (!err)
+		virtqueue_kick(vq);
+	return err;
+}
+
+static int send_cmd_id_stop(struct virtio_balloon *vb)
+{
+	struct scatterlist sg;
+	struct virtqueue *vq = vb->free_page_vq;
+	int err, unused;
+
+	/* Detach all the used buffers from the vq */
+	while (virtqueue_get_buf(vq, &unused))
+		;
+
+	sg_init_one(&sg, &vb->cmd_id_stop, sizeof(vb->cmd_id_stop));
+	err = virtqueue_add_outbuf(vq, &sg, 1, &vb->cmd_id_stop, GFP_KERNEL);
+	if (!err)
+		virtqueue_kick(vq);
+	return err;
+}
+
+static int get_free_page_and_send(struct virtio_balloon *vb)
+{
+	struct virtqueue *vq = vb->free_page_vq;
+	struct page *page;
+	struct scatterlist sg;
+	int err, unused;
+	void *p;
+
+	/* Detach all the used buffers from the vq */
+	while (virtqueue_get_buf(vq, &unused))
+		;
+
+	page = alloc_pages(VIRTIO_BALLOON_FREE_PAGE_ALLOC_FLAG,
+			   VIRTIO_BALLOON_HINT_BLOCK_ORDER);
+	/*
+	 * When the allocation returns NULL, it indicates that we have got all
+	 * the possible free pages, so return -EINTR to stop.
+	 */
+	if (!page)
+		return -EINTR;
+
+	p = page_address(page);
+	sg_init_one(&sg, p, VIRTIO_BALLOON_HINT_BLOCK_BYTES);
+	/* There is always 1 entry reserved for the cmd id to use. */
+	if (vq->num_free > 1) {
+		err = virtqueue_add_inbuf(vq, &sg, 1, p, GFP_KERNEL);
+		if (unlikely(err)) {
+			free_pages((unsigned long)p,
+				   VIRTIO_BALLOON_HINT_BLOCK_ORDER);
+			return err;
+		}
+		virtqueue_kick(vq);
+		spin_lock_irq(&vb->free_page_list_lock);
+		balloon_page_push(&vb->free_page_list, page);
+		vb->num_free_page_blocks++;
+		spin_unlock_irq(&vb->free_page_list_lock);
+	} else {
+		/*
+		 * The vq has no available entry to add this page block, so
+		 * just free it.
+		 */
+		free_pages((unsigned long)p, VIRTIO_BALLOON_HINT_BLOCK_ORDER);
+	}
+
+	return 0;
+}
+
+static int send_free_pages(struct virtio_balloon *vb)
+{
+	int err;
+	u32 cmd_id_active;
+
+	while (1) {
+		/*
+		 * If a stop id or a new cmd id was just received from host,
+		 * stop the reporting.
+		 */
+		cmd_id_active = virtio32_to_cpu(vb->vdev, vb->cmd_id_active);
+		if (unlikely(cmd_id_active !=
+			     virtio_balloon_cmd_id_received(vb)))
+			break;
+
+		/*
+		 * The free page blocks are allocated and sent to host one by
+		 * one.
+		 */
+		err = get_free_page_and_send(vb);
+		if (err == -EINTR)
+			break;
+		else if (unlikely(err))
+			return err;
+	}
+
+	return 0;
+}
+
+static void virtio_balloon_report_free_page(struct virtio_balloon *vb)
+{
+	int err;
+	struct device *dev = &vb->vdev->dev;
+
+	/* Start by sending the received cmd id to host with an outbuf. */
+	err = send_cmd_id_start(vb);
+	if (unlikely(err))
+		dev_err(dev, "Failed to send a start id, err = %d\n", err);
+
+	err = send_free_pages(vb);
+	if (unlikely(err))
+		dev_err(dev, "Failed to send a free page, err = %d\n", err);
+
+	/* End by sending a stop id to host with an outbuf. */
+	err = send_cmd_id_stop(vb);
+	if (unlikely(err))
+		dev_err(dev, "Failed to send a stop id, err = %d\n", err);
+}
+
+static void report_free_page_func(struct work_struct *work)
+{
+	struct virtio_balloon *vb = container_of(work, struct virtio_balloon,
+						 report_free_page_work);
+	u32 cmd_id_received;
+
+	cmd_id_received = virtio_balloon_cmd_id_received(vb);
+	if (cmd_id_received == VIRTIO_BALLOON_CMD_ID_DONE) {
+		/* Pass ULONG_MAX to give back all the free pages */
+		return_free_pages_to_mm(vb, ULONG_MAX);
+	} else if (cmd_id_received != VIRTIO_BALLOON_CMD_ID_STOP &&
+		   cmd_id_received !=
+		   virtio32_to_cpu(vb->vdev, vb->cmd_id_active)) {
+		virtio_balloon_report_free_page(vb);
+	}
+}
+
+#ifdef CONFIG_BALLOON_COMPACTION
+/*
+ * virtballoon_migratepage - perform the balloon page migration on behalf of
+ *			     a compation thread.     (called under page lock)
+ * @vb_dev_info: the balloon device
+ * @newpage: page that will replace the isolated page after migration finishes.
+ * @page   : the isolated (old) page that is about to be migrated to newpage.
+ * @mode   : compaction mode -- not used for balloon page migration.
+ *
+ * After a ballooned page gets isolated by compaction procedures, this is the
+ * function that performs the page migration on behalf of a compaction thread
+ * The page migration for virtio balloon is done in a simple swap fashion which
+ * follows these two macro steps:
+ *  1) insert newpage into vb->pages list and update the host about it;
+ *  2) update the host about the old page removed from vb->pages list;
+ *
+ * This function preforms the balloon page migration task.
+ * Called through balloon_mapping->a_ops->migratepage
+ */
+static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info,
+		struct page *newpage, struct page *page, enum migrate_mode mode)
+{
+	struct virtio_balloon *vb = container_of(vb_dev_info,
+			struct virtio_balloon, vb_dev_info);
+	unsigned long flags;
+
+	/*
+	 * In order to avoid lock contention while migrating pages concurrently
+	 * to leak_balloon() or fill_balloon() we just give up the balloon_lock
+	 * this turn, as it is easier to retry the page migration later.
+	 * This also prevents fill_balloon() getting stuck into a mutex
+	 * recursion in the case it ends up triggering memory compaction
+	 * while it is attempting to inflate the ballon.
+	 */
+	if (!mutex_trylock(&vb->balloon_lock))
+		return -EAGAIN;
+
+	get_page(newpage); /* balloon reference */
+
+	/*
+	  * When we migrate a page to a different zone and adjusted the
+	  * managed page count when inflating, we have to fixup the count of
+	  * both involved zones.
+	  */
+	if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM) &&
+	    page_zone(page) != page_zone(newpage)) {
+		adjust_managed_page_count(page, 1);
+		adjust_managed_page_count(newpage, -1);
+	}
+
+	/* balloon's page migration 1st step  -- inflate "newpage" */
+	spin_lock_irqsave(&vb_dev_info->pages_lock, flags);
+	balloon_page_insert(vb_dev_info, newpage);
+	vb_dev_info->isolated_pages--;
+	__count_vm_event(BALLOON_MIGRATE);
+	spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags);
+	vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
+	set_page_pfns(vb, vb->pfns, newpage);
+	tell_host(vb, vb->inflate_vq);
+
+	/* balloon's page migration 2nd step -- deflate "page" */
+	spin_lock_irqsave(&vb_dev_info->pages_lock, flags);
+	balloon_page_delete(page);
+	spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags);
+	vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
+	set_page_pfns(vb, vb->pfns, page);
+	tell_host(vb, vb->deflate_vq);
+
+	mutex_unlock(&vb->balloon_lock);
+
+	put_page(page); /* balloon reference */
+
+	return MIGRATEPAGE_SUCCESS;
+}
+
+static int balloon_init_fs_context(struct fs_context *fc)
+{
+	return init_pseudo(fc, BALLOON_KVM_MAGIC) ? 0 : -ENOMEM;
+}
+
+static struct file_system_type balloon_fs = {
+	.name           = "balloon-kvm",
+	.init_fs_context = balloon_init_fs_context,
+	.kill_sb        = kill_anon_super,
+};
+
+#endif /* CONFIG_BALLOON_COMPACTION */
+
+static unsigned long shrink_free_pages(struct virtio_balloon *vb,
+				       unsigned long pages_to_free)
+{
+	unsigned long blocks_to_free, blocks_freed;
+
+	pages_to_free = round_up(pages_to_free,
+				 VIRTIO_BALLOON_HINT_BLOCK_PAGES);
+	blocks_to_free = pages_to_free / VIRTIO_BALLOON_HINT_BLOCK_PAGES;
+	blocks_freed = return_free_pages_to_mm(vb, blocks_to_free);
+
+	return blocks_freed * VIRTIO_BALLOON_HINT_BLOCK_PAGES;
+}
+
+static unsigned long virtio_balloon_shrinker_scan(struct shrinker *shrinker,
+						  struct shrink_control *sc)
+{
+	struct virtio_balloon *vb = container_of(shrinker,
+					struct virtio_balloon, shrinker);
+
+	return shrink_free_pages(vb, sc->nr_to_scan);
+}
+
+static unsigned long virtio_balloon_shrinker_count(struct shrinker *shrinker,
+						   struct shrink_control *sc)
+{
+	struct virtio_balloon *vb = container_of(shrinker,
+					struct virtio_balloon, shrinker);
+
+	return vb->num_free_page_blocks * VIRTIO_BALLOON_HINT_BLOCK_PAGES;
+}
+
+static int virtio_balloon_oom_notify(struct notifier_block *nb,
+				     unsigned long dummy, void *parm)
+{
+	struct virtio_balloon *vb = container_of(nb,
+						 struct virtio_balloon, oom_nb);
+	unsigned long *freed = parm;
+
+	*freed += leak_balloon(vb, VIRTIO_BALLOON_OOM_NR_PAGES) /
+		  VIRTIO_BALLOON_PAGES_PER_PAGE;
+	update_balloon_size(vb);
+
+	return NOTIFY_OK;
+}
+
+static void virtio_balloon_unregister_shrinker(struct virtio_balloon *vb)
+{
+	unregister_shrinker(&vb->shrinker);
+}
+
+static int virtio_balloon_register_shrinker(struct virtio_balloon *vb)
+{
+	vb->shrinker.scan_objects = virtio_balloon_shrinker_scan;
+	vb->shrinker.count_objects = virtio_balloon_shrinker_count;
+	vb->shrinker.seeks = DEFAULT_SEEKS;
+
+	return register_shrinker(&vb->shrinker);
+}
+
+static int virtballoon_probe(struct virtio_device *vdev)
+{
+	struct virtio_balloon *vb;
+	int err;
+
+	if (!vdev->config->get) {
+		dev_err(&vdev->dev, "%s failure: config access disabled\n",
+			__func__);
+		return -EINVAL;
+	}
+
+	vdev->priv = vb = kzalloc(sizeof(*vb), GFP_KERNEL);
+	if (!vb) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	INIT_WORK(&vb->update_balloon_stats_work, update_balloon_stats_func);
+	INIT_WORK(&vb->update_balloon_size_work, update_balloon_size_func);
+	spin_lock_init(&vb->stop_update_lock);
+	mutex_init(&vb->balloon_lock);
+	init_waitqueue_head(&vb->acked);
+	vb->vdev = vdev;
+
+	balloon_devinfo_init(&vb->vb_dev_info);
+
+	err = init_vqs(vb);
+	if (err)
+		goto out_free_vb;
+
+#ifdef CONFIG_BALLOON_COMPACTION
+	balloon_mnt = kern_mount(&balloon_fs);
+	if (IS_ERR(balloon_mnt)) {
+		err = PTR_ERR(balloon_mnt);
+		goto out_del_vqs;
+	}
+
+	vb->vb_dev_info.migratepage = virtballoon_migratepage;
+	vb->vb_dev_info.inode = alloc_anon_inode(balloon_mnt->mnt_sb);
+	if (IS_ERR(vb->vb_dev_info.inode)) {
+		err = PTR_ERR(vb->vb_dev_info.inode);
+		goto out_kern_unmount;
+	}
+	vb->vb_dev_info.inode->i_mapping->a_ops = &balloon_aops;
+#endif
+	if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
+		/*
+		 * There is always one entry reserved for cmd id, so the ring
+		 * size needs to be at least two to report free page hints.
+		 */
+		if (virtqueue_get_vring_size(vb->free_page_vq) < 2) {
+			err = -ENOSPC;
+			goto out_iput;
+		}
+		vb->balloon_wq = alloc_workqueue("balloon-wq",
+					WQ_FREEZABLE | WQ_CPU_INTENSIVE, 0);
+		if (!vb->balloon_wq) {
+			err = -ENOMEM;
+			goto out_iput;
+		}
+		INIT_WORK(&vb->report_free_page_work, report_free_page_func);
+		vb->cmd_id_received_cache = VIRTIO_BALLOON_CMD_ID_STOP;
+		vb->cmd_id_active = cpu_to_virtio32(vb->vdev,
+						  VIRTIO_BALLOON_CMD_ID_STOP);
+		vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,
+						  VIRTIO_BALLOON_CMD_ID_STOP);
+		spin_lock_init(&vb->free_page_list_lock);
+		INIT_LIST_HEAD(&vb->free_page_list);
+		/*
+		 * We're allowed to reuse any free pages, even if they are
+		 * still to be processed by the host.
+		 */
+		err = virtio_balloon_register_shrinker(vb);
+		if (err)
+			goto out_del_balloon_wq;
+	}
+
+	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) {
+		vb->oom_nb.notifier_call = virtio_balloon_oom_notify;
+		vb->oom_nb.priority = VIRTIO_BALLOON_OOM_NOTIFY_PRIORITY;
+		err = register_oom_notifier(&vb->oom_nb);
+		if (err < 0)
+			goto out_unregister_shrinker;
+	}
+
+	if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
+		/* Start with poison val of 0 representing general init */
+		__u32 poison_val = 0;
+
+		/*
+		 * Let the hypervisor know that we are expecting a
+		 * specific value to be written back in balloon pages.
+		 *
+		 * If the PAGE_POISON value was larger than a byte we would
+		 * need to byte swap poison_val here to guarantee it is
+		 * little-endian. However for now it is a single byte so we
+		 * can pass it as-is.
+		 */
+		if (!want_init_on_free())
+			memset(&poison_val, PAGE_POISON, sizeof(poison_val));
+
+		virtio_cwrite_le(vb->vdev, struct virtio_balloon_config,
+				 poison_val, &poison_val);
+	}
+
+	vb->pr_dev_info.report = virtballoon_free_page_report;
+	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) {
+		unsigned int capacity;
+
+		capacity = virtqueue_get_vring_size(vb->reporting_vq);
+		if (capacity < PAGE_REPORTING_CAPACITY) {
+			err = -ENOSPC;
+			goto out_unregister_oom;
+		}
+
+		err = page_reporting_register(&vb->pr_dev_info);
+		if (err)
+			goto out_unregister_oom;
+	}
+
+	virtio_device_ready(vdev);
+
+	if (towards_target(vb))
+		virtballoon_changed(vdev);
+	return 0;
+
+out_unregister_oom:
+	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
+		unregister_oom_notifier(&vb->oom_nb);
+out_unregister_shrinker:
+	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
+		virtio_balloon_unregister_shrinker(vb);
+out_del_balloon_wq:
+	if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
+		destroy_workqueue(vb->balloon_wq);
+out_iput:
+#ifdef CONFIG_BALLOON_COMPACTION
+	iput(vb->vb_dev_info.inode);
+out_kern_unmount:
+	kern_unmount(balloon_mnt);
+out_del_vqs:
+#endif
+	vdev->config->del_vqs(vdev);
+out_free_vb:
+	kfree(vb);
+out:
+	return err;
+}
+
+static void remove_common(struct virtio_balloon *vb)
+{
+	/* There might be pages left in the balloon: free them. */
+	while (vb->num_pages)
+		leak_balloon(vb, vb->num_pages);
+	update_balloon_size(vb);
+
+	/* There might be free pages that are being reported: release them. */
+	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
+		return_free_pages_to_mm(vb, ULONG_MAX);
+
+	/* Now we reset the device so we can clean up the queues. */
+	vb->vdev->config->reset(vb->vdev);
+
+	vb->vdev->config->del_vqs(vb->vdev);
+}
+
+static void virtballoon_remove(struct virtio_device *vdev)
+{
+	struct virtio_balloon *vb = vdev->priv;
+
+	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING))
+		page_reporting_unregister(&vb->pr_dev_info);
+	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
+		unregister_oom_notifier(&vb->oom_nb);
+	if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
+		virtio_balloon_unregister_shrinker(vb);
+	spin_lock_irq(&vb->stop_update_lock);
+	vb->stop_update = true;
+	spin_unlock_irq(&vb->stop_update_lock);
+	cancel_work_sync(&vb->update_balloon_size_work);
+	cancel_work_sync(&vb->update_balloon_stats_work);
+
+	if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
+		cancel_work_sync(&vb->report_free_page_work);
+		destroy_workqueue(vb->balloon_wq);
+	}
+
+	remove_common(vb);
+#ifdef CONFIG_BALLOON_COMPACTION
+	if (vb->vb_dev_info.inode)
+		iput(vb->vb_dev_info.inode);
+
+	kern_unmount(balloon_mnt);
+#endif
+	kfree(vb);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int virtballoon_freeze(struct virtio_device *vdev)
+{
+	struct virtio_balloon *vb = vdev->priv;
+
+	/*
+	 * The workqueue is already frozen by the PM core before this
+	 * function is called.
+	 */
+	remove_common(vb);
+	return 0;
+}
+
+static int virtballoon_restore(struct virtio_device *vdev)
+{
+	struct virtio_balloon *vb = vdev->priv;
+	int ret;
+
+	ret = init_vqs(vdev->priv);
+	if (ret)
+		return ret;
+
+	virtio_device_ready(vdev);
+
+	if (towards_target(vb))
+		virtballoon_changed(vdev);
+	update_balloon_size(vb);
+	return 0;
+}
+#endif
+
+static int virtballoon_validate(struct virtio_device *vdev)
+{
+	/*
+	 * Inform the hypervisor that our pages are poisoned or
+	 * initialized. If we cannot do that then we should disable
+	 * page reporting as it could potentially change the contents
+	 * of our free pages.
+	 */
+	if (!want_init_on_free() &&
+	    (IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY) ||
+	     !page_poisoning_enabled()))
+		__virtio_clear_bit(vdev, VIRTIO_BALLOON_F_PAGE_POISON);
+	else if (!virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON))
+		__virtio_clear_bit(vdev, VIRTIO_BALLOON_F_REPORTING);
+
+	__virtio_clear_bit(vdev, VIRTIO_F_ACCESS_PLATFORM);
+	return 0;
+}
+
+static unsigned int features[] = {
+	VIRTIO_BALLOON_F_MUST_TELL_HOST,
+	VIRTIO_BALLOON_F_STATS_VQ,
+	VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
+	VIRTIO_BALLOON_F_FREE_PAGE_HINT,
+	VIRTIO_BALLOON_F_PAGE_POISON,
+	VIRTIO_BALLOON_F_REPORTING,
+};
+
+static struct virtio_driver virtio_balloon_driver = {
+	.feature_table = features,
+	.feature_table_size = ARRAY_SIZE(features),
+	.driver.name =	KBUILD_MODNAME,
+	.driver.owner =	THIS_MODULE,
+	.id_table =	id_table,
+	.validate =	virtballoon_validate,
+	.probe =	virtballoon_probe,
+	.remove =	virtballoon_remove,
+	.config_changed = virtballoon_changed,
+#ifdef CONFIG_PM_SLEEP
+	.freeze	=	virtballoon_freeze,
+	.restore =	virtballoon_restore,
+#endif
+};
+
+module_virtio_driver(virtio_balloon_driver);
+MODULE_DEVICE_TABLE(virtio, id_table);
+MODULE_DESCRIPTION("Virtio balloon driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/virtio/virtio_dma_buf.c b/drivers/virtio/virtio_dma_buf.c
new file mode 100644
index 000000000..5127a2f0c
--- /dev/null
+++ b/drivers/virtio/virtio_dma_buf.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * dma-bufs for virtio exported objects
+ *
+ * Copyright (C) 2020 Google, Inc.
+ */
+
+#include <linux/module.h>
+#include <linux/virtio_dma_buf.h>
+
+/**
+ * virtio_dma_buf_export - Creates a new dma-buf for a virtio exported object
+ * @exp_info: [in] see dma_buf_export(). ops MUST refer to a dma_buf_ops
+ *	struct embedded in a virtio_dma_buf_ops.
+ *
+ * This wraps dma_buf_export() to allow virtio drivers to create a dma-buf
+ * for an virtio exported object that can be queried by other virtio drivers
+ * for the object's UUID.
+ */
+struct dma_buf *virtio_dma_buf_export
+	(const struct dma_buf_export_info *exp_info)
+{
+	const struct virtio_dma_buf_ops *virtio_ops =
+		container_of(exp_info->ops,
+			     const struct virtio_dma_buf_ops, ops);
+
+	if (!exp_info->ops ||
+	    exp_info->ops->attach != &virtio_dma_buf_attach ||
+	    !virtio_ops->get_uuid) {
+		return ERR_PTR(-EINVAL);
+	}
+
+	return dma_buf_export(exp_info);
+}
+EXPORT_SYMBOL(virtio_dma_buf_export);
+
+/**
+ * virtio_dma_buf_attach - mandatory attach callback for virtio dma-bufs
+ */
+int virtio_dma_buf_attach(struct dma_buf *dma_buf,
+			  struct dma_buf_attachment *attach)
+{
+	int ret;
+	const struct virtio_dma_buf_ops *ops =
+		container_of(dma_buf->ops,
+			     const struct virtio_dma_buf_ops, ops);
+
+	if (ops->device_attach) {
+		ret = ops->device_attach(dma_buf, attach);
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+EXPORT_SYMBOL(virtio_dma_buf_attach);
+
+/**
+ * is_virtio_dma_buf - returns true if the given dma-buf is a virtio dma-buf
+ * @dma_buf: buffer to query
+ */
+bool is_virtio_dma_buf(struct dma_buf *dma_buf)
+{
+	return dma_buf->ops->attach == &virtio_dma_buf_attach;
+}
+EXPORT_SYMBOL(is_virtio_dma_buf);
+
+/**
+ * virtio_dma_buf_get_uuid - gets a virtio dma-buf's exported object's uuid
+ * @dma_buf: [in] buffer to query
+ * @uuid: [out] the uuid
+ *
+ * Returns: 0 on success, negative on failure.
+ */
+int virtio_dma_buf_get_uuid(struct dma_buf *dma_buf,
+			    uuid_t *uuid)
+{
+	const struct virtio_dma_buf_ops *ops =
+		container_of(dma_buf->ops,
+			     const struct virtio_dma_buf_ops, ops);
+
+	if (!is_virtio_dma_buf(dma_buf))
+		return -EINVAL;
+
+	return ops->get_uuid(dma_buf, uuid);
+}
+EXPORT_SYMBOL(virtio_dma_buf_get_uuid);
+
+MODULE_LICENSE("GPL");
diff --git a/drivers/virtio/virtio_input.c b/drivers/virtio/virtio_input.c
new file mode 100644
index 000000000..f1f6208ed
--- /dev/null
+++ b/drivers/virtio/virtio_input.c
@@ -0,0 +1,390 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/module.h>
+#include <linux/virtio.h>
+#include <linux/virtio_config.h>
+#include <linux/input.h>
+#include <linux/slab.h>
+
+#include <uapi/linux/virtio_ids.h>
+#include <uapi/linux/virtio_input.h>
+
+struct virtio_input {
+	struct virtio_device       *vdev;
+	struct input_dev           *idev;
+	char                       name[64];
+	char                       serial[64];
+	char                       phys[64];
+	struct virtqueue           *evt, *sts;
+	struct virtio_input_event  evts[64];
+	spinlock_t                 lock;
+	bool                       ready;
+};
+
+static void virtinput_queue_evtbuf(struct virtio_input *vi,
+				   struct virtio_input_event *evtbuf)
+{
+	struct scatterlist sg[1];
+
+	sg_init_one(sg, evtbuf, sizeof(*evtbuf));
+	virtqueue_add_inbuf(vi->evt, sg, 1, evtbuf, GFP_ATOMIC);
+}
+
+static void virtinput_recv_events(struct virtqueue *vq)
+{
+	struct virtio_input *vi = vq->vdev->priv;
+	struct virtio_input_event *event;
+	unsigned long flags;
+	unsigned int len;
+
+	spin_lock_irqsave(&vi->lock, flags);
+	if (vi->ready) {
+		while ((event = virtqueue_get_buf(vi->evt, &len)) != NULL) {
+			spin_unlock_irqrestore(&vi->lock, flags);
+			input_event(vi->idev,
+				    le16_to_cpu(event->type),
+				    le16_to_cpu(event->code),
+				    le32_to_cpu(event->value));
+			spin_lock_irqsave(&vi->lock, flags);
+			virtinput_queue_evtbuf(vi, event);
+		}
+		virtqueue_kick(vq);
+	}
+	spin_unlock_irqrestore(&vi->lock, flags);
+}
+
+/*
+ * On error we are losing the status update, which isn't critical as
+ * this is typically used for stuff like keyboard leds.
+ */
+static int virtinput_send_status(struct virtio_input *vi,
+				 u16 type, u16 code, s32 value)
+{
+	struct virtio_input_event *stsbuf;
+	struct scatterlist sg[1];
+	unsigned long flags;
+	int rc;
+
+	stsbuf = kzalloc(sizeof(*stsbuf), GFP_ATOMIC);
+	if (!stsbuf)
+		return -ENOMEM;
+
+	stsbuf->type  = cpu_to_le16(type);
+	stsbuf->code  = cpu_to_le16(code);
+	stsbuf->value = cpu_to_le32(value);
+	sg_init_one(sg, stsbuf, sizeof(*stsbuf));
+
+	spin_lock_irqsave(&vi->lock, flags);
+	if (vi->ready) {
+		rc = virtqueue_add_outbuf(vi->sts, sg, 1, stsbuf, GFP_ATOMIC);
+		virtqueue_kick(vi->sts);
+	} else {
+		rc = -ENODEV;
+	}
+	spin_unlock_irqrestore(&vi->lock, flags);
+
+	if (rc != 0)
+		kfree(stsbuf);
+	return rc;
+}
+
+static void virtinput_recv_status(struct virtqueue *vq)
+{
+	struct virtio_input *vi = vq->vdev->priv;
+	struct virtio_input_event *stsbuf;
+	unsigned long flags;
+	unsigned int len;
+
+	spin_lock_irqsave(&vi->lock, flags);
+	while ((stsbuf = virtqueue_get_buf(vi->sts, &len)) != NULL)
+		kfree(stsbuf);
+	spin_unlock_irqrestore(&vi->lock, flags);
+}
+
+static int virtinput_status(struct input_dev *idev, unsigned int type,
+			    unsigned int code, int value)
+{
+	struct virtio_input *vi = input_get_drvdata(idev);
+
+	return virtinput_send_status(vi, type, code, value);
+}
+
+static u8 virtinput_cfg_select(struct virtio_input *vi,
+			       u8 select, u8 subsel)
+{
+	u8 size;
+
+	virtio_cwrite_le(vi->vdev, struct virtio_input_config, select, &select);
+	virtio_cwrite_le(vi->vdev, struct virtio_input_config, subsel, &subsel);
+	virtio_cread_le(vi->vdev, struct virtio_input_config, size, &size);
+	return size;
+}
+
+static void virtinput_cfg_bits(struct virtio_input *vi, int select, int subsel,
+			       unsigned long *bits, unsigned int bitcount)
+{
+	unsigned int bit;
+	u8 *virtio_bits;
+	u8 bytes;
+
+	bytes = virtinput_cfg_select(vi, select, subsel);
+	if (!bytes)
+		return;
+	if (bitcount > bytes * 8)
+		bitcount = bytes * 8;
+
+	/*
+	 * Bitmap in virtio config space is a simple stream of bytes,
+	 * with the first byte carrying bits 0-7, second bits 8-15 and
+	 * so on.
+	 */
+	virtio_bits = kzalloc(bytes, GFP_KERNEL);
+	if (!virtio_bits)
+		return;
+	virtio_cread_bytes(vi->vdev, offsetof(struct virtio_input_config,
+					      u.bitmap),
+			   virtio_bits, bytes);
+	for (bit = 0; bit < bitcount; bit++) {
+		if (virtio_bits[bit / 8] & (1 << (bit % 8)))
+			__set_bit(bit, bits);
+	}
+	kfree(virtio_bits);
+
+	if (select == VIRTIO_INPUT_CFG_EV_BITS)
+		__set_bit(subsel, vi->idev->evbit);
+}
+
+static void virtinput_cfg_abs(struct virtio_input *vi, int abs)
+{
+	u32 mi, ma, re, fu, fl;
+
+	virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_ABS_INFO, abs);
+	virtio_cread_le(vi->vdev, struct virtio_input_config, u.abs.min, &mi);
+	virtio_cread_le(vi->vdev, struct virtio_input_config, u.abs.max, &ma);
+	virtio_cread_le(vi->vdev, struct virtio_input_config, u.abs.res, &re);
+	virtio_cread_le(vi->vdev, struct virtio_input_config, u.abs.fuzz, &fu);
+	virtio_cread_le(vi->vdev, struct virtio_input_config, u.abs.flat, &fl);
+	input_set_abs_params(vi->idev, abs, mi, ma, fu, fl);
+	input_abs_set_res(vi->idev, abs, re);
+}
+
+static int virtinput_init_vqs(struct virtio_input *vi)
+{
+	struct virtqueue *vqs[2];
+	vq_callback_t *cbs[] = { virtinput_recv_events,
+				 virtinput_recv_status };
+	static const char * const names[] = { "events", "status" };
+	int err;
+
+	err = virtio_find_vqs(vi->vdev, 2, vqs, cbs, names, NULL);
+	if (err)
+		return err;
+	vi->evt = vqs[0];
+	vi->sts = vqs[1];
+
+	return 0;
+}
+
+static void virtinput_fill_evt(struct virtio_input *vi)
+{
+	unsigned long flags;
+	int i, size;
+
+	spin_lock_irqsave(&vi->lock, flags);
+	size = virtqueue_get_vring_size(vi->evt);
+	if (size > ARRAY_SIZE(vi->evts))
+		size = ARRAY_SIZE(vi->evts);
+	for (i = 0; i < size; i++)
+		virtinput_queue_evtbuf(vi, &vi->evts[i]);
+	virtqueue_kick(vi->evt);
+	spin_unlock_irqrestore(&vi->lock, flags);
+}
+
+static int virtinput_probe(struct virtio_device *vdev)
+{
+	struct virtio_input *vi;
+	unsigned long flags;
+	size_t size;
+	int abs, err;
+
+	if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
+		return -ENODEV;
+
+	vi = kzalloc(sizeof(*vi), GFP_KERNEL);
+	if (!vi)
+		return -ENOMEM;
+
+	vdev->priv = vi;
+	vi->vdev = vdev;
+	spin_lock_init(&vi->lock);
+
+	err = virtinput_init_vqs(vi);
+	if (err)
+		goto err_init_vq;
+
+	vi->idev = input_allocate_device();
+	if (!vi->idev) {
+		err = -ENOMEM;
+		goto err_input_alloc;
+	}
+	input_set_drvdata(vi->idev, vi);
+
+	size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_ID_NAME, 0);
+	virtio_cread_bytes(vi->vdev, offsetof(struct virtio_input_config,
+					      u.string),
+			   vi->name, min(size, sizeof(vi->name)));
+	size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_ID_SERIAL, 0);
+	virtio_cread_bytes(vi->vdev, offsetof(struct virtio_input_config,
+					      u.string),
+			   vi->serial, min(size, sizeof(vi->serial)));
+	snprintf(vi->phys, sizeof(vi->phys),
+		 "virtio%d/input0", vdev->index);
+	vi->idev->name = vi->name;
+	vi->idev->phys = vi->phys;
+	vi->idev->uniq = vi->serial;
+
+	size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_ID_DEVIDS, 0);
+	if (size >= sizeof(struct virtio_input_devids)) {
+		virtio_cread_le(vi->vdev, struct virtio_input_config,
+				u.ids.bustype, &vi->idev->id.bustype);
+		virtio_cread_le(vi->vdev, struct virtio_input_config,
+				u.ids.vendor, &vi->idev->id.vendor);
+		virtio_cread_le(vi->vdev, struct virtio_input_config,
+				u.ids.product, &vi->idev->id.product);
+		virtio_cread_le(vi->vdev, struct virtio_input_config,
+				u.ids.version, &vi->idev->id.version);
+	} else {
+		vi->idev->id.bustype = BUS_VIRTUAL;
+	}
+
+	virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_PROP_BITS, 0,
+			   vi->idev->propbit, INPUT_PROP_CNT);
+	size = virtinput_cfg_select(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_REP);
+	if (size)
+		__set_bit(EV_REP, vi->idev->evbit);
+
+	vi->idev->dev.parent = &vdev->dev;
+	vi->idev->event = virtinput_status;
+
+	/* device -> kernel */
+	virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_KEY,
+			   vi->idev->keybit, KEY_CNT);
+	virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_REL,
+			   vi->idev->relbit, REL_CNT);
+	virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_ABS,
+			   vi->idev->absbit, ABS_CNT);
+	virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_MSC,
+			   vi->idev->mscbit, MSC_CNT);
+	virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_SW,
+			   vi->idev->swbit,  SW_CNT);
+
+	/* kernel -> device */
+	virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_LED,
+			   vi->idev->ledbit, LED_CNT);
+	virtinput_cfg_bits(vi, VIRTIO_INPUT_CFG_EV_BITS, EV_SND,
+			   vi->idev->sndbit, SND_CNT);
+
+	if (test_bit(EV_ABS, vi->idev->evbit)) {
+		for (abs = 0; abs < ABS_CNT; abs++) {
+			if (!test_bit(abs, vi->idev->absbit))
+				continue;
+			virtinput_cfg_abs(vi, abs);
+		}
+	}
+
+	virtio_device_ready(vdev);
+	vi->ready = true;
+	err = input_register_device(vi->idev);
+	if (err)
+		goto err_input_register;
+
+	virtinput_fill_evt(vi);
+	return 0;
+
+err_input_register:
+	spin_lock_irqsave(&vi->lock, flags);
+	vi->ready = false;
+	spin_unlock_irqrestore(&vi->lock, flags);
+	input_free_device(vi->idev);
+err_input_alloc:
+	vdev->config->del_vqs(vdev);
+err_init_vq:
+	kfree(vi);
+	return err;
+}
+
+static void virtinput_remove(struct virtio_device *vdev)
+{
+	struct virtio_input *vi = vdev->priv;
+	void *buf;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vi->lock, flags);
+	vi->ready = false;
+	spin_unlock_irqrestore(&vi->lock, flags);
+
+	input_unregister_device(vi->idev);
+	vdev->config->reset(vdev);
+	while ((buf = virtqueue_detach_unused_buf(vi->sts)) != NULL)
+		kfree(buf);
+	vdev->config->del_vqs(vdev);
+	kfree(vi);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int virtinput_freeze(struct virtio_device *vdev)
+{
+	struct virtio_input *vi = vdev->priv;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vi->lock, flags);
+	vi->ready = false;
+	spin_unlock_irqrestore(&vi->lock, flags);
+
+	vdev->config->del_vqs(vdev);
+	return 0;
+}
+
+static int virtinput_restore(struct virtio_device *vdev)
+{
+	struct virtio_input *vi = vdev->priv;
+	int err;
+
+	err = virtinput_init_vqs(vi);
+	if (err)
+		return err;
+
+	virtio_device_ready(vdev);
+	vi->ready = true;
+	virtinput_fill_evt(vi);
+	return 0;
+}
+#endif
+
+static unsigned int features[] = {
+	/* none */
+};
+static const struct virtio_device_id id_table[] = {
+	{ VIRTIO_ID_INPUT, VIRTIO_DEV_ANY_ID },
+	{ 0 },
+};
+
+static struct virtio_driver virtio_input_driver = {
+	.driver.name         = KBUILD_MODNAME,
+	.driver.owner        = THIS_MODULE,
+	.feature_table       = features,
+	.feature_table_size  = ARRAY_SIZE(features),
+	.id_table            = id_table,
+	.probe               = virtinput_probe,
+	.remove              = virtinput_remove,
+#ifdef CONFIG_PM_SLEEP
+	.freeze	             = virtinput_freeze,
+	.restore             = virtinput_restore,
+#endif
+};
+
+module_virtio_driver(virtio_input_driver);
+MODULE_DEVICE_TABLE(virtio, id_table);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Virtio input device driver");
+MODULE_AUTHOR("Gerd Hoffmann <kraxel@redhat.com>");
diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
new file mode 100644
index 000000000..181e2f18b
--- /dev/null
+++ b/drivers/virtio/virtio_mem.c
@@ -0,0 +1,1954 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Virtio-mem device driver.
+ *
+ * Copyright Red Hat, Inc. 2020
+ *
+ * Author(s): David Hildenbrand <david@redhat.com>
+ */
+
+#include <linux/virtio.h>
+#include <linux/virtio_mem.h>
+#include <linux/workqueue.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/memory_hotplug.h>
+#include <linux/memory.h>
+#include <linux/hrtimer.h>
+#include <linux/crash_dump.h>
+#include <linux/mutex.h>
+#include <linux/bitmap.h>
+#include <linux/lockdep.h>
+
+#include <acpi/acpi_numa.h>
+
+static bool unplug_online = true;
+module_param(unplug_online, bool, 0644);
+MODULE_PARM_DESC(unplug_online, "Try to unplug online memory");
+
+enum virtio_mem_mb_state {
+	/* Unplugged, not added to Linux. Can be reused later. */
+	VIRTIO_MEM_MB_STATE_UNUSED = 0,
+	/* (Partially) plugged, not added to Linux. Error on add_memory(). */
+	VIRTIO_MEM_MB_STATE_PLUGGED,
+	/* Fully plugged, fully added to Linux, offline. */
+	VIRTIO_MEM_MB_STATE_OFFLINE,
+	/* Partially plugged, fully added to Linux, offline. */
+	VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL,
+	/* Fully plugged, fully added to Linux, online. */
+	VIRTIO_MEM_MB_STATE_ONLINE,
+	/* Partially plugged, fully added to Linux, online. */
+	VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL,
+	VIRTIO_MEM_MB_STATE_COUNT
+};
+
+struct virtio_mem {
+	struct virtio_device *vdev;
+
+	/* We might first have to unplug all memory when starting up. */
+	bool unplug_all_required;
+
+	/* Workqueue that processes the plug/unplug requests. */
+	struct work_struct wq;
+	atomic_t config_changed;
+
+	/* Virtqueue for guest->host requests. */
+	struct virtqueue *vq;
+
+	/* Wait for a host response to a guest request. */
+	wait_queue_head_t host_resp;
+
+	/* Space for one guest request and the host response. */
+	struct virtio_mem_req req;
+	struct virtio_mem_resp resp;
+
+	/* The current size of the device. */
+	uint64_t plugged_size;
+	/* The requested size of the device. */
+	uint64_t requested_size;
+
+	/* The device block size (for communicating with the device). */
+	uint64_t device_block_size;
+	/* The translated node id. NUMA_NO_NODE in case not specified. */
+	int nid;
+	/* Physical start address of the memory region. */
+	uint64_t addr;
+	/* Maximum region size in bytes. */
+	uint64_t region_size;
+
+	/* The subblock size. */
+	uint64_t subblock_size;
+	/* The number of subblocks per memory block. */
+	uint32_t nb_sb_per_mb;
+
+	/* Id of the first memory block of this device. */
+	unsigned long first_mb_id;
+	/* Id of the last memory block of this device. */
+	unsigned long last_mb_id;
+	/* Id of the last usable memory block of this device. */
+	unsigned long last_usable_mb_id;
+	/* Id of the next memory bock to prepare when needed. */
+	unsigned long next_mb_id;
+
+	/* The parent resource for all memory added via this device. */
+	struct resource *parent_resource;
+	/*
+	 * Copy of "System RAM (virtio_mem)" to be used for
+	 * add_memory_driver_managed().
+	 */
+	const char *resource_name;
+
+	/* Summary of all memory block states. */
+	unsigned long nb_mb_state[VIRTIO_MEM_MB_STATE_COUNT];
+#define VIRTIO_MEM_NB_OFFLINE_THRESHOLD		10
+
+	/*
+	 * One byte state per memory block.
+	 *
+	 * Allocated via vmalloc(). When preparing new blocks, resized
+	 * (alloc+copy+free) when needed (crossing pages with the next mb).
+	 * (when crossing pages).
+	 *
+	 * With 128MB memory blocks, we have states for 512GB of memory in one
+	 * page.
+	 */
+	uint8_t *mb_state;
+
+	/*
+	 * $nb_sb_per_mb bit per memory block. Handled similar to mb_state.
+	 *
+	 * With 4MB subblocks, we manage 128GB of memory in one page.
+	 */
+	unsigned long *sb_bitmap;
+
+	/*
+	 * Mutex that protects the nb_mb_state, mb_state, and sb_bitmap.
+	 *
+	 * When this lock is held the pointers can't change, ONLINE and
+	 * OFFLINE blocks can't change the state and no subblocks will get
+	 * plugged/unplugged.
+	 */
+	struct mutex hotplug_mutex;
+	bool hotplug_active;
+
+	/* An error occurred we cannot handle - stop processing requests. */
+	bool broken;
+
+	/* The driver is being removed. */
+	spinlock_t removal_lock;
+	bool removing;
+
+	/* Timer for retrying to plug/unplug memory. */
+	struct hrtimer retry_timer;
+	unsigned int retry_timer_ms;
+#define VIRTIO_MEM_RETRY_TIMER_MIN_MS		50000
+#define VIRTIO_MEM_RETRY_TIMER_MAX_MS		300000
+
+	/* Memory notifier (online/offline events). */
+	struct notifier_block memory_notifier;
+
+	/* Next device in the list of virtio-mem devices. */
+	struct list_head next;
+};
+
+/*
+ * We have to share a single online_page callback among all virtio-mem
+ * devices. We use RCU to iterate the list in the callback.
+ */
+static DEFINE_MUTEX(virtio_mem_mutex);
+static LIST_HEAD(virtio_mem_devices);
+
+static void virtio_mem_online_page_cb(struct page *page, unsigned int order);
+
+/*
+ * Register a virtio-mem device so it will be considered for the online_page
+ * callback.
+ */
+static int register_virtio_mem_device(struct virtio_mem *vm)
+{
+	int rc = 0;
+
+	/* First device registers the callback. */
+	mutex_lock(&virtio_mem_mutex);
+	if (list_empty(&virtio_mem_devices))
+		rc = set_online_page_callback(&virtio_mem_online_page_cb);
+	if (!rc)
+		list_add_rcu(&vm->next, &virtio_mem_devices);
+	mutex_unlock(&virtio_mem_mutex);
+
+	return rc;
+}
+
+/*
+ * Unregister a virtio-mem device so it will no longer be considered for the
+ * online_page callback.
+ */
+static void unregister_virtio_mem_device(struct virtio_mem *vm)
+{
+	/* Last device unregisters the callback. */
+	mutex_lock(&virtio_mem_mutex);
+	list_del_rcu(&vm->next);
+	if (list_empty(&virtio_mem_devices))
+		restore_online_page_callback(&virtio_mem_online_page_cb);
+	mutex_unlock(&virtio_mem_mutex);
+
+	synchronize_rcu();
+}
+
+/*
+ * Calculate the memory block id of a given address.
+ */
+static unsigned long virtio_mem_phys_to_mb_id(unsigned long addr)
+{
+	return addr / memory_block_size_bytes();
+}
+
+/*
+ * Calculate the physical start address of a given memory block id.
+ */
+static unsigned long virtio_mem_mb_id_to_phys(unsigned long mb_id)
+{
+	return mb_id * memory_block_size_bytes();
+}
+
+/*
+ * Calculate the subblock id of a given address.
+ */
+static unsigned long virtio_mem_phys_to_sb_id(struct virtio_mem *vm,
+					      unsigned long addr)
+{
+	const unsigned long mb_id = virtio_mem_phys_to_mb_id(addr);
+	const unsigned long mb_addr = virtio_mem_mb_id_to_phys(mb_id);
+
+	return (addr - mb_addr) / vm->subblock_size;
+}
+
+/*
+ * Set the state of a memory block, taking care of the state counter.
+ */
+static void virtio_mem_mb_set_state(struct virtio_mem *vm, unsigned long mb_id,
+				    enum virtio_mem_mb_state state)
+{
+	const unsigned long idx = mb_id - vm->first_mb_id;
+	enum virtio_mem_mb_state old_state;
+
+	old_state = vm->mb_state[idx];
+	vm->mb_state[idx] = state;
+
+	BUG_ON(vm->nb_mb_state[old_state] == 0);
+	vm->nb_mb_state[old_state]--;
+	vm->nb_mb_state[state]++;
+}
+
+/*
+ * Get the state of a memory block.
+ */
+static enum virtio_mem_mb_state virtio_mem_mb_get_state(struct virtio_mem *vm,
+							unsigned long mb_id)
+{
+	const unsigned long idx = mb_id - vm->first_mb_id;
+
+	return vm->mb_state[idx];
+}
+
+/*
+ * Prepare the state array for the next memory block.
+ */
+static int virtio_mem_mb_state_prepare_next_mb(struct virtio_mem *vm)
+{
+	unsigned long old_bytes = vm->next_mb_id - vm->first_mb_id + 1;
+	unsigned long new_bytes = vm->next_mb_id - vm->first_mb_id + 2;
+	int old_pages = PFN_UP(old_bytes);
+	int new_pages = PFN_UP(new_bytes);
+	uint8_t *new_mb_state;
+
+	if (vm->mb_state && old_pages == new_pages)
+		return 0;
+
+	new_mb_state = vzalloc(new_pages * PAGE_SIZE);
+	if (!new_mb_state)
+		return -ENOMEM;
+
+	mutex_lock(&vm->hotplug_mutex);
+	if (vm->mb_state)
+		memcpy(new_mb_state, vm->mb_state, old_pages * PAGE_SIZE);
+	vfree(vm->mb_state);
+	vm->mb_state = new_mb_state;
+	mutex_unlock(&vm->hotplug_mutex);
+
+	return 0;
+}
+
+#define virtio_mem_for_each_mb_state(_vm, _mb_id, _state) \
+	for (_mb_id = _vm->first_mb_id; \
+	     _mb_id < _vm->next_mb_id && _vm->nb_mb_state[_state]; \
+	     _mb_id++) \
+		if (virtio_mem_mb_get_state(_vm, _mb_id) == _state)
+
+#define virtio_mem_for_each_mb_state_rev(_vm, _mb_id, _state) \
+	for (_mb_id = _vm->next_mb_id - 1; \
+	     _mb_id >= _vm->first_mb_id && _vm->nb_mb_state[_state]; \
+	     _mb_id--) \
+		if (virtio_mem_mb_get_state(_vm, _mb_id) == _state)
+
+/*
+ * Mark all selected subblocks plugged.
+ *
+ * Will not modify the state of the memory block.
+ */
+static void virtio_mem_mb_set_sb_plugged(struct virtio_mem *vm,
+					 unsigned long mb_id, int sb_id,
+					 int count)
+{
+	const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id;
+
+	__bitmap_set(vm->sb_bitmap, bit, count);
+}
+
+/*
+ * Mark all selected subblocks unplugged.
+ *
+ * Will not modify the state of the memory block.
+ */
+static void virtio_mem_mb_set_sb_unplugged(struct virtio_mem *vm,
+					   unsigned long mb_id, int sb_id,
+					   int count)
+{
+	const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id;
+
+	__bitmap_clear(vm->sb_bitmap, bit, count);
+}
+
+/*
+ * Test if all selected subblocks are plugged.
+ */
+static bool virtio_mem_mb_test_sb_plugged(struct virtio_mem *vm,
+					  unsigned long mb_id, int sb_id,
+					  int count)
+{
+	const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id;
+
+	if (count == 1)
+		return test_bit(bit, vm->sb_bitmap);
+
+	/* TODO: Helper similar to bitmap_set() */
+	return find_next_zero_bit(vm->sb_bitmap, bit + count, bit) >=
+	       bit + count;
+}
+
+/*
+ * Test if all selected subblocks are unplugged.
+ */
+static bool virtio_mem_mb_test_sb_unplugged(struct virtio_mem *vm,
+					    unsigned long mb_id, int sb_id,
+					    int count)
+{
+	const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id;
+
+	/* TODO: Helper similar to bitmap_set() */
+	return find_next_bit(vm->sb_bitmap, bit + count, bit) >= bit + count;
+}
+
+/*
+ * Find the first unplugged subblock. Returns vm->nb_sb_per_mb in case there is
+ * none.
+ */
+static int virtio_mem_mb_first_unplugged_sb(struct virtio_mem *vm,
+					    unsigned long mb_id)
+{
+	const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb;
+
+	return find_next_zero_bit(vm->sb_bitmap, bit + vm->nb_sb_per_mb, bit) -
+	       bit;
+}
+
+/*
+ * Prepare the subblock bitmap for the next memory block.
+ */
+static int virtio_mem_sb_bitmap_prepare_next_mb(struct virtio_mem *vm)
+{
+	const unsigned long old_nb_mb = vm->next_mb_id - vm->first_mb_id;
+	const unsigned long old_nb_bits = old_nb_mb * vm->nb_sb_per_mb;
+	const unsigned long new_nb_bits = (old_nb_mb + 1) * vm->nb_sb_per_mb;
+	int old_pages = PFN_UP(BITS_TO_LONGS(old_nb_bits) * sizeof(long));
+	int new_pages = PFN_UP(BITS_TO_LONGS(new_nb_bits) * sizeof(long));
+	unsigned long *new_sb_bitmap, *old_sb_bitmap;
+
+	if (vm->sb_bitmap && old_pages == new_pages)
+		return 0;
+
+	new_sb_bitmap = vzalloc(new_pages * PAGE_SIZE);
+	if (!new_sb_bitmap)
+		return -ENOMEM;
+
+	mutex_lock(&vm->hotplug_mutex);
+	if (new_sb_bitmap)
+		memcpy(new_sb_bitmap, vm->sb_bitmap, old_pages * PAGE_SIZE);
+
+	old_sb_bitmap = vm->sb_bitmap;
+	vm->sb_bitmap = new_sb_bitmap;
+	mutex_unlock(&vm->hotplug_mutex);
+
+	vfree(old_sb_bitmap);
+	return 0;
+}
+
+/*
+ * Try to add a memory block to Linux. This will usually only fail
+ * if out of memory.
+ *
+ * Must not be called with the vm->hotplug_mutex held (possible deadlock with
+ * onlining code).
+ *
+ * Will not modify the state of the memory block.
+ */
+static int virtio_mem_mb_add(struct virtio_mem *vm, unsigned long mb_id)
+{
+	const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
+	int nid = vm->nid;
+
+	if (nid == NUMA_NO_NODE)
+		nid = memory_add_physaddr_to_nid(addr);
+
+	/*
+	 * When force-unloading the driver and we still have memory added to
+	 * Linux, the resource name has to stay.
+	 */
+	if (!vm->resource_name) {
+		vm->resource_name = kstrdup_const("System RAM (virtio_mem)",
+						  GFP_KERNEL);
+		if (!vm->resource_name)
+			return -ENOMEM;
+	}
+
+	dev_dbg(&vm->vdev->dev, "adding memory block: %lu\n", mb_id);
+	return add_memory_driver_managed(nid, addr, memory_block_size_bytes(),
+					 vm->resource_name,
+					 MEMHP_MERGE_RESOURCE);
+}
+
+/*
+ * Try to remove a memory block from Linux. Will only fail if the memory block
+ * is not offline.
+ *
+ * Must not be called with the vm->hotplug_mutex held (possible deadlock with
+ * onlining code).
+ *
+ * Will not modify the state of the memory block.
+ */
+static int virtio_mem_mb_remove(struct virtio_mem *vm, unsigned long mb_id)
+{
+	const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
+	int nid = vm->nid;
+
+	if (nid == NUMA_NO_NODE)
+		nid = memory_add_physaddr_to_nid(addr);
+
+	dev_dbg(&vm->vdev->dev, "removing memory block: %lu\n", mb_id);
+	return remove_memory(nid, addr, memory_block_size_bytes());
+}
+
+/*
+ * Try to offline and remove a memory block from Linux.
+ *
+ * Must not be called with the vm->hotplug_mutex held (possible deadlock with
+ * onlining code).
+ *
+ * Will not modify the state of the memory block.
+ */
+static int virtio_mem_mb_offline_and_remove(struct virtio_mem *vm,
+					    unsigned long mb_id)
+{
+	const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
+	int nid = vm->nid;
+
+	if (nid == NUMA_NO_NODE)
+		nid = memory_add_physaddr_to_nid(addr);
+
+	dev_dbg(&vm->vdev->dev, "offlining and removing memory block: %lu\n",
+		mb_id);
+	return offline_and_remove_memory(nid, addr, memory_block_size_bytes());
+}
+
+/*
+ * Trigger the workqueue so the device can perform its magic.
+ */
+static void virtio_mem_retry(struct virtio_mem *vm)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&vm->removal_lock, flags);
+	if (!vm->removing)
+		queue_work(system_freezable_wq, &vm->wq);
+	spin_unlock_irqrestore(&vm->removal_lock, flags);
+}
+
+static int virtio_mem_translate_node_id(struct virtio_mem *vm, uint16_t node_id)
+{
+	int node = NUMA_NO_NODE;
+
+#if defined(CONFIG_ACPI_NUMA)
+	if (virtio_has_feature(vm->vdev, VIRTIO_MEM_F_ACPI_PXM))
+		node = pxm_to_node(node_id);
+#endif
+	return node;
+}
+
+/*
+ * Test if a virtio-mem device overlaps with the given range. Can be called
+ * from (notifier) callbacks lockless.
+ */
+static bool virtio_mem_overlaps_range(struct virtio_mem *vm,
+				      unsigned long start, unsigned long size)
+{
+	unsigned long dev_start = virtio_mem_mb_id_to_phys(vm->first_mb_id);
+	unsigned long dev_end = virtio_mem_mb_id_to_phys(vm->last_mb_id) +
+				memory_block_size_bytes();
+
+	return start < dev_end && dev_start < start + size;
+}
+
+/*
+ * Test if a virtio-mem device owns a memory block. Can be called from
+ * (notifier) callbacks lockless.
+ */
+static bool virtio_mem_owned_mb(struct virtio_mem *vm, unsigned long mb_id)
+{
+	return mb_id >= vm->first_mb_id && mb_id <= vm->last_mb_id;
+}
+
+static int virtio_mem_notify_going_online(struct virtio_mem *vm,
+					  unsigned long mb_id)
+{
+	switch (virtio_mem_mb_get_state(vm, mb_id)) {
+	case VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL:
+	case VIRTIO_MEM_MB_STATE_OFFLINE:
+		return NOTIFY_OK;
+	default:
+		break;
+	}
+	dev_warn_ratelimited(&vm->vdev->dev,
+			     "memory block onlining denied\n");
+	return NOTIFY_BAD;
+}
+
+static void virtio_mem_notify_offline(struct virtio_mem *vm,
+				      unsigned long mb_id)
+{
+	switch (virtio_mem_mb_get_state(vm, mb_id)) {
+	case VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL:
+		virtio_mem_mb_set_state(vm, mb_id,
+					VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL);
+		break;
+	case VIRTIO_MEM_MB_STATE_ONLINE:
+		virtio_mem_mb_set_state(vm, mb_id,
+					VIRTIO_MEM_MB_STATE_OFFLINE);
+		break;
+	default:
+		BUG();
+		break;
+	}
+
+	/*
+	 * Trigger the workqueue, maybe we can now unplug memory. Also,
+	 * when we offline and remove a memory block, this will re-trigger
+	 * us immediately - which is often nice because the removal of
+	 * the memory block (e.g., memmap) might have freed up memory
+	 * on other memory blocks we manage.
+	 */
+	virtio_mem_retry(vm);
+}
+
+static void virtio_mem_notify_online(struct virtio_mem *vm, unsigned long mb_id)
+{
+	unsigned long nb_offline;
+
+	switch (virtio_mem_mb_get_state(vm, mb_id)) {
+	case VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL:
+		virtio_mem_mb_set_state(vm, mb_id,
+					VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL);
+		break;
+	case VIRTIO_MEM_MB_STATE_OFFLINE:
+		virtio_mem_mb_set_state(vm, mb_id, VIRTIO_MEM_MB_STATE_ONLINE);
+		break;
+	default:
+		BUG();
+		break;
+	}
+	nb_offline = vm->nb_mb_state[VIRTIO_MEM_MB_STATE_OFFLINE] +
+		     vm->nb_mb_state[VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL];
+
+	/* see if we can add new blocks now that we onlined one block */
+	if (nb_offline == VIRTIO_MEM_NB_OFFLINE_THRESHOLD - 1)
+		virtio_mem_retry(vm);
+}
+
+static void virtio_mem_notify_going_offline(struct virtio_mem *vm,
+					    unsigned long mb_id)
+{
+	const unsigned long nr_pages = PFN_DOWN(vm->subblock_size);
+	struct page *page;
+	unsigned long pfn;
+	int sb_id, i;
+
+	for (sb_id = 0; sb_id < vm->nb_sb_per_mb; sb_id++) {
+		if (virtio_mem_mb_test_sb_plugged(vm, mb_id, sb_id, 1))
+			continue;
+		/*
+		 * Drop our reference to the pages so the memory can get
+		 * offlined and add the unplugged pages to the managed
+		 * page counters (so offlining code can correctly subtract
+		 * them again).
+		 */
+		pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
+			       sb_id * vm->subblock_size);
+		adjust_managed_page_count(pfn_to_page(pfn), nr_pages);
+		for (i = 0; i < nr_pages; i++) {
+			page = pfn_to_page(pfn + i);
+			if (WARN_ON(!page_ref_dec_and_test(page)))
+				dump_page(page, "unplugged page referenced");
+		}
+	}
+}
+
+static void virtio_mem_notify_cancel_offline(struct virtio_mem *vm,
+					     unsigned long mb_id)
+{
+	const unsigned long nr_pages = PFN_DOWN(vm->subblock_size);
+	unsigned long pfn;
+	int sb_id, i;
+
+	for (sb_id = 0; sb_id < vm->nb_sb_per_mb; sb_id++) {
+		if (virtio_mem_mb_test_sb_plugged(vm, mb_id, sb_id, 1))
+			continue;
+		/*
+		 * Get the reference we dropped when going offline and
+		 * subtract the unplugged pages from the managed page
+		 * counters.
+		 */
+		pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
+			       sb_id * vm->subblock_size);
+		adjust_managed_page_count(pfn_to_page(pfn), -nr_pages);
+		for (i = 0; i < nr_pages; i++)
+			page_ref_inc(pfn_to_page(pfn + i));
+	}
+}
+
+/*
+ * This callback will either be called synchronously from add_memory() or
+ * asynchronously (e.g., triggered via user space). We have to be careful
+ * with locking when calling add_memory().
+ */
+static int virtio_mem_memory_notifier_cb(struct notifier_block *nb,
+					 unsigned long action, void *arg)
+{
+	struct virtio_mem *vm = container_of(nb, struct virtio_mem,
+					     memory_notifier);
+	struct memory_notify *mhp = arg;
+	const unsigned long start = PFN_PHYS(mhp->start_pfn);
+	const unsigned long size = PFN_PHYS(mhp->nr_pages);
+	const unsigned long mb_id = virtio_mem_phys_to_mb_id(start);
+	int rc = NOTIFY_OK;
+
+	if (!virtio_mem_overlaps_range(vm, start, size))
+		return NOTIFY_DONE;
+
+	/*
+	 * Memory is onlined/offlined in memory block granularity. We cannot
+	 * cross virtio-mem device boundaries and memory block boundaries. Bail
+	 * out if this ever changes.
+	 */
+	if (WARN_ON_ONCE(size != memory_block_size_bytes() ||
+			 !IS_ALIGNED(start, memory_block_size_bytes())))
+		return NOTIFY_BAD;
+
+	/*
+	 * Avoid circular locking lockdep warnings. We lock the mutex
+	 * e.g., in MEM_GOING_ONLINE and unlock it in MEM_ONLINE. The
+	 * blocking_notifier_call_chain() has it's own lock, which gets unlocked
+	 * between both notifier calls and will bail out. False positive.
+	 */
+	lockdep_off();
+
+	switch (action) {
+	case MEM_GOING_OFFLINE:
+		mutex_lock(&vm->hotplug_mutex);
+		if (vm->removing) {
+			rc = notifier_from_errno(-EBUSY);
+			mutex_unlock(&vm->hotplug_mutex);
+			break;
+		}
+		vm->hotplug_active = true;
+		virtio_mem_notify_going_offline(vm, mb_id);
+		break;
+	case MEM_GOING_ONLINE:
+		mutex_lock(&vm->hotplug_mutex);
+		if (vm->removing) {
+			rc = notifier_from_errno(-EBUSY);
+			mutex_unlock(&vm->hotplug_mutex);
+			break;
+		}
+		vm->hotplug_active = true;
+		rc = virtio_mem_notify_going_online(vm, mb_id);
+		break;
+	case MEM_OFFLINE:
+		virtio_mem_notify_offline(vm, mb_id);
+		vm->hotplug_active = false;
+		mutex_unlock(&vm->hotplug_mutex);
+		break;
+	case MEM_ONLINE:
+		virtio_mem_notify_online(vm, mb_id);
+		vm->hotplug_active = false;
+		mutex_unlock(&vm->hotplug_mutex);
+		break;
+	case MEM_CANCEL_OFFLINE:
+		if (!vm->hotplug_active)
+			break;
+		virtio_mem_notify_cancel_offline(vm, mb_id);
+		vm->hotplug_active = false;
+		mutex_unlock(&vm->hotplug_mutex);
+		break;
+	case MEM_CANCEL_ONLINE:
+		if (!vm->hotplug_active)
+			break;
+		vm->hotplug_active = false;
+		mutex_unlock(&vm->hotplug_mutex);
+		break;
+	default:
+		break;
+	}
+
+	lockdep_on();
+
+	return rc;
+}
+
+/*
+ * Set a range of pages PG_offline. Remember pages that were never onlined
+ * (via generic_online_page()) using PageDirty().
+ */
+static void virtio_mem_set_fake_offline(unsigned long pfn,
+					unsigned int nr_pages, bool onlined)
+{
+	for (; nr_pages--; pfn++) {
+		struct page *page = pfn_to_page(pfn);
+
+		__SetPageOffline(page);
+		if (!onlined) {
+			SetPageDirty(page);
+			/* FIXME: remove after cleanups */
+			ClearPageReserved(page);
+		}
+	}
+}
+
+/*
+ * Clear PG_offline from a range of pages. If the pages were never onlined,
+ * (via generic_online_page()), clear PageDirty().
+ */
+static void virtio_mem_clear_fake_offline(unsigned long pfn,
+					  unsigned int nr_pages, bool onlined)
+{
+	for (; nr_pages--; pfn++) {
+		struct page *page = pfn_to_page(pfn);
+
+		__ClearPageOffline(page);
+		if (!onlined)
+			ClearPageDirty(page);
+	}
+}
+
+/*
+ * Release a range of fake-offline pages to the buddy, effectively
+ * fake-onlining them.
+ */
+static void virtio_mem_fake_online(unsigned long pfn, unsigned int nr_pages)
+{
+	const int order = MAX_ORDER - 1;
+	int i;
+
+	/*
+	 * We are always called with subblock granularity, which is at least
+	 * aligned to MAX_ORDER - 1.
+	 */
+	for (i = 0; i < nr_pages; i += 1 << order) {
+		struct page *page = pfn_to_page(pfn + i);
+
+		/*
+		 * If the page is PageDirty(), it was kept fake-offline when
+		 * onlining the memory block. Otherwise, it was allocated
+		 * using alloc_contig_range(). All pages in a subblock are
+		 * alike.
+		 */
+		if (PageDirty(page)) {
+			virtio_mem_clear_fake_offline(pfn + i, 1 << order,
+						      false);
+			generic_online_page(page, order);
+		} else {
+			virtio_mem_clear_fake_offline(pfn + i, 1 << order,
+						      true);
+			free_contig_range(pfn + i, 1 << order);
+			adjust_managed_page_count(page, 1 << order);
+		}
+	}
+}
+
+static void virtio_mem_online_page_cb(struct page *page, unsigned int order)
+{
+	const unsigned long addr = page_to_phys(page);
+	const unsigned long mb_id = virtio_mem_phys_to_mb_id(addr);
+	struct virtio_mem *vm;
+	int sb_id;
+
+	/*
+	 * We exploit here that subblocks have at least MAX_ORDER - 1
+	 * size/alignment and that this callback is is called with such a
+	 * size/alignment. So we cannot cross subblocks and therefore
+	 * also not memory blocks.
+	 */
+	rcu_read_lock();
+	list_for_each_entry_rcu(vm, &virtio_mem_devices, next) {
+		if (!virtio_mem_owned_mb(vm, mb_id))
+			continue;
+
+		sb_id = virtio_mem_phys_to_sb_id(vm, addr);
+		/*
+		 * If plugged, online the pages, otherwise, set them fake
+		 * offline (PageOffline).
+		 */
+		if (virtio_mem_mb_test_sb_plugged(vm, mb_id, sb_id, 1))
+			generic_online_page(page, order);
+		else
+			virtio_mem_set_fake_offline(PFN_DOWN(addr), 1 << order,
+						    false);
+		rcu_read_unlock();
+		return;
+	}
+	rcu_read_unlock();
+
+	/* not virtio-mem memory, but e.g., a DIMM. online it */
+	generic_online_page(page, order);
+}
+
+static uint64_t virtio_mem_send_request(struct virtio_mem *vm,
+					const struct virtio_mem_req *req)
+{
+	struct scatterlist *sgs[2], sg_req, sg_resp;
+	unsigned int len;
+	int rc;
+
+	/* don't use the request residing on the stack (vaddr) */
+	vm->req = *req;
+
+	/* out: buffer for request */
+	sg_init_one(&sg_req, &vm->req, sizeof(vm->req));
+	sgs[0] = &sg_req;
+
+	/* in: buffer for response */
+	sg_init_one(&sg_resp, &vm->resp, sizeof(vm->resp));
+	sgs[1] = &sg_resp;
+
+	rc = virtqueue_add_sgs(vm->vq, sgs, 1, 1, vm, GFP_KERNEL);
+	if (rc < 0)
+		return rc;
+
+	virtqueue_kick(vm->vq);
+
+	/* wait for a response */
+	wait_event(vm->host_resp, virtqueue_get_buf(vm->vq, &len));
+
+	return virtio16_to_cpu(vm->vdev, vm->resp.type);
+}
+
+static int virtio_mem_send_plug_request(struct virtio_mem *vm, uint64_t addr,
+					uint64_t size)
+{
+	const uint64_t nb_vm_blocks = size / vm->device_block_size;
+	const struct virtio_mem_req req = {
+		.type = cpu_to_virtio16(vm->vdev, VIRTIO_MEM_REQ_PLUG),
+		.u.plug.addr = cpu_to_virtio64(vm->vdev, addr),
+		.u.plug.nb_blocks = cpu_to_virtio16(vm->vdev, nb_vm_blocks),
+	};
+
+	if (atomic_read(&vm->config_changed))
+		return -EAGAIN;
+
+	switch (virtio_mem_send_request(vm, &req)) {
+	case VIRTIO_MEM_RESP_ACK:
+		vm->plugged_size += size;
+		return 0;
+	case VIRTIO_MEM_RESP_NACK:
+		return -EAGAIN;
+	case VIRTIO_MEM_RESP_BUSY:
+		return -ETXTBSY;
+	case VIRTIO_MEM_RESP_ERROR:
+		return -EINVAL;
+	default:
+		return -ENOMEM;
+	}
+}
+
+static int virtio_mem_send_unplug_request(struct virtio_mem *vm, uint64_t addr,
+					  uint64_t size)
+{
+	const uint64_t nb_vm_blocks = size / vm->device_block_size;
+	const struct virtio_mem_req req = {
+		.type = cpu_to_virtio16(vm->vdev, VIRTIO_MEM_REQ_UNPLUG),
+		.u.unplug.addr = cpu_to_virtio64(vm->vdev, addr),
+		.u.unplug.nb_blocks = cpu_to_virtio16(vm->vdev, nb_vm_blocks),
+	};
+
+	if (atomic_read(&vm->config_changed))
+		return -EAGAIN;
+
+	switch (virtio_mem_send_request(vm, &req)) {
+	case VIRTIO_MEM_RESP_ACK:
+		vm->plugged_size -= size;
+		return 0;
+	case VIRTIO_MEM_RESP_BUSY:
+		return -ETXTBSY;
+	case VIRTIO_MEM_RESP_ERROR:
+		return -EINVAL;
+	default:
+		return -ENOMEM;
+	}
+}
+
+static int virtio_mem_send_unplug_all_request(struct virtio_mem *vm)
+{
+	const struct virtio_mem_req req = {
+		.type = cpu_to_virtio16(vm->vdev, VIRTIO_MEM_REQ_UNPLUG_ALL),
+	};
+
+	switch (virtio_mem_send_request(vm, &req)) {
+	case VIRTIO_MEM_RESP_ACK:
+		vm->unplug_all_required = false;
+		vm->plugged_size = 0;
+		/* usable region might have shrunk */
+		atomic_set(&vm->config_changed, 1);
+		return 0;
+	case VIRTIO_MEM_RESP_BUSY:
+		return -ETXTBSY;
+	default:
+		return -ENOMEM;
+	}
+}
+
+/*
+ * Plug selected subblocks. Updates the plugged state, but not the state
+ * of the memory block.
+ */
+static int virtio_mem_mb_plug_sb(struct virtio_mem *vm, unsigned long mb_id,
+				 int sb_id, int count)
+{
+	const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id) +
+			      sb_id * vm->subblock_size;
+	const uint64_t size = count * vm->subblock_size;
+	int rc;
+
+	dev_dbg(&vm->vdev->dev, "plugging memory block: %lu : %i - %i\n", mb_id,
+		sb_id, sb_id + count - 1);
+
+	rc = virtio_mem_send_plug_request(vm, addr, size);
+	if (!rc)
+		virtio_mem_mb_set_sb_plugged(vm, mb_id, sb_id, count);
+	return rc;
+}
+
+/*
+ * Unplug selected subblocks. Updates the plugged state, but not the state
+ * of the memory block.
+ */
+static int virtio_mem_mb_unplug_sb(struct virtio_mem *vm, unsigned long mb_id,
+				   int sb_id, int count)
+{
+	const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id) +
+			      sb_id * vm->subblock_size;
+	const uint64_t size = count * vm->subblock_size;
+	int rc;
+
+	dev_dbg(&vm->vdev->dev, "unplugging memory block: %lu : %i - %i\n",
+		mb_id, sb_id, sb_id + count - 1);
+
+	rc = virtio_mem_send_unplug_request(vm, addr, size);
+	if (!rc)
+		virtio_mem_mb_set_sb_unplugged(vm, mb_id, sb_id, count);
+	return rc;
+}
+
+/*
+ * Unplug the desired number of plugged subblocks of a offline or not-added
+ * memory block. Will fail if any subblock cannot get unplugged (instead of
+ * skipping it).
+ *
+ * Will not modify the state of the memory block.
+ *
+ * Note: can fail after some subblocks were unplugged.
+ */
+static int virtio_mem_mb_unplug_any_sb(struct virtio_mem *vm,
+				       unsigned long mb_id, uint64_t *nb_sb)
+{
+	int sb_id, count;
+	int rc;
+
+	sb_id = vm->nb_sb_per_mb - 1;
+	while (*nb_sb) {
+		/* Find the next candidate subblock */
+		while (sb_id >= 0 &&
+		       virtio_mem_mb_test_sb_unplugged(vm, mb_id, sb_id, 1))
+			sb_id--;
+		if (sb_id < 0)
+			break;
+		/* Try to unplug multiple subblocks at a time */
+		count = 1;
+		while (count < *nb_sb && sb_id > 0 &&
+		       virtio_mem_mb_test_sb_plugged(vm, mb_id, sb_id - 1, 1)) {
+			count++;
+			sb_id--;
+		}
+
+		rc = virtio_mem_mb_unplug_sb(vm, mb_id, sb_id, count);
+		if (rc)
+			return rc;
+		*nb_sb -= count;
+		sb_id--;
+	}
+
+	return 0;
+}
+
+/*
+ * Unplug all plugged subblocks of an offline or not-added memory block.
+ *
+ * Will not modify the state of the memory block.
+ *
+ * Note: can fail after some subblocks were unplugged.
+ */
+static int virtio_mem_mb_unplug(struct virtio_mem *vm, unsigned long mb_id)
+{
+	uint64_t nb_sb = vm->nb_sb_per_mb;
+
+	return virtio_mem_mb_unplug_any_sb(vm, mb_id, &nb_sb);
+}
+
+/*
+ * Prepare tracking data for the next memory block.
+ */
+static int virtio_mem_prepare_next_mb(struct virtio_mem *vm,
+				      unsigned long *mb_id)
+{
+	int rc;
+
+	if (vm->next_mb_id > vm->last_usable_mb_id)
+		return -ENOSPC;
+
+	/* Resize the state array if required. */
+	rc = virtio_mem_mb_state_prepare_next_mb(vm);
+	if (rc)
+		return rc;
+
+	/* Resize the subblock bitmap if required. */
+	rc = virtio_mem_sb_bitmap_prepare_next_mb(vm);
+	if (rc)
+		return rc;
+
+	vm->nb_mb_state[VIRTIO_MEM_MB_STATE_UNUSED]++;
+	*mb_id = vm->next_mb_id++;
+	return 0;
+}
+
+/*
+ * Don't add too many blocks that are not onlined yet to avoid running OOM.
+ */
+static bool virtio_mem_too_many_mb_offline(struct virtio_mem *vm)
+{
+	unsigned long nb_offline;
+
+	nb_offline = vm->nb_mb_state[VIRTIO_MEM_MB_STATE_OFFLINE] +
+		     vm->nb_mb_state[VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL];
+	return nb_offline >= VIRTIO_MEM_NB_OFFLINE_THRESHOLD;
+}
+
+/*
+ * Try to plug the desired number of subblocks and add the memory block
+ * to Linux.
+ *
+ * Will modify the state of the memory block.
+ */
+static int virtio_mem_mb_plug_and_add(struct virtio_mem *vm,
+				      unsigned long mb_id,
+				      uint64_t *nb_sb)
+{
+	const int count = min_t(int, *nb_sb, vm->nb_sb_per_mb);
+	int rc, rc2;
+
+	if (WARN_ON_ONCE(!count))
+		return -EINVAL;
+
+	/*
+	 * Plug the requested number of subblocks before adding it to linux,
+	 * so that onlining will directly online all plugged subblocks.
+	 */
+	rc = virtio_mem_mb_plug_sb(vm, mb_id, 0, count);
+	if (rc)
+		return rc;
+
+	/*
+	 * Mark the block properly offline before adding it to Linux,
+	 * so the memory notifiers will find the block in the right state.
+	 */
+	if (count == vm->nb_sb_per_mb)
+		virtio_mem_mb_set_state(vm, mb_id,
+					VIRTIO_MEM_MB_STATE_OFFLINE);
+	else
+		virtio_mem_mb_set_state(vm, mb_id,
+					VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL);
+
+	/* Add the memory block to linux - if that fails, try to unplug. */
+	rc = virtio_mem_mb_add(vm, mb_id);
+	if (rc) {
+		enum virtio_mem_mb_state new_state = VIRTIO_MEM_MB_STATE_UNUSED;
+
+		dev_err(&vm->vdev->dev,
+			"adding memory block %lu failed with %d\n", mb_id, rc);
+		rc2 = virtio_mem_mb_unplug_sb(vm, mb_id, 0, count);
+
+		/*
+		 * TODO: Linux MM does not properly clean up yet in all cases
+		 * where adding of memory failed - especially on -ENOMEM.
+		 */
+		if (rc2)
+			new_state = VIRTIO_MEM_MB_STATE_PLUGGED;
+		virtio_mem_mb_set_state(vm, mb_id, new_state);
+		return rc;
+	}
+
+	*nb_sb -= count;
+	return 0;
+}
+
+/*
+ * Try to plug the desired number of subblocks of a memory block that
+ * is already added to Linux.
+ *
+ * Will modify the state of the memory block.
+ *
+ * Note: Can fail after some subblocks were successfully plugged.
+ */
+static int virtio_mem_mb_plug_any_sb(struct virtio_mem *vm, unsigned long mb_id,
+				     uint64_t *nb_sb, bool online)
+{
+	unsigned long pfn, nr_pages;
+	int sb_id, count;
+	int rc;
+
+	if (WARN_ON_ONCE(!*nb_sb))
+		return -EINVAL;
+
+	while (*nb_sb) {
+		sb_id = virtio_mem_mb_first_unplugged_sb(vm, mb_id);
+		if (sb_id >= vm->nb_sb_per_mb)
+			break;
+		count = 1;
+		while (count < *nb_sb &&
+		       sb_id + count < vm->nb_sb_per_mb &&
+		       !virtio_mem_mb_test_sb_plugged(vm, mb_id, sb_id + count,
+						      1))
+			count++;
+
+		rc = virtio_mem_mb_plug_sb(vm, mb_id, sb_id, count);
+		if (rc)
+			return rc;
+		*nb_sb -= count;
+		if (!online)
+			continue;
+
+		/* fake-online the pages if the memory block is online */
+		pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
+			       sb_id * vm->subblock_size);
+		nr_pages = PFN_DOWN(count * vm->subblock_size);
+		virtio_mem_fake_online(pfn, nr_pages);
+	}
+
+	if (virtio_mem_mb_test_sb_plugged(vm, mb_id, 0, vm->nb_sb_per_mb)) {
+		if (online)
+			virtio_mem_mb_set_state(vm, mb_id,
+						VIRTIO_MEM_MB_STATE_ONLINE);
+		else
+			virtio_mem_mb_set_state(vm, mb_id,
+						VIRTIO_MEM_MB_STATE_OFFLINE);
+	}
+
+	return 0;
+}
+
+/*
+ * Try to plug the requested amount of memory.
+ */
+static int virtio_mem_plug_request(struct virtio_mem *vm, uint64_t diff)
+{
+	uint64_t nb_sb = diff / vm->subblock_size;
+	unsigned long mb_id;
+	int rc;
+
+	if (!nb_sb)
+		return 0;
+
+	/* Don't race with onlining/offlining */
+	mutex_lock(&vm->hotplug_mutex);
+
+	/* Try to plug subblocks of partially plugged online blocks. */
+	virtio_mem_for_each_mb_state(vm, mb_id,
+				     VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL) {
+		rc = virtio_mem_mb_plug_any_sb(vm, mb_id, &nb_sb, true);
+		if (rc || !nb_sb)
+			goto out_unlock;
+		cond_resched();
+	}
+
+	/* Try to plug subblocks of partially plugged offline blocks. */
+	virtio_mem_for_each_mb_state(vm, mb_id,
+				     VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL) {
+		rc = virtio_mem_mb_plug_any_sb(vm, mb_id, &nb_sb, false);
+		if (rc || !nb_sb)
+			goto out_unlock;
+		cond_resched();
+	}
+
+	/*
+	 * We won't be working on online/offline memory blocks from this point,
+	 * so we can't race with memory onlining/offlining. Drop the mutex.
+	 */
+	mutex_unlock(&vm->hotplug_mutex);
+
+	/* Try to plug and add unused blocks */
+	virtio_mem_for_each_mb_state(vm, mb_id, VIRTIO_MEM_MB_STATE_UNUSED) {
+		if (virtio_mem_too_many_mb_offline(vm))
+			return -ENOSPC;
+
+		rc = virtio_mem_mb_plug_and_add(vm, mb_id, &nb_sb);
+		if (rc || !nb_sb)
+			return rc;
+		cond_resched();
+	}
+
+	/* Try to prepare, plug and add new blocks */
+	while (nb_sb) {
+		if (virtio_mem_too_many_mb_offline(vm))
+			return -ENOSPC;
+
+		rc = virtio_mem_prepare_next_mb(vm, &mb_id);
+		if (rc)
+			return rc;
+		rc = virtio_mem_mb_plug_and_add(vm, mb_id, &nb_sb);
+		if (rc)
+			return rc;
+		cond_resched();
+	}
+
+	return 0;
+out_unlock:
+	mutex_unlock(&vm->hotplug_mutex);
+	return rc;
+}
+
+/*
+ * Unplug the desired number of plugged subblocks of an offline memory block.
+ * Will fail if any subblock cannot get unplugged (instead of skipping it).
+ *
+ * Will modify the state of the memory block. Might temporarily drop the
+ * hotplug_mutex.
+ *
+ * Note: Can fail after some subblocks were successfully unplugged.
+ */
+static int virtio_mem_mb_unplug_any_sb_offline(struct virtio_mem *vm,
+					       unsigned long mb_id,
+					       uint64_t *nb_sb)
+{
+	int rc;
+
+	rc = virtio_mem_mb_unplug_any_sb(vm, mb_id, nb_sb);
+
+	/* some subblocks might have been unplugged even on failure */
+	if (!virtio_mem_mb_test_sb_plugged(vm, mb_id, 0, vm->nb_sb_per_mb))
+		virtio_mem_mb_set_state(vm, mb_id,
+					VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL);
+	if (rc)
+		return rc;
+
+	if (virtio_mem_mb_test_sb_unplugged(vm, mb_id, 0, vm->nb_sb_per_mb)) {
+		/*
+		 * Remove the block from Linux - this should never fail.
+		 * Hinder the block from getting onlined by marking it
+		 * unplugged. Temporarily drop the mutex, so
+		 * any pending GOING_ONLINE requests can be serviced/rejected.
+		 */
+		virtio_mem_mb_set_state(vm, mb_id,
+					VIRTIO_MEM_MB_STATE_UNUSED);
+
+		mutex_unlock(&vm->hotplug_mutex);
+		rc = virtio_mem_mb_remove(vm, mb_id);
+		BUG_ON(rc);
+		mutex_lock(&vm->hotplug_mutex);
+	}
+	return 0;
+}
+
+/*
+ * Unplug the given plugged subblocks of an online memory block.
+ *
+ * Will modify the state of the memory block.
+ */
+static int virtio_mem_mb_unplug_sb_online(struct virtio_mem *vm,
+					  unsigned long mb_id, int sb_id,
+					  int count)
+{
+	const unsigned long nr_pages = PFN_DOWN(vm->subblock_size) * count;
+	unsigned long start_pfn;
+	int rc;
+
+	start_pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
+			     sb_id * vm->subblock_size);
+	rc = alloc_contig_range(start_pfn, start_pfn + nr_pages,
+				MIGRATE_MOVABLE, GFP_KERNEL);
+	if (rc == -ENOMEM)
+		/* whoops, out of memory */
+		return rc;
+	if (rc)
+		return -EBUSY;
+
+	/* Mark it as fake-offline before unplugging it */
+	virtio_mem_set_fake_offline(start_pfn, nr_pages, true);
+	adjust_managed_page_count(pfn_to_page(start_pfn), -nr_pages);
+
+	/* Try to unplug the allocated memory */
+	rc = virtio_mem_mb_unplug_sb(vm, mb_id, sb_id, count);
+	if (rc) {
+		/* Return the memory to the buddy. */
+		virtio_mem_fake_online(start_pfn, nr_pages);
+		return rc;
+	}
+
+	virtio_mem_mb_set_state(vm, mb_id,
+				VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL);
+	return 0;
+}
+
+/*
+ * Unplug the desired number of plugged subblocks of an online memory block.
+ * Will skip subblock that are busy.
+ *
+ * Will modify the state of the memory block. Might temporarily drop the
+ * hotplug_mutex.
+ *
+ * Note: Can fail after some subblocks were successfully unplugged. Can
+ *       return 0 even if subblocks were busy and could not get unplugged.
+ */
+static int virtio_mem_mb_unplug_any_sb_online(struct virtio_mem *vm,
+					      unsigned long mb_id,
+					      uint64_t *nb_sb)
+{
+	int rc, sb_id;
+
+	/* If possible, try to unplug the complete block in one shot. */
+	if (*nb_sb >= vm->nb_sb_per_mb &&
+	    virtio_mem_mb_test_sb_plugged(vm, mb_id, 0, vm->nb_sb_per_mb)) {
+		rc = virtio_mem_mb_unplug_sb_online(vm, mb_id, 0,
+						    vm->nb_sb_per_mb);
+		if (!rc) {
+			*nb_sb -= vm->nb_sb_per_mb;
+			goto unplugged;
+		} else if (rc != -EBUSY)
+			return rc;
+	}
+
+	/* Fallback to single subblocks. */
+	for (sb_id = vm->nb_sb_per_mb - 1; sb_id >= 0 && *nb_sb; sb_id--) {
+		/* Find the next candidate subblock */
+		while (sb_id >= 0 &&
+		       !virtio_mem_mb_test_sb_plugged(vm, mb_id, sb_id, 1))
+			sb_id--;
+		if (sb_id < 0)
+			break;
+
+		rc = virtio_mem_mb_unplug_sb_online(vm, mb_id, sb_id, 1);
+		if (rc == -EBUSY)
+			continue;
+		else if (rc)
+			return rc;
+		*nb_sb -= 1;
+	}
+
+unplugged:
+	/*
+	 * Once all subblocks of a memory block were unplugged, offline and
+	 * remove it. This will usually not fail, as no memory is in use
+	 * anymore - however some other notifiers might NACK the request.
+	 */
+	if (virtio_mem_mb_test_sb_unplugged(vm, mb_id, 0, vm->nb_sb_per_mb)) {
+		mutex_unlock(&vm->hotplug_mutex);
+		rc = virtio_mem_mb_offline_and_remove(vm, mb_id);
+		mutex_lock(&vm->hotplug_mutex);
+		if (!rc)
+			virtio_mem_mb_set_state(vm, mb_id,
+						VIRTIO_MEM_MB_STATE_UNUSED);
+	}
+
+	return 0;
+}
+
+/*
+ * Try to unplug the requested amount of memory.
+ */
+static int virtio_mem_unplug_request(struct virtio_mem *vm, uint64_t diff)
+{
+	uint64_t nb_sb = diff / vm->subblock_size;
+	unsigned long mb_id;
+	int rc;
+
+	if (!nb_sb)
+		return 0;
+
+	/*
+	 * We'll drop the mutex a couple of times when it is safe to do so.
+	 * This might result in some blocks switching the state (online/offline)
+	 * and we could miss them in this run - we will retry again later.
+	 */
+	mutex_lock(&vm->hotplug_mutex);
+
+	/* Try to unplug subblocks of partially plugged offline blocks. */
+	virtio_mem_for_each_mb_state_rev(vm, mb_id,
+					 VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL) {
+		rc = virtio_mem_mb_unplug_any_sb_offline(vm, mb_id,
+							 &nb_sb);
+		if (rc || !nb_sb)
+			goto out_unlock;
+		cond_resched();
+	}
+
+	/* Try to unplug subblocks of plugged offline blocks. */
+	virtio_mem_for_each_mb_state_rev(vm, mb_id,
+					 VIRTIO_MEM_MB_STATE_OFFLINE) {
+		rc = virtio_mem_mb_unplug_any_sb_offline(vm, mb_id,
+							 &nb_sb);
+		if (rc || !nb_sb)
+			goto out_unlock;
+		cond_resched();
+	}
+
+	if (!unplug_online) {
+		mutex_unlock(&vm->hotplug_mutex);
+		return 0;
+	}
+
+	/* Try to unplug subblocks of partially plugged online blocks. */
+	virtio_mem_for_each_mb_state_rev(vm, mb_id,
+					 VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL) {
+		rc = virtio_mem_mb_unplug_any_sb_online(vm, mb_id,
+							&nb_sb);
+		if (rc || !nb_sb)
+			goto out_unlock;
+		mutex_unlock(&vm->hotplug_mutex);
+		cond_resched();
+		mutex_lock(&vm->hotplug_mutex);
+	}
+
+	/* Try to unplug subblocks of plugged online blocks. */
+	virtio_mem_for_each_mb_state_rev(vm, mb_id,
+					 VIRTIO_MEM_MB_STATE_ONLINE) {
+		rc = virtio_mem_mb_unplug_any_sb_online(vm, mb_id,
+							&nb_sb);
+		if (rc || !nb_sb)
+			goto out_unlock;
+		mutex_unlock(&vm->hotplug_mutex);
+		cond_resched();
+		mutex_lock(&vm->hotplug_mutex);
+	}
+
+	mutex_unlock(&vm->hotplug_mutex);
+	return nb_sb ? -EBUSY : 0;
+out_unlock:
+	mutex_unlock(&vm->hotplug_mutex);
+	return rc;
+}
+
+/*
+ * Try to unplug all blocks that couldn't be unplugged before, for example,
+ * because the hypervisor was busy.
+ */
+static int virtio_mem_unplug_pending_mb(struct virtio_mem *vm)
+{
+	unsigned long mb_id;
+	int rc;
+
+	virtio_mem_for_each_mb_state(vm, mb_id, VIRTIO_MEM_MB_STATE_PLUGGED) {
+		rc = virtio_mem_mb_unplug(vm, mb_id);
+		if (rc)
+			return rc;
+		virtio_mem_mb_set_state(vm, mb_id, VIRTIO_MEM_MB_STATE_UNUSED);
+	}
+
+	return 0;
+}
+
+/*
+ * Update all parts of the config that could have changed.
+ */
+static void virtio_mem_refresh_config(struct virtio_mem *vm)
+{
+	const uint64_t phys_limit = 1UL << MAX_PHYSMEM_BITS;
+	uint64_t new_plugged_size, usable_region_size, end_addr;
+
+	/* the plugged_size is just a reflection of what _we_ did previously */
+	virtio_cread_le(vm->vdev, struct virtio_mem_config, plugged_size,
+			&new_plugged_size);
+	if (WARN_ON_ONCE(new_plugged_size != vm->plugged_size))
+		vm->plugged_size = new_plugged_size;
+
+	/* calculate the last usable memory block id */
+	virtio_cread_le(vm->vdev, struct virtio_mem_config,
+			usable_region_size, &usable_region_size);
+	end_addr = vm->addr + usable_region_size;
+	end_addr = min(end_addr, phys_limit);
+	vm->last_usable_mb_id = virtio_mem_phys_to_mb_id(end_addr) - 1;
+
+	/* see if there is a request to change the size */
+	virtio_cread_le(vm->vdev, struct virtio_mem_config, requested_size,
+			&vm->requested_size);
+
+	dev_info(&vm->vdev->dev, "plugged size: 0x%llx", vm->plugged_size);
+	dev_info(&vm->vdev->dev, "requested size: 0x%llx", vm->requested_size);
+}
+
+/*
+ * Workqueue function for handling plug/unplug requests and config updates.
+ */
+static void virtio_mem_run_wq(struct work_struct *work)
+{
+	struct virtio_mem *vm = container_of(work, struct virtio_mem, wq);
+	uint64_t diff;
+	int rc;
+
+	hrtimer_cancel(&vm->retry_timer);
+
+	if (vm->broken)
+		return;
+
+retry:
+	rc = 0;
+
+	/* Make sure we start with a clean state if there are leftovers. */
+	if (unlikely(vm->unplug_all_required))
+		rc = virtio_mem_send_unplug_all_request(vm);
+
+	if (atomic_read(&vm->config_changed)) {
+		atomic_set(&vm->config_changed, 0);
+		virtio_mem_refresh_config(vm);
+	}
+
+	/* Unplug any leftovers from previous runs */
+	if (!rc)
+		rc = virtio_mem_unplug_pending_mb(vm);
+
+	if (!rc && vm->requested_size != vm->plugged_size) {
+		if (vm->requested_size > vm->plugged_size) {
+			diff = vm->requested_size - vm->plugged_size;
+			rc = virtio_mem_plug_request(vm, diff);
+		} else {
+			diff = vm->plugged_size - vm->requested_size;
+			rc = virtio_mem_unplug_request(vm, diff);
+		}
+	}
+
+	switch (rc) {
+	case 0:
+		vm->retry_timer_ms = VIRTIO_MEM_RETRY_TIMER_MIN_MS;
+		break;
+	case -ENOSPC:
+		/*
+		 * We cannot add any more memory (alignment, physical limit)
+		 * or we have too many offline memory blocks.
+		 */
+		break;
+	case -ETXTBSY:
+		/*
+		 * The hypervisor cannot process our request right now
+		 * (e.g., out of memory, migrating);
+		 */
+	case -EBUSY:
+		/*
+		 * We cannot free up any memory to unplug it (all plugged memory
+		 * is busy).
+		 */
+	case -ENOMEM:
+		/* Out of memory, try again later. */
+		hrtimer_start(&vm->retry_timer, ms_to_ktime(vm->retry_timer_ms),
+			      HRTIMER_MODE_REL);
+		break;
+	case -EAGAIN:
+		/* Retry immediately (e.g., the config changed). */
+		goto retry;
+	default:
+		/* Unknown error, mark as broken */
+		dev_err(&vm->vdev->dev,
+			"unknown error, marking device broken: %d\n", rc);
+		vm->broken = true;
+	}
+}
+
+static enum hrtimer_restart virtio_mem_timer_expired(struct hrtimer *timer)
+{
+	struct virtio_mem *vm = container_of(timer, struct virtio_mem,
+					     retry_timer);
+
+	virtio_mem_retry(vm);
+	vm->retry_timer_ms = min_t(unsigned int, vm->retry_timer_ms * 2,
+				   VIRTIO_MEM_RETRY_TIMER_MAX_MS);
+	return HRTIMER_NORESTART;
+}
+
+static void virtio_mem_handle_response(struct virtqueue *vq)
+{
+	struct virtio_mem *vm = vq->vdev->priv;
+
+	wake_up(&vm->host_resp);
+}
+
+static int virtio_mem_init_vq(struct virtio_mem *vm)
+{
+	struct virtqueue *vq;
+
+	vq = virtio_find_single_vq(vm->vdev, virtio_mem_handle_response,
+				   "guest-request");
+	if (IS_ERR(vq))
+		return PTR_ERR(vq);
+	vm->vq = vq;
+
+	return 0;
+}
+
+static int virtio_mem_init(struct virtio_mem *vm)
+{
+	const uint64_t phys_limit = 1UL << MAX_PHYSMEM_BITS;
+	uint16_t node_id;
+
+	if (!vm->vdev->config->get) {
+		dev_err(&vm->vdev->dev, "config access disabled\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * We don't want to (un)plug or reuse any memory when in kdump. The
+	 * memory is still accessible (but not mapped).
+	 */
+	if (is_kdump_kernel()) {
+		dev_warn(&vm->vdev->dev, "disabled in kdump kernel\n");
+		return -EBUSY;
+	}
+
+	/* Fetch all properties that can't change. */
+	virtio_cread_le(vm->vdev, struct virtio_mem_config, plugged_size,
+			&vm->plugged_size);
+	virtio_cread_le(vm->vdev, struct virtio_mem_config, block_size,
+			&vm->device_block_size);
+	virtio_cread_le(vm->vdev, struct virtio_mem_config, node_id,
+			&node_id);
+	vm->nid = virtio_mem_translate_node_id(vm, node_id);
+	virtio_cread_le(vm->vdev, struct virtio_mem_config, addr, &vm->addr);
+	virtio_cread_le(vm->vdev, struct virtio_mem_config, region_size,
+			&vm->region_size);
+
+	/*
+	 * We always hotplug memory in memory block granularity. This way,
+	 * we have to wait for exactly one memory block to online.
+	 */
+	if (vm->device_block_size > memory_block_size_bytes()) {
+		dev_err(&vm->vdev->dev,
+			"The block size is not supported (too big).\n");
+		return -EINVAL;
+	}
+
+	/* bad device setup - warn only */
+	if (!IS_ALIGNED(vm->addr, memory_block_size_bytes()))
+		dev_warn(&vm->vdev->dev,
+			 "The alignment of the physical start address can make some memory unusable.\n");
+	if (!IS_ALIGNED(vm->addr + vm->region_size, memory_block_size_bytes()))
+		dev_warn(&vm->vdev->dev,
+			 "The alignment of the physical end address can make some memory unusable.\n");
+	if (vm->addr + vm->region_size > phys_limit)
+		dev_warn(&vm->vdev->dev,
+			 "Some memory is not addressable. This can make some memory unusable.\n");
+
+	/*
+	 * Calculate the subblock size:
+	 * - At least MAX_ORDER - 1 / pageblock_order.
+	 * - At least the device block size.
+	 * In the worst case, a single subblock per memory block.
+	 */
+	vm->subblock_size = PAGE_SIZE * 1ul << max_t(uint32_t, MAX_ORDER - 1,
+						     pageblock_order);
+	vm->subblock_size = max_t(uint64_t, vm->device_block_size,
+				  vm->subblock_size);
+	vm->nb_sb_per_mb = memory_block_size_bytes() / vm->subblock_size;
+
+	/* Round up to the next full memory block */
+	vm->first_mb_id = virtio_mem_phys_to_mb_id(vm->addr - 1 +
+						   memory_block_size_bytes());
+	vm->next_mb_id = vm->first_mb_id;
+	vm->last_mb_id = virtio_mem_phys_to_mb_id(vm->addr +
+			 vm->region_size) - 1;
+
+	dev_info(&vm->vdev->dev, "start address: 0x%llx", vm->addr);
+	dev_info(&vm->vdev->dev, "region size: 0x%llx", vm->region_size);
+	dev_info(&vm->vdev->dev, "device block size: 0x%llx",
+		 (unsigned long long)vm->device_block_size);
+	dev_info(&vm->vdev->dev, "memory block size: 0x%lx",
+		 memory_block_size_bytes());
+	dev_info(&vm->vdev->dev, "subblock size: 0x%llx",
+		 (unsigned long long)vm->subblock_size);
+	if (vm->nid != NUMA_NO_NODE)
+		dev_info(&vm->vdev->dev, "nid: %d", vm->nid);
+
+	return 0;
+}
+
+static int virtio_mem_create_resource(struct virtio_mem *vm)
+{
+	/*
+	 * When force-unloading the driver and removing the device, we
+	 * could have a garbage pointer. Duplicate the string.
+	 */
+	const char *name = kstrdup(dev_name(&vm->vdev->dev), GFP_KERNEL);
+
+	if (!name)
+		return -ENOMEM;
+
+	vm->parent_resource = __request_mem_region(vm->addr, vm->region_size,
+						   name, IORESOURCE_SYSTEM_RAM);
+	if (!vm->parent_resource) {
+		kfree(name);
+		dev_warn(&vm->vdev->dev, "could not reserve device region\n");
+		dev_info(&vm->vdev->dev,
+			 "reloading the driver is not supported\n");
+		return -EBUSY;
+	}
+
+	/* The memory is not actually busy - make add_memory() work. */
+	vm->parent_resource->flags &= ~IORESOURCE_BUSY;
+	return 0;
+}
+
+static void virtio_mem_delete_resource(struct virtio_mem *vm)
+{
+	const char *name;
+
+	if (!vm->parent_resource)
+		return;
+
+	name = vm->parent_resource->name;
+	release_resource(vm->parent_resource);
+	kfree(vm->parent_resource);
+	kfree(name);
+	vm->parent_resource = NULL;
+}
+
+static int virtio_mem_probe(struct virtio_device *vdev)
+{
+	struct virtio_mem *vm;
+	int rc;
+
+	BUILD_BUG_ON(sizeof(struct virtio_mem_req) != 24);
+	BUILD_BUG_ON(sizeof(struct virtio_mem_resp) != 10);
+
+	vdev->priv = vm = kzalloc(sizeof(*vm), GFP_KERNEL);
+	if (!vm)
+		return -ENOMEM;
+
+	init_waitqueue_head(&vm->host_resp);
+	vm->vdev = vdev;
+	INIT_WORK(&vm->wq, virtio_mem_run_wq);
+	mutex_init(&vm->hotplug_mutex);
+	INIT_LIST_HEAD(&vm->next);
+	spin_lock_init(&vm->removal_lock);
+	hrtimer_init(&vm->retry_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	vm->retry_timer.function = virtio_mem_timer_expired;
+	vm->retry_timer_ms = VIRTIO_MEM_RETRY_TIMER_MIN_MS;
+
+	/* register the virtqueue */
+	rc = virtio_mem_init_vq(vm);
+	if (rc)
+		goto out_free_vm;
+
+	/* initialize the device by querying the config */
+	rc = virtio_mem_init(vm);
+	if (rc)
+		goto out_del_vq;
+
+	/* create the parent resource for all memory */
+	rc = virtio_mem_create_resource(vm);
+	if (rc)
+		goto out_del_vq;
+
+	/*
+	 * If we still have memory plugged, we have to unplug all memory first.
+	 * Registering our parent resource makes sure that this memory isn't
+	 * actually in use (e.g., trying to reload the driver).
+	 */
+	if (vm->plugged_size) {
+		vm->unplug_all_required = 1;
+		dev_info(&vm->vdev->dev, "unplugging all memory is required\n");
+	}
+
+	/* register callbacks */
+	vm->memory_notifier.notifier_call = virtio_mem_memory_notifier_cb;
+	rc = register_memory_notifier(&vm->memory_notifier);
+	if (rc)
+		goto out_del_resource;
+	rc = register_virtio_mem_device(vm);
+	if (rc)
+		goto out_unreg_mem;
+
+	virtio_device_ready(vdev);
+
+	/* trigger a config update to start processing the requested_size */
+	atomic_set(&vm->config_changed, 1);
+	queue_work(system_freezable_wq, &vm->wq);
+
+	return 0;
+out_unreg_mem:
+	unregister_memory_notifier(&vm->memory_notifier);
+out_del_resource:
+	virtio_mem_delete_resource(vm);
+out_del_vq:
+	vdev->config->del_vqs(vdev);
+out_free_vm:
+	kfree(vm);
+	vdev->priv = NULL;
+
+	return rc;
+}
+
+static void virtio_mem_remove(struct virtio_device *vdev)
+{
+	struct virtio_mem *vm = vdev->priv;
+	unsigned long mb_id;
+	int rc;
+
+	/*
+	 * Make sure the workqueue won't be triggered anymore and no memory
+	 * blocks can be onlined/offlined until we're finished here.
+	 */
+	mutex_lock(&vm->hotplug_mutex);
+	spin_lock_irq(&vm->removal_lock);
+	vm->removing = true;
+	spin_unlock_irq(&vm->removal_lock);
+	mutex_unlock(&vm->hotplug_mutex);
+
+	/* wait until the workqueue stopped */
+	cancel_work_sync(&vm->wq);
+	hrtimer_cancel(&vm->retry_timer);
+
+	/*
+	 * After we unregistered our callbacks, user space can online partially
+	 * plugged offline blocks. Make sure to remove them.
+	 */
+	virtio_mem_for_each_mb_state(vm, mb_id,
+				     VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL) {
+		rc = virtio_mem_mb_remove(vm, mb_id);
+		BUG_ON(rc);
+		virtio_mem_mb_set_state(vm, mb_id, VIRTIO_MEM_MB_STATE_UNUSED);
+	}
+	/*
+	 * After we unregistered our callbacks, user space can no longer
+	 * offline partially plugged online memory blocks. No need to worry
+	 * about them.
+	 */
+
+	/* unregister callbacks */
+	unregister_virtio_mem_device(vm);
+	unregister_memory_notifier(&vm->memory_notifier);
+
+	/*
+	 * There is no way we could reliably remove all memory we have added to
+	 * the system. And there is no way to stop the driver/device from going
+	 * away. Warn at least.
+	 */
+	if (vm->nb_mb_state[VIRTIO_MEM_MB_STATE_OFFLINE] ||
+	    vm->nb_mb_state[VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL] ||
+	    vm->nb_mb_state[VIRTIO_MEM_MB_STATE_ONLINE] ||
+	    vm->nb_mb_state[VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL]) {
+		dev_warn(&vdev->dev, "device still has system memory added\n");
+	} else {
+		virtio_mem_delete_resource(vm);
+		kfree_const(vm->resource_name);
+	}
+
+	/* remove all tracking data - no locking needed */
+	vfree(vm->mb_state);
+	vfree(vm->sb_bitmap);
+
+	/* reset the device and cleanup the queues */
+	vdev->config->reset(vdev);
+	vdev->config->del_vqs(vdev);
+
+	kfree(vm);
+	vdev->priv = NULL;
+}
+
+static void virtio_mem_config_changed(struct virtio_device *vdev)
+{
+	struct virtio_mem *vm = vdev->priv;
+
+	atomic_set(&vm->config_changed, 1);
+	virtio_mem_retry(vm);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int virtio_mem_freeze(struct virtio_device *vdev)
+{
+	/*
+	 * When restarting the VM, all memory is usually unplugged. Don't
+	 * allow to suspend/hibernate.
+	 */
+	dev_err(&vdev->dev, "save/restore not supported.\n");
+	return -EPERM;
+}
+
+static int virtio_mem_restore(struct virtio_device *vdev)
+{
+	return -EPERM;
+}
+#endif
+
+static unsigned int virtio_mem_features[] = {
+#if defined(CONFIG_NUMA) && defined(CONFIG_ACPI_NUMA)
+	VIRTIO_MEM_F_ACPI_PXM,
+#endif
+};
+
+static const struct virtio_device_id virtio_mem_id_table[] = {
+	{ VIRTIO_ID_MEM, VIRTIO_DEV_ANY_ID },
+	{ 0 },
+};
+
+static struct virtio_driver virtio_mem_driver = {
+	.feature_table = virtio_mem_features,
+	.feature_table_size = ARRAY_SIZE(virtio_mem_features),
+	.driver.name = KBUILD_MODNAME,
+	.driver.owner = THIS_MODULE,
+	.id_table = virtio_mem_id_table,
+	.probe = virtio_mem_probe,
+	.remove = virtio_mem_remove,
+	.config_changed = virtio_mem_config_changed,
+#ifdef CONFIG_PM_SLEEP
+	.freeze	=	virtio_mem_freeze,
+	.restore =	virtio_mem_restore,
+#endif
+};
+
+module_virtio_driver(virtio_mem_driver);
+MODULE_DEVICE_TABLE(virtio, virtio_mem_id_table);
+MODULE_AUTHOR("David Hildenbrand <david@redhat.com>");
+MODULE_DESCRIPTION("Virtio-mem driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
new file mode 100644
index 000000000..7fcc307fa
--- /dev/null
+++ b/drivers/virtio/virtio_mmio.c
@@ -0,0 +1,842 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Virtio memory mapped device driver
+ *
+ * Copyright 2011-2014, ARM Ltd.
+ *
+ * This module allows virtio devices to be used over a virtual, memory mapped
+ * platform device.
+ *
+ * The guest device(s) may be instantiated in one of three equivalent ways:
+ *
+ * 1. Static platform device in board's code, eg.:
+ *
+ *	static struct platform_device v2m_virtio_device = {
+ *		.name = "virtio-mmio",
+ *		.id = -1,
+ *		.num_resources = 2,
+ *		.resource = (struct resource []) {
+ *			{
+ *				.start = 0x1001e000,
+ *				.end = 0x1001e0ff,
+ *				.flags = IORESOURCE_MEM,
+ *			}, {
+ *				.start = 42 + 32,
+ *				.end = 42 + 32,
+ *				.flags = IORESOURCE_IRQ,
+ *			},
+ *		}
+ *	};
+ *
+ * 2. Device Tree node, eg.:
+ *
+ *		virtio_block@1e000 {
+ *			compatible = "virtio,mmio";
+ *			reg = <0x1e000 0x100>;
+ *			interrupts = <42>;
+ *		}
+ *
+ * 3. Kernel module (or command line) parameter. Can be used more than once -
+ *    one device will be created for each one. Syntax:
+ *
+ *		[virtio_mmio.]device=<size>@<baseaddr>:<irq>[:<id>]
+ *    where:
+ *		<size>     := size (can use standard suffixes like K, M or G)
+ *		<baseaddr> := physical base address
+ *		<irq>      := interrupt number (as passed to request_irq())
+ *		<id>       := (optional) platform device id
+ *    eg.:
+ *		virtio_mmio.device=0x100@0x100b0000:48 \
+ *				virtio_mmio.device=1K@0x1001e000:74
+ *
+ * Based on Virtio PCI driver by Anthony Liguori, copyright IBM Corp. 2007
+ */
+
+#define pr_fmt(fmt) "virtio-mmio: " fmt
+
+#include <linux/acpi.h>
+#include <linux/dma-mapping.h>
+#include <linux/highmem.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/virtio.h>
+#include <linux/virtio_config.h>
+#include <uapi/linux/virtio_mmio.h>
+#include <linux/virtio_ring.h>
+
+
+
+/* The alignment to use between consumer and producer parts of vring.
+ * Currently hardcoded to the page size. */
+#define VIRTIO_MMIO_VRING_ALIGN		PAGE_SIZE
+
+
+
+#define to_virtio_mmio_device(_plat_dev) \
+	container_of(_plat_dev, struct virtio_mmio_device, vdev)
+
+struct virtio_mmio_device {
+	struct virtio_device vdev;
+	struct platform_device *pdev;
+
+	void __iomem *base;
+	unsigned long version;
+
+	/* a list of queues so we can dispatch IRQs */
+	spinlock_t lock;
+	struct list_head virtqueues;
+};
+
+struct virtio_mmio_vq_info {
+	/* the actual virtqueue */
+	struct virtqueue *vq;
+
+	/* the list node for the virtqueues list */
+	struct list_head node;
+};
+
+
+
+/* Configuration interface */
+
+static u64 vm_get_features(struct virtio_device *vdev)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+	u64 features;
+
+	writel(1, vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES_SEL);
+	features = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES);
+	features <<= 32;
+
+	writel(0, vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES_SEL);
+	features |= readl(vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES);
+
+	return features;
+}
+
+static int vm_finalize_features(struct virtio_device *vdev)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+
+	/* Give virtio_ring a chance to accept features. */
+	vring_transport_features(vdev);
+
+	/* Make sure there is are no mixed devices */
+	if (vm_dev->version == 2 &&
+			!__virtio_test_bit(vdev, VIRTIO_F_VERSION_1)) {
+		dev_err(&vdev->dev, "New virtio-mmio devices (version 2) must provide VIRTIO_F_VERSION_1 feature!\n");
+		return -EINVAL;
+	}
+
+	writel(1, vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES_SEL);
+	writel((u32)(vdev->features >> 32),
+			vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES);
+
+	writel(0, vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES_SEL);
+	writel((u32)vdev->features,
+			vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES);
+
+	return 0;
+}
+
+static void vm_get(struct virtio_device *vdev, unsigned offset,
+		   void *buf, unsigned len)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+	void __iomem *base = vm_dev->base + VIRTIO_MMIO_CONFIG;
+	u8 b;
+	__le16 w;
+	__le32 l;
+
+	if (vm_dev->version == 1) {
+		u8 *ptr = buf;
+		int i;
+
+		for (i = 0; i < len; i++)
+			ptr[i] = readb(base + offset + i);
+		return;
+	}
+
+	switch (len) {
+	case 1:
+		b = readb(base + offset);
+		memcpy(buf, &b, sizeof b);
+		break;
+	case 2:
+		w = cpu_to_le16(readw(base + offset));
+		memcpy(buf, &w, sizeof w);
+		break;
+	case 4:
+		l = cpu_to_le32(readl(base + offset));
+		memcpy(buf, &l, sizeof l);
+		break;
+	case 8:
+		l = cpu_to_le32(readl(base + offset));
+		memcpy(buf, &l, sizeof l);
+		l = cpu_to_le32(ioread32(base + offset + sizeof l));
+		memcpy(buf + sizeof l, &l, sizeof l);
+		break;
+	default:
+		BUG();
+	}
+}
+
+static void vm_set(struct virtio_device *vdev, unsigned offset,
+		   const void *buf, unsigned len)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+	void __iomem *base = vm_dev->base + VIRTIO_MMIO_CONFIG;
+	u8 b;
+	__le16 w;
+	__le32 l;
+
+	if (vm_dev->version == 1) {
+		const u8 *ptr = buf;
+		int i;
+
+		for (i = 0; i < len; i++)
+			writeb(ptr[i], base + offset + i);
+
+		return;
+	}
+
+	switch (len) {
+	case 1:
+		memcpy(&b, buf, sizeof b);
+		writeb(b, base + offset);
+		break;
+	case 2:
+		memcpy(&w, buf, sizeof w);
+		writew(le16_to_cpu(w), base + offset);
+		break;
+	case 4:
+		memcpy(&l, buf, sizeof l);
+		writel(le32_to_cpu(l), base + offset);
+		break;
+	case 8:
+		memcpy(&l, buf, sizeof l);
+		writel(le32_to_cpu(l), base + offset);
+		memcpy(&l, buf + sizeof l, sizeof l);
+		writel(le32_to_cpu(l), base + offset + sizeof l);
+		break;
+	default:
+		BUG();
+	}
+}
+
+static u32 vm_generation(struct virtio_device *vdev)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+
+	if (vm_dev->version == 1)
+		return 0;
+	else
+		return readl(vm_dev->base + VIRTIO_MMIO_CONFIG_GENERATION);
+}
+
+static u8 vm_get_status(struct virtio_device *vdev)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+
+	return readl(vm_dev->base + VIRTIO_MMIO_STATUS) & 0xff;
+}
+
+static void vm_set_status(struct virtio_device *vdev, u8 status)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+
+	/* We should never be setting status to 0. */
+	BUG_ON(status == 0);
+
+	writel(status, vm_dev->base + VIRTIO_MMIO_STATUS);
+}
+
+static void vm_reset(struct virtio_device *vdev)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+
+	/* 0 status means a reset. */
+	writel(0, vm_dev->base + VIRTIO_MMIO_STATUS);
+}
+
+
+
+/* Transport interface */
+
+/* the notify function used when creating a virt queue */
+static bool vm_notify(struct virtqueue *vq)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
+
+	/* We write the queue's selector into the notification register to
+	 * signal the other end */
+	writel(vq->index, vm_dev->base + VIRTIO_MMIO_QUEUE_NOTIFY);
+	return true;
+}
+
+/* Notify all virtqueues on an interrupt. */
+static irqreturn_t vm_interrupt(int irq, void *opaque)
+{
+	struct virtio_mmio_device *vm_dev = opaque;
+	struct virtio_mmio_vq_info *info;
+	unsigned long status;
+	unsigned long flags;
+	irqreturn_t ret = IRQ_NONE;
+
+	/* Read and acknowledge interrupts */
+	status = readl(vm_dev->base + VIRTIO_MMIO_INTERRUPT_STATUS);
+	writel(status, vm_dev->base + VIRTIO_MMIO_INTERRUPT_ACK);
+
+	if (unlikely(status & VIRTIO_MMIO_INT_CONFIG)) {
+		virtio_config_changed(&vm_dev->vdev);
+		ret = IRQ_HANDLED;
+	}
+
+	if (likely(status & VIRTIO_MMIO_INT_VRING)) {
+		spin_lock_irqsave(&vm_dev->lock, flags);
+		list_for_each_entry(info, &vm_dev->virtqueues, node)
+			ret |= vring_interrupt(irq, info->vq);
+		spin_unlock_irqrestore(&vm_dev->lock, flags);
+	}
+
+	return ret;
+}
+
+
+
+static void vm_del_vq(struct virtqueue *vq)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
+	struct virtio_mmio_vq_info *info = vq->priv;
+	unsigned long flags;
+	unsigned int index = vq->index;
+
+	spin_lock_irqsave(&vm_dev->lock, flags);
+	list_del(&info->node);
+	spin_unlock_irqrestore(&vm_dev->lock, flags);
+
+	/* Select and deactivate the queue */
+	writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
+	if (vm_dev->version == 1) {
+		writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
+	} else {
+		writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
+		WARN_ON(readl(vm_dev->base + VIRTIO_MMIO_QUEUE_READY));
+	}
+
+	vring_del_virtqueue(vq);
+
+	kfree(info);
+}
+
+static void vm_del_vqs(struct virtio_device *vdev)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+	struct virtqueue *vq, *n;
+
+	list_for_each_entry_safe(vq, n, &vdev->vqs, list)
+		vm_del_vq(vq);
+
+	free_irq(platform_get_irq(vm_dev->pdev, 0), vm_dev);
+}
+
+static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
+				  void (*callback)(struct virtqueue *vq),
+				  const char *name, bool ctx)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+	struct virtio_mmio_vq_info *info;
+	struct virtqueue *vq;
+	unsigned long flags;
+	unsigned int num;
+	int err;
+
+	if (!name)
+		return NULL;
+
+	/* Select the queue we're interested in */
+	writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
+
+	/* Queue shouldn't already be set up. */
+	if (readl(vm_dev->base + (vm_dev->version == 1 ?
+			VIRTIO_MMIO_QUEUE_PFN : VIRTIO_MMIO_QUEUE_READY))) {
+		err = -ENOENT;
+		goto error_available;
+	}
+
+	/* Allocate and fill out our active queue description */
+	info = kmalloc(sizeof(*info), GFP_KERNEL);
+	if (!info) {
+		err = -ENOMEM;
+		goto error_kmalloc;
+	}
+
+	num = readl(vm_dev->base + VIRTIO_MMIO_QUEUE_NUM_MAX);
+	if (num == 0) {
+		err = -ENOENT;
+		goto error_new_virtqueue;
+	}
+
+	/* Create the vring */
+	vq = vring_create_virtqueue(index, num, VIRTIO_MMIO_VRING_ALIGN, vdev,
+				 true, true, ctx, vm_notify, callback, name);
+	if (!vq) {
+		err = -ENOMEM;
+		goto error_new_virtqueue;
+	}
+
+	/* Activate the queue */
+	writel(virtqueue_get_vring_size(vq), vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
+	if (vm_dev->version == 1) {
+		u64 q_pfn = virtqueue_get_desc_addr(vq) >> PAGE_SHIFT;
+
+		/*
+		 * virtio-mmio v1 uses a 32bit QUEUE PFN. If we have something
+		 * that doesn't fit in 32bit, fail the setup rather than
+		 * pretending to be successful.
+		 */
+		if (q_pfn >> 32) {
+			dev_err(&vdev->dev,
+				"platform bug: legacy virtio-mmio must not be used with RAM above 0x%llxGB\n",
+				0x1ULL << (32 + PAGE_SHIFT - 30));
+			err = -E2BIG;
+			goto error_bad_pfn;
+		}
+
+		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
+		writel(q_pfn, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
+	} else {
+		u64 addr;
+
+		addr = virtqueue_get_desc_addr(vq);
+		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_LOW);
+		writel((u32)(addr >> 32),
+				vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_HIGH);
+
+		addr = virtqueue_get_avail_addr(vq);
+		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_LOW);
+		writel((u32)(addr >> 32),
+				vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_HIGH);
+
+		addr = virtqueue_get_used_addr(vq);
+		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_USED_LOW);
+		writel((u32)(addr >> 32),
+				vm_dev->base + VIRTIO_MMIO_QUEUE_USED_HIGH);
+
+		writel(1, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
+	}
+
+	vq->priv = info;
+	info->vq = vq;
+
+	spin_lock_irqsave(&vm_dev->lock, flags);
+	list_add(&info->node, &vm_dev->virtqueues);
+	spin_unlock_irqrestore(&vm_dev->lock, flags);
+
+	return vq;
+
+error_bad_pfn:
+	vring_del_virtqueue(vq);
+error_new_virtqueue:
+	if (vm_dev->version == 1) {
+		writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
+	} else {
+		writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
+		WARN_ON(readl(vm_dev->base + VIRTIO_MMIO_QUEUE_READY));
+	}
+	kfree(info);
+error_kmalloc:
+error_available:
+	return ERR_PTR(err);
+}
+
+static int vm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
+		       struct virtqueue *vqs[],
+		       vq_callback_t *callbacks[],
+		       const char * const names[],
+		       const bool *ctx,
+		       struct irq_affinity *desc)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+	int irq = platform_get_irq(vm_dev->pdev, 0);
+	int i, err, queue_idx = 0;
+
+	if (irq < 0)
+		return irq;
+
+	err = request_irq(irq, vm_interrupt, IRQF_SHARED,
+			dev_name(&vdev->dev), vm_dev);
+	if (err)
+		return err;
+
+	for (i = 0; i < nvqs; ++i) {
+		if (!names[i]) {
+			vqs[i] = NULL;
+			continue;
+		}
+
+		vqs[i] = vm_setup_vq(vdev, queue_idx++, callbacks[i], names[i],
+				     ctx ? ctx[i] : false);
+		if (IS_ERR(vqs[i])) {
+			vm_del_vqs(vdev);
+			return PTR_ERR(vqs[i]);
+		}
+	}
+
+	return 0;
+}
+
+static const char *vm_bus_name(struct virtio_device *vdev)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+
+	return vm_dev->pdev->name;
+}
+
+static bool vm_get_shm_region(struct virtio_device *vdev,
+			      struct virtio_shm_region *region, u8 id)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+	u64 len, addr;
+
+	/* Select the region we're interested in */
+	writel(id, vm_dev->base + VIRTIO_MMIO_SHM_SEL);
+
+	/* Read the region size */
+	len = (u64) readl(vm_dev->base + VIRTIO_MMIO_SHM_LEN_LOW);
+	len |= (u64) readl(vm_dev->base + VIRTIO_MMIO_SHM_LEN_HIGH) << 32;
+
+	region->len = len;
+
+	/* Check if region length is -1. If that's the case, the shared memory
+	 * region does not exist and there is no need to proceed further.
+	 */
+	if (len == ~(u64)0)
+		return false;
+
+	/* Read the region base address */
+	addr = (u64) readl(vm_dev->base + VIRTIO_MMIO_SHM_BASE_LOW);
+	addr |= (u64) readl(vm_dev->base + VIRTIO_MMIO_SHM_BASE_HIGH) << 32;
+
+	region->addr = addr;
+
+	return true;
+}
+
+static const struct virtio_config_ops virtio_mmio_config_ops = {
+	.get		= vm_get,
+	.set		= vm_set,
+	.generation	= vm_generation,
+	.get_status	= vm_get_status,
+	.set_status	= vm_set_status,
+	.reset		= vm_reset,
+	.find_vqs	= vm_find_vqs,
+	.del_vqs	= vm_del_vqs,
+	.get_features	= vm_get_features,
+	.finalize_features = vm_finalize_features,
+	.bus_name	= vm_bus_name,
+	.get_shm_region = vm_get_shm_region,
+};
+
+#ifdef CONFIG_PM_SLEEP
+static int virtio_mmio_freeze(struct device *dev)
+{
+	struct virtio_mmio_device *vm_dev = dev_get_drvdata(dev);
+
+	return virtio_device_freeze(&vm_dev->vdev);
+}
+
+static int virtio_mmio_restore(struct device *dev)
+{
+	struct virtio_mmio_device *vm_dev = dev_get_drvdata(dev);
+
+	if (vm_dev->version == 1)
+		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
+
+	return virtio_device_restore(&vm_dev->vdev);
+}
+
+static const struct dev_pm_ops virtio_mmio_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(virtio_mmio_freeze, virtio_mmio_restore)
+};
+#endif
+
+static void virtio_mmio_release_dev(struct device *_d)
+{
+	struct virtio_device *vdev =
+			container_of(_d, struct virtio_device, dev);
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+
+	kfree(vm_dev);
+}
+
+/* Platform device */
+
+static int virtio_mmio_probe(struct platform_device *pdev)
+{
+	struct virtio_mmio_device *vm_dev;
+	unsigned long magic;
+	int rc;
+
+	vm_dev = kzalloc(sizeof(*vm_dev), GFP_KERNEL);
+	if (!vm_dev)
+		return -ENOMEM;
+
+	vm_dev->vdev.dev.parent = &pdev->dev;
+	vm_dev->vdev.dev.release = virtio_mmio_release_dev;
+	vm_dev->vdev.config = &virtio_mmio_config_ops;
+	vm_dev->pdev = pdev;
+	INIT_LIST_HEAD(&vm_dev->virtqueues);
+	spin_lock_init(&vm_dev->lock);
+
+	vm_dev->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(vm_dev->base)) {
+		rc = PTR_ERR(vm_dev->base);
+		goto free_vm_dev;
+	}
+
+	/* Check magic value */
+	magic = readl(vm_dev->base + VIRTIO_MMIO_MAGIC_VALUE);
+	if (magic != ('v' | 'i' << 8 | 'r' << 16 | 't' << 24)) {
+		dev_warn(&pdev->dev, "Wrong magic value 0x%08lx!\n", magic);
+		rc = -ENODEV;
+		goto free_vm_dev;
+	}
+
+	/* Check device version */
+	vm_dev->version = readl(vm_dev->base + VIRTIO_MMIO_VERSION);
+	if (vm_dev->version < 1 || vm_dev->version > 2) {
+		dev_err(&pdev->dev, "Version %ld not supported!\n",
+				vm_dev->version);
+		rc = -ENXIO;
+		goto free_vm_dev;
+	}
+
+	vm_dev->vdev.id.device = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_ID);
+	if (vm_dev->vdev.id.device == 0) {
+		/*
+		 * virtio-mmio device with an ID 0 is a (dummy) placeholder
+		 * with no function. End probing now with no error reported.
+		 */
+		rc = -ENODEV;
+		goto free_vm_dev;
+	}
+	vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);
+
+	if (vm_dev->version == 1) {
+		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
+
+		rc = dma_set_mask(&pdev->dev, DMA_BIT_MASK(64));
+		/*
+		 * In the legacy case, ensure our coherently-allocated virtio
+		 * ring will be at an address expressable as a 32-bit PFN.
+		 */
+		if (!rc)
+			dma_set_coherent_mask(&pdev->dev,
+					      DMA_BIT_MASK(32 + PAGE_SHIFT));
+	} else {
+		rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
+	}
+	if (rc)
+		rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
+	if (rc)
+		dev_warn(&pdev->dev, "Failed to enable 64-bit or 32-bit DMA.  Trying to continue, but this might not work.\n");
+
+	platform_set_drvdata(pdev, vm_dev);
+
+	rc = register_virtio_device(&vm_dev->vdev);
+	if (rc)
+		put_device(&vm_dev->vdev.dev);
+
+	return rc;
+
+free_vm_dev:
+	kfree(vm_dev);
+	return rc;
+}
+
+static int virtio_mmio_remove(struct platform_device *pdev)
+{
+	struct virtio_mmio_device *vm_dev = platform_get_drvdata(pdev);
+	unregister_virtio_device(&vm_dev->vdev);
+
+	return 0;
+}
+
+
+
+/* Devices list parameter */
+
+#if defined(CONFIG_VIRTIO_MMIO_CMDLINE_DEVICES)
+
+static struct device vm_cmdline_parent = {
+	.init_name = "virtio-mmio-cmdline",
+};
+
+static int vm_cmdline_parent_registered;
+static int vm_cmdline_id;
+
+static int vm_cmdline_set(const char *device,
+		const struct kernel_param *kp)
+{
+	int err;
+	struct resource resources[2] = {};
+	char *str;
+	long long int base, size;
+	unsigned int irq;
+	int processed, consumed = 0;
+	struct platform_device *pdev;
+
+	/* Consume "size" part of the command line parameter */
+	size = memparse(device, &str);
+
+	/* Get "@<base>:<irq>[:<id>]" chunks */
+	processed = sscanf(str, "@%lli:%u%n:%d%n",
+			&base, &irq, &consumed,
+			&vm_cmdline_id, &consumed);
+
+	/*
+	 * sscanf() must process at least 2 chunks; also there
+	 * must be no extra characters after the last chunk, so
+	 * str[consumed] must be '\0'
+	 */
+	if (processed < 2 || str[consumed] || irq == 0)
+		return -EINVAL;
+
+	resources[0].flags = IORESOURCE_MEM;
+	resources[0].start = base;
+	resources[0].end = base + size - 1;
+
+	resources[1].flags = IORESOURCE_IRQ;
+	resources[1].start = resources[1].end = irq;
+
+	if (!vm_cmdline_parent_registered) {
+		err = device_register(&vm_cmdline_parent);
+		if (err) {
+			put_device(&vm_cmdline_parent);
+			pr_err("Failed to register parent device!\n");
+			return err;
+		}
+		vm_cmdline_parent_registered = 1;
+	}
+
+	pr_info("Registering device virtio-mmio.%d at 0x%llx-0x%llx, IRQ %d.\n",
+		       vm_cmdline_id,
+		       (unsigned long long)resources[0].start,
+		       (unsigned long long)resources[0].end,
+		       (int)resources[1].start);
+
+	pdev = platform_device_register_resndata(&vm_cmdline_parent,
+			"virtio-mmio", vm_cmdline_id++,
+			resources, ARRAY_SIZE(resources), NULL, 0);
+
+	return PTR_ERR_OR_ZERO(pdev);
+}
+
+static int vm_cmdline_get_device(struct device *dev, void *data)
+{
+	char *buffer = data;
+	unsigned int len = strlen(buffer);
+	struct platform_device *pdev = to_platform_device(dev);
+
+	snprintf(buffer + len, PAGE_SIZE - len, "0x%llx@0x%llx:%llu:%d\n",
+			pdev->resource[0].end - pdev->resource[0].start + 1ULL,
+			(unsigned long long)pdev->resource[0].start,
+			(unsigned long long)pdev->resource[1].start,
+			pdev->id);
+	return 0;
+}
+
+static int vm_cmdline_get(char *buffer, const struct kernel_param *kp)
+{
+	buffer[0] = '\0';
+	device_for_each_child(&vm_cmdline_parent, buffer,
+			vm_cmdline_get_device);
+	return strlen(buffer) + 1;
+}
+
+static const struct kernel_param_ops vm_cmdline_param_ops = {
+	.set = vm_cmdline_set,
+	.get = vm_cmdline_get,
+};
+
+device_param_cb(device, &vm_cmdline_param_ops, NULL, S_IRUSR);
+
+static int vm_unregister_cmdline_device(struct device *dev,
+		void *data)
+{
+	platform_device_unregister(to_platform_device(dev));
+
+	return 0;
+}
+
+static void vm_unregister_cmdline_devices(void)
+{
+	if (vm_cmdline_parent_registered) {
+		device_for_each_child(&vm_cmdline_parent, NULL,
+				vm_unregister_cmdline_device);
+		device_unregister(&vm_cmdline_parent);
+		vm_cmdline_parent_registered = 0;
+	}
+}
+
+#else
+
+static void vm_unregister_cmdline_devices(void)
+{
+}
+
+#endif
+
+/* Platform driver */
+
+static const struct of_device_id virtio_mmio_match[] = {
+	{ .compatible = "virtio,mmio", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, virtio_mmio_match);
+
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id virtio_mmio_acpi_match[] = {
+	{ "LNRO0005", },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, virtio_mmio_acpi_match);
+#endif
+
+static struct platform_driver virtio_mmio_driver = {
+	.probe		= virtio_mmio_probe,
+	.remove		= virtio_mmio_remove,
+	.driver		= {
+		.name	= "virtio-mmio",
+		.of_match_table	= virtio_mmio_match,
+		.acpi_match_table = ACPI_PTR(virtio_mmio_acpi_match),
+#ifdef CONFIG_PM_SLEEP
+		.pm	= &virtio_mmio_pm_ops,
+#endif
+	},
+};
+
+static int __init virtio_mmio_init(void)
+{
+	return platform_driver_register(&virtio_mmio_driver);
+}
+
+static void __exit virtio_mmio_exit(void)
+{
+	platform_driver_unregister(&virtio_mmio_driver);
+	vm_unregister_cmdline_devices();
+}
+
+module_init(virtio_mmio_init);
+module_exit(virtio_mmio_exit);
+
+MODULE_AUTHOR("Pawel Moll <pawel.moll@arm.com>");
+MODULE_DESCRIPTION("Platform bus driver for memory mapped virtio devices");
+MODULE_LICENSE("GPL");
diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
new file mode 100644
index 000000000..1e890ef17
--- /dev/null
+++ b/drivers/virtio/virtio_pci_common.c
@@ -0,0 +1,641 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Virtio PCI driver - common functionality for all device versions
+ *
+ * This module allows virtio devices to be used over a virtual PCI device.
+ * This can be used with QEMU based VMMs like KVM or Xen.
+ *
+ * Copyright IBM Corp. 2007
+ * Copyright Red Hat, Inc. 2014
+ *
+ * Authors:
+ *  Anthony Liguori  <aliguori@us.ibm.com>
+ *  Rusty Russell <rusty@rustcorp.com.au>
+ *  Michael S. Tsirkin <mst@redhat.com>
+ */
+
+#include "virtio_pci_common.h"
+
+static bool force_legacy = false;
+
+#if IS_ENABLED(CONFIG_VIRTIO_PCI_LEGACY)
+module_param(force_legacy, bool, 0444);
+MODULE_PARM_DESC(force_legacy,
+		 "Force legacy mode for transitional virtio 1 devices");
+#endif
+
+/* wait for pending irq handlers */
+void vp_synchronize_vectors(struct virtio_device *vdev)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	int i;
+
+	if (vp_dev->intx_enabled)
+		synchronize_irq(vp_dev->pci_dev->irq);
+
+	for (i = 0; i < vp_dev->msix_vectors; ++i)
+		synchronize_irq(pci_irq_vector(vp_dev->pci_dev, i));
+}
+
+/* the notify function used when creating a virt queue */
+bool vp_notify(struct virtqueue *vq)
+{
+	/* we write the queue's selector into the notification register to
+	 * signal the other end */
+	iowrite16(vq->index, (void __iomem *)vq->priv);
+	return true;
+}
+
+/* Handle a configuration change: Tell driver if it wants to know. */
+static irqreturn_t vp_config_changed(int irq, void *opaque)
+{
+	struct virtio_pci_device *vp_dev = opaque;
+
+	virtio_config_changed(&vp_dev->vdev);
+	return IRQ_HANDLED;
+}
+
+/* Notify all virtqueues on an interrupt. */
+static irqreturn_t vp_vring_interrupt(int irq, void *opaque)
+{
+	struct virtio_pci_device *vp_dev = opaque;
+	struct virtio_pci_vq_info *info;
+	irqreturn_t ret = IRQ_NONE;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vp_dev->lock, flags);
+	list_for_each_entry(info, &vp_dev->virtqueues, node) {
+		if (vring_interrupt(irq, info->vq) == IRQ_HANDLED)
+			ret = IRQ_HANDLED;
+	}
+	spin_unlock_irqrestore(&vp_dev->lock, flags);
+
+	return ret;
+}
+
+/* A small wrapper to also acknowledge the interrupt when it's handled.
+ * I really need an EIO hook for the vring so I can ack the interrupt once we
+ * know that we'll be handling the IRQ but before we invoke the callback since
+ * the callback may notify the host which results in the host attempting to
+ * raise an interrupt that we would then mask once we acknowledged the
+ * interrupt. */
+static irqreturn_t vp_interrupt(int irq, void *opaque)
+{
+	struct virtio_pci_device *vp_dev = opaque;
+	u8 isr;
+
+	/* reading the ISR has the effect of also clearing it so it's very
+	 * important to save off the value. */
+	isr = ioread8(vp_dev->isr);
+
+	/* It's definitely not us if the ISR was not high */
+	if (!isr)
+		return IRQ_NONE;
+
+	/* Configuration change?  Tell driver if it wants to know. */
+	if (isr & VIRTIO_PCI_ISR_CONFIG)
+		vp_config_changed(irq, opaque);
+
+	return vp_vring_interrupt(irq, opaque);
+}
+
+static int vp_request_msix_vectors(struct virtio_device *vdev, int nvectors,
+				   bool per_vq_vectors, struct irq_affinity *desc)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	const char *name = dev_name(&vp_dev->vdev.dev);
+	unsigned flags = PCI_IRQ_MSIX;
+	unsigned i, v;
+	int err = -ENOMEM;
+
+	vp_dev->msix_vectors = nvectors;
+
+	vp_dev->msix_names = kmalloc_array(nvectors,
+					   sizeof(*vp_dev->msix_names),
+					   GFP_KERNEL);
+	if (!vp_dev->msix_names)
+		goto error;
+	vp_dev->msix_affinity_masks
+		= kcalloc(nvectors, sizeof(*vp_dev->msix_affinity_masks),
+			  GFP_KERNEL);
+	if (!vp_dev->msix_affinity_masks)
+		goto error;
+	for (i = 0; i < nvectors; ++i)
+		if (!alloc_cpumask_var(&vp_dev->msix_affinity_masks[i],
+					GFP_KERNEL))
+			goto error;
+
+	if (desc) {
+		flags |= PCI_IRQ_AFFINITY;
+		desc->pre_vectors++; /* virtio config vector */
+	}
+
+	err = pci_alloc_irq_vectors_affinity(vp_dev->pci_dev, nvectors,
+					     nvectors, flags, desc);
+	if (err < 0)
+		goto error;
+	vp_dev->msix_enabled = 1;
+
+	/* Set the vector used for configuration */
+	v = vp_dev->msix_used_vectors;
+	snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
+		 "%s-config", name);
+	err = request_irq(pci_irq_vector(vp_dev->pci_dev, v),
+			  vp_config_changed, 0, vp_dev->msix_names[v],
+			  vp_dev);
+	if (err)
+		goto error;
+	++vp_dev->msix_used_vectors;
+
+	v = vp_dev->config_vector(vp_dev, v);
+	/* Verify we had enough resources to assign the vector */
+	if (v == VIRTIO_MSI_NO_VECTOR) {
+		err = -EBUSY;
+		goto error;
+	}
+
+	if (!per_vq_vectors) {
+		/* Shared vector for all VQs */
+		v = vp_dev->msix_used_vectors;
+		snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
+			 "%s-virtqueues", name);
+		err = request_irq(pci_irq_vector(vp_dev->pci_dev, v),
+				  vp_vring_interrupt, 0, vp_dev->msix_names[v],
+				  vp_dev);
+		if (err)
+			goto error;
+		++vp_dev->msix_used_vectors;
+	}
+	return 0;
+error:
+	return err;
+}
+
+static struct virtqueue *vp_setup_vq(struct virtio_device *vdev, unsigned index,
+				     void (*callback)(struct virtqueue *vq),
+				     const char *name,
+				     bool ctx,
+				     u16 msix_vec)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	struct virtio_pci_vq_info *info = kmalloc(sizeof *info, GFP_KERNEL);
+	struct virtqueue *vq;
+	unsigned long flags;
+
+	/* fill out our structure that represents an active queue */
+	if (!info)
+		return ERR_PTR(-ENOMEM);
+
+	vq = vp_dev->setup_vq(vp_dev, info, index, callback, name, ctx,
+			      msix_vec);
+	if (IS_ERR(vq))
+		goto out_info;
+
+	info->vq = vq;
+	if (callback) {
+		spin_lock_irqsave(&vp_dev->lock, flags);
+		list_add(&info->node, &vp_dev->virtqueues);
+		spin_unlock_irqrestore(&vp_dev->lock, flags);
+	} else {
+		INIT_LIST_HEAD(&info->node);
+	}
+
+	vp_dev->vqs[index] = info;
+	return vq;
+
+out_info:
+	kfree(info);
+	return vq;
+}
+
+static void vp_del_vq(struct virtqueue *vq)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
+	struct virtio_pci_vq_info *info = vp_dev->vqs[vq->index];
+	unsigned long flags;
+
+	spin_lock_irqsave(&vp_dev->lock, flags);
+	list_del(&info->node);
+	spin_unlock_irqrestore(&vp_dev->lock, flags);
+
+	vp_dev->del_vq(info);
+	kfree(info);
+}
+
+/* the config->del_vqs() implementation */
+void vp_del_vqs(struct virtio_device *vdev)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	struct virtqueue *vq, *n;
+	int i;
+
+	list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
+		if (vp_dev->per_vq_vectors) {
+			int v = vp_dev->vqs[vq->index]->msix_vector;
+
+			if (v != VIRTIO_MSI_NO_VECTOR) {
+				int irq = pci_irq_vector(vp_dev->pci_dev, v);
+
+				irq_set_affinity_hint(irq, NULL);
+				free_irq(irq, vq);
+			}
+		}
+		vp_del_vq(vq);
+	}
+	vp_dev->per_vq_vectors = false;
+
+	if (vp_dev->intx_enabled) {
+		free_irq(vp_dev->pci_dev->irq, vp_dev);
+		vp_dev->intx_enabled = 0;
+	}
+
+	for (i = 0; i < vp_dev->msix_used_vectors; ++i)
+		free_irq(pci_irq_vector(vp_dev->pci_dev, i), vp_dev);
+
+	if (vp_dev->msix_affinity_masks) {
+		for (i = 0; i < vp_dev->msix_vectors; i++)
+			free_cpumask_var(vp_dev->msix_affinity_masks[i]);
+	}
+
+	if (vp_dev->msix_enabled) {
+		/* Disable the vector used for configuration */
+		vp_dev->config_vector(vp_dev, VIRTIO_MSI_NO_VECTOR);
+
+		pci_free_irq_vectors(vp_dev->pci_dev);
+		vp_dev->msix_enabled = 0;
+	}
+
+	vp_dev->msix_vectors = 0;
+	vp_dev->msix_used_vectors = 0;
+	kfree(vp_dev->msix_names);
+	vp_dev->msix_names = NULL;
+	kfree(vp_dev->msix_affinity_masks);
+	vp_dev->msix_affinity_masks = NULL;
+	kfree(vp_dev->vqs);
+	vp_dev->vqs = NULL;
+}
+
+static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
+		struct virtqueue *vqs[], vq_callback_t *callbacks[],
+		const char * const names[], bool per_vq_vectors,
+		const bool *ctx,
+		struct irq_affinity *desc)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	u16 msix_vec;
+	int i, err, nvectors, allocated_vectors, queue_idx = 0;
+
+	vp_dev->vqs = kcalloc(nvqs, sizeof(*vp_dev->vqs), GFP_KERNEL);
+	if (!vp_dev->vqs)
+		return -ENOMEM;
+
+	if (per_vq_vectors) {
+		/* Best option: one for change interrupt, one per vq. */
+		nvectors = 1;
+		for (i = 0; i < nvqs; ++i)
+			if (names[i] && callbacks[i])
+				++nvectors;
+	} else {
+		/* Second best: one for change, shared for all vqs. */
+		nvectors = 2;
+	}
+
+	err = vp_request_msix_vectors(vdev, nvectors, per_vq_vectors,
+				      per_vq_vectors ? desc : NULL);
+	if (err)
+		goto error_find;
+
+	vp_dev->per_vq_vectors = per_vq_vectors;
+	allocated_vectors = vp_dev->msix_used_vectors;
+	for (i = 0; i < nvqs; ++i) {
+		if (!names[i]) {
+			vqs[i] = NULL;
+			continue;
+		}
+
+		if (!callbacks[i])
+			msix_vec = VIRTIO_MSI_NO_VECTOR;
+		else if (vp_dev->per_vq_vectors)
+			msix_vec = allocated_vectors++;
+		else
+			msix_vec = VP_MSIX_VQ_VECTOR;
+		vqs[i] = vp_setup_vq(vdev, queue_idx++, callbacks[i], names[i],
+				     ctx ? ctx[i] : false,
+				     msix_vec);
+		if (IS_ERR(vqs[i])) {
+			err = PTR_ERR(vqs[i]);
+			goto error_find;
+		}
+
+		if (!vp_dev->per_vq_vectors || msix_vec == VIRTIO_MSI_NO_VECTOR)
+			continue;
+
+		/* allocate per-vq irq if available and necessary */
+		snprintf(vp_dev->msix_names[msix_vec],
+			 sizeof *vp_dev->msix_names,
+			 "%s-%s",
+			 dev_name(&vp_dev->vdev.dev), names[i]);
+		err = request_irq(pci_irq_vector(vp_dev->pci_dev, msix_vec),
+				  vring_interrupt, 0,
+				  vp_dev->msix_names[msix_vec],
+				  vqs[i]);
+		if (err)
+			goto error_find;
+	}
+	return 0;
+
+error_find:
+	vp_del_vqs(vdev);
+	return err;
+}
+
+static int vp_find_vqs_intx(struct virtio_device *vdev, unsigned nvqs,
+		struct virtqueue *vqs[], vq_callback_t *callbacks[],
+		const char * const names[], const bool *ctx)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	int i, err, queue_idx = 0;
+
+	vp_dev->vqs = kcalloc(nvqs, sizeof(*vp_dev->vqs), GFP_KERNEL);
+	if (!vp_dev->vqs)
+		return -ENOMEM;
+
+	err = request_irq(vp_dev->pci_dev->irq, vp_interrupt, IRQF_SHARED,
+			dev_name(&vdev->dev), vp_dev);
+	if (err)
+		goto out_del_vqs;
+
+	vp_dev->intx_enabled = 1;
+	vp_dev->per_vq_vectors = false;
+	for (i = 0; i < nvqs; ++i) {
+		if (!names[i]) {
+			vqs[i] = NULL;
+			continue;
+		}
+		vqs[i] = vp_setup_vq(vdev, queue_idx++, callbacks[i], names[i],
+				     ctx ? ctx[i] : false,
+				     VIRTIO_MSI_NO_VECTOR);
+		if (IS_ERR(vqs[i])) {
+			err = PTR_ERR(vqs[i]);
+			goto out_del_vqs;
+		}
+	}
+
+	return 0;
+out_del_vqs:
+	vp_del_vqs(vdev);
+	return err;
+}
+
+/* the config->find_vqs() implementation */
+int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs,
+		struct virtqueue *vqs[], vq_callback_t *callbacks[],
+		const char * const names[], const bool *ctx,
+		struct irq_affinity *desc)
+{
+	int err;
+
+	/* Try MSI-X with one vector per queue. */
+	err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, true, ctx, desc);
+	if (!err)
+		return 0;
+	/* Fallback: MSI-X with one vector for config, one shared for queues. */
+	err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, false, ctx, desc);
+	if (!err)
+		return 0;
+	/* Finally fall back to regular interrupts. */
+	return vp_find_vqs_intx(vdev, nvqs, vqs, callbacks, names, ctx);
+}
+
+const char *vp_bus_name(struct virtio_device *vdev)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+
+	return pci_name(vp_dev->pci_dev);
+}
+
+/* Setup the affinity for a virtqueue:
+ * - force the affinity for per vq vector
+ * - OR over all affinities for shared MSI
+ * - ignore the affinity request if we're using INTX
+ */
+int vp_set_vq_affinity(struct virtqueue *vq, const struct cpumask *cpu_mask)
+{
+	struct virtio_device *vdev = vq->vdev;
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	struct virtio_pci_vq_info *info = vp_dev->vqs[vq->index];
+	struct cpumask *mask;
+	unsigned int irq;
+
+	if (!vq->callback)
+		return -EINVAL;
+
+	if (vp_dev->msix_enabled) {
+		mask = vp_dev->msix_affinity_masks[info->msix_vector];
+		irq = pci_irq_vector(vp_dev->pci_dev, info->msix_vector);
+		if (!cpu_mask)
+			irq_set_affinity_hint(irq, NULL);
+		else {
+			cpumask_copy(mask, cpu_mask);
+			irq_set_affinity_hint(irq, mask);
+		}
+	}
+	return 0;
+}
+
+const struct cpumask *vp_get_vq_affinity(struct virtio_device *vdev, int index)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+
+	if (!vp_dev->per_vq_vectors ||
+	    vp_dev->vqs[index]->msix_vector == VIRTIO_MSI_NO_VECTOR)
+		return NULL;
+
+	return pci_irq_get_affinity(vp_dev->pci_dev,
+				    vp_dev->vqs[index]->msix_vector);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int virtio_pci_freeze(struct device *dev)
+{
+	struct pci_dev *pci_dev = to_pci_dev(dev);
+	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
+	int ret;
+
+	ret = virtio_device_freeze(&vp_dev->vdev);
+
+	if (!ret)
+		pci_disable_device(pci_dev);
+	return ret;
+}
+
+static int virtio_pci_restore(struct device *dev)
+{
+	struct pci_dev *pci_dev = to_pci_dev(dev);
+	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
+	int ret;
+
+	ret = pci_enable_device(pci_dev);
+	if (ret)
+		return ret;
+
+	pci_set_master(pci_dev);
+	return virtio_device_restore(&vp_dev->vdev);
+}
+
+static const struct dev_pm_ops virtio_pci_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(virtio_pci_freeze, virtio_pci_restore)
+};
+#endif
+
+
+/* Qumranet donated their vendor ID for devices 0x1000 thru 0x10FF. */
+static const struct pci_device_id virtio_pci_id_table[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_REDHAT_QUMRANET, PCI_ANY_ID) },
+	{ 0 }
+};
+
+MODULE_DEVICE_TABLE(pci, virtio_pci_id_table);
+
+static void virtio_pci_release_dev(struct device *_d)
+{
+	struct virtio_device *vdev = dev_to_virtio(_d);
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+
+	/* As struct device is a kobject, it's not safe to
+	 * free the memory (including the reference counter itself)
+	 * until it's release callback. */
+	kfree(vp_dev);
+}
+
+static int virtio_pci_probe(struct pci_dev *pci_dev,
+			    const struct pci_device_id *id)
+{
+	struct virtio_pci_device *vp_dev, *reg_dev = NULL;
+	int rc;
+
+	/* allocate our structure and fill it out */
+	vp_dev = kzalloc(sizeof(struct virtio_pci_device), GFP_KERNEL);
+	if (!vp_dev)
+		return -ENOMEM;
+
+	pci_set_drvdata(pci_dev, vp_dev);
+	vp_dev->vdev.dev.parent = &pci_dev->dev;
+	vp_dev->vdev.dev.release = virtio_pci_release_dev;
+	vp_dev->pci_dev = pci_dev;
+	INIT_LIST_HEAD(&vp_dev->virtqueues);
+	spin_lock_init(&vp_dev->lock);
+
+	/* enable the device */
+	rc = pci_enable_device(pci_dev);
+	if (rc)
+		goto err_enable_device;
+
+	if (force_legacy) {
+		rc = virtio_pci_legacy_probe(vp_dev);
+		/* Also try modern mode if we can't map BAR0 (no IO space). */
+		if (rc == -ENODEV || rc == -ENOMEM)
+			rc = virtio_pci_modern_probe(vp_dev);
+		if (rc)
+			goto err_probe;
+	} else {
+		rc = virtio_pci_modern_probe(vp_dev);
+		if (rc == -ENODEV)
+			rc = virtio_pci_legacy_probe(vp_dev);
+		if (rc)
+			goto err_probe;
+	}
+
+	pci_set_master(pci_dev);
+
+	rc = register_virtio_device(&vp_dev->vdev);
+	reg_dev = vp_dev;
+	if (rc)
+		goto err_register;
+
+	return 0;
+
+err_register:
+	if (vp_dev->ioaddr)
+	     virtio_pci_legacy_remove(vp_dev);
+	else
+	     virtio_pci_modern_remove(vp_dev);
+err_probe:
+	pci_disable_device(pci_dev);
+err_enable_device:
+	if (reg_dev)
+		put_device(&vp_dev->vdev.dev);
+	else
+		kfree(vp_dev);
+	return rc;
+}
+
+static void virtio_pci_remove(struct pci_dev *pci_dev)
+{
+	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
+	struct device *dev = get_device(&vp_dev->vdev.dev);
+
+	/*
+	 * Device is marked broken on surprise removal so that virtio upper
+	 * layers can abort any ongoing operation.
+	 */
+	if (!pci_device_is_present(pci_dev))
+		virtio_break_device(&vp_dev->vdev);
+
+	pci_disable_sriov(pci_dev);
+
+	unregister_virtio_device(&vp_dev->vdev);
+
+	if (vp_dev->ioaddr)
+		virtio_pci_legacy_remove(vp_dev);
+	else
+		virtio_pci_modern_remove(vp_dev);
+
+	pci_disable_device(pci_dev);
+	put_device(dev);
+}
+
+static int virtio_pci_sriov_configure(struct pci_dev *pci_dev, int num_vfs)
+{
+	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
+	struct virtio_device *vdev = &vp_dev->vdev;
+	int ret;
+
+	if (!(vdev->config->get_status(vdev) & VIRTIO_CONFIG_S_DRIVER_OK))
+		return -EBUSY;
+
+	if (!__virtio_test_bit(vdev, VIRTIO_F_SR_IOV))
+		return -EINVAL;
+
+	if (pci_vfs_assigned(pci_dev))
+		return -EPERM;
+
+	if (num_vfs == 0) {
+		pci_disable_sriov(pci_dev);
+		return 0;
+	}
+
+	ret = pci_enable_sriov(pci_dev, num_vfs);
+	if (ret < 0)
+		return ret;
+
+	return num_vfs;
+}
+
+static struct pci_driver virtio_pci_driver = {
+	.name		= "virtio-pci",
+	.id_table	= virtio_pci_id_table,
+	.probe		= virtio_pci_probe,
+	.remove		= virtio_pci_remove,
+#ifdef CONFIG_PM_SLEEP
+	.driver.pm	= &virtio_pci_pm_ops,
+#endif
+	.sriov_configure = virtio_pci_sriov_configure,
+};
+
+module_pci_driver(virtio_pci_driver);
+
+MODULE_AUTHOR("Anthony Liguori <aliguori@us.ibm.com>");
+MODULE_DESCRIPTION("virtio-pci");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("1");
diff --git a/drivers/virtio/virtio_pci_common.h b/drivers/virtio/virtio_pci_common.h
new file mode 100644
index 000000000..b2f0eb406
--- /dev/null
+++ b/drivers/virtio/virtio_pci_common.h
@@ -0,0 +1,160 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _DRIVERS_VIRTIO_VIRTIO_PCI_COMMON_H
+#define _DRIVERS_VIRTIO_VIRTIO_PCI_COMMON_H
+/*
+ * Virtio PCI driver - APIs for common functionality for all device versions
+ *
+ * This module allows virtio devices to be used over a virtual PCI device.
+ * This can be used with QEMU based VMMs like KVM or Xen.
+ *
+ * Copyright IBM Corp. 2007
+ * Copyright Red Hat, Inc. 2014
+ *
+ * Authors:
+ *  Anthony Liguori  <aliguori@us.ibm.com>
+ *  Rusty Russell <rusty@rustcorp.com.au>
+ *  Michael S. Tsirkin <mst@redhat.com>
+ */
+
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/pci.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+#include <linux/virtio.h>
+#include <linux/virtio_config.h>
+#include <linux/virtio_ring.h>
+#include <linux/virtio_pci.h>
+#include <linux/highmem.h>
+#include <linux/spinlock.h>
+
+struct virtio_pci_vq_info {
+	/* the actual virtqueue */
+	struct virtqueue *vq;
+
+	/* the list node for the virtqueues list */
+	struct list_head node;
+
+	/* MSI-X vector (or none) */
+	unsigned msix_vector;
+};
+
+/* Our device structure */
+struct virtio_pci_device {
+	struct virtio_device vdev;
+	struct pci_dev *pci_dev;
+
+	/* In legacy mode, these two point to within ->legacy. */
+	/* Where to read and clear interrupt */
+	u8 __iomem *isr;
+
+	/* Modern only fields */
+	/* The IO mapping for the PCI config space (non-legacy mode) */
+	struct virtio_pci_common_cfg __iomem *common;
+	/* Device-specific data (non-legacy mode)  */
+	void __iomem *device;
+	/* Base of vq notifications (non-legacy mode). */
+	void __iomem *notify_base;
+
+	/* So we can sanity-check accesses. */
+	size_t notify_len;
+	size_t device_len;
+
+	/* Capability for when we need to map notifications per-vq. */
+	int notify_map_cap;
+
+	/* Multiply queue_notify_off by this value. (non-legacy mode). */
+	u32 notify_offset_multiplier;
+
+	int modern_bars;
+
+	/* Legacy only field */
+	/* the IO mapping for the PCI config space */
+	void __iomem *ioaddr;
+
+	/* a list of queues so we can dispatch IRQs */
+	spinlock_t lock;
+	struct list_head virtqueues;
+
+	/* array of all queues for house-keeping */
+	struct virtio_pci_vq_info **vqs;
+
+	/* MSI-X support */
+	int msix_enabled;
+	int intx_enabled;
+	cpumask_var_t *msix_affinity_masks;
+	/* Name strings for interrupts. This size should be enough,
+	 * and I'm too lazy to allocate each name separately. */
+	char (*msix_names)[256];
+	/* Number of available vectors */
+	unsigned msix_vectors;
+	/* Vectors allocated, excluding per-vq vectors if any */
+	unsigned msix_used_vectors;
+
+	/* Whether we have vector per vq */
+	bool per_vq_vectors;
+
+	struct virtqueue *(*setup_vq)(struct virtio_pci_device *vp_dev,
+				      struct virtio_pci_vq_info *info,
+				      unsigned idx,
+				      void (*callback)(struct virtqueue *vq),
+				      const char *name,
+				      bool ctx,
+				      u16 msix_vec);
+	void (*del_vq)(struct virtio_pci_vq_info *info);
+
+	u16 (*config_vector)(struct virtio_pci_device *vp_dev, u16 vector);
+};
+
+/* Constants for MSI-X */
+/* Use first vector for configuration changes, second and the rest for
+ * virtqueues Thus, we need at least 2 vectors for MSI. */
+enum {
+	VP_MSIX_CONFIG_VECTOR = 0,
+	VP_MSIX_VQ_VECTOR = 1,
+};
+
+/* Convert a generic virtio device to our structure */
+static struct virtio_pci_device *to_vp_device(struct virtio_device *vdev)
+{
+	return container_of(vdev, struct virtio_pci_device, vdev);
+}
+
+/* wait for pending irq handlers */
+void vp_synchronize_vectors(struct virtio_device *vdev);
+/* the notify function used when creating a virt queue */
+bool vp_notify(struct virtqueue *vq);
+/* the config->del_vqs() implementation */
+void vp_del_vqs(struct virtio_device *vdev);
+/* the config->find_vqs() implementation */
+int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs,
+		struct virtqueue *vqs[], vq_callback_t *callbacks[],
+		const char * const names[], const bool *ctx,
+		struct irq_affinity *desc);
+const char *vp_bus_name(struct virtio_device *vdev);
+
+/* Setup the affinity for a virtqueue:
+ * - force the affinity for per vq vector
+ * - OR over all affinities for shared MSI
+ * - ignore the affinity request if we're using INTX
+ */
+int vp_set_vq_affinity(struct virtqueue *vq, const struct cpumask *cpu_mask);
+
+const struct cpumask *vp_get_vq_affinity(struct virtio_device *vdev, int index);
+
+#if IS_ENABLED(CONFIG_VIRTIO_PCI_LEGACY)
+int virtio_pci_legacy_probe(struct virtio_pci_device *);
+void virtio_pci_legacy_remove(struct virtio_pci_device *);
+#else
+static inline int virtio_pci_legacy_probe(struct virtio_pci_device *vp_dev)
+{
+	return -ENODEV;
+}
+static inline void virtio_pci_legacy_remove(struct virtio_pci_device *vp_dev)
+{
+}
+#endif
+int virtio_pci_modern_probe(struct virtio_pci_device *);
+void virtio_pci_modern_remove(struct virtio_pci_device *);
+
+#endif
diff --git a/drivers/virtio/virtio_pci_legacy.c b/drivers/virtio/virtio_pci_legacy.c
new file mode 100644
index 000000000..d62e9835a
--- /dev/null
+++ b/drivers/virtio/virtio_pci_legacy.c
@@ -0,0 +1,279 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Virtio PCI driver - legacy device support
+ *
+ * This module allows virtio devices to be used over a virtual PCI device.
+ * This can be used with QEMU based VMMs like KVM or Xen.
+ *
+ * Copyright IBM Corp. 2007
+ * Copyright Red Hat, Inc. 2014
+ *
+ * Authors:
+ *  Anthony Liguori  <aliguori@us.ibm.com>
+ *  Rusty Russell <rusty@rustcorp.com.au>
+ *  Michael S. Tsirkin <mst@redhat.com>
+ */
+
+#include "virtio_pci_common.h"
+
+/* virtio config->get_features() implementation */
+static u64 vp_get_features(struct virtio_device *vdev)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+
+	/* When someone needs more than 32 feature bits, we'll need to
+	 * steal a bit to indicate that the rest are somewhere else. */
+	return ioread32(vp_dev->ioaddr + VIRTIO_PCI_HOST_FEATURES);
+}
+
+/* virtio config->finalize_features() implementation */
+static int vp_finalize_features(struct virtio_device *vdev)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+
+	/* Give virtio_ring a chance to accept features. */
+	vring_transport_features(vdev);
+
+	/* Make sure we don't have any features > 32 bits! */
+	BUG_ON((u32)vdev->features != vdev->features);
+
+	/* We only support 32 feature bits. */
+	iowrite32(vdev->features, vp_dev->ioaddr + VIRTIO_PCI_GUEST_FEATURES);
+
+	return 0;
+}
+
+/* virtio config->get() implementation */
+static void vp_get(struct virtio_device *vdev, unsigned offset,
+		   void *buf, unsigned len)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	void __iomem *ioaddr = vp_dev->ioaddr +
+			VIRTIO_PCI_CONFIG_OFF(vp_dev->msix_enabled) +
+			offset;
+	u8 *ptr = buf;
+	int i;
+
+	for (i = 0; i < len; i++)
+		ptr[i] = ioread8(ioaddr + i);
+}
+
+/* the config->set() implementation.  it's symmetric to the config->get()
+ * implementation */
+static void vp_set(struct virtio_device *vdev, unsigned offset,
+		   const void *buf, unsigned len)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	void __iomem *ioaddr = vp_dev->ioaddr +
+			VIRTIO_PCI_CONFIG_OFF(vp_dev->msix_enabled) +
+			offset;
+	const u8 *ptr = buf;
+	int i;
+
+	for (i = 0; i < len; i++)
+		iowrite8(ptr[i], ioaddr + i);
+}
+
+/* config->{get,set}_status() implementations */
+static u8 vp_get_status(struct virtio_device *vdev)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	return ioread8(vp_dev->ioaddr + VIRTIO_PCI_STATUS);
+}
+
+static void vp_set_status(struct virtio_device *vdev, u8 status)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	/* We should never be setting status to 0. */
+	BUG_ON(status == 0);
+	iowrite8(status, vp_dev->ioaddr + VIRTIO_PCI_STATUS);
+}
+
+static void vp_reset(struct virtio_device *vdev)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	/* 0 status means a reset. */
+	iowrite8(0, vp_dev->ioaddr + VIRTIO_PCI_STATUS);
+	/* Flush out the status write, and flush in device writes,
+	 * including MSi-X interrupts, if any. */
+	ioread8(vp_dev->ioaddr + VIRTIO_PCI_STATUS);
+	/* Flush pending VQ/configuration callbacks. */
+	vp_synchronize_vectors(vdev);
+}
+
+static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
+{
+	/* Setup the vector used for configuration events */
+	iowrite16(vector, vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
+	/* Verify we had enough resources to assign the vector */
+	/* Will also flush the write out to device */
+	return ioread16(vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
+}
+
+static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
+				  struct virtio_pci_vq_info *info,
+				  unsigned index,
+				  void (*callback)(struct virtqueue *vq),
+				  const char *name,
+				  bool ctx,
+				  u16 msix_vec)
+{
+	struct virtqueue *vq;
+	u16 num;
+	int err;
+	u64 q_pfn;
+
+	/* Select the queue we're interested in */
+	iowrite16(index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
+
+	/* Check if queue is either not available or already active. */
+	num = ioread16(vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NUM);
+	if (!num || ioread32(vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN))
+		return ERR_PTR(-ENOENT);
+
+	info->msix_vector = msix_vec;
+
+	/* create the vring */
+	vq = vring_create_virtqueue(index, num,
+				    VIRTIO_PCI_VRING_ALIGN, &vp_dev->vdev,
+				    true, false, ctx,
+				    vp_notify, callback, name);
+	if (!vq)
+		return ERR_PTR(-ENOMEM);
+
+	q_pfn = virtqueue_get_desc_addr(vq) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT;
+	if (q_pfn >> 32) {
+		dev_err(&vp_dev->pci_dev->dev,
+			"platform bug: legacy virtio-mmio must not be used with RAM above 0x%llxGB\n",
+			0x1ULL << (32 + PAGE_SHIFT - 30));
+		err = -E2BIG;
+		goto out_del_vq;
+	}
+
+	/* activate the queue */
+	iowrite32(q_pfn, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
+
+	vq->priv = (void __force *)vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NOTIFY;
+
+	if (msix_vec != VIRTIO_MSI_NO_VECTOR) {
+		iowrite16(msix_vec, vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
+		msix_vec = ioread16(vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
+		if (msix_vec == VIRTIO_MSI_NO_VECTOR) {
+			err = -EBUSY;
+			goto out_deactivate;
+		}
+	}
+
+	return vq;
+
+out_deactivate:
+	iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
+out_del_vq:
+	vring_del_virtqueue(vq);
+	return ERR_PTR(err);
+}
+
+static void del_vq(struct virtio_pci_vq_info *info)
+{
+	struct virtqueue *vq = info->vq;
+	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
+
+	iowrite16(vq->index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
+
+	if (vp_dev->msix_enabled) {
+		iowrite16(VIRTIO_MSI_NO_VECTOR,
+			  vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
+		/* Flush the write out to device */
+		ioread8(vp_dev->ioaddr + VIRTIO_PCI_ISR);
+	}
+
+	/* Select and deactivate the queue */
+	iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
+
+	vring_del_virtqueue(vq);
+}
+
+static const struct virtio_config_ops virtio_pci_config_ops = {
+	.get		= vp_get,
+	.set		= vp_set,
+	.get_status	= vp_get_status,
+	.set_status	= vp_set_status,
+	.reset		= vp_reset,
+	.find_vqs	= vp_find_vqs,
+	.del_vqs	= vp_del_vqs,
+	.get_features	= vp_get_features,
+	.finalize_features = vp_finalize_features,
+	.bus_name	= vp_bus_name,
+	.set_vq_affinity = vp_set_vq_affinity,
+	.get_vq_affinity = vp_get_vq_affinity,
+};
+
+/* the PCI probing function */
+int virtio_pci_legacy_probe(struct virtio_pci_device *vp_dev)
+{
+	struct pci_dev *pci_dev = vp_dev->pci_dev;
+	int rc;
+
+	/* We only own devices >= 0x1000 and <= 0x103f: leave the rest. */
+	if (pci_dev->device < 0x1000 || pci_dev->device > 0x103f)
+		return -ENODEV;
+
+	if (pci_dev->revision != VIRTIO_PCI_ABI_VERSION) {
+		printk(KERN_ERR "virtio_pci: expected ABI version %d, got %d\n",
+		       VIRTIO_PCI_ABI_VERSION, pci_dev->revision);
+		return -ENODEV;
+	}
+
+	rc = dma_set_mask(&pci_dev->dev, DMA_BIT_MASK(64));
+	if (rc) {
+		rc = dma_set_mask_and_coherent(&pci_dev->dev, DMA_BIT_MASK(32));
+	} else {
+		/*
+		 * The virtio ring base address is expressed as a 32-bit PFN,
+		 * with a page size of 1 << VIRTIO_PCI_QUEUE_ADDR_SHIFT.
+		 */
+		dma_set_coherent_mask(&pci_dev->dev,
+				DMA_BIT_MASK(32 + VIRTIO_PCI_QUEUE_ADDR_SHIFT));
+	}
+
+	if (rc)
+		dev_warn(&pci_dev->dev, "Failed to enable 64-bit or 32-bit DMA.  Trying to continue, but this might not work.\n");
+
+	rc = pci_request_region(pci_dev, 0, "virtio-pci-legacy");
+	if (rc)
+		return rc;
+
+	rc = -ENOMEM;
+	vp_dev->ioaddr = pci_iomap(pci_dev, 0, 0);
+	if (!vp_dev->ioaddr)
+		goto err_iomap;
+
+	vp_dev->isr = vp_dev->ioaddr + VIRTIO_PCI_ISR;
+
+	/* we use the subsystem vendor/device id as the virtio vendor/device
+	 * id.  this allows us to use the same PCI vendor/device id for all
+	 * virtio devices and to identify the particular virtio driver by
+	 * the subsystem ids */
+	vp_dev->vdev.id.vendor = pci_dev->subsystem_vendor;
+	vp_dev->vdev.id.device = pci_dev->subsystem_device;
+
+	vp_dev->vdev.config = &virtio_pci_config_ops;
+
+	vp_dev->config_vector = vp_config_vector;
+	vp_dev->setup_vq = setup_vq;
+	vp_dev->del_vq = del_vq;
+
+	return 0;
+
+err_iomap:
+	pci_release_region(pci_dev, 0);
+	return rc;
+}
+
+void virtio_pci_legacy_remove(struct virtio_pci_device *vp_dev)
+{
+	struct pci_dev *pci_dev = vp_dev->pci_dev;
+
+	pci_iounmap(pci_dev, vp_dev->ioaddr);
+	pci_release_region(pci_dev, 0);
+}
diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
new file mode 100644
index 000000000..3d6ae5a5e
--- /dev/null
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -0,0 +1,831 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Virtio PCI driver - modern (virtio 1.0) device support
+ *
+ * This module allows virtio devices to be used over a virtual PCI device.
+ * This can be used with QEMU based VMMs like KVM or Xen.
+ *
+ * Copyright IBM Corp. 2007
+ * Copyright Red Hat, Inc. 2014
+ *
+ * Authors:
+ *  Anthony Liguori  <aliguori@us.ibm.com>
+ *  Rusty Russell <rusty@rustcorp.com.au>
+ *  Michael S. Tsirkin <mst@redhat.com>
+ */
+
+#include <linux/delay.h>
+#define VIRTIO_PCI_NO_LEGACY
+#define VIRTIO_RING_NO_LEGACY
+#include "virtio_pci_common.h"
+
+/*
+ * Type-safe wrappers for io accesses.
+ * Use these to enforce at compile time the following spec requirement:
+ *
+ * The driver MUST access each field using the “natural” access
+ * method, i.e. 32-bit accesses for 32-bit fields, 16-bit accesses
+ * for 16-bit fields and 8-bit accesses for 8-bit fields.
+ */
+static inline u8 vp_ioread8(const u8 __iomem *addr)
+{
+	return ioread8(addr);
+}
+static inline u16 vp_ioread16 (const __le16 __iomem *addr)
+{
+	return ioread16(addr);
+}
+
+static inline u32 vp_ioread32(const __le32 __iomem *addr)
+{
+	return ioread32(addr);
+}
+
+static inline void vp_iowrite8(u8 value, u8 __iomem *addr)
+{
+	iowrite8(value, addr);
+}
+
+static inline void vp_iowrite16(u16 value, __le16 __iomem *addr)
+{
+	iowrite16(value, addr);
+}
+
+static inline void vp_iowrite32(u32 value, __le32 __iomem *addr)
+{
+	iowrite32(value, addr);
+}
+
+static void vp_iowrite64_twopart(u64 val,
+				 __le32 __iomem *lo, __le32 __iomem *hi)
+{
+	vp_iowrite32((u32)val, lo);
+	vp_iowrite32(val >> 32, hi);
+}
+
+static void __iomem *map_capability(struct pci_dev *dev, int off,
+				    size_t minlen,
+				    u32 align,
+				    u32 start, u32 size,
+				    size_t *len)
+{
+	u8 bar;
+	u32 offset, length;
+	void __iomem *p;
+
+	pci_read_config_byte(dev, off + offsetof(struct virtio_pci_cap,
+						 bar),
+			     &bar);
+	pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, offset),
+			     &offset);
+	pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, length),
+			      &length);
+
+	if (length <= start) {
+		dev_err(&dev->dev,
+			"virtio_pci: bad capability len %u (>%u expected)\n",
+			length, start);
+		return NULL;
+	}
+
+	if (length - start < minlen) {
+		dev_err(&dev->dev,
+			"virtio_pci: bad capability len %u (>=%zu expected)\n",
+			length, minlen);
+		return NULL;
+	}
+
+	length -= start;
+
+	if (start + offset < offset) {
+		dev_err(&dev->dev,
+			"virtio_pci: map wrap-around %u+%u\n",
+			start, offset);
+		return NULL;
+	}
+
+	offset += start;
+
+	if (offset & (align - 1)) {
+		dev_err(&dev->dev,
+			"virtio_pci: offset %u not aligned to %u\n",
+			offset, align);
+		return NULL;
+	}
+
+	if (length > size)
+		length = size;
+
+	if (len)
+		*len = length;
+
+	if (minlen + offset < minlen ||
+	    minlen + offset > pci_resource_len(dev, bar)) {
+		dev_err(&dev->dev,
+			"virtio_pci: map virtio %zu@%u "
+			"out of range on bar %i length %lu\n",
+			minlen, offset,
+			bar, (unsigned long)pci_resource_len(dev, bar));
+		return NULL;
+	}
+
+	p = pci_iomap_range(dev, bar, offset, length);
+	if (!p)
+		dev_err(&dev->dev,
+			"virtio_pci: unable to map virtio %u@%u on bar %i\n",
+			length, offset, bar);
+	return p;
+}
+
+/* virtio config->get_features() implementation */
+static u64 vp_get_features(struct virtio_device *vdev)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	u64 features;
+
+	vp_iowrite32(0, &vp_dev->common->device_feature_select);
+	features = vp_ioread32(&vp_dev->common->device_feature);
+	vp_iowrite32(1, &vp_dev->common->device_feature_select);
+	features |= ((u64)vp_ioread32(&vp_dev->common->device_feature) << 32);
+
+	return features;
+}
+
+static void vp_transport_features(struct virtio_device *vdev, u64 features)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	struct pci_dev *pci_dev = vp_dev->pci_dev;
+
+	if ((features & BIT_ULL(VIRTIO_F_SR_IOV)) &&
+			pci_find_ext_capability(pci_dev, PCI_EXT_CAP_ID_SRIOV))
+		__virtio_set_bit(vdev, VIRTIO_F_SR_IOV);
+}
+
+/* virtio config->finalize_features() implementation */
+static int vp_finalize_features(struct virtio_device *vdev)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	u64 features = vdev->features;
+
+	/* Give virtio_ring a chance to accept features. */
+	vring_transport_features(vdev);
+
+	/* Give virtio_pci a chance to accept features. */
+	vp_transport_features(vdev, features);
+
+	if (!__virtio_test_bit(vdev, VIRTIO_F_VERSION_1)) {
+		dev_err(&vdev->dev, "virtio: device uses modern interface "
+			"but does not have VIRTIO_F_VERSION_1\n");
+		return -EINVAL;
+	}
+
+	vp_iowrite32(0, &vp_dev->common->guest_feature_select);
+	vp_iowrite32((u32)vdev->features, &vp_dev->common->guest_feature);
+	vp_iowrite32(1, &vp_dev->common->guest_feature_select);
+	vp_iowrite32(vdev->features >> 32, &vp_dev->common->guest_feature);
+
+	return 0;
+}
+
+/* virtio config->get() implementation */
+static void vp_get(struct virtio_device *vdev, unsigned offset,
+		   void *buf, unsigned len)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	u8 b;
+	__le16 w;
+	__le32 l;
+
+	BUG_ON(offset + len > vp_dev->device_len);
+
+	switch (len) {
+	case 1:
+		b = ioread8(vp_dev->device + offset);
+		memcpy(buf, &b, sizeof b);
+		break;
+	case 2:
+		w = cpu_to_le16(ioread16(vp_dev->device + offset));
+		memcpy(buf, &w, sizeof w);
+		break;
+	case 4:
+		l = cpu_to_le32(ioread32(vp_dev->device + offset));
+		memcpy(buf, &l, sizeof l);
+		break;
+	case 8:
+		l = cpu_to_le32(ioread32(vp_dev->device + offset));
+		memcpy(buf, &l, sizeof l);
+		l = cpu_to_le32(ioread32(vp_dev->device + offset + sizeof l));
+		memcpy(buf + sizeof l, &l, sizeof l);
+		break;
+	default:
+		BUG();
+	}
+}
+
+/* the config->set() implementation.  it's symmetric to the config->get()
+ * implementation */
+static void vp_set(struct virtio_device *vdev, unsigned offset,
+		   const void *buf, unsigned len)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	u8 b;
+	__le16 w;
+	__le32 l;
+
+	BUG_ON(offset + len > vp_dev->device_len);
+
+	switch (len) {
+	case 1:
+		memcpy(&b, buf, sizeof b);
+		iowrite8(b, vp_dev->device + offset);
+		break;
+	case 2:
+		memcpy(&w, buf, sizeof w);
+		iowrite16(le16_to_cpu(w), vp_dev->device + offset);
+		break;
+	case 4:
+		memcpy(&l, buf, sizeof l);
+		iowrite32(le32_to_cpu(l), vp_dev->device + offset);
+		break;
+	case 8:
+		memcpy(&l, buf, sizeof l);
+		iowrite32(le32_to_cpu(l), vp_dev->device + offset);
+		memcpy(&l, buf + sizeof l, sizeof l);
+		iowrite32(le32_to_cpu(l), vp_dev->device + offset + sizeof l);
+		break;
+	default:
+		BUG();
+	}
+}
+
+static u32 vp_generation(struct virtio_device *vdev)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	return vp_ioread8(&vp_dev->common->config_generation);
+}
+
+/* config->{get,set}_status() implementations */
+static u8 vp_get_status(struct virtio_device *vdev)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	return vp_ioread8(&vp_dev->common->device_status);
+}
+
+static void vp_set_status(struct virtio_device *vdev, u8 status)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	/* We should never be setting status to 0. */
+	BUG_ON(status == 0);
+	vp_iowrite8(status, &vp_dev->common->device_status);
+}
+
+static void vp_reset(struct virtio_device *vdev)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	/* 0 status means a reset. */
+	vp_iowrite8(0, &vp_dev->common->device_status);
+	/* After writing 0 to device_status, the driver MUST wait for a read of
+	 * device_status to return 0 before reinitializing the device.
+	 * This will flush out the status write, and flush in device writes,
+	 * including MSI-X interrupts, if any.
+	 */
+	while (vp_ioread8(&vp_dev->common->device_status))
+		msleep(1);
+	/* Flush pending VQ/configuration callbacks. */
+	vp_synchronize_vectors(vdev);
+}
+
+static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
+{
+	/* Setup the vector used for configuration events */
+	vp_iowrite16(vector, &vp_dev->common->msix_config);
+	/* Verify we had enough resources to assign the vector */
+	/* Will also flush the write out to device */
+	return vp_ioread16(&vp_dev->common->msix_config);
+}
+
+static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
+				  struct virtio_pci_vq_info *info,
+				  unsigned index,
+				  void (*callback)(struct virtqueue *vq),
+				  const char *name,
+				  bool ctx,
+				  u16 msix_vec)
+{
+	struct virtio_pci_common_cfg __iomem *cfg = vp_dev->common;
+	struct virtqueue *vq;
+	u16 num, off;
+	int err;
+
+	if (index >= vp_ioread16(&cfg->num_queues))
+		return ERR_PTR(-ENOENT);
+
+	/* Select the queue we're interested in */
+	vp_iowrite16(index, &cfg->queue_select);
+
+	/* Check if queue is either not available or already active. */
+	num = vp_ioread16(&cfg->queue_size);
+	if (!num || vp_ioread16(&cfg->queue_enable))
+		return ERR_PTR(-ENOENT);
+
+	if (num & (num - 1)) {
+		dev_warn(&vp_dev->pci_dev->dev, "bad queue size %u", num);
+		return ERR_PTR(-EINVAL);
+	}
+
+	/* get offset of notification word for this vq */
+	off = vp_ioread16(&cfg->queue_notify_off);
+
+	info->msix_vector = msix_vec;
+
+	/* create the vring */
+	vq = vring_create_virtqueue(index, num,
+				    SMP_CACHE_BYTES, &vp_dev->vdev,
+				    true, true, ctx,
+				    vp_notify, callback, name);
+	if (!vq)
+		return ERR_PTR(-ENOMEM);
+
+	/* activate the queue */
+	vp_iowrite16(virtqueue_get_vring_size(vq), &cfg->queue_size);
+	vp_iowrite64_twopart(virtqueue_get_desc_addr(vq),
+			     &cfg->queue_desc_lo, &cfg->queue_desc_hi);
+	vp_iowrite64_twopart(virtqueue_get_avail_addr(vq),
+			     &cfg->queue_avail_lo, &cfg->queue_avail_hi);
+	vp_iowrite64_twopart(virtqueue_get_used_addr(vq),
+			     &cfg->queue_used_lo, &cfg->queue_used_hi);
+
+	if (vp_dev->notify_base) {
+		/* offset should not wrap */
+		if ((u64)off * vp_dev->notify_offset_multiplier + 2
+		    > vp_dev->notify_len) {
+			dev_warn(&vp_dev->pci_dev->dev,
+				 "bad notification offset %u (x %u) "
+				 "for queue %u > %zd",
+				 off, vp_dev->notify_offset_multiplier,
+				 index, vp_dev->notify_len);
+			err = -EINVAL;
+			goto err_map_notify;
+		}
+		vq->priv = (void __force *)vp_dev->notify_base +
+			off * vp_dev->notify_offset_multiplier;
+	} else {
+		vq->priv = (void __force *)map_capability(vp_dev->pci_dev,
+					  vp_dev->notify_map_cap, 2, 2,
+					  off * vp_dev->notify_offset_multiplier, 2,
+					  NULL);
+	}
+
+	if (!vq->priv) {
+		err = -ENOMEM;
+		goto err_map_notify;
+	}
+
+	if (msix_vec != VIRTIO_MSI_NO_VECTOR) {
+		vp_iowrite16(msix_vec, &cfg->queue_msix_vector);
+		msix_vec = vp_ioread16(&cfg->queue_msix_vector);
+		if (msix_vec == VIRTIO_MSI_NO_VECTOR) {
+			err = -EBUSY;
+			goto err_assign_vector;
+		}
+	}
+
+	return vq;
+
+err_assign_vector:
+	if (!vp_dev->notify_base)
+		pci_iounmap(vp_dev->pci_dev, (void __iomem __force *)vq->priv);
+err_map_notify:
+	vring_del_virtqueue(vq);
+	return ERR_PTR(err);
+}
+
+static int vp_modern_find_vqs(struct virtio_device *vdev, unsigned nvqs,
+			      struct virtqueue *vqs[],
+			      vq_callback_t *callbacks[],
+			      const char * const names[], const bool *ctx,
+			      struct irq_affinity *desc)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	struct virtqueue *vq;
+	int rc = vp_find_vqs(vdev, nvqs, vqs, callbacks, names, ctx, desc);
+
+	if (rc)
+		return rc;
+
+	/* Select and activate all queues. Has to be done last: once we do
+	 * this, there's no way to go back except reset.
+	 */
+	list_for_each_entry(vq, &vdev->vqs, list) {
+		vp_iowrite16(vq->index, &vp_dev->common->queue_select);
+		vp_iowrite16(1, &vp_dev->common->queue_enable);
+	}
+
+	return 0;
+}
+
+static void del_vq(struct virtio_pci_vq_info *info)
+{
+	struct virtqueue *vq = info->vq;
+	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
+
+	vp_iowrite16(vq->index, &vp_dev->common->queue_select);
+
+	if (vp_dev->msix_enabled) {
+		vp_iowrite16(VIRTIO_MSI_NO_VECTOR,
+			     &vp_dev->common->queue_msix_vector);
+		/* Flush the write out to device */
+		vp_ioread16(&vp_dev->common->queue_msix_vector);
+	}
+
+	if (!vp_dev->notify_base)
+		pci_iounmap(vp_dev->pci_dev, (void __force __iomem *)vq->priv);
+
+	vring_del_virtqueue(vq);
+}
+
+static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
+				   u8 *bar, u64 *offset, u64 *len)
+{
+	int pos;
+
+	for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR); pos > 0;
+	     pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
+		u8 type, cap_len, id;
+		u32 tmp32;
+		u64 res_offset, res_length;
+
+		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
+							 cfg_type), &type);
+		if (type != VIRTIO_PCI_CAP_SHARED_MEMORY_CFG)
+			continue;
+
+		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
+							 cap_len), &cap_len);
+		if (cap_len != sizeof(struct virtio_pci_cap64)) {
+			dev_err(&dev->dev, "%s: shm cap with bad size offset:"
+				" %d size: %d\n", __func__, pos, cap_len);
+			continue;
+		}
+
+		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
+							 id), &id);
+		if (id != required_id)
+			continue;
+
+		/* Type, and ID match, looks good */
+		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
+							 bar), bar);
+
+		/* Read the lower 32bit of length and offset */
+		pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap,
+							  offset), &tmp32);
+		res_offset = tmp32;
+		pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap,
+							  length), &tmp32);
+		res_length = tmp32;
+
+		/* and now the top half */
+		pci_read_config_dword(dev,
+				      pos + offsetof(struct virtio_pci_cap64,
+						     offset_hi), &tmp32);
+		res_offset |= ((u64)tmp32) << 32;
+		pci_read_config_dword(dev,
+				      pos + offsetof(struct virtio_pci_cap64,
+						     length_hi), &tmp32);
+		res_length |= ((u64)tmp32) << 32;
+
+		*offset = res_offset;
+		*len = res_length;
+
+		return pos;
+	}
+	return 0;
+}
+
+static bool vp_get_shm_region(struct virtio_device *vdev,
+			      struct virtio_shm_region *region, u8 id)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	struct pci_dev *pci_dev = vp_dev->pci_dev;
+	u8 bar;
+	u64 offset, len;
+	phys_addr_t phys_addr;
+	size_t bar_len;
+
+	if (!virtio_pci_find_shm_cap(pci_dev, id, &bar, &offset, &len))
+		return false;
+
+	phys_addr = pci_resource_start(pci_dev, bar);
+	bar_len = pci_resource_len(pci_dev, bar);
+
+	if ((offset + len) < offset) {
+		dev_err(&pci_dev->dev, "%s: cap offset+len overflow detected\n",
+			__func__);
+		return false;
+	}
+
+	if (offset + len > bar_len) {
+		dev_err(&pci_dev->dev, "%s: bar shorter than cap offset+len\n",
+			__func__);
+		return false;
+	}
+
+	region->len = len;
+	region->addr = (u64) phys_addr + offset;
+
+	return true;
+}
+
+static const struct virtio_config_ops virtio_pci_config_nodev_ops = {
+	.get		= NULL,
+	.set		= NULL,
+	.generation	= vp_generation,
+	.get_status	= vp_get_status,
+	.set_status	= vp_set_status,
+	.reset		= vp_reset,
+	.find_vqs	= vp_modern_find_vqs,
+	.del_vqs	= vp_del_vqs,
+	.get_features	= vp_get_features,
+	.finalize_features = vp_finalize_features,
+	.bus_name	= vp_bus_name,
+	.set_vq_affinity = vp_set_vq_affinity,
+	.get_vq_affinity = vp_get_vq_affinity,
+	.get_shm_region  = vp_get_shm_region,
+};
+
+static const struct virtio_config_ops virtio_pci_config_ops = {
+	.get		= vp_get,
+	.set		= vp_set,
+	.generation	= vp_generation,
+	.get_status	= vp_get_status,
+	.set_status	= vp_set_status,
+	.reset		= vp_reset,
+	.find_vqs	= vp_modern_find_vqs,
+	.del_vqs	= vp_del_vqs,
+	.get_features	= vp_get_features,
+	.finalize_features = vp_finalize_features,
+	.bus_name	= vp_bus_name,
+	.set_vq_affinity = vp_set_vq_affinity,
+	.get_vq_affinity = vp_get_vq_affinity,
+	.get_shm_region  = vp_get_shm_region,
+};
+
+/**
+ * virtio_pci_find_capability - walk capabilities to find device info.
+ * @dev: the pci device
+ * @cfg_type: the VIRTIO_PCI_CAP_* value we seek
+ * @ioresource_types: IORESOURCE_MEM and/or IORESOURCE_IO.
+ * @bars: the bitmask of BARs
+ *
+ * Returns offset of the capability, or 0.
+ */
+static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type,
+					     u32 ioresource_types, int *bars)
+{
+	int pos;
+
+	for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR);
+	     pos > 0;
+	     pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
+		u8 type, bar;
+		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
+							 cfg_type),
+				     &type);
+		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
+							 bar),
+				     &bar);
+
+		/* Ignore structures with reserved BAR values */
+		if (bar > 0x5)
+			continue;
+
+		if (type == cfg_type) {
+			if (pci_resource_len(dev, bar) &&
+			    pci_resource_flags(dev, bar) & ioresource_types) {
+				*bars |= (1 << bar);
+				return pos;
+			}
+		}
+	}
+	return 0;
+}
+
+/* This is part of the ABI.  Don't screw with it. */
+static inline void check_offsets(void)
+{
+	/* Note: disk space was harmed in compilation of this function. */
+	BUILD_BUG_ON(VIRTIO_PCI_CAP_VNDR !=
+		     offsetof(struct virtio_pci_cap, cap_vndr));
+	BUILD_BUG_ON(VIRTIO_PCI_CAP_NEXT !=
+		     offsetof(struct virtio_pci_cap, cap_next));
+	BUILD_BUG_ON(VIRTIO_PCI_CAP_LEN !=
+		     offsetof(struct virtio_pci_cap, cap_len));
+	BUILD_BUG_ON(VIRTIO_PCI_CAP_CFG_TYPE !=
+		     offsetof(struct virtio_pci_cap, cfg_type));
+	BUILD_BUG_ON(VIRTIO_PCI_CAP_BAR !=
+		     offsetof(struct virtio_pci_cap, bar));
+	BUILD_BUG_ON(VIRTIO_PCI_CAP_OFFSET !=
+		     offsetof(struct virtio_pci_cap, offset));
+	BUILD_BUG_ON(VIRTIO_PCI_CAP_LENGTH !=
+		     offsetof(struct virtio_pci_cap, length));
+	BUILD_BUG_ON(VIRTIO_PCI_NOTIFY_CAP_MULT !=
+		     offsetof(struct virtio_pci_notify_cap,
+			      notify_off_multiplier));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_DFSELECT !=
+		     offsetof(struct virtio_pci_common_cfg,
+			      device_feature_select));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_DF !=
+		     offsetof(struct virtio_pci_common_cfg, device_feature));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_GFSELECT !=
+		     offsetof(struct virtio_pci_common_cfg,
+			      guest_feature_select));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_GF !=
+		     offsetof(struct virtio_pci_common_cfg, guest_feature));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_MSIX !=
+		     offsetof(struct virtio_pci_common_cfg, msix_config));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_NUMQ !=
+		     offsetof(struct virtio_pci_common_cfg, num_queues));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_STATUS !=
+		     offsetof(struct virtio_pci_common_cfg, device_status));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_CFGGENERATION !=
+		     offsetof(struct virtio_pci_common_cfg, config_generation));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_SELECT !=
+		     offsetof(struct virtio_pci_common_cfg, queue_select));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_SIZE !=
+		     offsetof(struct virtio_pci_common_cfg, queue_size));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_MSIX !=
+		     offsetof(struct virtio_pci_common_cfg, queue_msix_vector));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_ENABLE !=
+		     offsetof(struct virtio_pci_common_cfg, queue_enable));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_NOFF !=
+		     offsetof(struct virtio_pci_common_cfg, queue_notify_off));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_DESCLO !=
+		     offsetof(struct virtio_pci_common_cfg, queue_desc_lo));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_DESCHI !=
+		     offsetof(struct virtio_pci_common_cfg, queue_desc_hi));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_AVAILLO !=
+		     offsetof(struct virtio_pci_common_cfg, queue_avail_lo));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_AVAILHI !=
+		     offsetof(struct virtio_pci_common_cfg, queue_avail_hi));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_USEDLO !=
+		     offsetof(struct virtio_pci_common_cfg, queue_used_lo));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_USEDHI !=
+		     offsetof(struct virtio_pci_common_cfg, queue_used_hi));
+}
+
+/* the PCI probing function */
+int virtio_pci_modern_probe(struct virtio_pci_device *vp_dev)
+{
+	struct pci_dev *pci_dev = vp_dev->pci_dev;
+	int err, common, isr, notify, device;
+	u32 notify_length;
+	u32 notify_offset;
+
+	check_offsets();
+
+	/* We only own devices >= 0x1000 and <= 0x107f: leave the rest. */
+	if (pci_dev->device < 0x1000 || pci_dev->device > 0x107f)
+		return -ENODEV;
+
+	if (pci_dev->device < 0x1040) {
+		/* Transitional devices: use the PCI subsystem device id as
+		 * virtio device id, same as legacy driver always did.
+		 */
+		vp_dev->vdev.id.device = pci_dev->subsystem_device;
+	} else {
+		/* Modern devices: simply use PCI device id, but start from 0x1040. */
+		vp_dev->vdev.id.device = pci_dev->device - 0x1040;
+	}
+	vp_dev->vdev.id.vendor = pci_dev->subsystem_vendor;
+
+	/* check for a common config: if not, use legacy mode (bar 0). */
+	common = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_COMMON_CFG,
+					    IORESOURCE_IO | IORESOURCE_MEM,
+					    &vp_dev->modern_bars);
+	if (!common) {
+		dev_info(&pci_dev->dev,
+			 "virtio_pci: leaving for legacy driver\n");
+		return -ENODEV;
+	}
+
+	/* If common is there, these should be too... */
+	isr = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_ISR_CFG,
+					 IORESOURCE_IO | IORESOURCE_MEM,
+					 &vp_dev->modern_bars);
+	notify = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_NOTIFY_CFG,
+					    IORESOURCE_IO | IORESOURCE_MEM,
+					    &vp_dev->modern_bars);
+	if (!isr || !notify) {
+		dev_err(&pci_dev->dev,
+			"virtio_pci: missing capabilities %i/%i/%i\n",
+			common, isr, notify);
+		return -EINVAL;
+	}
+
+	err = dma_set_mask_and_coherent(&pci_dev->dev, DMA_BIT_MASK(64));
+	if (err)
+		err = dma_set_mask_and_coherent(&pci_dev->dev,
+						DMA_BIT_MASK(32));
+	if (err)
+		dev_warn(&pci_dev->dev, "Failed to enable 64-bit or 32-bit DMA.  Trying to continue, but this might not work.\n");
+
+	/* Device capability is only mandatory for devices that have
+	 * device-specific configuration.
+	 */
+	device = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_DEVICE_CFG,
+					    IORESOURCE_IO | IORESOURCE_MEM,
+					    &vp_dev->modern_bars);
+
+	err = pci_request_selected_regions(pci_dev, vp_dev->modern_bars,
+					   "virtio-pci-modern");
+	if (err)
+		return err;
+
+	err = -EINVAL;
+	vp_dev->common = map_capability(pci_dev, common,
+					sizeof(struct virtio_pci_common_cfg), 4,
+					0, sizeof(struct virtio_pci_common_cfg),
+					NULL);
+	if (!vp_dev->common)
+		goto err_map_common;
+	vp_dev->isr = map_capability(pci_dev, isr, sizeof(u8), 1,
+				     0, 1,
+				     NULL);
+	if (!vp_dev->isr)
+		goto err_map_isr;
+
+	/* Read notify_off_multiplier from config space. */
+	pci_read_config_dword(pci_dev,
+			      notify + offsetof(struct virtio_pci_notify_cap,
+						notify_off_multiplier),
+			      &vp_dev->notify_offset_multiplier);
+	/* Read notify length and offset from config space. */
+	pci_read_config_dword(pci_dev,
+			      notify + offsetof(struct virtio_pci_notify_cap,
+						cap.length),
+			      &notify_length);
+
+	pci_read_config_dword(pci_dev,
+			      notify + offsetof(struct virtio_pci_notify_cap,
+						cap.offset),
+			      &notify_offset);
+
+	/* We don't know how many VQs we'll map, ahead of the time.
+	 * If notify length is small, map it all now.
+	 * Otherwise, map each VQ individually later.
+	 */
+	if ((u64)notify_length + (notify_offset % PAGE_SIZE) <= PAGE_SIZE) {
+		vp_dev->notify_base = map_capability(pci_dev, notify, 2, 2,
+						     0, notify_length,
+						     &vp_dev->notify_len);
+		if (!vp_dev->notify_base)
+			goto err_map_notify;
+	} else {
+		vp_dev->notify_map_cap = notify;
+	}
+
+	/* Again, we don't know how much we should map, but PAGE_SIZE
+	 * is more than enough for all existing devices.
+	 */
+	if (device) {
+		vp_dev->device = map_capability(pci_dev, device, 0, 4,
+						0, PAGE_SIZE,
+						&vp_dev->device_len);
+		if (!vp_dev->device)
+			goto err_map_device;
+
+		vp_dev->vdev.config = &virtio_pci_config_ops;
+	} else {
+		vp_dev->vdev.config = &virtio_pci_config_nodev_ops;
+	}
+
+	vp_dev->config_vector = vp_config_vector;
+	vp_dev->setup_vq = setup_vq;
+	vp_dev->del_vq = del_vq;
+
+	return 0;
+
+err_map_device:
+	if (vp_dev->notify_base)
+		pci_iounmap(pci_dev, vp_dev->notify_base);
+err_map_notify:
+	pci_iounmap(pci_dev, vp_dev->isr);
+err_map_isr:
+	pci_iounmap(pci_dev, vp_dev->common);
+err_map_common:
+	return err;
+}
+
+void virtio_pci_modern_remove(struct virtio_pci_device *vp_dev)
+{
+	struct pci_dev *pci_dev = vp_dev->pci_dev;
+
+	if (vp_dev->device)
+		pci_iounmap(pci_dev, vp_dev->device);
+	if (vp_dev->notify_base)
+		pci_iounmap(pci_dev, vp_dev->notify_base);
+	pci_iounmap(pci_dev, vp_dev->isr);
+	pci_iounmap(pci_dev, vp_dev->common);
+	pci_release_selected_regions(pci_dev, vp_dev->modern_bars);
+}
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
new file mode 100644
index 000000000..cf0e8e189
--- /dev/null
+++ b/drivers/virtio/virtio_ring.c
@@ -0,0 +1,2352 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Virtio ring implementation.
+ *
+ *  Copyright 2007 Rusty Russell IBM Corporation
+ */
+#include <linux/virtio.h>
+#include <linux/virtio_ring.h>
+#include <linux/virtio_config.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/hrtimer.h>
+#include <linux/dma-mapping.h>
+#include <xen/xen.h>
+
+#ifdef DEBUG
+/* For development, we want to crash whenever the ring is screwed. */
+#define BAD_RING(_vq, fmt, args...)				\
+	do {							\
+		dev_err(&(_vq)->vq.vdev->dev,			\
+			"%s:"fmt, (_vq)->vq.name, ##args);	\
+		BUG();						\
+	} while (0)
+/* Caller is supposed to guarantee no reentry. */
+#define START_USE(_vq)						\
+	do {							\
+		if ((_vq)->in_use)				\
+			panic("%s:in_use = %i\n",		\
+			      (_vq)->vq.name, (_vq)->in_use);	\
+		(_vq)->in_use = __LINE__;			\
+	} while (0)
+#define END_USE(_vq) \
+	do { BUG_ON(!(_vq)->in_use); (_vq)->in_use = 0; } while(0)
+#define LAST_ADD_TIME_UPDATE(_vq)				\
+	do {							\
+		ktime_t now = ktime_get();			\
+								\
+		/* No kick or get, with .1 second between?  Warn. */ \
+		if ((_vq)->last_add_time_valid)			\
+			WARN_ON(ktime_to_ms(ktime_sub(now,	\
+				(_vq)->last_add_time)) > 100);	\
+		(_vq)->last_add_time = now;			\
+		(_vq)->last_add_time_valid = true;		\
+	} while (0)
+#define LAST_ADD_TIME_CHECK(_vq)				\
+	do {							\
+		if ((_vq)->last_add_time_valid) {		\
+			WARN_ON(ktime_to_ms(ktime_sub(ktime_get(), \
+				      (_vq)->last_add_time)) > 100); \
+		}						\
+	} while (0)
+#define LAST_ADD_TIME_INVALID(_vq)				\
+	((_vq)->last_add_time_valid = false)
+#else
+#define BAD_RING(_vq, fmt, args...)				\
+	do {							\
+		dev_err(&_vq->vq.vdev->dev,			\
+			"%s:"fmt, (_vq)->vq.name, ##args);	\
+		(_vq)->broken = true;				\
+	} while (0)
+#define START_USE(vq)
+#define END_USE(vq)
+#define LAST_ADD_TIME_UPDATE(vq)
+#define LAST_ADD_TIME_CHECK(vq)
+#define LAST_ADD_TIME_INVALID(vq)
+#endif
+
+struct vring_desc_state_split {
+	void *data;			/* Data for callback. */
+	struct vring_desc *indir_desc;	/* Indirect descriptor, if any. */
+};
+
+struct vring_desc_state_packed {
+	void *data;			/* Data for callback. */
+	struct vring_packed_desc *indir_desc; /* Indirect descriptor, if any. */
+	u16 num;			/* Descriptor list length. */
+	u16 next;			/* The next desc state in a list. */
+	u16 last;			/* The last desc state in a list. */
+};
+
+struct vring_desc_extra_packed {
+	dma_addr_t addr;		/* Buffer DMA addr. */
+	u32 len;			/* Buffer length. */
+	u16 flags;			/* Descriptor flags. */
+};
+
+struct vring_virtqueue {
+	struct virtqueue vq;
+
+	/* Is this a packed ring? */
+	bool packed_ring;
+
+	/* Is DMA API used? */
+	bool use_dma_api;
+
+	/* Can we use weak barriers? */
+	bool weak_barriers;
+
+	/* Other side has made a mess, don't try any more. */
+	bool broken;
+
+	/* Host supports indirect buffers */
+	bool indirect;
+
+	/* Host publishes avail event idx */
+	bool event;
+
+	/* Head of free buffer list. */
+	unsigned int free_head;
+	/* Number we've added since last sync. */
+	unsigned int num_added;
+
+	/* Last used index we've seen. */
+	u16 last_used_idx;
+
+	union {
+		/* Available for split ring */
+		struct {
+			/* Actual memory layout for this queue. */
+			struct vring vring;
+
+			/* Last written value to avail->flags */
+			u16 avail_flags_shadow;
+
+			/*
+			 * Last written value to avail->idx in
+			 * guest byte order.
+			 */
+			u16 avail_idx_shadow;
+
+			/* Per-descriptor state. */
+			struct vring_desc_state_split *desc_state;
+
+			/* DMA address and size information */
+			dma_addr_t queue_dma_addr;
+			size_t queue_size_in_bytes;
+		} split;
+
+		/* Available for packed ring */
+		struct {
+			/* Actual memory layout for this queue. */
+			struct {
+				unsigned int num;
+				struct vring_packed_desc *desc;
+				struct vring_packed_desc_event *driver;
+				struct vring_packed_desc_event *device;
+			} vring;
+
+			/* Driver ring wrap counter. */
+			bool avail_wrap_counter;
+
+			/* Device ring wrap counter. */
+			bool used_wrap_counter;
+
+			/* Avail used flags. */
+			u16 avail_used_flags;
+
+			/* Index of the next avail descriptor. */
+			u16 next_avail_idx;
+
+			/*
+			 * Last written value to driver->flags in
+			 * guest byte order.
+			 */
+			u16 event_flags_shadow;
+
+			/* Per-descriptor state. */
+			struct vring_desc_state_packed *desc_state;
+			struct vring_desc_extra_packed *desc_extra;
+
+			/* DMA address and size information */
+			dma_addr_t ring_dma_addr;
+			dma_addr_t driver_event_dma_addr;
+			dma_addr_t device_event_dma_addr;
+			size_t ring_size_in_bytes;
+			size_t event_size_in_bytes;
+		} packed;
+	};
+
+	/* How to notify other side. FIXME: commonalize hcalls! */
+	bool (*notify)(struct virtqueue *vq);
+
+	/* DMA, allocation, and size information */
+	bool we_own_ring;
+
+#ifdef DEBUG
+	/* They're supposed to lock for us. */
+	unsigned int in_use;
+
+	/* Figure out if their kicks are too delayed. */
+	bool last_add_time_valid;
+	ktime_t last_add_time;
+#endif
+};
+
+
+/*
+ * Helpers.
+ */
+
+#define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
+
+static inline bool virtqueue_use_indirect(struct virtqueue *_vq,
+					  unsigned int total_sg)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	/*
+	 * If the host supports indirect descriptor tables, and we have multiple
+	 * buffers, then go indirect. FIXME: tune this threshold
+	 */
+	return (vq->indirect && total_sg > 1 && vq->vq.num_free);
+}
+
+/*
+ * Modern virtio devices have feature bits to specify whether they need a
+ * quirk and bypass the IOMMU. If not there, just use the DMA API.
+ *
+ * If there, the interaction between virtio and DMA API is messy.
+ *
+ * On most systems with virtio, physical addresses match bus addresses,
+ * and it doesn't particularly matter whether we use the DMA API.
+ *
+ * On some systems, including Xen and any system with a physical device
+ * that speaks virtio behind a physical IOMMU, we must use the DMA API
+ * for virtio DMA to work at all.
+ *
+ * On other systems, including SPARC and PPC64, virtio-pci devices are
+ * enumerated as though they are behind an IOMMU, but the virtio host
+ * ignores the IOMMU, so we must either pretend that the IOMMU isn't
+ * there or somehow map everything as the identity.
+ *
+ * For the time being, we preserve historic behavior and bypass the DMA
+ * API.
+ *
+ * TODO: install a per-device DMA ops structure that does the right thing
+ * taking into account all the above quirks, and use the DMA API
+ * unconditionally on data path.
+ */
+
+static bool vring_use_dma_api(struct virtio_device *vdev)
+{
+	if (!virtio_has_dma_quirk(vdev))
+		return true;
+
+	/* Otherwise, we are left to guess. */
+	/*
+	 * In theory, it's possible to have a buggy QEMU-supposed
+	 * emulated Q35 IOMMU and Xen enabled at the same time.  On
+	 * such a configuration, virtio has never worked and will
+	 * not work without an even larger kludge.  Instead, enable
+	 * the DMA API if we're a Xen guest, which at least allows
+	 * all of the sensible Xen configurations to work correctly.
+	 */
+	if (xen_domain())
+		return true;
+
+	return false;
+}
+
+size_t virtio_max_dma_size(struct virtio_device *vdev)
+{
+	size_t max_segment_size = SIZE_MAX;
+
+	if (vring_use_dma_api(vdev))
+		max_segment_size = dma_max_mapping_size(vdev->dev.parent);
+
+	return max_segment_size;
+}
+EXPORT_SYMBOL_GPL(virtio_max_dma_size);
+
+static void *vring_alloc_queue(struct virtio_device *vdev, size_t size,
+			      dma_addr_t *dma_handle, gfp_t flag)
+{
+	if (vring_use_dma_api(vdev)) {
+		return dma_alloc_coherent(vdev->dev.parent, size,
+					  dma_handle, flag);
+	} else {
+		void *queue = alloc_pages_exact(PAGE_ALIGN(size), flag);
+
+		if (queue) {
+			phys_addr_t phys_addr = virt_to_phys(queue);
+			*dma_handle = (dma_addr_t)phys_addr;
+
+			/*
+			 * Sanity check: make sure we dind't truncate
+			 * the address.  The only arches I can find that
+			 * have 64-bit phys_addr_t but 32-bit dma_addr_t
+			 * are certain non-highmem MIPS and x86
+			 * configurations, but these configurations
+			 * should never allocate physical pages above 32
+			 * bits, so this is fine.  Just in case, throw a
+			 * warning and abort if we end up with an
+			 * unrepresentable address.
+			 */
+			if (WARN_ON_ONCE(*dma_handle != phys_addr)) {
+				free_pages_exact(queue, PAGE_ALIGN(size));
+				return NULL;
+			}
+		}
+		return queue;
+	}
+}
+
+static void vring_free_queue(struct virtio_device *vdev, size_t size,
+			     void *queue, dma_addr_t dma_handle)
+{
+	if (vring_use_dma_api(vdev))
+		dma_free_coherent(vdev->dev.parent, size, queue, dma_handle);
+	else
+		free_pages_exact(queue, PAGE_ALIGN(size));
+}
+
+/*
+ * The DMA ops on various arches are rather gnarly right now, and
+ * making all of the arch DMA ops work on the vring device itself
+ * is a mess.  For now, we use the parent device for DMA ops.
+ */
+static inline struct device *vring_dma_dev(const struct vring_virtqueue *vq)
+{
+	return vq->vq.vdev->dev.parent;
+}
+
+/* Map one sg entry. */
+static dma_addr_t vring_map_one_sg(const struct vring_virtqueue *vq,
+				   struct scatterlist *sg,
+				   enum dma_data_direction direction)
+{
+	if (!vq->use_dma_api)
+		return (dma_addr_t)sg_phys(sg);
+
+	/*
+	 * We can't use dma_map_sg, because we don't use scatterlists in
+	 * the way it expects (we don't guarantee that the scatterlist
+	 * will exist for the lifetime of the mapping).
+	 */
+	return dma_map_page(vring_dma_dev(vq),
+			    sg_page(sg), sg->offset, sg->length,
+			    direction);
+}
+
+static dma_addr_t vring_map_single(const struct vring_virtqueue *vq,
+				   void *cpu_addr, size_t size,
+				   enum dma_data_direction direction)
+{
+	if (!vq->use_dma_api)
+		return (dma_addr_t)virt_to_phys(cpu_addr);
+
+	return dma_map_single(vring_dma_dev(vq),
+			      cpu_addr, size, direction);
+}
+
+static int vring_mapping_error(const struct vring_virtqueue *vq,
+			       dma_addr_t addr)
+{
+	if (!vq->use_dma_api)
+		return 0;
+
+	return dma_mapping_error(vring_dma_dev(vq), addr);
+}
+
+
+/*
+ * Split ring specific functions - *_split().
+ */
+
+static void vring_unmap_one_split(const struct vring_virtqueue *vq,
+				  struct vring_desc *desc)
+{
+	u16 flags;
+
+	if (!vq->use_dma_api)
+		return;
+
+	flags = virtio16_to_cpu(vq->vq.vdev, desc->flags);
+
+	if (flags & VRING_DESC_F_INDIRECT) {
+		dma_unmap_single(vring_dma_dev(vq),
+				 virtio64_to_cpu(vq->vq.vdev, desc->addr),
+				 virtio32_to_cpu(vq->vq.vdev, desc->len),
+				 (flags & VRING_DESC_F_WRITE) ?
+				 DMA_FROM_DEVICE : DMA_TO_DEVICE);
+	} else {
+		dma_unmap_page(vring_dma_dev(vq),
+			       virtio64_to_cpu(vq->vq.vdev, desc->addr),
+			       virtio32_to_cpu(vq->vq.vdev, desc->len),
+			       (flags & VRING_DESC_F_WRITE) ?
+			       DMA_FROM_DEVICE : DMA_TO_DEVICE);
+	}
+}
+
+static struct vring_desc *alloc_indirect_split(struct virtqueue *_vq,
+					       unsigned int total_sg,
+					       gfp_t gfp)
+{
+	struct vring_desc *desc;
+	unsigned int i;
+
+	/*
+	 * We require lowmem mappings for the descriptors because
+	 * otherwise virt_to_phys will give us bogus addresses in the
+	 * virtqueue.
+	 */
+	gfp &= ~__GFP_HIGHMEM;
+
+	desc = kmalloc_array(total_sg, sizeof(struct vring_desc), gfp);
+	if (!desc)
+		return NULL;
+
+	for (i = 0; i < total_sg; i++)
+		desc[i].next = cpu_to_virtio16(_vq->vdev, i + 1);
+	return desc;
+}
+
+static inline int virtqueue_add_split(struct virtqueue *_vq,
+				      struct scatterlist *sgs[],
+				      unsigned int total_sg,
+				      unsigned int out_sgs,
+				      unsigned int in_sgs,
+				      void *data,
+				      void *ctx,
+				      gfp_t gfp)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	struct scatterlist *sg;
+	struct vring_desc *desc;
+	unsigned int i, n, avail, descs_used, prev, err_idx;
+	int head;
+	bool indirect;
+
+	START_USE(vq);
+
+	BUG_ON(data == NULL);
+	BUG_ON(ctx && vq->indirect);
+
+	if (unlikely(vq->broken)) {
+		END_USE(vq);
+		return -EIO;
+	}
+
+	LAST_ADD_TIME_UPDATE(vq);
+
+	BUG_ON(total_sg == 0);
+
+	head = vq->free_head;
+
+	if (virtqueue_use_indirect(_vq, total_sg))
+		desc = alloc_indirect_split(_vq, total_sg, gfp);
+	else {
+		desc = NULL;
+		WARN_ON_ONCE(total_sg > vq->split.vring.num && !vq->indirect);
+	}
+
+	if (desc) {
+		/* Use a single buffer which doesn't continue */
+		indirect = true;
+		/* Set up rest to use this indirect table. */
+		i = 0;
+		descs_used = 1;
+	} else {
+		indirect = false;
+		desc = vq->split.vring.desc;
+		i = head;
+		descs_used = total_sg;
+	}
+
+	if (vq->vq.num_free < descs_used) {
+		pr_debug("Can't add buf len %i - avail = %i\n",
+			 descs_used, vq->vq.num_free);
+		/* FIXME: for historical reasons, we force a notify here if
+		 * there are outgoing parts to the buffer.  Presumably the
+		 * host should service the ring ASAP. */
+		if (out_sgs)
+			vq->notify(&vq->vq);
+		if (indirect)
+			kfree(desc);
+		END_USE(vq);
+		return -ENOSPC;
+	}
+
+	for (n = 0; n < out_sgs; n++) {
+		for (sg = sgs[n]; sg; sg = sg_next(sg)) {
+			dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_TO_DEVICE);
+			if (vring_mapping_error(vq, addr))
+				goto unmap_release;
+
+			desc[i].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_NEXT);
+			desc[i].addr = cpu_to_virtio64(_vq->vdev, addr);
+			desc[i].len = cpu_to_virtio32(_vq->vdev, sg->length);
+			prev = i;
+			i = virtio16_to_cpu(_vq->vdev, desc[i].next);
+		}
+	}
+	for (; n < (out_sgs + in_sgs); n++) {
+		for (sg = sgs[n]; sg; sg = sg_next(sg)) {
+			dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_FROM_DEVICE);
+			if (vring_mapping_error(vq, addr))
+				goto unmap_release;
+
+			desc[i].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_NEXT | VRING_DESC_F_WRITE);
+			desc[i].addr = cpu_to_virtio64(_vq->vdev, addr);
+			desc[i].len = cpu_to_virtio32(_vq->vdev, sg->length);
+			prev = i;
+			i = virtio16_to_cpu(_vq->vdev, desc[i].next);
+		}
+	}
+	/* Last one doesn't continue. */
+	desc[prev].flags &= cpu_to_virtio16(_vq->vdev, ~VRING_DESC_F_NEXT);
+
+	if (indirect) {
+		/* Now that the indirect table is filled in, map it. */
+		dma_addr_t addr = vring_map_single(
+			vq, desc, total_sg * sizeof(struct vring_desc),
+			DMA_TO_DEVICE);
+		if (vring_mapping_error(vq, addr))
+			goto unmap_release;
+
+		vq->split.vring.desc[head].flags = cpu_to_virtio16(_vq->vdev,
+				VRING_DESC_F_INDIRECT);
+		vq->split.vring.desc[head].addr = cpu_to_virtio64(_vq->vdev,
+				addr);
+
+		vq->split.vring.desc[head].len = cpu_to_virtio32(_vq->vdev,
+				total_sg * sizeof(struct vring_desc));
+	}
+
+	/* We're using some buffers from the free list. */
+	vq->vq.num_free -= descs_used;
+
+	/* Update free pointer */
+	if (indirect)
+		vq->free_head = virtio16_to_cpu(_vq->vdev,
+					vq->split.vring.desc[head].next);
+	else
+		vq->free_head = i;
+
+	/* Store token and indirect buffer state. */
+	vq->split.desc_state[head].data = data;
+	if (indirect)
+		vq->split.desc_state[head].indir_desc = desc;
+	else
+		vq->split.desc_state[head].indir_desc = ctx;
+
+	/* Put entry in available array (but don't update avail->idx until they
+	 * do sync). */
+	avail = vq->split.avail_idx_shadow & (vq->split.vring.num - 1);
+	vq->split.vring.avail->ring[avail] = cpu_to_virtio16(_vq->vdev, head);
+
+	/* Descriptors and available array need to be set before we expose the
+	 * new available array entries. */
+	virtio_wmb(vq->weak_barriers);
+	vq->split.avail_idx_shadow++;
+	vq->split.vring.avail->idx = cpu_to_virtio16(_vq->vdev,
+						vq->split.avail_idx_shadow);
+	vq->num_added++;
+
+	pr_debug("Added buffer head %i to %p\n", head, vq);
+	END_USE(vq);
+
+	/* This is very unlikely, but theoretically possible.  Kick
+	 * just in case. */
+	if (unlikely(vq->num_added == (1 << 16) - 1))
+		virtqueue_kick(_vq);
+
+	return 0;
+
+unmap_release:
+	err_idx = i;
+
+	if (indirect)
+		i = 0;
+	else
+		i = head;
+
+	for (n = 0; n < total_sg; n++) {
+		if (i == err_idx)
+			break;
+		vring_unmap_one_split(vq, &desc[i]);
+		i = virtio16_to_cpu(_vq->vdev, desc[i].next);
+	}
+
+	if (indirect)
+		kfree(desc);
+
+	END_USE(vq);
+	return -ENOMEM;
+}
+
+static bool virtqueue_kick_prepare_split(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	u16 new, old;
+	bool needs_kick;
+
+	START_USE(vq);
+	/* We need to expose available array entries before checking avail
+	 * event. */
+	virtio_mb(vq->weak_barriers);
+
+	old = vq->split.avail_idx_shadow - vq->num_added;
+	new = vq->split.avail_idx_shadow;
+	vq->num_added = 0;
+
+	LAST_ADD_TIME_CHECK(vq);
+	LAST_ADD_TIME_INVALID(vq);
+
+	if (vq->event) {
+		needs_kick = vring_need_event(virtio16_to_cpu(_vq->vdev,
+					vring_avail_event(&vq->split.vring)),
+					      new, old);
+	} else {
+		needs_kick = !(vq->split.vring.used->flags &
+					cpu_to_virtio16(_vq->vdev,
+						VRING_USED_F_NO_NOTIFY));
+	}
+	END_USE(vq);
+	return needs_kick;
+}
+
+static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
+			     void **ctx)
+{
+	unsigned int i, j;
+	__virtio16 nextflag = cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT);
+
+	/* Clear data ptr. */
+	vq->split.desc_state[head].data = NULL;
+
+	/* Put back on free list: unmap first-level descriptors and find end */
+	i = head;
+
+	while (vq->split.vring.desc[i].flags & nextflag) {
+		vring_unmap_one_split(vq, &vq->split.vring.desc[i]);
+		i = virtio16_to_cpu(vq->vq.vdev, vq->split.vring.desc[i].next);
+		vq->vq.num_free++;
+	}
+
+	vring_unmap_one_split(vq, &vq->split.vring.desc[i]);
+	vq->split.vring.desc[i].next = cpu_to_virtio16(vq->vq.vdev,
+						vq->free_head);
+	vq->free_head = head;
+
+	/* Plus final descriptor */
+	vq->vq.num_free++;
+
+	if (vq->indirect) {
+		struct vring_desc *indir_desc =
+				vq->split.desc_state[head].indir_desc;
+		u32 len;
+
+		/* Free the indirect table, if any, now that it's unmapped. */
+		if (!indir_desc)
+			return;
+
+		len = virtio32_to_cpu(vq->vq.vdev,
+				vq->split.vring.desc[head].len);
+
+		BUG_ON(!(vq->split.vring.desc[head].flags &
+			 cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_INDIRECT)));
+		BUG_ON(len == 0 || len % sizeof(struct vring_desc));
+
+		for (j = 0; j < len / sizeof(struct vring_desc); j++)
+			vring_unmap_one_split(vq, &indir_desc[j]);
+
+		kfree(indir_desc);
+		vq->split.desc_state[head].indir_desc = NULL;
+	} else if (ctx) {
+		*ctx = vq->split.desc_state[head].indir_desc;
+	}
+}
+
+static inline bool more_used_split(const struct vring_virtqueue *vq)
+{
+	return vq->last_used_idx != virtio16_to_cpu(vq->vq.vdev,
+			vq->split.vring.used->idx);
+}
+
+static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
+					 unsigned int *len,
+					 void **ctx)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	void *ret;
+	unsigned int i;
+	u16 last_used;
+
+	START_USE(vq);
+
+	if (unlikely(vq->broken)) {
+		END_USE(vq);
+		return NULL;
+	}
+
+	if (!more_used_split(vq)) {
+		pr_debug("No more buffers in queue\n");
+		END_USE(vq);
+		return NULL;
+	}
+
+	/* Only get used array entries after they have been exposed by host. */
+	virtio_rmb(vq->weak_barriers);
+
+	last_used = (vq->last_used_idx & (vq->split.vring.num - 1));
+	i = virtio32_to_cpu(_vq->vdev,
+			vq->split.vring.used->ring[last_used].id);
+	*len = virtio32_to_cpu(_vq->vdev,
+			vq->split.vring.used->ring[last_used].len);
+
+	if (unlikely(i >= vq->split.vring.num)) {
+		BAD_RING(vq, "id %u out of range\n", i);
+		return NULL;
+	}
+	if (unlikely(!vq->split.desc_state[i].data)) {
+		BAD_RING(vq, "id %u is not a head!\n", i);
+		return NULL;
+	}
+
+	/* detach_buf_split clears data, so grab it now. */
+	ret = vq->split.desc_state[i].data;
+	detach_buf_split(vq, i, ctx);
+	vq->last_used_idx++;
+	/* If we expect an interrupt for the next entry, tell host
+	 * by writing event index and flush out the write before
+	 * the read in the next get_buf call. */
+	if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT))
+		virtio_store_mb(vq->weak_barriers,
+				&vring_used_event(&vq->split.vring),
+				cpu_to_virtio16(_vq->vdev, vq->last_used_idx));
+
+	LAST_ADD_TIME_INVALID(vq);
+
+	END_USE(vq);
+	return ret;
+}
+
+static void virtqueue_disable_cb_split(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) {
+		vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
+		if (!vq->event)
+			vq->split.vring.avail->flags =
+				cpu_to_virtio16(_vq->vdev,
+						vq->split.avail_flags_shadow);
+	}
+}
+
+static unsigned virtqueue_enable_cb_prepare_split(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	u16 last_used_idx;
+
+	START_USE(vq);
+
+	/* We optimistically turn back on interrupts, then check if there was
+	 * more to do. */
+	/* Depending on the VIRTIO_RING_F_EVENT_IDX feature, we need to
+	 * either clear the flags bit or point the event index at the next
+	 * entry. Always do both to keep code simple. */
+	if (vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT) {
+		vq->split.avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT;
+		if (!vq->event)
+			vq->split.vring.avail->flags =
+				cpu_to_virtio16(_vq->vdev,
+						vq->split.avail_flags_shadow);
+	}
+	vring_used_event(&vq->split.vring) = cpu_to_virtio16(_vq->vdev,
+			last_used_idx = vq->last_used_idx);
+	END_USE(vq);
+	return last_used_idx;
+}
+
+static bool virtqueue_poll_split(struct virtqueue *_vq, unsigned last_used_idx)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	return (u16)last_used_idx != virtio16_to_cpu(_vq->vdev,
+			vq->split.vring.used->idx);
+}
+
+static bool virtqueue_enable_cb_delayed_split(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	u16 bufs;
+
+	START_USE(vq);
+
+	/* We optimistically turn back on interrupts, then check if there was
+	 * more to do. */
+	/* Depending on the VIRTIO_RING_F_USED_EVENT_IDX feature, we need to
+	 * either clear the flags bit or point the event index at the next
+	 * entry. Always update the event index to keep code simple. */
+	if (vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT) {
+		vq->split.avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT;
+		if (!vq->event)
+			vq->split.vring.avail->flags =
+				cpu_to_virtio16(_vq->vdev,
+						vq->split.avail_flags_shadow);
+	}
+	/* TODO: tune this threshold */
+	bufs = (u16)(vq->split.avail_idx_shadow - vq->last_used_idx) * 3 / 4;
+
+	virtio_store_mb(vq->weak_barriers,
+			&vring_used_event(&vq->split.vring),
+			cpu_to_virtio16(_vq->vdev, vq->last_used_idx + bufs));
+
+	if (unlikely((u16)(virtio16_to_cpu(_vq->vdev, vq->split.vring.used->idx)
+					- vq->last_used_idx) > bufs)) {
+		END_USE(vq);
+		return false;
+	}
+
+	END_USE(vq);
+	return true;
+}
+
+static void *virtqueue_detach_unused_buf_split(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	unsigned int i;
+	void *buf;
+
+	START_USE(vq);
+
+	for (i = 0; i < vq->split.vring.num; i++) {
+		if (!vq->split.desc_state[i].data)
+			continue;
+		/* detach_buf_split clears data, so grab it now. */
+		buf = vq->split.desc_state[i].data;
+		detach_buf_split(vq, i, NULL);
+		vq->split.avail_idx_shadow--;
+		vq->split.vring.avail->idx = cpu_to_virtio16(_vq->vdev,
+				vq->split.avail_idx_shadow);
+		END_USE(vq);
+		return buf;
+	}
+	/* That should have freed everything. */
+	BUG_ON(vq->vq.num_free != vq->split.vring.num);
+
+	END_USE(vq);
+	return NULL;
+}
+
+static struct virtqueue *vring_create_virtqueue_split(
+	unsigned int index,
+	unsigned int num,
+	unsigned int vring_align,
+	struct virtio_device *vdev,
+	bool weak_barriers,
+	bool may_reduce_num,
+	bool context,
+	bool (*notify)(struct virtqueue *),
+	void (*callback)(struct virtqueue *),
+	const char *name)
+{
+	struct virtqueue *vq;
+	void *queue = NULL;
+	dma_addr_t dma_addr;
+	size_t queue_size_in_bytes;
+	struct vring vring;
+
+	/* We assume num is a power of 2. */
+	if (num & (num - 1)) {
+		dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num);
+		return NULL;
+	}
+
+	/* TODO: allocate each queue chunk individually */
+	for (; num && vring_size(num, vring_align) > PAGE_SIZE; num /= 2) {
+		queue = vring_alloc_queue(vdev, vring_size(num, vring_align),
+					  &dma_addr,
+					  GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
+		if (queue)
+			break;
+		if (!may_reduce_num)
+			return NULL;
+	}
+
+	if (!num)
+		return NULL;
+
+	if (!queue) {
+		/* Try to get a single page. You are my only hope! */
+		queue = vring_alloc_queue(vdev, vring_size(num, vring_align),
+					  &dma_addr, GFP_KERNEL|__GFP_ZERO);
+	}
+	if (!queue)
+		return NULL;
+
+	queue_size_in_bytes = vring_size(num, vring_align);
+	vring_init(&vring, num, queue, vring_align);
+
+	vq = __vring_new_virtqueue(index, vring, vdev, weak_barriers, context,
+				   notify, callback, name);
+	if (!vq) {
+		vring_free_queue(vdev, queue_size_in_bytes, queue,
+				 dma_addr);
+		return NULL;
+	}
+
+	to_vvq(vq)->split.queue_dma_addr = dma_addr;
+	to_vvq(vq)->split.queue_size_in_bytes = queue_size_in_bytes;
+	to_vvq(vq)->we_own_ring = true;
+
+	return vq;
+}
+
+
+/*
+ * Packed ring specific functions - *_packed().
+ */
+
+static void vring_unmap_state_packed(const struct vring_virtqueue *vq,
+				     struct vring_desc_extra_packed *state)
+{
+	u16 flags;
+
+	if (!vq->use_dma_api)
+		return;
+
+	flags = state->flags;
+
+	if (flags & VRING_DESC_F_INDIRECT) {
+		dma_unmap_single(vring_dma_dev(vq),
+				 state->addr, state->len,
+				 (flags & VRING_DESC_F_WRITE) ?
+				 DMA_FROM_DEVICE : DMA_TO_DEVICE);
+	} else {
+		dma_unmap_page(vring_dma_dev(vq),
+			       state->addr, state->len,
+			       (flags & VRING_DESC_F_WRITE) ?
+			       DMA_FROM_DEVICE : DMA_TO_DEVICE);
+	}
+}
+
+static void vring_unmap_desc_packed(const struct vring_virtqueue *vq,
+				   struct vring_packed_desc *desc)
+{
+	u16 flags;
+
+	if (!vq->use_dma_api)
+		return;
+
+	flags = le16_to_cpu(desc->flags);
+
+	if (flags & VRING_DESC_F_INDIRECT) {
+		dma_unmap_single(vring_dma_dev(vq),
+				 le64_to_cpu(desc->addr),
+				 le32_to_cpu(desc->len),
+				 (flags & VRING_DESC_F_WRITE) ?
+				 DMA_FROM_DEVICE : DMA_TO_DEVICE);
+	} else {
+		dma_unmap_page(vring_dma_dev(vq),
+			       le64_to_cpu(desc->addr),
+			       le32_to_cpu(desc->len),
+			       (flags & VRING_DESC_F_WRITE) ?
+			       DMA_FROM_DEVICE : DMA_TO_DEVICE);
+	}
+}
+
+static struct vring_packed_desc *alloc_indirect_packed(unsigned int total_sg,
+						       gfp_t gfp)
+{
+	struct vring_packed_desc *desc;
+
+	/*
+	 * We require lowmem mappings for the descriptors because
+	 * otherwise virt_to_phys will give us bogus addresses in the
+	 * virtqueue.
+	 */
+	gfp &= ~__GFP_HIGHMEM;
+
+	desc = kmalloc_array(total_sg, sizeof(struct vring_packed_desc), gfp);
+
+	return desc;
+}
+
+static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
+				       struct scatterlist *sgs[],
+				       unsigned int total_sg,
+				       unsigned int out_sgs,
+				       unsigned int in_sgs,
+				       void *data,
+				       gfp_t gfp)
+{
+	struct vring_packed_desc *desc;
+	struct scatterlist *sg;
+	unsigned int i, n, err_idx;
+	u16 head, id;
+	dma_addr_t addr;
+
+	head = vq->packed.next_avail_idx;
+	desc = alloc_indirect_packed(total_sg, gfp);
+	if (!desc)
+		return -ENOMEM;
+
+	if (unlikely(vq->vq.num_free < 1)) {
+		pr_debug("Can't add buf len 1 - avail = 0\n");
+		kfree(desc);
+		END_USE(vq);
+		return -ENOSPC;
+	}
+
+	i = 0;
+	id = vq->free_head;
+	BUG_ON(id == vq->packed.vring.num);
+
+	for (n = 0; n < out_sgs + in_sgs; n++) {
+		for (sg = sgs[n]; sg; sg = sg_next(sg)) {
+			addr = vring_map_one_sg(vq, sg, n < out_sgs ?
+					DMA_TO_DEVICE : DMA_FROM_DEVICE);
+			if (vring_mapping_error(vq, addr))
+				goto unmap_release;
+
+			desc[i].flags = cpu_to_le16(n < out_sgs ?
+						0 : VRING_DESC_F_WRITE);
+			desc[i].addr = cpu_to_le64(addr);
+			desc[i].len = cpu_to_le32(sg->length);
+			i++;
+		}
+	}
+
+	/* Now that the indirect table is filled in, map it. */
+	addr = vring_map_single(vq, desc,
+			total_sg * sizeof(struct vring_packed_desc),
+			DMA_TO_DEVICE);
+	if (vring_mapping_error(vq, addr))
+		goto unmap_release;
+
+	vq->packed.vring.desc[head].addr = cpu_to_le64(addr);
+	vq->packed.vring.desc[head].len = cpu_to_le32(total_sg *
+				sizeof(struct vring_packed_desc));
+	vq->packed.vring.desc[head].id = cpu_to_le16(id);
+
+	if (vq->use_dma_api) {
+		vq->packed.desc_extra[id].addr = addr;
+		vq->packed.desc_extra[id].len = total_sg *
+				sizeof(struct vring_packed_desc);
+		vq->packed.desc_extra[id].flags = VRING_DESC_F_INDIRECT |
+						  vq->packed.avail_used_flags;
+	}
+
+	/*
+	 * A driver MUST NOT make the first descriptor in the list
+	 * available before all subsequent descriptors comprising
+	 * the list are made available.
+	 */
+	virtio_wmb(vq->weak_barriers);
+	vq->packed.vring.desc[head].flags = cpu_to_le16(VRING_DESC_F_INDIRECT |
+						vq->packed.avail_used_flags);
+
+	/* We're using some buffers from the free list. */
+	vq->vq.num_free -= 1;
+
+	/* Update free pointer */
+	n = head + 1;
+	if (n >= vq->packed.vring.num) {
+		n = 0;
+		vq->packed.avail_wrap_counter ^= 1;
+		vq->packed.avail_used_flags ^=
+				1 << VRING_PACKED_DESC_F_AVAIL |
+				1 << VRING_PACKED_DESC_F_USED;
+	}
+	vq->packed.next_avail_idx = n;
+	vq->free_head = vq->packed.desc_state[id].next;
+
+	/* Store token and indirect buffer state. */
+	vq->packed.desc_state[id].num = 1;
+	vq->packed.desc_state[id].data = data;
+	vq->packed.desc_state[id].indir_desc = desc;
+	vq->packed.desc_state[id].last = id;
+
+	vq->num_added += 1;
+
+	pr_debug("Added buffer head %i to %p\n", head, vq);
+	END_USE(vq);
+
+	return 0;
+
+unmap_release:
+	err_idx = i;
+
+	for (i = 0; i < err_idx; i++)
+		vring_unmap_desc_packed(vq, &desc[i]);
+
+	kfree(desc);
+
+	END_USE(vq);
+	return -ENOMEM;
+}
+
+static inline int virtqueue_add_packed(struct virtqueue *_vq,
+				       struct scatterlist *sgs[],
+				       unsigned int total_sg,
+				       unsigned int out_sgs,
+				       unsigned int in_sgs,
+				       void *data,
+				       void *ctx,
+				       gfp_t gfp)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	struct vring_packed_desc *desc;
+	struct scatterlist *sg;
+	unsigned int i, n, c, descs_used, err_idx;
+	__le16 head_flags, flags;
+	u16 head, id, prev, curr, avail_used_flags;
+	int err;
+
+	START_USE(vq);
+
+	BUG_ON(data == NULL);
+	BUG_ON(ctx && vq->indirect);
+
+	if (unlikely(vq->broken)) {
+		END_USE(vq);
+		return -EIO;
+	}
+
+	LAST_ADD_TIME_UPDATE(vq);
+
+	BUG_ON(total_sg == 0);
+
+	if (virtqueue_use_indirect(_vq, total_sg)) {
+		err = virtqueue_add_indirect_packed(vq, sgs, total_sg, out_sgs,
+						    in_sgs, data, gfp);
+		if (err != -ENOMEM) {
+			END_USE(vq);
+			return err;
+		}
+
+		/* fall back on direct */
+	}
+
+	head = vq->packed.next_avail_idx;
+	avail_used_flags = vq->packed.avail_used_flags;
+
+	WARN_ON_ONCE(total_sg > vq->packed.vring.num && !vq->indirect);
+
+	desc = vq->packed.vring.desc;
+	i = head;
+	descs_used = total_sg;
+
+	if (unlikely(vq->vq.num_free < descs_used)) {
+		pr_debug("Can't add buf len %i - avail = %i\n",
+			 descs_used, vq->vq.num_free);
+		END_USE(vq);
+		return -ENOSPC;
+	}
+
+	id = vq->free_head;
+	BUG_ON(id == vq->packed.vring.num);
+
+	curr = id;
+	c = 0;
+	for (n = 0; n < out_sgs + in_sgs; n++) {
+		for (sg = sgs[n]; sg; sg = sg_next(sg)) {
+			dma_addr_t addr = vring_map_one_sg(vq, sg, n < out_sgs ?
+					DMA_TO_DEVICE : DMA_FROM_DEVICE);
+			if (vring_mapping_error(vq, addr))
+				goto unmap_release;
+
+			flags = cpu_to_le16(vq->packed.avail_used_flags |
+				    (++c == total_sg ? 0 : VRING_DESC_F_NEXT) |
+				    (n < out_sgs ? 0 : VRING_DESC_F_WRITE));
+			if (i == head)
+				head_flags = flags;
+			else
+				desc[i].flags = flags;
+
+			desc[i].addr = cpu_to_le64(addr);
+			desc[i].len = cpu_to_le32(sg->length);
+			desc[i].id = cpu_to_le16(id);
+
+			if (unlikely(vq->use_dma_api)) {
+				vq->packed.desc_extra[curr].addr = addr;
+				vq->packed.desc_extra[curr].len = sg->length;
+				vq->packed.desc_extra[curr].flags =
+					le16_to_cpu(flags);
+			}
+			prev = curr;
+			curr = vq->packed.desc_state[curr].next;
+
+			if ((unlikely(++i >= vq->packed.vring.num))) {
+				i = 0;
+				vq->packed.avail_used_flags ^=
+					1 << VRING_PACKED_DESC_F_AVAIL |
+					1 << VRING_PACKED_DESC_F_USED;
+			}
+		}
+	}
+
+	if (i <= head)
+		vq->packed.avail_wrap_counter ^= 1;
+
+	/* We're using some buffers from the free list. */
+	vq->vq.num_free -= descs_used;
+
+	/* Update free pointer */
+	vq->packed.next_avail_idx = i;
+	vq->free_head = curr;
+
+	/* Store token. */
+	vq->packed.desc_state[id].num = descs_used;
+	vq->packed.desc_state[id].data = data;
+	vq->packed.desc_state[id].indir_desc = ctx;
+	vq->packed.desc_state[id].last = prev;
+
+	/*
+	 * A driver MUST NOT make the first descriptor in the list
+	 * available before all subsequent descriptors comprising
+	 * the list are made available.
+	 */
+	virtio_wmb(vq->weak_barriers);
+	vq->packed.vring.desc[head].flags = head_flags;
+	vq->num_added += descs_used;
+
+	pr_debug("Added buffer head %i to %p\n", head, vq);
+	END_USE(vq);
+
+	return 0;
+
+unmap_release:
+	err_idx = i;
+	i = head;
+
+	vq->packed.avail_used_flags = avail_used_flags;
+
+	for (n = 0; n < total_sg; n++) {
+		if (i == err_idx)
+			break;
+		vring_unmap_desc_packed(vq, &desc[i]);
+		i++;
+		if (i >= vq->packed.vring.num)
+			i = 0;
+	}
+
+	END_USE(vq);
+	return -EIO;
+}
+
+static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	u16 new, old, off_wrap, flags, wrap_counter, event_idx;
+	bool needs_kick;
+	union {
+		struct {
+			__le16 off_wrap;
+			__le16 flags;
+		};
+		u32 u32;
+	} snapshot;
+
+	START_USE(vq);
+
+	/*
+	 * We need to expose the new flags value before checking notification
+	 * suppressions.
+	 */
+	virtio_mb(vq->weak_barriers);
+
+	old = vq->packed.next_avail_idx - vq->num_added;
+	new = vq->packed.next_avail_idx;
+	vq->num_added = 0;
+
+	snapshot.u32 = *(u32 *)vq->packed.vring.device;
+	flags = le16_to_cpu(snapshot.flags);
+
+	LAST_ADD_TIME_CHECK(vq);
+	LAST_ADD_TIME_INVALID(vq);
+
+	if (flags != VRING_PACKED_EVENT_FLAG_DESC) {
+		needs_kick = (flags != VRING_PACKED_EVENT_FLAG_DISABLE);
+		goto out;
+	}
+
+	off_wrap = le16_to_cpu(snapshot.off_wrap);
+
+	wrap_counter = off_wrap >> VRING_PACKED_EVENT_F_WRAP_CTR;
+	event_idx = off_wrap & ~(1 << VRING_PACKED_EVENT_F_WRAP_CTR);
+	if (wrap_counter != vq->packed.avail_wrap_counter)
+		event_idx -= vq->packed.vring.num;
+
+	needs_kick = vring_need_event(event_idx, new, old);
+out:
+	END_USE(vq);
+	return needs_kick;
+}
+
+static void detach_buf_packed(struct vring_virtqueue *vq,
+			      unsigned int id, void **ctx)
+{
+	struct vring_desc_state_packed *state = NULL;
+	struct vring_packed_desc *desc;
+	unsigned int i, curr;
+
+	state = &vq->packed.desc_state[id];
+
+	/* Clear data ptr. */
+	state->data = NULL;
+
+	vq->packed.desc_state[state->last].next = vq->free_head;
+	vq->free_head = id;
+	vq->vq.num_free += state->num;
+
+	if (unlikely(vq->use_dma_api)) {
+		curr = id;
+		for (i = 0; i < state->num; i++) {
+			vring_unmap_state_packed(vq,
+				&vq->packed.desc_extra[curr]);
+			curr = vq->packed.desc_state[curr].next;
+		}
+	}
+
+	if (vq->indirect) {
+		u32 len;
+
+		/* Free the indirect table, if any, now that it's unmapped. */
+		desc = state->indir_desc;
+		if (!desc)
+			return;
+
+		if (vq->use_dma_api) {
+			len = vq->packed.desc_extra[id].len;
+			for (i = 0; i < len / sizeof(struct vring_packed_desc);
+					i++)
+				vring_unmap_desc_packed(vq, &desc[i]);
+		}
+		kfree(desc);
+		state->indir_desc = NULL;
+	} else if (ctx) {
+		*ctx = state->indir_desc;
+	}
+}
+
+static inline bool is_used_desc_packed(const struct vring_virtqueue *vq,
+				       u16 idx, bool used_wrap_counter)
+{
+	bool avail, used;
+	u16 flags;
+
+	flags = le16_to_cpu(vq->packed.vring.desc[idx].flags);
+	avail = !!(flags & (1 << VRING_PACKED_DESC_F_AVAIL));
+	used = !!(flags & (1 << VRING_PACKED_DESC_F_USED));
+
+	return avail == used && used == used_wrap_counter;
+}
+
+static inline bool more_used_packed(const struct vring_virtqueue *vq)
+{
+	return is_used_desc_packed(vq, vq->last_used_idx,
+			vq->packed.used_wrap_counter);
+}
+
+static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq,
+					  unsigned int *len,
+					  void **ctx)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	u16 last_used, id;
+	void *ret;
+
+	START_USE(vq);
+
+	if (unlikely(vq->broken)) {
+		END_USE(vq);
+		return NULL;
+	}
+
+	if (!more_used_packed(vq)) {
+		pr_debug("No more buffers in queue\n");
+		END_USE(vq);
+		return NULL;
+	}
+
+	/* Only get used elements after they have been exposed by host. */
+	virtio_rmb(vq->weak_barriers);
+
+	last_used = vq->last_used_idx;
+	id = le16_to_cpu(vq->packed.vring.desc[last_used].id);
+	*len = le32_to_cpu(vq->packed.vring.desc[last_used].len);
+
+	if (unlikely(id >= vq->packed.vring.num)) {
+		BAD_RING(vq, "id %u out of range\n", id);
+		return NULL;
+	}
+	if (unlikely(!vq->packed.desc_state[id].data)) {
+		BAD_RING(vq, "id %u is not a head!\n", id);
+		return NULL;
+	}
+
+	/* detach_buf_packed clears data, so grab it now. */
+	ret = vq->packed.desc_state[id].data;
+	detach_buf_packed(vq, id, ctx);
+
+	vq->last_used_idx += vq->packed.desc_state[id].num;
+	if (unlikely(vq->last_used_idx >= vq->packed.vring.num)) {
+		vq->last_used_idx -= vq->packed.vring.num;
+		vq->packed.used_wrap_counter ^= 1;
+	}
+
+	/*
+	 * If we expect an interrupt for the next entry, tell host
+	 * by writing event index and flush out the write before
+	 * the read in the next get_buf call.
+	 */
+	if (vq->packed.event_flags_shadow == VRING_PACKED_EVENT_FLAG_DESC)
+		virtio_store_mb(vq->weak_barriers,
+				&vq->packed.vring.driver->off_wrap,
+				cpu_to_le16(vq->last_used_idx |
+					(vq->packed.used_wrap_counter <<
+					 VRING_PACKED_EVENT_F_WRAP_CTR)));
+
+	LAST_ADD_TIME_INVALID(vq);
+
+	END_USE(vq);
+	return ret;
+}
+
+static void virtqueue_disable_cb_packed(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	if (vq->packed.event_flags_shadow != VRING_PACKED_EVENT_FLAG_DISABLE) {
+		vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
+		vq->packed.vring.driver->flags =
+			cpu_to_le16(vq->packed.event_flags_shadow);
+	}
+}
+
+static unsigned virtqueue_enable_cb_prepare_packed(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	START_USE(vq);
+
+	/*
+	 * We optimistically turn back on interrupts, then check if there was
+	 * more to do.
+	 */
+
+	if (vq->event) {
+		vq->packed.vring.driver->off_wrap =
+			cpu_to_le16(vq->last_used_idx |
+				(vq->packed.used_wrap_counter <<
+				 VRING_PACKED_EVENT_F_WRAP_CTR));
+		/*
+		 * We need to update event offset and event wrap
+		 * counter first before updating event flags.
+		 */
+		virtio_wmb(vq->weak_barriers);
+	}
+
+	if (vq->packed.event_flags_shadow == VRING_PACKED_EVENT_FLAG_DISABLE) {
+		vq->packed.event_flags_shadow = vq->event ?
+				VRING_PACKED_EVENT_FLAG_DESC :
+				VRING_PACKED_EVENT_FLAG_ENABLE;
+		vq->packed.vring.driver->flags =
+				cpu_to_le16(vq->packed.event_flags_shadow);
+	}
+
+	END_USE(vq);
+	return vq->last_used_idx | ((u16)vq->packed.used_wrap_counter <<
+			VRING_PACKED_EVENT_F_WRAP_CTR);
+}
+
+static bool virtqueue_poll_packed(struct virtqueue *_vq, u16 off_wrap)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	bool wrap_counter;
+	u16 used_idx;
+
+	wrap_counter = off_wrap >> VRING_PACKED_EVENT_F_WRAP_CTR;
+	used_idx = off_wrap & ~(1 << VRING_PACKED_EVENT_F_WRAP_CTR);
+
+	return is_used_desc_packed(vq, used_idx, wrap_counter);
+}
+
+static bool virtqueue_enable_cb_delayed_packed(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	u16 used_idx, wrap_counter;
+	u16 bufs;
+
+	START_USE(vq);
+
+	/*
+	 * We optimistically turn back on interrupts, then check if there was
+	 * more to do.
+	 */
+
+	if (vq->event) {
+		/* TODO: tune this threshold */
+		bufs = (vq->packed.vring.num - vq->vq.num_free) * 3 / 4;
+		wrap_counter = vq->packed.used_wrap_counter;
+
+		used_idx = vq->last_used_idx + bufs;
+		if (used_idx >= vq->packed.vring.num) {
+			used_idx -= vq->packed.vring.num;
+			wrap_counter ^= 1;
+		}
+
+		vq->packed.vring.driver->off_wrap = cpu_to_le16(used_idx |
+			(wrap_counter << VRING_PACKED_EVENT_F_WRAP_CTR));
+
+		/*
+		 * We need to update event offset and event wrap
+		 * counter first before updating event flags.
+		 */
+		virtio_wmb(vq->weak_barriers);
+	}
+
+	if (vq->packed.event_flags_shadow == VRING_PACKED_EVENT_FLAG_DISABLE) {
+		vq->packed.event_flags_shadow = vq->event ?
+				VRING_PACKED_EVENT_FLAG_DESC :
+				VRING_PACKED_EVENT_FLAG_ENABLE;
+		vq->packed.vring.driver->flags =
+				cpu_to_le16(vq->packed.event_flags_shadow);
+	}
+
+	/*
+	 * We need to update event suppression structure first
+	 * before re-checking for more used buffers.
+	 */
+	virtio_mb(vq->weak_barriers);
+
+	if (is_used_desc_packed(vq,
+				vq->last_used_idx,
+				vq->packed.used_wrap_counter)) {
+		END_USE(vq);
+		return false;
+	}
+
+	END_USE(vq);
+	return true;
+}
+
+static void *virtqueue_detach_unused_buf_packed(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	unsigned int i;
+	void *buf;
+
+	START_USE(vq);
+
+	for (i = 0; i < vq->packed.vring.num; i++) {
+		if (!vq->packed.desc_state[i].data)
+			continue;
+		/* detach_buf clears data, so grab it now. */
+		buf = vq->packed.desc_state[i].data;
+		detach_buf_packed(vq, i, NULL);
+		END_USE(vq);
+		return buf;
+	}
+	/* That should have freed everything. */
+	BUG_ON(vq->vq.num_free != vq->packed.vring.num);
+
+	END_USE(vq);
+	return NULL;
+}
+
+static struct virtqueue *vring_create_virtqueue_packed(
+	unsigned int index,
+	unsigned int num,
+	unsigned int vring_align,
+	struct virtio_device *vdev,
+	bool weak_barriers,
+	bool may_reduce_num,
+	bool context,
+	bool (*notify)(struct virtqueue *),
+	void (*callback)(struct virtqueue *),
+	const char *name)
+{
+	struct vring_virtqueue *vq;
+	struct vring_packed_desc *ring;
+	struct vring_packed_desc_event *driver, *device;
+	dma_addr_t ring_dma_addr, driver_event_dma_addr, device_event_dma_addr;
+	size_t ring_size_in_bytes, event_size_in_bytes;
+	unsigned int i;
+
+	ring_size_in_bytes = num * sizeof(struct vring_packed_desc);
+
+	ring = vring_alloc_queue(vdev, ring_size_in_bytes,
+				 &ring_dma_addr,
+				 GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
+	if (!ring)
+		goto err_ring;
+
+	event_size_in_bytes = sizeof(struct vring_packed_desc_event);
+
+	driver = vring_alloc_queue(vdev, event_size_in_bytes,
+				   &driver_event_dma_addr,
+				   GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
+	if (!driver)
+		goto err_driver;
+
+	device = vring_alloc_queue(vdev, event_size_in_bytes,
+				   &device_event_dma_addr,
+				   GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
+	if (!device)
+		goto err_device;
+
+	vq = kmalloc(sizeof(*vq), GFP_KERNEL);
+	if (!vq)
+		goto err_vq;
+
+	vq->vq.callback = callback;
+	vq->vq.vdev = vdev;
+	vq->vq.name = name;
+	vq->vq.num_free = num;
+	vq->vq.index = index;
+	vq->we_own_ring = true;
+	vq->notify = notify;
+	vq->weak_barriers = weak_barriers;
+	vq->broken = false;
+	vq->last_used_idx = 0;
+	vq->num_added = 0;
+	vq->packed_ring = true;
+	vq->use_dma_api = vring_use_dma_api(vdev);
+#ifdef DEBUG
+	vq->in_use = false;
+	vq->last_add_time_valid = false;
+#endif
+
+	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
+		!context;
+	vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
+
+	if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
+		vq->weak_barriers = false;
+
+	vq->packed.ring_dma_addr = ring_dma_addr;
+	vq->packed.driver_event_dma_addr = driver_event_dma_addr;
+	vq->packed.device_event_dma_addr = device_event_dma_addr;
+
+	vq->packed.ring_size_in_bytes = ring_size_in_bytes;
+	vq->packed.event_size_in_bytes = event_size_in_bytes;
+
+	vq->packed.vring.num = num;
+	vq->packed.vring.desc = ring;
+	vq->packed.vring.driver = driver;
+	vq->packed.vring.device = device;
+
+	vq->packed.next_avail_idx = 0;
+	vq->packed.avail_wrap_counter = 1;
+	vq->packed.used_wrap_counter = 1;
+	vq->packed.event_flags_shadow = 0;
+	vq->packed.avail_used_flags = 1 << VRING_PACKED_DESC_F_AVAIL;
+
+	vq->packed.desc_state = kmalloc_array(num,
+			sizeof(struct vring_desc_state_packed),
+			GFP_KERNEL);
+	if (!vq->packed.desc_state)
+		goto err_desc_state;
+
+	memset(vq->packed.desc_state, 0,
+		num * sizeof(struct vring_desc_state_packed));
+
+	/* Put everything in free lists. */
+	vq->free_head = 0;
+	for (i = 0; i < num-1; i++)
+		vq->packed.desc_state[i].next = i + 1;
+
+	vq->packed.desc_extra = kmalloc_array(num,
+			sizeof(struct vring_desc_extra_packed),
+			GFP_KERNEL);
+	if (!vq->packed.desc_extra)
+		goto err_desc_extra;
+
+	memset(vq->packed.desc_extra, 0,
+		num * sizeof(struct vring_desc_extra_packed));
+
+	/* No callback?  Tell other side not to bother us. */
+	if (!callback) {
+		vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
+		vq->packed.vring.driver->flags =
+			cpu_to_le16(vq->packed.event_flags_shadow);
+	}
+
+	spin_lock(&vdev->vqs_list_lock);
+	list_add_tail(&vq->vq.list, &vdev->vqs);
+	spin_unlock(&vdev->vqs_list_lock);
+	return &vq->vq;
+
+err_desc_extra:
+	kfree(vq->packed.desc_state);
+err_desc_state:
+	kfree(vq);
+err_vq:
+	vring_free_queue(vdev, event_size_in_bytes, device, device_event_dma_addr);
+err_device:
+	vring_free_queue(vdev, event_size_in_bytes, driver, driver_event_dma_addr);
+err_driver:
+	vring_free_queue(vdev, ring_size_in_bytes, ring, ring_dma_addr);
+err_ring:
+	return NULL;
+}
+
+
+/*
+ * Generic functions and exported symbols.
+ */
+
+static inline int virtqueue_add(struct virtqueue *_vq,
+				struct scatterlist *sgs[],
+				unsigned int total_sg,
+				unsigned int out_sgs,
+				unsigned int in_sgs,
+				void *data,
+				void *ctx,
+				gfp_t gfp)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	return vq->packed_ring ? virtqueue_add_packed(_vq, sgs, total_sg,
+					out_sgs, in_sgs, data, ctx, gfp) :
+				 virtqueue_add_split(_vq, sgs, total_sg,
+					out_sgs, in_sgs, data, ctx, gfp);
+}
+
+/**
+ * virtqueue_add_sgs - expose buffers to other end
+ * @_vq: the struct virtqueue we're talking about.
+ * @sgs: array of terminated scatterlists.
+ * @out_sgs: the number of scatterlists readable by other side
+ * @in_sgs: the number of scatterlists which are writable (after readable ones)
+ * @data: the token identifying the buffer.
+ * @gfp: how to do memory allocations (if necessary).
+ *
+ * Caller must ensure we don't call this with other virtqueue operations
+ * at the same time (except where noted).
+ *
+ * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
+ */
+int virtqueue_add_sgs(struct virtqueue *_vq,
+		      struct scatterlist *sgs[],
+		      unsigned int out_sgs,
+		      unsigned int in_sgs,
+		      void *data,
+		      gfp_t gfp)
+{
+	unsigned int i, total_sg = 0;
+
+	/* Count them first. */
+	for (i = 0; i < out_sgs + in_sgs; i++) {
+		struct scatterlist *sg;
+
+		for (sg = sgs[i]; sg; sg = sg_next(sg))
+			total_sg++;
+	}
+	return virtqueue_add(_vq, sgs, total_sg, out_sgs, in_sgs,
+			     data, NULL, gfp);
+}
+EXPORT_SYMBOL_GPL(virtqueue_add_sgs);
+
+/**
+ * virtqueue_add_outbuf - expose output buffers to other end
+ * @vq: the struct virtqueue we're talking about.
+ * @sg: scatterlist (must be well-formed and terminated!)
+ * @num: the number of entries in @sg readable by other side
+ * @data: the token identifying the buffer.
+ * @gfp: how to do memory allocations (if necessary).
+ *
+ * Caller must ensure we don't call this with other virtqueue operations
+ * at the same time (except where noted).
+ *
+ * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
+ */
+int virtqueue_add_outbuf(struct virtqueue *vq,
+			 struct scatterlist *sg, unsigned int num,
+			 void *data,
+			 gfp_t gfp)
+{
+	return virtqueue_add(vq, &sg, num, 1, 0, data, NULL, gfp);
+}
+EXPORT_SYMBOL_GPL(virtqueue_add_outbuf);
+
+/**
+ * virtqueue_add_inbuf - expose input buffers to other end
+ * @vq: the struct virtqueue we're talking about.
+ * @sg: scatterlist (must be well-formed and terminated!)
+ * @num: the number of entries in @sg writable by other side
+ * @data: the token identifying the buffer.
+ * @gfp: how to do memory allocations (if necessary).
+ *
+ * Caller must ensure we don't call this with other virtqueue operations
+ * at the same time (except where noted).
+ *
+ * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
+ */
+int virtqueue_add_inbuf(struct virtqueue *vq,
+			struct scatterlist *sg, unsigned int num,
+			void *data,
+			gfp_t gfp)
+{
+	return virtqueue_add(vq, &sg, num, 0, 1, data, NULL, gfp);
+}
+EXPORT_SYMBOL_GPL(virtqueue_add_inbuf);
+
+/**
+ * virtqueue_add_inbuf_ctx - expose input buffers to other end
+ * @vq: the struct virtqueue we're talking about.
+ * @sg: scatterlist (must be well-formed and terminated!)
+ * @num: the number of entries in @sg writable by other side
+ * @data: the token identifying the buffer.
+ * @ctx: extra context for the token
+ * @gfp: how to do memory allocations (if necessary).
+ *
+ * Caller must ensure we don't call this with other virtqueue operations
+ * at the same time (except where noted).
+ *
+ * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
+ */
+int virtqueue_add_inbuf_ctx(struct virtqueue *vq,
+			struct scatterlist *sg, unsigned int num,
+			void *data,
+			void *ctx,
+			gfp_t gfp)
+{
+	return virtqueue_add(vq, &sg, num, 0, 1, data, ctx, gfp);
+}
+EXPORT_SYMBOL_GPL(virtqueue_add_inbuf_ctx);
+
+/**
+ * virtqueue_kick_prepare - first half of split virtqueue_kick call.
+ * @_vq: the struct virtqueue
+ *
+ * Instead of virtqueue_kick(), you can do:
+ *	if (virtqueue_kick_prepare(vq))
+ *		virtqueue_notify(vq);
+ *
+ * This is sometimes useful because the virtqueue_kick_prepare() needs
+ * to be serialized, but the actual virtqueue_notify() call does not.
+ */
+bool virtqueue_kick_prepare(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	return vq->packed_ring ? virtqueue_kick_prepare_packed(_vq) :
+				 virtqueue_kick_prepare_split(_vq);
+}
+EXPORT_SYMBOL_GPL(virtqueue_kick_prepare);
+
+/**
+ * virtqueue_notify - second half of split virtqueue_kick call.
+ * @_vq: the struct virtqueue
+ *
+ * This does not need to be serialized.
+ *
+ * Returns false if host notify failed or queue is broken, otherwise true.
+ */
+bool virtqueue_notify(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	if (unlikely(vq->broken))
+		return false;
+
+	/* Prod other side to tell it about changes. */
+	if (!vq->notify(_vq)) {
+		vq->broken = true;
+		return false;
+	}
+	return true;
+}
+EXPORT_SYMBOL_GPL(virtqueue_notify);
+
+/**
+ * virtqueue_kick - update after add_buf
+ * @vq: the struct virtqueue
+ *
+ * After one or more virtqueue_add_* calls, invoke this to kick
+ * the other side.
+ *
+ * Caller must ensure we don't call this with other virtqueue
+ * operations at the same time (except where noted).
+ *
+ * Returns false if kick failed, otherwise true.
+ */
+bool virtqueue_kick(struct virtqueue *vq)
+{
+	if (virtqueue_kick_prepare(vq))
+		return virtqueue_notify(vq);
+	return true;
+}
+EXPORT_SYMBOL_GPL(virtqueue_kick);
+
+/**
+ * virtqueue_get_buf - get the next used buffer
+ * @_vq: the struct virtqueue we're talking about.
+ * @len: the length written into the buffer
+ * @ctx: extra context for the token
+ *
+ * If the device wrote data into the buffer, @len will be set to the
+ * amount written.  This means you don't need to clear the buffer
+ * beforehand to ensure there's no data leakage in the case of short
+ * writes.
+ *
+ * Caller must ensure we don't call this with other virtqueue
+ * operations at the same time (except where noted).
+ *
+ * Returns NULL if there are no used buffers, or the "data" token
+ * handed to virtqueue_add_*().
+ */
+void *virtqueue_get_buf_ctx(struct virtqueue *_vq, unsigned int *len,
+			    void **ctx)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	return vq->packed_ring ? virtqueue_get_buf_ctx_packed(_vq, len, ctx) :
+				 virtqueue_get_buf_ctx_split(_vq, len, ctx);
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_buf_ctx);
+
+void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len)
+{
+	return virtqueue_get_buf_ctx(_vq, len, NULL);
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_buf);
+/**
+ * virtqueue_disable_cb - disable callbacks
+ * @_vq: the struct virtqueue we're talking about.
+ *
+ * Note that this is not necessarily synchronous, hence unreliable and only
+ * useful as an optimization.
+ *
+ * Unlike other operations, this need not be serialized.
+ */
+void virtqueue_disable_cb(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	if (vq->packed_ring)
+		virtqueue_disable_cb_packed(_vq);
+	else
+		virtqueue_disable_cb_split(_vq);
+}
+EXPORT_SYMBOL_GPL(virtqueue_disable_cb);
+
+/**
+ * virtqueue_enable_cb_prepare - restart callbacks after disable_cb
+ * @_vq: the struct virtqueue we're talking about.
+ *
+ * This re-enables callbacks; it returns current queue state
+ * in an opaque unsigned value. This value should be later tested by
+ * virtqueue_poll, to detect a possible race between the driver checking for
+ * more work, and enabling callbacks.
+ *
+ * Caller must ensure we don't call this with other virtqueue
+ * operations at the same time (except where noted).
+ */
+unsigned virtqueue_enable_cb_prepare(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	return vq->packed_ring ? virtqueue_enable_cb_prepare_packed(_vq) :
+				 virtqueue_enable_cb_prepare_split(_vq);
+}
+EXPORT_SYMBOL_GPL(virtqueue_enable_cb_prepare);
+
+/**
+ * virtqueue_poll - query pending used buffers
+ * @_vq: the struct virtqueue we're talking about.
+ * @last_used_idx: virtqueue state (from call to virtqueue_enable_cb_prepare).
+ *
+ * Returns "true" if there are pending used buffers in the queue.
+ *
+ * This does not need to be serialized.
+ */
+bool virtqueue_poll(struct virtqueue *_vq, unsigned last_used_idx)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	if (unlikely(vq->broken))
+		return false;
+
+	virtio_mb(vq->weak_barriers);
+	return vq->packed_ring ? virtqueue_poll_packed(_vq, last_used_idx) :
+				 virtqueue_poll_split(_vq, last_used_idx);
+}
+EXPORT_SYMBOL_GPL(virtqueue_poll);
+
+/**
+ * virtqueue_enable_cb - restart callbacks after disable_cb.
+ * @_vq: the struct virtqueue we're talking about.
+ *
+ * This re-enables callbacks; it returns "false" if there are pending
+ * buffers in the queue, to detect a possible race between the driver
+ * checking for more work, and enabling callbacks.
+ *
+ * Caller must ensure we don't call this with other virtqueue
+ * operations at the same time (except where noted).
+ */
+bool virtqueue_enable_cb(struct virtqueue *_vq)
+{
+	unsigned last_used_idx = virtqueue_enable_cb_prepare(_vq);
+
+	return !virtqueue_poll(_vq, last_used_idx);
+}
+EXPORT_SYMBOL_GPL(virtqueue_enable_cb);
+
+/**
+ * virtqueue_enable_cb_delayed - restart callbacks after disable_cb.
+ * @_vq: the struct virtqueue we're talking about.
+ *
+ * This re-enables callbacks but hints to the other side to delay
+ * interrupts until most of the available buffers have been processed;
+ * it returns "false" if there are many pending buffers in the queue,
+ * to detect a possible race between the driver checking for more work,
+ * and enabling callbacks.
+ *
+ * Caller must ensure we don't call this with other virtqueue
+ * operations at the same time (except where noted).
+ */
+bool virtqueue_enable_cb_delayed(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	return vq->packed_ring ? virtqueue_enable_cb_delayed_packed(_vq) :
+				 virtqueue_enable_cb_delayed_split(_vq);
+}
+EXPORT_SYMBOL_GPL(virtqueue_enable_cb_delayed);
+
+/**
+ * virtqueue_detach_unused_buf - detach first unused buffer
+ * @_vq: the struct virtqueue we're talking about.
+ *
+ * Returns NULL or the "data" token handed to virtqueue_add_*().
+ * This is not valid on an active queue; it is useful only for device
+ * shutdown.
+ */
+void *virtqueue_detach_unused_buf(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	return vq->packed_ring ? virtqueue_detach_unused_buf_packed(_vq) :
+				 virtqueue_detach_unused_buf_split(_vq);
+}
+EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf);
+
+static inline bool more_used(const struct vring_virtqueue *vq)
+{
+	return vq->packed_ring ? more_used_packed(vq) : more_used_split(vq);
+}
+
+irqreturn_t vring_interrupt(int irq, void *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	if (!more_used(vq)) {
+		pr_debug("virtqueue interrupt with no work for %p\n", vq);
+		return IRQ_NONE;
+	}
+
+	if (unlikely(vq->broken))
+		return IRQ_HANDLED;
+
+	pr_debug("virtqueue callback for %p (%p)\n", vq, vq->vq.callback);
+	if (vq->vq.callback)
+		vq->vq.callback(&vq->vq);
+
+	return IRQ_HANDLED;
+}
+EXPORT_SYMBOL_GPL(vring_interrupt);
+
+/* Only available for split ring */
+struct virtqueue *__vring_new_virtqueue(unsigned int index,
+					struct vring vring,
+					struct virtio_device *vdev,
+					bool weak_barriers,
+					bool context,
+					bool (*notify)(struct virtqueue *),
+					void (*callback)(struct virtqueue *),
+					const char *name)
+{
+	unsigned int i;
+	struct vring_virtqueue *vq;
+
+	if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
+		return NULL;
+
+	vq = kmalloc(sizeof(*vq), GFP_KERNEL);
+	if (!vq)
+		return NULL;
+
+	vq->packed_ring = false;
+	vq->vq.callback = callback;
+	vq->vq.vdev = vdev;
+	vq->vq.name = name;
+	vq->vq.num_free = vring.num;
+	vq->vq.index = index;
+	vq->we_own_ring = false;
+	vq->notify = notify;
+	vq->weak_barriers = weak_barriers;
+	vq->broken = false;
+	vq->last_used_idx = 0;
+	vq->num_added = 0;
+	vq->use_dma_api = vring_use_dma_api(vdev);
+#ifdef DEBUG
+	vq->in_use = false;
+	vq->last_add_time_valid = false;
+#endif
+
+	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
+		!context;
+	vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
+
+	if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
+		vq->weak_barriers = false;
+
+	vq->split.queue_dma_addr = 0;
+	vq->split.queue_size_in_bytes = 0;
+
+	vq->split.vring = vring;
+	vq->split.avail_flags_shadow = 0;
+	vq->split.avail_idx_shadow = 0;
+
+	/* No callback?  Tell other side not to bother us. */
+	if (!callback) {
+		vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
+		if (!vq->event)
+			vq->split.vring.avail->flags = cpu_to_virtio16(vdev,
+					vq->split.avail_flags_shadow);
+	}
+
+	vq->split.desc_state = kmalloc_array(vring.num,
+			sizeof(struct vring_desc_state_split), GFP_KERNEL);
+	if (!vq->split.desc_state) {
+		kfree(vq);
+		return NULL;
+	}
+
+	/* Put everything in free lists. */
+	vq->free_head = 0;
+	for (i = 0; i < vring.num-1; i++)
+		vq->split.vring.desc[i].next = cpu_to_virtio16(vdev, i + 1);
+	memset(vq->split.desc_state, 0, vring.num *
+			sizeof(struct vring_desc_state_split));
+
+	spin_lock(&vdev->vqs_list_lock);
+	list_add_tail(&vq->vq.list, &vdev->vqs);
+	spin_unlock(&vdev->vqs_list_lock);
+	return &vq->vq;
+}
+EXPORT_SYMBOL_GPL(__vring_new_virtqueue);
+
+struct virtqueue *vring_create_virtqueue(
+	unsigned int index,
+	unsigned int num,
+	unsigned int vring_align,
+	struct virtio_device *vdev,
+	bool weak_barriers,
+	bool may_reduce_num,
+	bool context,
+	bool (*notify)(struct virtqueue *),
+	void (*callback)(struct virtqueue *),
+	const char *name)
+{
+
+	if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
+		return vring_create_virtqueue_packed(index, num, vring_align,
+				vdev, weak_barriers, may_reduce_num,
+				context, notify, callback, name);
+
+	return vring_create_virtqueue_split(index, num, vring_align,
+			vdev, weak_barriers, may_reduce_num,
+			context, notify, callback, name);
+}
+EXPORT_SYMBOL_GPL(vring_create_virtqueue);
+
+/* Only available for split ring */
+struct virtqueue *vring_new_virtqueue(unsigned int index,
+				      unsigned int num,
+				      unsigned int vring_align,
+				      struct virtio_device *vdev,
+				      bool weak_barriers,
+				      bool context,
+				      void *pages,
+				      bool (*notify)(struct virtqueue *vq),
+				      void (*callback)(struct virtqueue *vq),
+				      const char *name)
+{
+	struct vring vring;
+
+	if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
+		return NULL;
+
+	vring_init(&vring, num, pages, vring_align);
+	return __vring_new_virtqueue(index, vring, vdev, weak_barriers, context,
+				     notify, callback, name);
+}
+EXPORT_SYMBOL_GPL(vring_new_virtqueue);
+
+void vring_del_virtqueue(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	if (vq->we_own_ring) {
+		if (vq->packed_ring) {
+			vring_free_queue(vq->vq.vdev,
+					 vq->packed.ring_size_in_bytes,
+					 vq->packed.vring.desc,
+					 vq->packed.ring_dma_addr);
+
+			vring_free_queue(vq->vq.vdev,
+					 vq->packed.event_size_in_bytes,
+					 vq->packed.vring.driver,
+					 vq->packed.driver_event_dma_addr);
+
+			vring_free_queue(vq->vq.vdev,
+					 vq->packed.event_size_in_bytes,
+					 vq->packed.vring.device,
+					 vq->packed.device_event_dma_addr);
+
+			kfree(vq->packed.desc_state);
+			kfree(vq->packed.desc_extra);
+		} else {
+			vring_free_queue(vq->vq.vdev,
+					 vq->split.queue_size_in_bytes,
+					 vq->split.vring.desc,
+					 vq->split.queue_dma_addr);
+		}
+	}
+	if (!vq->packed_ring)
+		kfree(vq->split.desc_state);
+	spin_lock(&vq->vq.vdev->vqs_list_lock);
+	list_del(&_vq->list);
+	spin_unlock(&vq->vq.vdev->vqs_list_lock);
+	kfree(vq);
+}
+EXPORT_SYMBOL_GPL(vring_del_virtqueue);
+
+/* Manipulates transport-specific feature bits. */
+void vring_transport_features(struct virtio_device *vdev)
+{
+	unsigned int i;
+
+	for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) {
+		switch (i) {
+		case VIRTIO_RING_F_INDIRECT_DESC:
+			break;
+		case VIRTIO_RING_F_EVENT_IDX:
+			break;
+		case VIRTIO_F_VERSION_1:
+			break;
+		case VIRTIO_F_ACCESS_PLATFORM:
+			break;
+		case VIRTIO_F_RING_PACKED:
+			break;
+		case VIRTIO_F_ORDER_PLATFORM:
+			break;
+		default:
+			/* We don't understand this bit. */
+			__virtio_clear_bit(vdev, i);
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(vring_transport_features);
+
+/**
+ * virtqueue_get_vring_size - return the size of the virtqueue's vring
+ * @_vq: the struct virtqueue containing the vring of interest.
+ *
+ * Returns the size of the vring.  This is mainly used for boasting to
+ * userspace.  Unlike other operations, this need not be serialized.
+ */
+unsigned int virtqueue_get_vring_size(struct virtqueue *_vq)
+{
+
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	return vq->packed_ring ? vq->packed.vring.num : vq->split.vring.num;
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_vring_size);
+
+bool virtqueue_is_broken(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	return READ_ONCE(vq->broken);
+}
+EXPORT_SYMBOL_GPL(virtqueue_is_broken);
+
+/*
+ * This should prevent the device from being used, allowing drivers to
+ * recover.  You may need to grab appropriate locks to flush.
+ */
+void virtio_break_device(struct virtio_device *dev)
+{
+	struct virtqueue *_vq;
+
+	spin_lock(&dev->vqs_list_lock);
+	list_for_each_entry(_vq, &dev->vqs, list) {
+		struct vring_virtqueue *vq = to_vvq(_vq);
+
+		/* Pairs with READ_ONCE() in virtqueue_is_broken(). */
+		WRITE_ONCE(vq->broken, true);
+	}
+	spin_unlock(&dev->vqs_list_lock);
+}
+EXPORT_SYMBOL_GPL(virtio_break_device);
+
+dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	BUG_ON(!vq->we_own_ring);
+
+	if (vq->packed_ring)
+		return vq->packed.ring_dma_addr;
+
+	return vq->split.queue_dma_addr;
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_desc_addr);
+
+dma_addr_t virtqueue_get_avail_addr(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	BUG_ON(!vq->we_own_ring);
+
+	if (vq->packed_ring)
+		return vq->packed.driver_event_dma_addr;
+
+	return vq->split.queue_dma_addr +
+		((char *)vq->split.vring.avail - (char *)vq->split.vring.desc);
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_avail_addr);
+
+dma_addr_t virtqueue_get_used_addr(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	BUG_ON(!vq->we_own_ring);
+
+	if (vq->packed_ring)
+		return vq->packed.device_event_dma_addr;
+
+	return vq->split.queue_dma_addr +
+		((char *)vq->split.vring.used - (char *)vq->split.vring.desc);
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_used_addr);
+
+/* Only available for split ring */
+const struct vring *virtqueue_get_vring(struct virtqueue *vq)
+{
+	return &to_vvq(vq)->split.vring;
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_vring);
+
+MODULE_LICENSE("GPL");
diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
new file mode 100644
index 000000000..3f95dedcc
--- /dev/null
+++ b/drivers/virtio/virtio_vdpa.c
@@ -0,0 +1,396 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * VIRTIO based driver for vDPA device
+ *
+ * Copyright (c) 2020, Red Hat. All rights reserved.
+ *     Author: Jason Wang <jasowang@redhat.com>
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/uuid.h>
+#include <linux/virtio.h>
+#include <linux/vdpa.h>
+#include <linux/virtio_config.h>
+#include <linux/virtio_ring.h>
+
+#define MOD_VERSION  "0.1"
+#define MOD_AUTHOR   "Jason Wang <jasowang@redhat.com>"
+#define MOD_DESC     "vDPA bus driver for virtio devices"
+#define MOD_LICENSE  "GPL v2"
+
+struct virtio_vdpa_device {
+	struct virtio_device vdev;
+	struct vdpa_device *vdpa;
+	u64 features;
+
+	/* The lock to protect virtqueue list */
+	spinlock_t lock;
+	/* List of virtio_vdpa_vq_info */
+	struct list_head virtqueues;
+};
+
+struct virtio_vdpa_vq_info {
+	/* the actual virtqueue */
+	struct virtqueue *vq;
+
+	/* the list node for the virtqueues list */
+	struct list_head node;
+};
+
+static inline struct virtio_vdpa_device *
+to_virtio_vdpa_device(struct virtio_device *dev)
+{
+	return container_of(dev, struct virtio_vdpa_device, vdev);
+}
+
+static struct vdpa_device *vd_get_vdpa(struct virtio_device *vdev)
+{
+	return to_virtio_vdpa_device(vdev)->vdpa;
+}
+
+static void virtio_vdpa_get(struct virtio_device *vdev, unsigned offset,
+			    void *buf, unsigned len)
+{
+	struct vdpa_device *vdpa = vd_get_vdpa(vdev);
+
+	vdpa_get_config(vdpa, offset, buf, len);
+}
+
+static void virtio_vdpa_set(struct virtio_device *vdev, unsigned offset,
+			    const void *buf, unsigned len)
+{
+	struct vdpa_device *vdpa = vd_get_vdpa(vdev);
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	ops->set_config(vdpa, offset, buf, len);
+}
+
+static u32 virtio_vdpa_generation(struct virtio_device *vdev)
+{
+	struct vdpa_device *vdpa = vd_get_vdpa(vdev);
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	if (ops->get_generation)
+		return ops->get_generation(vdpa);
+
+	return 0;
+}
+
+static u8 virtio_vdpa_get_status(struct virtio_device *vdev)
+{
+	struct vdpa_device *vdpa = vd_get_vdpa(vdev);
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	return ops->get_status(vdpa);
+}
+
+static void virtio_vdpa_set_status(struct virtio_device *vdev, u8 status)
+{
+	struct vdpa_device *vdpa = vd_get_vdpa(vdev);
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	return ops->set_status(vdpa, status);
+}
+
+static void virtio_vdpa_reset(struct virtio_device *vdev)
+{
+	struct vdpa_device *vdpa = vd_get_vdpa(vdev);
+
+	vdpa_reset(vdpa);
+}
+
+static bool virtio_vdpa_notify(struct virtqueue *vq)
+{
+	struct vdpa_device *vdpa = vd_get_vdpa(vq->vdev);
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	ops->kick_vq(vdpa, vq->index);
+
+	return true;
+}
+
+static irqreturn_t virtio_vdpa_config_cb(void *private)
+{
+	struct virtio_vdpa_device *vd_dev = private;
+
+	virtio_config_changed(&vd_dev->vdev);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t virtio_vdpa_virtqueue_cb(void *private)
+{
+	struct virtio_vdpa_vq_info *info = private;
+
+	return vring_interrupt(0, info->vq);
+}
+
+static struct virtqueue *
+virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
+		     void (*callback)(struct virtqueue *vq),
+		     const char *name, bool ctx)
+{
+	struct virtio_vdpa_device *vd_dev = to_virtio_vdpa_device(vdev);
+	struct vdpa_device *vdpa = vd_get_vdpa(vdev);
+	const struct vdpa_config_ops *ops = vdpa->config;
+	struct virtio_vdpa_vq_info *info;
+	struct vdpa_callback cb;
+	struct virtqueue *vq;
+	u64 desc_addr, driver_addr, device_addr;
+	unsigned long flags;
+	u32 align, num;
+	int err;
+
+	if (!name)
+		return NULL;
+
+	if (index >= vdpa->nvqs)
+		return ERR_PTR(-ENOENT);
+
+	/* Queue shouldn't already be set up. */
+	if (ops->get_vq_ready(vdpa, index))
+		return ERR_PTR(-ENOENT);
+
+	/* Allocate and fill out our active queue description */
+	info = kmalloc(sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return ERR_PTR(-ENOMEM);
+
+	num = ops->get_vq_num_max(vdpa);
+	if (num == 0) {
+		err = -ENOENT;
+		goto error_new_virtqueue;
+	}
+
+	/* Create the vring */
+	align = ops->get_vq_align(vdpa);
+	vq = vring_create_virtqueue(index, num, align, vdev,
+				    true, true, ctx,
+				    virtio_vdpa_notify, callback, name);
+	if (!vq) {
+		err = -ENOMEM;
+		goto error_new_virtqueue;
+	}
+
+	/* Setup virtqueue callback */
+	cb.callback = virtio_vdpa_virtqueue_cb;
+	cb.private = info;
+	ops->set_vq_cb(vdpa, index, &cb);
+	ops->set_vq_num(vdpa, index, virtqueue_get_vring_size(vq));
+
+	desc_addr = virtqueue_get_desc_addr(vq);
+	driver_addr = virtqueue_get_avail_addr(vq);
+	device_addr = virtqueue_get_used_addr(vq);
+
+	if (ops->set_vq_address(vdpa, index,
+				desc_addr, driver_addr,
+				device_addr)) {
+		err = -EINVAL;
+		goto err_vq;
+	}
+
+	ops->set_vq_ready(vdpa, index, 1);
+
+	vq->priv = info;
+	info->vq = vq;
+
+	spin_lock_irqsave(&vd_dev->lock, flags);
+	list_add(&info->node, &vd_dev->virtqueues);
+	spin_unlock_irqrestore(&vd_dev->lock, flags);
+
+	return vq;
+
+err_vq:
+	vring_del_virtqueue(vq);
+error_new_virtqueue:
+	ops->set_vq_ready(vdpa, index, 0);
+	/* VDPA driver should make sure vq is stopeed here */
+	WARN_ON(ops->get_vq_ready(vdpa, index));
+	kfree(info);
+	return ERR_PTR(err);
+}
+
+static void virtio_vdpa_del_vq(struct virtqueue *vq)
+{
+	struct virtio_vdpa_device *vd_dev = to_virtio_vdpa_device(vq->vdev);
+	struct vdpa_device *vdpa = vd_dev->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	struct virtio_vdpa_vq_info *info = vq->priv;
+	unsigned int index = vq->index;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vd_dev->lock, flags);
+	list_del(&info->node);
+	spin_unlock_irqrestore(&vd_dev->lock, flags);
+
+	/* Select and deactivate the queue */
+	ops->set_vq_ready(vdpa, index, 0);
+	WARN_ON(ops->get_vq_ready(vdpa, index));
+
+	vring_del_virtqueue(vq);
+
+	kfree(info);
+}
+
+static void virtio_vdpa_del_vqs(struct virtio_device *vdev)
+{
+	struct virtqueue *vq, *n;
+
+	list_for_each_entry_safe(vq, n, &vdev->vqs, list)
+		virtio_vdpa_del_vq(vq);
+}
+
+static int virtio_vdpa_find_vqs(struct virtio_device *vdev, unsigned nvqs,
+				struct virtqueue *vqs[],
+				vq_callback_t *callbacks[],
+				const char * const names[],
+				const bool *ctx,
+				struct irq_affinity *desc)
+{
+	struct virtio_vdpa_device *vd_dev = to_virtio_vdpa_device(vdev);
+	struct vdpa_device *vdpa = vd_get_vdpa(vdev);
+	const struct vdpa_config_ops *ops = vdpa->config;
+	struct vdpa_callback cb;
+	int i, err, queue_idx = 0;
+
+	for (i = 0; i < nvqs; ++i) {
+		if (!names[i]) {
+			vqs[i] = NULL;
+			continue;
+		}
+
+		vqs[i] = virtio_vdpa_setup_vq(vdev, queue_idx++,
+					      callbacks[i], names[i], ctx ?
+					      ctx[i] : false);
+		if (IS_ERR(vqs[i])) {
+			err = PTR_ERR(vqs[i]);
+			goto err_setup_vq;
+		}
+	}
+
+	cb.callback = virtio_vdpa_config_cb;
+	cb.private = vd_dev;
+	ops->set_config_cb(vdpa, &cb);
+
+	return 0;
+
+err_setup_vq:
+	virtio_vdpa_del_vqs(vdev);
+	return err;
+}
+
+static u64 virtio_vdpa_get_features(struct virtio_device *vdev)
+{
+	struct vdpa_device *vdpa = vd_get_vdpa(vdev);
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	return ops->get_features(vdpa);
+}
+
+static int virtio_vdpa_finalize_features(struct virtio_device *vdev)
+{
+	struct vdpa_device *vdpa = vd_get_vdpa(vdev);
+
+	/* Give virtio_ring a chance to accept features. */
+	vring_transport_features(vdev);
+
+	return vdpa_set_features(vdpa, vdev->features);
+}
+
+static const char *virtio_vdpa_bus_name(struct virtio_device *vdev)
+{
+	struct virtio_vdpa_device *vd_dev = to_virtio_vdpa_device(vdev);
+	struct vdpa_device *vdpa = vd_dev->vdpa;
+
+	return dev_name(&vdpa->dev);
+}
+
+static const struct virtio_config_ops virtio_vdpa_config_ops = {
+	.get		= virtio_vdpa_get,
+	.set		= virtio_vdpa_set,
+	.generation	= virtio_vdpa_generation,
+	.get_status	= virtio_vdpa_get_status,
+	.set_status	= virtio_vdpa_set_status,
+	.reset		= virtio_vdpa_reset,
+	.find_vqs	= virtio_vdpa_find_vqs,
+	.del_vqs	= virtio_vdpa_del_vqs,
+	.get_features	= virtio_vdpa_get_features,
+	.finalize_features = virtio_vdpa_finalize_features,
+	.bus_name	= virtio_vdpa_bus_name,
+};
+
+static void virtio_vdpa_release_dev(struct device *_d)
+{
+	struct virtio_device *vdev =
+	       container_of(_d, struct virtio_device, dev);
+	struct virtio_vdpa_device *vd_dev =
+	       container_of(vdev, struct virtio_vdpa_device, vdev);
+
+	kfree(vd_dev);
+}
+
+static int virtio_vdpa_probe(struct vdpa_device *vdpa)
+{
+	const struct vdpa_config_ops *ops = vdpa->config;
+	struct virtio_vdpa_device *vd_dev, *reg_dev = NULL;
+	int ret = -EINVAL;
+
+	vd_dev = kzalloc(sizeof(*vd_dev), GFP_KERNEL);
+	if (!vd_dev)
+		return -ENOMEM;
+
+	vd_dev->vdev.dev.parent = vdpa_get_dma_dev(vdpa);
+	vd_dev->vdev.dev.release = virtio_vdpa_release_dev;
+	vd_dev->vdev.config = &virtio_vdpa_config_ops;
+	vd_dev->vdpa = vdpa;
+	INIT_LIST_HEAD(&vd_dev->virtqueues);
+	spin_lock_init(&vd_dev->lock);
+
+	vd_dev->vdev.id.device = ops->get_device_id(vdpa);
+	if (vd_dev->vdev.id.device == 0)
+		goto err;
+
+	vd_dev->vdev.id.vendor = ops->get_vendor_id(vdpa);
+	ret = register_virtio_device(&vd_dev->vdev);
+	reg_dev = vd_dev;
+	if (ret)
+		goto err;
+
+	vdpa_set_drvdata(vdpa, vd_dev);
+
+	return 0;
+
+err:
+	if (reg_dev)
+		put_device(&vd_dev->vdev.dev);
+	else
+		kfree(vd_dev);
+	return ret;
+}
+
+static void virtio_vdpa_remove(struct vdpa_device *vdpa)
+{
+	struct virtio_vdpa_device *vd_dev = vdpa_get_drvdata(vdpa);
+
+	unregister_virtio_device(&vd_dev->vdev);
+}
+
+static struct vdpa_driver virtio_vdpa_driver = {
+	.driver = {
+		.name	= "virtio_vdpa",
+	},
+	.probe	= virtio_vdpa_probe,
+	.remove = virtio_vdpa_remove,
+};
+
+module_vdpa_driver(virtio_vdpa_driver);
+
+MODULE_VERSION(MOD_VERSION);
+MODULE_LICENSE(MOD_LICENSE);
+MODULE_AUTHOR(MOD_AUTHOR);
+MODULE_DESCRIPTION(MOD_DESC);