New upstream version 18.08upstream/18.08

Change-Id: I32fdf5e5016556d9c0a6d88ddaf1fc468961790a
Signed-off-by: Luca Boccassi <luca.boccassi@gmail.com>

13 files changed, 2889 insertions, 0 deletions

diff --git a/drivers/bus/vmbus/Makefile b/drivers/bus/vmbus/Makefile
new file mode 100644
index 00000000..deee9dd1
--- /dev/null
+++ b/drivers/bus/vmbus/Makefile
@@ -0,0 +1,36 @@
+# SPDX-License-Identifier: BSD-3-Clause
+
+include $(RTE_SDK)/mk/rte.vars.mk
+
+LIB = librte_bus_vmbus.a
+LIBABIVER := 1
+EXPORT_MAP := rte_bus_vmbus_version.map
+
+CFLAGS += -I$(SRCDIR)
+CFLAGS += -O3 $(WERROR_FLAGS)
+CFLAGS += -DALLOW_EXPERIMENTAL_API
+
+ifneq ($(CONFIG_RTE_EXEC_ENV_LINUXAPP),)
+SYSTEM := linux
+endif
+ifneq ($(CONFIG_RTE_EXEC_ENV_BSDAPP),)
+$(error "VMBUS not implemented for BSD yet")
+endif
+
+CFLAGS += -I$(RTE_SDK)/drivers/bus/vmbus/$(SYSTEM)
+CFLAGS += -I$(RTE_SDK)/lib/librte_eal/common
+CFLAGS += -I$(RTE_SDK)/lib/librte_eal/$(SYSTEM)app/eal
+
+LDLIBS += -lrte_eal -lrte_mbuf -lrte_mempool -lrte_ring
+LDLIBS += -lrte_ethdev
+
+include $(RTE_SDK)/drivers/bus/vmbus/$(SYSTEM)/Makefile
+SRCS-$(CONFIG_RTE_LIBRTE_VMBUS) := $(addprefix $(SYSTEM)/,$(SRCS))
+SRCS-$(CONFIG_RTE_LIBRTE_VMBUS) += vmbus_common.c
+SRCS-$(CONFIG_RTE_LIBRTE_VMBUS) += vmbus_channel.c vmbus_bufring.c
+SRCS-$(CONFIG_RTE_LIBRTE_VMBUS) += vmbus_common_uio.c
+
+SYMLINK-$(CONFIG_RTE_LIBRTE_VMBUS)-include += rte_bus_vmbus.h
+SYMLINK-$(CONFIG_RTE_LIBRTE_VMBUS)-include += rte_vmbus_reg.h
+
+include $(RTE_SDK)/mk/rte.lib.mk
diff --git a/drivers/bus/vmbus/linux/Makefile b/drivers/bus/vmbus/linux/Makefile
new file mode 100644
index 00000000..ef0d30b2
--- /dev/null
+++ b/drivers/bus/vmbus/linux/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: BSD-3-Clause
+
+SRCS += vmbus_bus.c vmbus_uio.c
diff --git a/drivers/bus/vmbus/linux/vmbus_bus.c b/drivers/bus/vmbus/linux/vmbus_bus.c
new file mode 100644
index 00000000..52d6a3c0
--- /dev/null
+++ b/drivers/bus/vmbus/linux/vmbus_bus.c
@@ -0,0 +1,355 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright (c) 2018, Microsoft Corporation.
+ * All Rights Reserved.
+ */
+
+#include <string.h>
+#include <unistd.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+
+#include <rte_eal.h>
+#include <rte_uuid.h>
+#include <rte_tailq.h>
+#include <rte_log.h>
+#include <rte_devargs.h>
+#include <rte_memory.h>
+#include <rte_malloc.h>
+#include <rte_bus_vmbus.h>
+
+#include "eal_filesystem.h"
+#include "private.h"
+
+/** Pathname of VMBUS devices directory. */
+#define SYSFS_VMBUS_DEVICES "/sys/bus/vmbus/devices"
+
+extern struct rte_vmbus_bus rte_vmbus_bus;
+
+/* Read sysfs file to get UUID */
+static int
+parse_sysfs_uuid(const char *filename, rte_uuid_t uu)
+{
+	char buf[BUFSIZ];
+	char *cp, *in = buf;
+	FILE *f;
+
+	f = fopen(filename, "r");
+	if (f == NULL) {
+		VMBUS_LOG(ERR, "cannot open sysfs value %s: %s",
+			  filename, strerror(errno));
+		return -1;
+	}
+
+	if (fgets(buf, sizeof(buf), f) == NULL) {
+		VMBUS_LOG(ERR, "cannot read sysfs value %s",
+				filename);
+		fclose(f);
+		return -1;
+	}
+	fclose(f);
+
+	cp = strchr(buf, '\n');
+	if (cp)
+		*cp = '\0';
+
+	/* strip { } notation */
+	if (buf[0] == '{') {
+		in = buf + 1;
+		cp = strchr(in, '}');
+		if (cp)
+			*cp = '\0';
+	}
+
+	if (rte_uuid_parse(in, uu) < 0) {
+		VMBUS_LOG(ERR, "%s %s not a valid UUID",
+			filename, buf);
+		return -1;
+	}
+
+	return 0;
+}
+
+static int
+get_sysfs_string(const char *filename, char *buf, size_t buflen)
+{
+	char *cp;
+	FILE *f;
+
+	f = fopen(filename, "r");
+	if (f == NULL) {
+		VMBUS_LOG(ERR, "cannot open sysfs value %s:%s",
+			  filename, strerror(errno));
+		return -1;
+	}
+
+	if (fgets(buf, buflen, f) == NULL) {
+		VMBUS_LOG(ERR, "cannot read sysfs value %s",
+				filename);
+		fclose(f);
+		return -1;
+	}
+	fclose(f);
+
+	/* remove trailing newline */
+	cp = memchr(buf, '\n', buflen);
+	if (cp)
+		*cp = '\0';
+
+	return 0;
+}
+
+static int
+vmbus_get_uio_dev(const struct rte_vmbus_device *dev,
+		  char *dstbuf, size_t buflen)
+{
+	char dirname[PATH_MAX];
+	unsigned int uio_num;
+	struct dirent *e;
+	DIR *dir;
+
+	/* Assume recent kernel where uio is in uio/uioX */
+	snprintf(dirname, sizeof(dirname),
+		 SYSFS_VMBUS_DEVICES "/%s/uio", dev->device.name);
+
+	dir = opendir(dirname);
+	if (dir == NULL)
+		return -1; /* Not a UIO device */
+
+	/* take the first file starting with "uio" */
+	while ((e = readdir(dir)) != NULL) {
+		const int prefix_len = 3;
+		char *endptr;
+
+		if (strncmp(e->d_name, "uio", prefix_len) != 0)
+			continue;
+
+		/* try uio%d */
+		errno = 0;
+		uio_num = strtoull(e->d_name + prefix_len, &endptr, 10);
+		if (errno == 0 && endptr != (e->d_name + prefix_len)) {
+			snprintf(dstbuf, buflen, "%s/uio%u", dirname, uio_num);
+			break;
+		}
+	}
+	closedir(dir);
+
+	if (e == NULL)
+		return -1;
+
+	return uio_num;
+}
+
+/* Check map names with kernel names */
+static const char *map_names[VMBUS_MAX_RESOURCE] = {
+	[HV_TXRX_RING_MAP] = "txrx_rings",
+	[HV_INT_PAGE_MAP]  = "int_page",
+	[HV_MON_PAGE_MAP]  = "monitor_page",
+	[HV_RECV_BUF_MAP]  = "recv:",
+	[HV_SEND_BUF_MAP]  = "send:",
+};
+
+
+/* map the resources of a vmbus device in virtual memory */
+int
+rte_vmbus_map_device(struct rte_vmbus_device *dev)
+{
+	char uioname[PATH_MAX], filename[PATH_MAX];
+	char dirname[PATH_MAX], mapname[64];
+	int i;
+
+	dev->uio_num = vmbus_get_uio_dev(dev, uioname, sizeof(uioname));
+	if (dev->uio_num < 0) {
+		VMBUS_LOG(DEBUG, "Not managed by UIO driver, skipped");
+		return 1;
+	}
+
+	/* Extract resource value */
+	for (i = 0; i < VMBUS_MAX_RESOURCE; i++) {
+		struct rte_mem_resource *res = &dev->resource[i];
+		unsigned long len, gpad = 0;
+		char *cp;
+
+		snprintf(dirname, sizeof(dirname),
+			 "%s/maps/map%d", uioname, i);
+
+		snprintf(filename, sizeof(filename),
+			 "%s/name", dirname);
+
+		if (get_sysfs_string(filename, mapname, sizeof(mapname)) < 0) {
+			VMBUS_LOG(ERR, "could not read %s", filename);
+			return -1;
+		}
+
+		if (strncmp(map_names[i], mapname, strlen(map_names[i])) != 0) {
+			VMBUS_LOG(ERR,
+				"unexpected resource %s (expected %s)",
+				mapname, map_names[i]);
+			return -1;
+		}
+
+		snprintf(filename, sizeof(filename),
+			 "%s/size", dirname);
+		if (eal_parse_sysfs_value(filename, &len) < 0) {
+			VMBUS_LOG(ERR,
+				"could not read %s", filename);
+			return -1;
+		}
+		res->len = len;
+
+		/* both send and receive buffers have gpad in name */
+		cp = memchr(mapname, ':', sizeof(mapname));
+		if (cp)
+			gpad = strtoul(cp+1, NULL, 0);
+
+		/* put the GPAD value in physical address */
+		res->phys_addr = gpad;
+	}
+
+	return vmbus_uio_map_resource(dev);
+}
+
+void
+rte_vmbus_unmap_device(struct rte_vmbus_device *dev)
+{
+	vmbus_uio_unmap_resource(dev);
+}
+
+/* Scan one vmbus sysfs entry, and fill the devices list from it. */
+static int
+vmbus_scan_one(const char *name)
+{
+	struct rte_vmbus_device *dev, *dev2;
+	char filename[PATH_MAX];
+	char dirname[PATH_MAX];
+	unsigned long tmp;
+
+	dev = calloc(1, sizeof(*dev));
+	if (dev == NULL)
+		return -1;
+
+	dev->device.name = strdup(name);
+	if (!dev->device.name)
+		goto error;
+
+	/* sysfs base directory
+	 *   /sys/bus/vmbus/devices/7a08391f-f5a0-4ac0-9802-d13fd964f8df
+	 * or on older kernel
+	 *   /sys/bus/vmbus/devices/vmbus_1
+	 */
+	snprintf(dirname, sizeof(dirname), "%s/%s",
+		 SYSFS_VMBUS_DEVICES, name);
+
+	/* get device id */
+	snprintf(filename, sizeof(filename), "%s/device_id", dirname);
+	if (parse_sysfs_uuid(filename, dev->device_id) < 0)
+		goto error;
+
+	/* get device class  */
+	snprintf(filename, sizeof(filename), "%s/class_id", dirname);
+	if (parse_sysfs_uuid(filename, dev->class_id) < 0)
+		goto error;
+
+	/* get relid */
+	snprintf(filename, sizeof(filename), "%s/id", dirname);
+	if (eal_parse_sysfs_value(filename, &tmp) < 0)
+		goto error;
+	dev->relid = tmp;
+
+	/* get monitor id */
+	snprintf(filename, sizeof(filename), "%s/monitor_id", dirname);
+	if (eal_parse_sysfs_value(filename, &tmp) < 0)
+		goto error;
+	dev->monitor_id = tmp;
+
+	/* get numa node (if present) */
+	snprintf(filename, sizeof(filename), "%s/numa_node",
+		 dirname);
+
+	if (access(filename, R_OK) == 0) {
+		if (eal_parse_sysfs_value(filename, &tmp) < 0)
+			goto error;
+		dev->device.numa_node = tmp;
+	} else {
+		/* if no NUMA support, set default to 0 */
+		dev->device.numa_node = SOCKET_ID_ANY;
+	}
+
+	/* device is valid, add in list (sorted) */
+	VMBUS_LOG(DEBUG, "Adding vmbus device %s", name);
+
+	TAILQ_FOREACH(dev2, &rte_vmbus_bus.device_list, next) {
+		int ret;
+
+		ret = rte_uuid_compare(dev->device_id, dev2->device_id);
+		if (ret > 0)
+			continue;
+
+		if (ret < 0) {
+			vmbus_insert_device(dev2, dev);
+		} else { /* already registered */
+			VMBUS_LOG(NOTICE,
+				"%s already registered", name);
+			free(dev);
+		}
+		return 0;
+	}
+
+	vmbus_add_device(dev);
+	return 0;
+error:
+	VMBUS_LOG(DEBUG, "failed");
+
+	free(dev);
+	return -1;
+}
+
+/*
+ * Scan the content of the vmbus, and the devices in the devices list
+ */
+int
+rte_vmbus_scan(void)
+{
+	struct dirent *e;
+	DIR *dir;
+
+	dir = opendir(SYSFS_VMBUS_DEVICES);
+	if (dir == NULL) {
+		if (errno == ENOENT)
+			return 0;
+
+		VMBUS_LOG(ERR, "opendir %s failed: %s",
+			  SYSFS_VMBUS_DEVICES, strerror(errno));
+		return -1;
+	}
+
+	while ((e = readdir(dir)) != NULL) {
+		if (e->d_name[0] == '.')
+			continue;
+
+		if (vmbus_scan_one(e->d_name) < 0)
+			goto error;
+	}
+	closedir(dir);
+	return 0;
+
+error:
+	closedir(dir);
+	return -1;
+}
+
+void rte_vmbus_irq_mask(struct rte_vmbus_device *device)
+{
+	vmbus_uio_irq_control(device, 1);
+}
+
+void rte_vmbus_irq_unmask(struct rte_vmbus_device *device)
+{
+	vmbus_uio_irq_control(device, 0);
+}
+
+int rte_vmbus_irq_read(struct rte_vmbus_device *device)
+{
+	return vmbus_uio_irq_read(device);
+}
diff --git a/drivers/bus/vmbus/linux/vmbus_uio.c b/drivers/bus/vmbus/linux/vmbus_uio.c
new file mode 100644
index 00000000..856c6d66
--- /dev/null
+++ b/drivers/bus/vmbus/linux/vmbus_uio.c
@@ -0,0 +1,398 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright (c) 2018, Microsoft Corporation.
+ * All Rights Reserved.
+ */
+
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <dirent.h>
+#include <inttypes.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+
+#include <rte_log.h>
+#include <rte_bus.h>
+#include <rte_memory.h>
+#include <rte_eal_memconfig.h>
+#include <rte_common.h>
+#include <rte_malloc.h>
+#include <rte_bus_vmbus.h>
+#include <rte_string_fns.h>
+
+#include "private.h"
+
+/** Pathname of VMBUS devices directory. */
+#define SYSFS_VMBUS_DEVICES "/sys/bus/vmbus/devices"
+
+static void *vmbus_map_addr;
+
+/* Control interrupts */
+void vmbus_uio_irq_control(struct rte_vmbus_device *dev, int32_t onoff)
+{
+	if (write(dev->intr_handle.fd, &onoff, sizeof(onoff)) < 0) {
+		VMBUS_LOG(ERR, "cannot write to %d:%s",
+			dev->intr_handle.fd, strerror(errno));
+	}
+}
+
+int vmbus_uio_irq_read(struct rte_vmbus_device *dev)
+{
+	int32_t count;
+	int cc;
+
+	cc = read(dev->intr_handle.fd, &count, sizeof(count));
+	if (cc < (int)sizeof(count)) {
+		if (cc < 0) {
+			VMBUS_LOG(ERR, "IRQ read failed %s",
+				  strerror(errno));
+			return -errno;
+		}
+		VMBUS_LOG(ERR, "can't read IRQ count");
+		return -EINVAL;
+	}
+
+	return count;
+}
+
+void
+vmbus_uio_free_resource(struct rte_vmbus_device *dev,
+		struct mapped_vmbus_resource *uio_res)
+{
+	rte_free(uio_res);
+
+	if (dev->intr_handle.uio_cfg_fd >= 0) {
+		close(dev->intr_handle.uio_cfg_fd);
+		dev->intr_handle.uio_cfg_fd = -1;
+	}
+
+	if (dev->intr_handle.fd >= 0) {
+		close(dev->intr_handle.fd);
+		dev->intr_handle.fd = -1;
+		dev->intr_handle.type = RTE_INTR_HANDLE_UNKNOWN;
+	}
+}
+
+int
+vmbus_uio_alloc_resource(struct rte_vmbus_device *dev,
+			 struct mapped_vmbus_resource **uio_res)
+{
+	char devname[PATH_MAX]; /* contains the /dev/uioX */
+
+	/* save fd if in primary process */
+	snprintf(devname, sizeof(devname), "/dev/uio%u", dev->uio_num);
+	dev->intr_handle.fd = open(devname, O_RDWR);
+	if (dev->intr_handle.fd < 0) {
+		VMBUS_LOG(ERR, "Cannot open %s: %s",
+			devname, strerror(errno));
+		goto error;
+	}
+	dev->intr_handle.type = RTE_INTR_HANDLE_UIO_INTX;
+
+	/* allocate the mapping details for secondary processes*/
+	*uio_res = rte_zmalloc("UIO_RES", sizeof(**uio_res), 0);
+	if (*uio_res == NULL) {
+		VMBUS_LOG(ERR, "cannot store uio mmap details");
+		goto error;
+	}
+
+	strlcpy((*uio_res)->path, devname, PATH_MAX);
+	rte_uuid_copy((*uio_res)->id, dev->device_id);
+
+	return 0;
+
+error:
+	vmbus_uio_free_resource(dev, *uio_res);
+	return -1;
+}
+
+static int
+find_max_end_va(const struct rte_memseg_list *msl, void *arg)
+{
+	size_t sz = msl->memseg_arr.len * msl->page_sz;
+	void *end_va = RTE_PTR_ADD(msl->base_va, sz);
+	void **max_va = arg;
+
+	if (*max_va < end_va)
+		*max_va = end_va;
+	return 0;
+}
+
+/*
+ * TODO: this should be part of memseg api.
+ *       code is duplicated from PCI.
+ */
+static void *
+vmbus_find_max_end_va(void)
+{
+	void *va = NULL;
+
+	rte_memseg_list_walk(find_max_end_va, &va);
+	return va;
+}
+
+int
+vmbus_uio_map_resource_by_index(struct rte_vmbus_device *dev, int idx,
+				struct mapped_vmbus_resource *uio_res,
+				int flags)
+{
+	size_t size = dev->resource[idx].len;
+	struct vmbus_map *maps = uio_res->maps;
+	void *mapaddr;
+	off_t offset;
+	int fd;
+
+	/* devname for mmap  */
+	fd = open(uio_res->path, O_RDWR);
+	if (fd < 0) {
+		VMBUS_LOG(ERR, "Cannot open %s: %s",
+			  uio_res->path, strerror(errno));
+		return -1;
+	}
+
+	/* try mapping somewhere close to the end of hugepages */
+	if (vmbus_map_addr == NULL)
+		vmbus_map_addr = vmbus_find_max_end_va();
+
+	/* offset is special in uio it indicates which resource */
+	offset = idx * PAGE_SIZE;
+
+	mapaddr = vmbus_map_resource(vmbus_map_addr, fd, offset, size, flags);
+	close(fd);
+
+	if (mapaddr == MAP_FAILED)
+		return -1;
+
+	dev->resource[idx].addr = mapaddr;
+	vmbus_map_addr = RTE_PTR_ADD(mapaddr, size);
+
+	/* Record result of sucessful mapping for use by secondary */
+	maps[idx].addr = mapaddr;
+	maps[idx].size = size;
+
+	return 0;
+}
+
+static int vmbus_uio_map_primary(struct vmbus_channel *chan,
+				 void **ring_buf, uint32_t *ring_size)
+{
+	struct mapped_vmbus_resource *uio_res;
+
+	uio_res = vmbus_uio_find_resource(chan->device);
+	if (!uio_res) {
+		VMBUS_LOG(ERR, "can not find resources!");
+		return -ENOMEM;
+	}
+
+	if (uio_res->nb_maps < VMBUS_MAX_RESOURCE) {
+		VMBUS_LOG(ERR, "VMBUS: only %u resources found!",
+			  uio_res->nb_maps);
+		return -EINVAL;
+	}
+
+	*ring_size = uio_res->maps[HV_TXRX_RING_MAP].size / 2;
+	*ring_buf  = uio_res->maps[HV_TXRX_RING_MAP].addr;
+	return 0;
+}
+
+static int vmbus_uio_map_subchan(const struct rte_vmbus_device *dev,
+				 const struct vmbus_channel *chan,
+				 void **ring_buf, uint32_t *ring_size)
+{
+	char ring_path[PATH_MAX];
+	size_t file_size;
+	struct stat sb;
+	int fd;
+
+	snprintf(ring_path, sizeof(ring_path),
+		 "%s/%s/channels/%u/ring",
+		 SYSFS_VMBUS_DEVICES, dev->device.name,
+		 chan->relid);
+
+	fd = open(ring_path, O_RDWR);
+	if (fd < 0) {
+		VMBUS_LOG(ERR, "Cannot open %s: %s",
+			  ring_path, strerror(errno));
+		return -errno;
+	}
+
+	if (fstat(fd, &sb) < 0) {
+		VMBUS_LOG(ERR, "Cannot state %s: %s",
+			  ring_path, strerror(errno));
+		close(fd);
+		return -errno;
+	}
+	file_size = sb.st_size;
+
+	if (file_size == 0 || (file_size & (PAGE_SIZE - 1))) {
+		VMBUS_LOG(ERR, "incorrect size %s: %zu",
+			  ring_path, file_size);
+
+		close(fd);
+		return -EINVAL;
+	}
+
+	*ring_size = file_size / 2;
+	*ring_buf = vmbus_map_resource(vmbus_map_addr, fd,
+				       0, sb.st_size, 0);
+	close(fd);
+
+	if (ring_buf == MAP_FAILED)
+		return -EIO;
+
+	vmbus_map_addr = RTE_PTR_ADD(ring_buf, file_size);
+	return 0;
+}
+
+int vmbus_uio_map_rings(struct vmbus_channel *chan)
+{
+	const struct rte_vmbus_device *dev = chan->device;
+	uint32_t ring_size;
+	void *ring_buf;
+	int ret;
+
+	/* Primary channel */
+	if (chan->subchannel_id == 0)
+		ret = vmbus_uio_map_primary(chan, &ring_buf, &ring_size);
+	else
+		ret = vmbus_uio_map_subchan(dev, chan, &ring_buf, &ring_size);
+
+	if (ret)
+		return ret;
+
+	vmbus_br_setup(&chan->txbr, ring_buf, ring_size);
+	vmbus_br_setup(&chan->rxbr, (char *)ring_buf + ring_size, ring_size);
+	return 0;
+}
+
+static int vmbus_uio_sysfs_read(const char *dir, const char *name,
+				unsigned long *val, unsigned long max_range)
+{
+	char path[PATH_MAX];
+	FILE *f;
+	int ret;
+
+	snprintf(path, sizeof(path), "%s/%s", dir, name);
+	f = fopen(path, "r");
+	if (!f) {
+		VMBUS_LOG(ERR, "can't open %s:%s",
+			  path, strerror(errno));
+		return -errno;
+	}
+
+	if (fscanf(f, "%lu", val) != 1)
+		ret = -EIO;
+	else if (*val > max_range)
+		ret = -ERANGE;
+	else
+		ret = 0;
+	fclose(f);
+
+	return ret;
+}
+
+static bool vmbus_uio_ring_present(const struct rte_vmbus_device *dev,
+				   uint32_t relid)
+{
+	char ring_path[PATH_MAX];
+
+	/* Check if kernel has subchannel sysfs files */
+	snprintf(ring_path, sizeof(ring_path),
+		 "%s/%s/channels/%u/ring",
+		 SYSFS_VMBUS_DEVICES, dev->device.name, relid);
+
+	return access(ring_path, R_OK|W_OK) == 0;
+}
+
+bool vmbus_uio_subchannels_supported(const struct rte_vmbus_device *dev,
+				     const struct vmbus_channel *chan)
+{
+	return vmbus_uio_ring_present(dev, chan->relid);
+}
+
+static bool vmbus_isnew_subchannel(struct vmbus_channel *primary,
+				   unsigned long id)
+{
+	const struct vmbus_channel *c;
+
+	STAILQ_FOREACH(c, &primary->subchannel_list, next) {
+		if (c->relid == id)
+			return false;
+	}
+	return true;
+}
+
+int vmbus_uio_get_subchan(struct vmbus_channel *primary,
+			  struct vmbus_channel **subchan)
+{
+	const struct rte_vmbus_device *dev = primary->device;
+	char chan_path[PATH_MAX], subchan_path[PATH_MAX];
+	struct dirent *ent;
+	DIR *chan_dir;
+
+	snprintf(chan_path, sizeof(chan_path),
+		 "%s/%s/channels",
+		 SYSFS_VMBUS_DEVICES, dev->device.name);
+
+	chan_dir = opendir(chan_path);
+	if (!chan_dir) {
+		VMBUS_LOG(ERR, "cannot open %s: %s",
+			  chan_path, strerror(errno));
+		return -errno;
+	}
+
+	while ((ent = readdir(chan_dir))) {
+		unsigned long relid, subid, monid;
+		char *endp;
+		int err;
+
+		if (ent->d_name[0] == '.')
+			continue;
+
+		errno = 0;
+		relid = strtoul(ent->d_name, &endp, 0);
+		if (*endp || errno != 0 || relid > UINT16_MAX) {
+			VMBUS_LOG(NOTICE, "not a valid channel relid: %s",
+				  ent->d_name);
+			continue;
+		}
+
+		snprintf(subchan_path, sizeof(subchan_path), "%s/%lu",
+			 chan_path, relid);
+		err = vmbus_uio_sysfs_read(subchan_path, "subchannel_id",
+					   &subid, UINT16_MAX);
+		if (err) {
+			VMBUS_LOG(NOTICE, "invalid subchannel id %lu",
+				  subid);
+			closedir(chan_dir);
+			return err;
+		}
+
+		if (subid == 0)
+			continue;	/* skip primary channel */
+
+		if (!vmbus_isnew_subchannel(primary, relid))
+			continue;
+
+		if (!vmbus_uio_ring_present(dev, relid))
+			continue;	/* Ring may not be ready yet */
+
+		err = vmbus_uio_sysfs_read(subchan_path, "monitor_id",
+					   &monid, UINT8_MAX);
+		if (err) {
+			VMBUS_LOG(NOTICE, "invalid monitor id %lu",
+				  monid);
+			return err;
+		}
+
+		err = vmbus_chan_create(dev, relid, subid, monid, subchan);
+		if (err) {
+			VMBUS_LOG(NOTICE, "subchannel setup failed");
+			return err;
+		}
+		break;
+	}
+	closedir(chan_dir);
+
+	return (ent == NULL) ? -ENOENT : 0;
+}
diff --git a/drivers/bus/vmbus/meson.build b/drivers/bus/vmbus/meson.build
new file mode 100644
index 00000000..18daabec
--- /dev/null
+++ b/drivers/bus/vmbus/meson.build
@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: BSD-3-Clause
+
+allow_experimental_apis = true
+
+install_headers('rte_bus_vmbus.h','rte_vmbus_reg.h')
+
+sources = files('vmbus_common.c',
+		'vmbus_channel.c',
+		'vmbus_bufring.c',
+		'vmbus_common_uio.c')
+
+if host_machine.system() == 'linux'
+	sources += files('linux/vmbus_bus.c',
+			'linux/vmbus_uio.c')
+	includes += include_directories('linux')
+else
+	build = false
+endif
diff --git a/drivers/bus/vmbus/private.h b/drivers/bus/vmbus/private.h
new file mode 100644
index 00000000..9964fc42
--- /dev/null
+++ b/drivers/bus/vmbus/private.h
@@ -0,0 +1,132 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright (c) 2018, Microsoft Corporation.
+ * All Rights Reserved.
+ */
+
+#ifndef _VMBUS_PRIVATE_H_
+#define _VMBUS_PRIVATE_H_
+
+#include <stdbool.h>
+#include <sys/uio.h>
+#include <rte_log.h>
+#include <rte_vmbus_reg.h>
+
+#ifndef PAGE_SIZE
+#define PAGE_SIZE	4096
+#endif
+
+extern int vmbus_logtype_bus;
+#define VMBUS_LOG(level, fmt, args...) \
+	rte_log(RTE_LOG_ ## level, vmbus_logtype_bus, "%s(): " fmt "\n", \
+		__func__, ##args)
+
+struct vmbus_br {
+	struct vmbus_bufring *vbr;
+	uint32_t	dsize;
+	uint32_t	windex; /* next available location */
+};
+
+#define UIO_NAME_MAX 64
+
+struct vmbus_map {
+	void *addr;	/* user mmap of resource */
+	uint64_t size;	/* length */
+};
+
+/*
+ * For multi-process we need to reproduce all vmbus mappings in secondary
+ * processes, so save them in a tailq.
+ */
+struct mapped_vmbus_resource {
+	TAILQ_ENTRY(mapped_vmbus_resource) next;
+
+	rte_uuid_t id;
+	int nb_maps;
+	struct vmbus_map maps[VMBUS_MAX_RESOURCE];
+	char path[PATH_MAX];
+};
+
+TAILQ_HEAD(mapped_vmbus_res_list, mapped_vmbus_resource);
+
+#define HV_MON_TRIG_LEN	32
+#define HV_MON_TRIG_MAX	4
+
+struct vmbus_channel {
+	STAILQ_HEAD(, vmbus_channel) subchannel_list;
+	STAILQ_ENTRY(vmbus_channel) next;
+	const struct rte_vmbus_device *device;
+
+	struct vmbus_br rxbr;
+	struct vmbus_br txbr;
+
+	uint16_t relid;
+	uint16_t subchannel_id;
+	uint8_t monitor_id;
+};
+
+#define VMBUS_MAX_CHANNELS	64
+
+int vmbus_chan_create(const struct rte_vmbus_device *device,
+		      uint16_t relid, uint16_t subid, uint8_t monitor_id,
+		      struct vmbus_channel **new_chan);
+
+void vmbus_add_device(struct rte_vmbus_device *vmbus_dev);
+void vmbus_insert_device(struct rte_vmbus_device *exist_vmbus_dev,
+			 struct rte_vmbus_device *new_vmbus_dev);
+void vmbus_remove_device(struct rte_vmbus_device *vmbus_device);
+
+void vmbus_uio_irq_control(struct rte_vmbus_device *dev, int32_t onoff);
+int vmbus_uio_irq_read(struct rte_vmbus_device *dev);
+
+int vmbus_uio_map_resource(struct rte_vmbus_device *dev);
+void vmbus_uio_unmap_resource(struct rte_vmbus_device *dev);
+
+int vmbus_uio_alloc_resource(struct rte_vmbus_device *dev,
+		struct mapped_vmbus_resource **uio_res);
+void vmbus_uio_free_resource(struct rte_vmbus_device *dev,
+		struct mapped_vmbus_resource *uio_res);
+
+struct mapped_vmbus_resource *
+vmbus_uio_find_resource(const struct rte_vmbus_device *dev);
+int vmbus_uio_map_resource_by_index(struct rte_vmbus_device *dev, int res_idx,
+				    struct mapped_vmbus_resource *uio_res,
+				    int flags);
+
+void *vmbus_map_resource(void *requested_addr, int fd, off_t offset,
+		size_t size, int additional_flags);
+void vmbus_unmap_resource(void *requested_addr, size_t size);
+
+bool vmbus_uio_subchannels_supported(const struct rte_vmbus_device *dev,
+				     const struct vmbus_channel *chan);
+int vmbus_uio_get_subchan(struct vmbus_channel *primary,
+			  struct vmbus_channel **subchan);
+int vmbus_uio_map_rings(struct vmbus_channel *chan);
+
+void vmbus_br_setup(struct vmbus_br *br, void *buf, unsigned int blen);
+
+/* Amount of space available for write */
+static inline uint32_t
+vmbus_br_availwrite(const struct vmbus_br *br, uint32_t windex)
+{
+	uint32_t rindex = br->vbr->rindex;
+
+	if (windex >= rindex)
+		return br->dsize - (windex - rindex);
+	else
+		return rindex - windex;
+}
+
+static inline uint32_t
+vmbus_br_availread(const struct vmbus_br *br)
+{
+	return br->dsize - vmbus_br_availwrite(br, br->vbr->windex);
+}
+
+int vmbus_txbr_write(struct vmbus_br *tbr, const struct iovec iov[], int iovlen,
+		     bool *need_sig);
+
+int vmbus_rxbr_peek(const struct vmbus_br *rbr, void *data, size_t dlen);
+
+int vmbus_rxbr_read(struct vmbus_br *rbr, void *data, size_t dlen, size_t hlen);
+
+#endif /* _VMBUS_PRIVATE_H_ */
diff --git a/drivers/bus/vmbus/rte_bus_vmbus.h b/drivers/bus/vmbus/rte_bus_vmbus.h
new file mode 100644
index 00000000..4a2c1f6f
--- /dev/null
+++ b/drivers/bus/vmbus/rte_bus_vmbus.h
@@ -0,0 +1,407 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright (c) 2018, Microsoft Corporation.
+ * All Rights Reserved.
+ */
+
+#ifndef _VMBUS_H_
+#define _VMBUS_H_
+
+/**
+ * @file
+ *
+ * VMBUS Interface
+ */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <errno.h>
+#include <sys/queue.h>
+#include <stdint.h>
+#include <inttypes.h>
+
+#include <rte_compat.h>
+#include <rte_uuid.h>
+#include <rte_debug.h>
+#include <rte_interrupts.h>
+#include <rte_dev.h>
+#include <rte_vmbus_reg.h>
+
+/* Forward declarations */
+struct rte_vmbus_device;
+struct rte_vmbus_driver;
+struct rte_vmbus_bus;
+struct vmbus_channel;
+struct vmbus_mon_page;
+
+TAILQ_HEAD(rte_vmbus_device_list, rte_vmbus_device);
+TAILQ_HEAD(rte_vmbus_driver_list, rte_vmbus_driver);
+
+/* VMBus iterators */
+#define FOREACH_DEVICE_ON_VMBUS(p)	\
+	TAILQ_FOREACH(p, &(rte_vmbus_bus.device_list), next)
+
+#define FOREACH_DRIVER_ON_VMBUS(p)	\
+	TAILQ_FOREACH(p, &(rte_vmbus_bus.driver_list), next)
+
+/** Maximum number of VMBUS resources. */
+enum hv_uio_map {
+	HV_TXRX_RING_MAP = 0,
+	HV_INT_PAGE_MAP,
+	HV_MON_PAGE_MAP,
+	HV_RECV_BUF_MAP,
+	HV_SEND_BUF_MAP
+};
+#define VMBUS_MAX_RESOURCE 5
+
+/**
+ * A structure describing a VMBUS device.
+ */
+struct rte_vmbus_device {
+	TAILQ_ENTRY(rte_vmbus_device) next;    /**< Next probed VMBUS device */
+	const struct rte_vmbus_driver *driver; /**< Associated driver */
+	struct rte_device device;              /**< Inherit core device */
+	rte_uuid_t device_id;		       /**< VMBUS device id */
+	rte_uuid_t class_id;		       /**< VMBUS device type */
+	uint32_t relid;			       /**< id for primary */
+	uint8_t monitor_id;		       /**< monitor page */
+	int uio_num;			       /**< UIO device number */
+	uint32_t *int_page;		       /**< VMBUS interrupt page */
+	struct vmbus_channel *primary;	       /**< VMBUS primary channel */
+	struct vmbus_mon_page *monitor_page;   /**< VMBUS monitor page */
+
+	struct rte_intr_handle intr_handle;    /**< Interrupt handle */
+	struct rte_mem_resource resource[VMBUS_MAX_RESOURCE];
+};
+
+/**
+ * Initialization function for the driver called during VMBUS probing.
+ */
+typedef int (vmbus_probe_t)(struct rte_vmbus_driver *,
+			    struct rte_vmbus_device *);
+
+/**
+ * Initialization function for the driver called during hot plugging.
+ */
+typedef int (vmbus_remove_t)(struct rte_vmbus_device *);
+
+/**
+ * A structure describing a VMBUS driver.
+ */
+struct rte_vmbus_driver {
+	TAILQ_ENTRY(rte_vmbus_driver) next; /**< Next in list. */
+	struct rte_driver driver;
+	struct rte_vmbus_bus *bus;          /**< VM bus reference. */
+	vmbus_probe_t *probe;               /**< Device Probe function. */
+	vmbus_remove_t *remove;             /**< Device Remove function. */
+
+	const rte_uuid_t *id_table;	    /**< ID table. */
+};
+
+
+/**
+ * Structure describing the VM bus
+ */
+struct rte_vmbus_bus {
+	struct rte_bus bus;               /**< Inherit the generic class */
+	struct rte_vmbus_device_list device_list;  /**< List of devices */
+	struct rte_vmbus_driver_list driver_list;  /**< List of drivers */
+};
+
+/**
+ * Scan the content of the VMBUS bus, and the devices in the devices
+ * list
+ *
+ * @return
+ *  0 on success, negative on error
+ */
+int rte_vmbus_scan(void);
+
+/**
+ * Probe the VMBUS bus
+ *
+ * @return
+ *   - 0 on success.
+ *   - !0 on error.
+ */
+int rte_vmbus_probe(void);
+
+/**
+ * Map the VMBUS device resources in user space virtual memory address
+ *
+ * @param dev
+ *   A pointer to a rte_vmbus_device structure describing the device
+ *   to use
+ *
+ * @return
+ *   0 on success, negative on error and positive if no driver
+ *   is found for the device.
+ */
+int rte_vmbus_map_device(struct rte_vmbus_device *dev);
+
+/**
+ * Unmap this device
+ *
+ * @param dev
+ *   A pointer to a rte_vmbus_device structure describing the device
+ *   to use
+ */
+void rte_vmbus_unmap_device(struct rte_vmbus_device *dev);
+
+/**
+ * Get connection to primary VMBUS channel
+ *
+ * @param device
+ *   A pointer to a rte_vmbus_device structure describing the device
+ * @param chan
+ *   A pointer to a VMBUS channel pointer that will be filled.
+ * @return
+ *   - 0 Success; channel opened.
+ *   - -ENOMEM: Not enough memory available.
+ *   - -EINVAL: Regions could not be mapped.
+ */
+int rte_vmbus_chan_open(struct rte_vmbus_device *device,
+			struct vmbus_channel **chan);
+
+/**
+ * Free connection to VMBUS channel
+ *
+ * @param chan
+ *    VMBUS channel
+ */
+void rte_vmbus_chan_close(struct vmbus_channel *chan);
+
+/**
+ * Gets the maximum number of channels supported on device
+ *
+ * @param device
+ *   A pointer to a rte_vmbus_device structure describing the device
+ * @return
+ *   Number of channels available.
+ */
+int rte_vmbus_max_channels(const struct rte_vmbus_device *device);
+
+/**
+ * Get a connection to new secondary vmbus channel
+ *
+ * @param primary
+ *   A pointer to primary VMBUS channel
+ * @param chan
+ *   A pointer to a secondary VMBUS channel pointer that will be filled.
+ * @return
+ *   - 0 Success; channel opened.
+ *   - -ENOMEM: Not enough memory available.
+ *   - -EINVAL: Regions could not be mapped.
+ */
+int rte_vmbus_subchan_open(struct vmbus_channel *primary,
+			   struct vmbus_channel **new_chan);
+
+/**
+ * Disable IRQ for device
+ *
+ * @param device
+ *    VMBUS device
+ */
+void rte_vmbus_irq_mask(struct rte_vmbus_device *device);
+
+/**
+ * Enable IRQ for device
+ *
+ * @param device
+ *    VMBUS device
+ */
+void rte_vmbus_irq_unmask(struct rte_vmbus_device *device);
+
+/**
+ * Read (and wait) for IRQ
+ *
+ * @param device
+ *    VMBUS device
+ */
+int rte_vmbus_irq_read(struct rte_vmbus_device *device);
+
+/**
+ * Test if channel is empty
+ *
+ * @param channel
+ *	Pointer to vmbus_channel structure.
+ * @return
+ *	Return true if no data present in incoming ring.
+ */
+bool rte_vmbus_chan_rx_empty(const struct vmbus_channel *channel);
+
+/**
+ * Send the specified buffer on the given channel
+ *
+ * @param channel
+ *	Pointer to vmbus_channel structure.
+ * @param type
+ *	Type of packet that is being send e.g. negotiate, time
+ *	packet etc.
+ * @param data
+ *	Pointer to the buffer to send
+ * @param dlen
+ *	Number of bytes of data to send
+ * @param xact
+ *	Identifier of the request
+ * @param flags
+ *	Message type inband, rxbuf, gpa
+ * @param need_sig
+ *	Is host signal tx is required (optional)
+ *
+ * Sends data in buffer directly to hyper-v via the vmbus
+ */
+int rte_vmbus_chan_send(struct vmbus_channel *channel, uint16_t type,
+			void *data, uint32_t dlen,
+			uint64_t xact, uint32_t flags, bool *need_sig);
+
+/**
+ * Explicitly signal host that data is available
+ *
+ * @param
+ *	Pointer to vmbus_channel structure.
+ *
+ * Used when batching multiple sends and only signaling host
+ * after the last send.
+ */
+void rte_vmbus_chan_signal_tx(const struct vmbus_channel *channel);
+
+/* Structure for scatter/gather I/O */
+struct iova_list {
+	rte_iova_t	addr;
+	uint32_t	len;
+};
+#define MAX_PAGE_BUFFER_COUNT		32
+
+/**
+ * Send a scattered buffer on the given channel
+ *
+ * @param channel
+ *	Pointer to vmbus_channel structure.
+ * @param type
+ *	Type of packet that is being send e.g. negotiate, time
+ *	packet etc.
+ * @param gpa
+ *	Array of buffers to send
+ * @param gpacnt
+ *	Number of elements in iov
+ * @param data
+ *	Pointer to the buffer additional data to send
+ * @param dlen
+ *	 Maximum size of what the the buffer will hold
+ * @param xact
+ *	Identifier of the request
+ * @param flags
+ *	Message type inband, rxbuf, gpa
+ * @param need_sig
+ *	Is host signal tx is required (optional)
+ *
+ * Sends data in buffer directly to hyper-v via the vmbus
+ */
+int rte_vmbus_chan_send_sglist(struct vmbus_channel *channel,
+			       struct vmbus_gpa gpa[], uint32_t gpacnt,
+			       void *data, uint32_t dlen,
+			       uint64_t xact, bool *need_sig);
+/**
+ * Receive response to request on the given channel
+ * skips the channel header.
+ *
+ * @param channel
+ *	Pointer to vmbus_channel structure.
+ * @param data
+ *	Pointer to the buffer you want to receive the data into.
+ * @param len
+ *	Pointer to size of receive buffer (in/out)
+ * @param
+ *	Pointer to received transaction_id
+ * @return
+ *   On success, returns 0
+ *   On failure, returns negative errno.
+ */
+int rte_vmbus_chan_recv(struct vmbus_channel *chan,
+			void *data, uint32_t *len,
+			uint64_t *request_id);
+
+/**
+ * Receive response to request on the given channel
+ * includes the channel header.
+ *
+ * @param channel
+ *	Pointer to vmbus_channel structure.
+ * @param data
+ *	Pointer to the buffer you want to receive the data into.
+ * @param len
+ *	Pointer to size of receive buffer (in/out)
+ * @return
+ *   On success, returns number of bytes read.
+ *   On failure, returns negative errno.
+ */
+int rte_vmbus_chan_recv_raw(struct vmbus_channel *chan,
+			    void *data, uint32_t *len);
+
+/**
+ * Notify host of bytes read (after recv_raw)
+ * Signals host if required.
+ *
+ * @param channel
+ *	Pointer to vmbus_channel structure.
+ * @param bytes_read
+ *	Number of bytes read since last signal
+ */
+void rte_vmbus_chan_signal_read(struct vmbus_channel *chan, uint32_t bytes_read);
+
+/**
+ * Determine sub channel index of the given channel
+ *
+ * @param channel
+ *	Pointer to vmbus_channel structure.
+ * @return
+ *   Sub channel index (0 for primary)
+ */
+uint16_t rte_vmbus_sub_channel_index(const struct vmbus_channel *chan);
+
+/**
+ * Register a VMBUS driver.
+ *
+ * @param driver
+ *   A pointer to a rte_vmbus_driver structure describing the driver
+ *   to be registered.
+ */
+void rte_vmbus_register(struct rte_vmbus_driver *driver);
+
+/**
+ * For debug dump contents of ring buffer.
+ *
+ * @param channel
+ *	Pointer to vmbus_channel structure.
+ */
+void rte_vmbus_chan_dump(FILE *f, const struct vmbus_channel *chan);
+
+/**
+ * Unregister a VMBUS driver.
+ *
+ * @param driver
+ *   A pointer to a rte_vmbus_driver structure describing the driver
+ *   to be unregistered.
+ */
+void rte_vmbus_unregister(struct rte_vmbus_driver *driver);
+
+/** Helper for VMBUS device registration from driver instance */
+#define RTE_PMD_REGISTER_VMBUS(nm, vmbus_drv)		\
+	RTE_INIT(vmbusinitfn_ ##nm);			\
+	static void vmbusinitfn_ ##nm(void)		\
+	{						\
+		(vmbus_drv).driver.name = RTE_STR(nm);	\
+		rte_vmbus_register(&vmbus_drv);		\
+	}						\
+	RTE_PMD_EXPORT_NAME(nm, __COUNTER__)
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _VMBUS_H_ */
diff --git a/drivers/bus/vmbus/rte_bus_vmbus_version.map b/drivers/bus/vmbus/rte_bus_vmbus_version.map
new file mode 100644
index 00000000..dabb9203
--- /dev/null
+++ b/drivers/bus/vmbus/rte_bus_vmbus_version.map
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+
+DPDK_18.08 {
+	global:
+
+	rte_vmbus_chan_close;
+	rte_vmbus_chan_open;
+	rte_vmbus_chan_recv;
+	rte_vmbus_chan_recv_raw;
+	rte_vmbus_chan_rx_empty;
+	rte_vmbus_chan_send;
+	rte_vmbus_chan_send_sglist;
+	rte_vmbus_chan_signal_read;
+	rte_vmbus_chan_signal_tx;
+	rte_vmbus_irq_mask;
+	rte_vmbus_irq_read;
+	rte_vmbus_irq_unmask;
+	rte_vmbus_map_device;
+	rte_vmbus_max_channels;
+	rte_vmbus_probe;
+	rte_vmbus_register;
+	rte_vmbus_scan;
+	rte_vmbus_sub_channel_index;
+	rte_vmbus_subchan_open;
+	rte_vmbus_unmap_device;
+	rte_vmbus_unregister;
+
+	local: *;
+};
diff --git a/drivers/bus/vmbus/rte_vmbus_reg.h b/drivers/bus/vmbus/rte_vmbus_reg.h
new file mode 100644
index 00000000..f5a0693d
--- /dev/null
+++ b/drivers/bus/vmbus/rte_vmbus_reg.h
@@ -0,0 +1,344 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright (c) 2018, Microsoft Corporation.
+ * All Rights Reserved.
+ */
+
+#ifndef _VMBUS_REG_H_
+#define _VMBUS_REG_H_
+
+/*
+ * Hyper-V SynIC message format.
+ */
+#define VMBUS_MSG_DSIZE_MAX		240
+#define VMBUS_MSG_SIZE			256
+
+struct vmbus_message {
+	uint32_t	type;	/* HYPERV_MSGTYPE_ */
+	uint8_t		dsize;	/* data size */
+	uint8_t		flags;	/* VMBUS_MSGFLAG_ */
+	uint16_t	rsvd;
+	uint64_t	id;
+	uint8_t		data[VMBUS_MSG_DSIZE_MAX];
+} __rte_packed;
+
+#define VMBUS_MSGFLAG_PENDING		0x01
+
+/*
+ * Hyper-V Monitor Notification Facility
+ */
+
+struct vmbus_mon_trig {
+	uint32_t	pending;
+	uint32_t	armed;
+} __rte_packed;
+
+#define VMBUS_MONTRIGS_MAX	4
+#define VMBUS_MONTRIG_LEN	32
+
+/*
+ * Hyper-V Monitor Notification Facility
+ */
+struct hyperv_mon_param {
+	uint32_t	connid;
+	uint16_t	evtflag_ofs;
+	uint16_t	rsvd;
+} __rte_packed;
+
+struct vmbus_mon_page {
+	uint32_t	state;
+	uint32_t	rsvd1;
+
+	struct vmbus_mon_trig trigs[VMBUS_MONTRIGS_MAX];
+	uint8_t		rsvd2[536];
+
+	uint16_t	lat[VMBUS_MONTRIGS_MAX][VMBUS_MONTRIG_LEN];
+	uint8_t		rsvd3[256];
+
+	struct hyperv_mon_param
+			param[VMBUS_MONTRIGS_MAX][VMBUS_MONTRIG_LEN];
+	uint8_t		rsvd4[1984];
+} __rte_packed;
+
+/*
+ * Buffer ring
+ */
+
+struct vmbus_bufring {
+	volatile uint32_t windex;
+	volatile uint32_t rindex;
+
+	/*
+	 * Interrupt mask {0,1}
+	 *
+	 * For TX bufring, host set this to 1, when it is processing
+	 * the TX bufring, so that we can safely skip the TX event
+	 * notification to host.
+	 *
+	 * For RX bufring, once this is set to 1 by us, host will not
+	 * further dispatch interrupts to us, even if there are data
+	 * pending on the RX bufring.  This effectively disables the
+	 * interrupt of the channel to which this RX bufring is attached.
+	 */
+	volatile uint32_t imask;
+
+	/*
+	 * Win8 uses some of the reserved bits to implement
+	 * interrupt driven flow management. On the send side
+	 * we can request that the receiver interrupt the sender
+	 * when the ring transitions from being full to being able
+	 * to handle a message of size "pending_send_sz".
+	 *
+	 * Add necessary state for this enhancement.
+	 */
+	volatile uint32_t pending_send;
+	uint32_t reserved1[12];
+
+	union {
+		struct {
+			uint32_t feat_pending_send_sz:1;
+		};
+		uint32_t value;
+	} feature_bits;
+
+	/* Pad it to PAGE_SIZE so that data starts on page boundary */
+	uint8_t	reserved2[4028];
+
+	/*
+	 * Ring data starts here + RingDataStartOffset
+	 * !!! DO NOT place any fields below this !!!
+	 */
+	uint8_t data[0];
+} __rte_packed;
+
+/*
+ * Channel packets
+ */
+
+/* Channel packet flags */
+#define VMBUS_CHANPKT_TYPE_INBAND      0x0006
+#define VMBUS_CHANPKT_TYPE_RXBUF       0x0007
+#define VMBUS_CHANPKT_TYPE_GPA         0x0009
+#define VMBUS_CHANPKT_TYPE_COMP        0x000b
+
+#define VMBUS_CHANPKT_FLAG_NONE        0
+#define VMBUS_CHANPKT_FLAG_RC          0x0001  /* report completion */
+
+#define VMBUS_CHANPKT_SIZE_SHIFT	3
+#define VMBUS_CHANPKT_SIZE_ALIGN	(1 << VMBUS_CHANPKT_SIZE_SHIFT)
+#define VMBUS_CHANPKT_HLEN_MIN		\
+	(sizeof(struct vmbus_chanpkt_hdr) >> VMBUS_CHANPKT_SIZE_SHIFT)
+
+static inline uint32_t
+vmbus_chanpkt_getlen(uint16_t pktlen)
+{
+	return (uint32_t)pktlen << VMBUS_CHANPKT_SIZE_SHIFT;
+}
+
+/*
+ * GPA stuffs.
+ */
+struct vmbus_gpa_range {
+	uint32_t       len;
+	uint32_t       ofs;
+	uint64_t       page[0];
+} __rte_packed;
+
+/* This is actually vmbus_gpa_range.gpa_page[1] */
+struct vmbus_gpa {
+	uint32_t	len;
+	uint32_t	ofs;
+	uint64_t	page;
+} __rte_packed;
+
+struct vmbus_chanpkt_hdr {
+	uint16_t	type;	/* VMBUS_CHANPKT_TYPE_ */
+	uint16_t	hlen;	/* header len, in 8 bytes */
+	uint16_t	tlen;	/* total len, in 8 bytes */
+	uint16_t	flags;	/* VMBUS_CHANPKT_FLAG_ */
+	uint64_t	xactid;
+} __rte_packed;
+
+static inline uint32_t
+vmbus_chanpkt_datalen(const struct vmbus_chanpkt_hdr *pkt)
+{
+	return vmbus_chanpkt_getlen(pkt->tlen)
+		- vmbus_chanpkt_getlen(pkt->hlen);
+}
+
+struct vmbus_chanpkt {
+	struct vmbus_chanpkt_hdr hdr;
+} __rte_packed;
+
+struct vmbus_rxbuf_desc {
+	uint32_t	len;
+	uint32_t	ofs;
+} __rte_packed;
+
+struct vmbus_chanpkt_rxbuf {
+	struct vmbus_chanpkt_hdr hdr;
+	uint16_t	rxbuf_id;
+	uint16_t	rsvd;
+	uint32_t	rxbuf_cnt;
+	struct vmbus_rxbuf_desc rxbuf[];
+} __rte_packed;
+
+struct vmbus_chanpkt_sglist {
+	struct vmbus_chanpkt_hdr hdr;
+	uint32_t	rsvd;
+	uint32_t	gpa_cnt;
+	struct vmbus_gpa gpa[];
+} __rte_packed;
+
+/*
+ * Channel messages
+ * - Embedded in vmbus_message.msg_data, e.g. response and notification.
+ * - Embedded in hypercall_postmsg_in.hc_data, e.g. request.
+ */
+
+#define VMBUS_CHANMSG_TYPE_CHOFFER		1	/* NOTE */
+#define VMBUS_CHANMSG_TYPE_CHRESCIND		2	/* NOTE */
+#define VMBUS_CHANMSG_TYPE_CHREQUEST		3	/* REQ */
+#define VMBUS_CHANMSG_TYPE_CHOFFER_DONE		4	/* NOTE */
+#define VMBUS_CHANMSG_TYPE_CHOPEN		5	/* REQ */
+#define VMBUS_CHANMSG_TYPE_CHOPEN_RESP		6	/* RESP */
+#define VMBUS_CHANMSG_TYPE_CHCLOSE		7	/* REQ */
+#define VMBUS_CHANMSG_TYPE_GPADL_CONN		8	/* REQ */
+#define VMBUS_CHANMSG_TYPE_GPADL_SUBCONN	9	/* REQ */
+#define VMBUS_CHANMSG_TYPE_GPADL_CONNRESP	10	/* RESP */
+#define VMBUS_CHANMSG_TYPE_GPADL_DISCONN	11	/* REQ */
+#define VMBUS_CHANMSG_TYPE_GPADL_DISCONNRESP	12	/* RESP */
+#define VMBUS_CHANMSG_TYPE_CHFREE		13	/* REQ */
+#define VMBUS_CHANMSG_TYPE_CONNECT		14	/* REQ */
+#define VMBUS_CHANMSG_TYPE_CONNECT_RESP		15	/* RESP */
+#define VMBUS_CHANMSG_TYPE_DISCONNECT		16	/* REQ */
+#define VMBUS_CHANMSG_TYPE_MAX			22
+
+struct vmbus_chanmsg_hdr {
+	uint32_t	type;	/* VMBUS_CHANMSG_TYPE_ */
+	uint32_t	rsvd;
+} __rte_packed;
+
+/* VMBUS_CHANMSG_TYPE_CONNECT */
+struct vmbus_chanmsg_connect {
+	struct vmbus_chanmsg_hdr hdr;
+	uint32_t	ver;
+	uint32_t	rsvd;
+	uint64_t	evtflags;
+	uint64_t	mnf1;
+	uint64_t	mnf2;
+} __rte_packed;
+
+/* VMBUS_CHANMSG_TYPE_CONNECT_RESP */
+struct vmbus_chanmsg_connect_resp {
+	struct vmbus_chanmsg_hdr hdr;
+	uint8_t		done;
+} __rte_packed;
+
+/* VMBUS_CHANMSG_TYPE_CHREQUEST */
+struct vmbus_chanmsg_chrequest {
+	struct vmbus_chanmsg_hdr hdr;
+} __rte_packed;
+
+/* VMBUS_CHANMSG_TYPE_DISCONNECT */
+struct vmbus_chanmsg_disconnect {
+	struct vmbus_chanmsg_hdr hdr;
+} __rte_packed;
+
+/* VMBUS_CHANMSG_TYPE_CHOPEN */
+struct vmbus_chanmsg_chopen {
+	struct vmbus_chanmsg_hdr hdr;
+	uint32_t	chanid;
+	uint32_t	openid;
+	uint32_t	gpadl;
+	uint32_t	vcpuid;
+	uint32_t	txbr_pgcnt;
+#define VMBUS_CHANMSG_CHOPEN_UDATA_SIZE	120
+	uint8_t		udata[VMBUS_CHANMSG_CHOPEN_UDATA_SIZE];
+} __rte_packed;
+
+/* VMBUS_CHANMSG_TYPE_CHOPEN_RESP */
+struct vmbus_chanmsg_chopen_resp {
+	struct vmbus_chanmsg_hdr hdr;
+	uint32_t	chanid;
+	uint32_t	openid;
+	uint32_t	status;
+} __rte_packed;
+
+/* VMBUS_CHANMSG_TYPE_GPADL_CONN */
+struct vmbus_chanmsg_gpadl_conn {
+	struct vmbus_chanmsg_hdr hdr;
+	uint32_t	chanid;
+	uint32_t	gpadl;
+	uint16_t	range_len;
+	uint16_t	range_cnt;
+	struct vmbus_gpa_range range;
+} __rte_packed;
+
+#define VMBUS_CHANMSG_GPADL_CONN_PGMAX		26
+
+/* VMBUS_CHANMSG_TYPE_GPADL_SUBCONN */
+struct vmbus_chanmsg_gpadl_subconn {
+	struct vmbus_chanmsg_hdr hdr;
+	uint32_t	msgno;
+	uint32_t	gpadl;
+	uint64_t	gpa_page[];
+} __rte_packed;
+
+#define VMBUS_CHANMSG_GPADL_SUBCONN_PGMAX	28
+
+/* VMBUS_CHANMSG_TYPE_GPADL_CONNRESP */
+struct vmbus_chanmsg_gpadl_connresp {
+	struct vmbus_chanmsg_hdr hdr;
+	uint32_t	chanid;
+	uint32_t	gpadl;
+	uint32_t	status;
+} __rte_packed;
+
+/* VMBUS_CHANMSG_TYPE_CHCLOSE */
+struct vmbus_chanmsg_chclose {
+	struct vmbus_chanmsg_hdr hdr;
+	uint32_t	chanid;
+} __rte_packed;
+
+/* VMBUS_CHANMSG_TYPE_GPADL_DISCONN */
+struct vmbus_chanmsg_gpadl_disconn {
+	struct vmbus_chanmsg_hdr hdr;
+	uint32_t	chanid;
+	uint32_t	gpadl;
+} __rte_packed;
+
+/* VMBUS_CHANMSG_TYPE_CHFREE */
+struct vmbus_chanmsg_chfree {
+	struct vmbus_chanmsg_hdr hdr;
+	uint32_t	chanid;
+} __rte_packed;
+
+/* VMBUS_CHANMSG_TYPE_CHRESCIND */
+struct vmbus_chanmsg_chrescind {
+	struct vmbus_chanmsg_hdr hdr;
+	uint32_t	chanid;
+} __rte_packed;
+
+/* VMBUS_CHANMSG_TYPE_CHOFFER */
+struct vmbus_chanmsg_choffer {
+	struct vmbus_chanmsg_hdr hdr;
+	rte_uuid_t	chtype;
+	rte_uuid_t	chinst;
+	uint64_t	chlat;	/* unit: 100ns */
+	uint32_t	chrev;
+	uint32_t	svrctx_sz;
+	uint16_t	chflags;
+	uint16_t	mmio_sz;	/* unit: MB */
+	uint8_t		udata[120];
+	uint16_t	subidx;
+	uint16_t	rsvd;
+	uint32_t	chanid;
+	uint8_t		montrig;
+	uint8_t		flags1;	/* VMBUS_CHOFFER_FLAG1_ */
+	uint16_t	flags2;
+	uint32_t	connid;
+} __rte_packed;
+
+#define VMBUS_CHOFFER_FLAG1_HASMNF	0x01
+
+#endif	/* !_VMBUS_REG_H_ */
diff --git a/drivers/bus/vmbus/vmbus_bufring.c b/drivers/bus/vmbus/vmbus_bufring.c
new file mode 100644
index 00000000..c8800160
--- /dev/null
+++ b/drivers/bus/vmbus/vmbus_bufring.c
@@ -0,0 +1,244 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright (c) 2009-2012,2016 Microsoft Corp.
+ * Copyright (c) 2012 NetApp Inc.
+ * Copyright (c) 2012 Citrix Inc.
+ * All rights reserved.
+ */
+
+#include <unistd.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <string.h>
+#include <sys/uio.h>
+
+#include <rte_eal.h>
+#include <rte_tailq.h>
+#include <rte_log.h>
+#include <rte_malloc.h>
+#include <rte_bus.h>
+#include <rte_atomic.h>
+#include <rte_memory.h>
+#include <rte_pause.h>
+#include <rte_bus_vmbus.h>
+
+#include "private.h"
+
+/* Increase bufring index by inc with wraparound */
+static inline uint32_t vmbus_br_idxinc(uint32_t idx, uint32_t inc, uint32_t sz)
+{
+	idx += inc;
+	if (idx >= sz)
+		idx -= sz;
+
+	return idx;
+}
+
+void vmbus_br_setup(struct vmbus_br *br, void *buf, unsigned int blen)
+{
+	br->vbr = buf;
+	br->windex = br->vbr->windex;
+	br->dsize = blen - sizeof(struct vmbus_bufring);
+}
+
+/*
+ * When we write to the ring buffer, check if the host needs to be
+ * signaled.
+ *
+ * The contract:
+ * - The host guarantees that while it is draining the TX bufring,
+ *   it will set the br_imask to indicate it does not need to be
+ *   interrupted when new data are added.
+ * - The host guarantees that it will completely drain the TX bufring
+ *   before exiting the read loop.  Further, once the TX bufring is
+ *   empty, it will clear the br_imask and re-check to see if new
+ *   data have arrived.
+ */
+static inline bool
+vmbus_txbr_need_signal(const struct vmbus_br *tbr, uint32_t old_windex)
+{
+	rte_smp_mb();
+	if (tbr->vbr->imask)
+		return false;
+
+	rte_smp_rmb();
+
+	/*
+	 * This is the only case we need to signal when the
+	 * ring transitions from being empty to non-empty.
+	 */
+	return old_windex == tbr->vbr->rindex;
+}
+
+static inline uint32_t
+vmbus_txbr_copyto(const struct vmbus_br *tbr, uint32_t windex,
+		  const void *src0, uint32_t cplen)
+{
+	uint8_t *br_data = tbr->vbr->data;
+	uint32_t br_dsize = tbr->dsize;
+	const uint8_t *src = src0;
+
+	/* XXX use double mapping like Linux kernel? */
+	if (cplen > br_dsize - windex) {
+		uint32_t fraglen = br_dsize - windex;
+
+		/* Wrap-around detected */
+		memcpy(br_data + windex, src, fraglen);
+		memcpy(br_data, src + fraglen, cplen - fraglen);
+	} else {
+		memcpy(br_data + windex, src, cplen);
+	}
+
+	return vmbus_br_idxinc(windex, cplen, br_dsize);
+}
+
+/*
+ * Write scattered channel packet to TX bufring.
+ *
+ * The offset of this channel packet is written as a 64bits value
+ * immediately after this channel packet.
+ *
+ * The write goes through three stages:
+ *  1. Reserve space in ring buffer for the new data.
+ *     Writer atomically moves priv_write_index.
+ *  2. Copy the new data into the ring.
+ *  3. Update the tail of the ring (visible to host) that indicates
+ *     next read location. Writer updates write_index
+ */
+int
+vmbus_txbr_write(struct vmbus_br *tbr, const struct iovec iov[], int iovlen,
+		 bool *need_sig)
+{
+	struct vmbus_bufring *vbr = tbr->vbr;
+	uint32_t ring_size = tbr->dsize;
+	uint32_t old_windex, next_windex, windex, total;
+	uint64_t save_windex;
+	int i;
+
+	total = 0;
+	for (i = 0; i < iovlen; i++)
+		total += iov[i].iov_len;
+	total += sizeof(save_windex);
+
+	/* Reserve space in ring */
+	do {
+		uint32_t avail;
+
+		/* Get current free location */
+		old_windex = tbr->windex;
+
+		/* Prevent compiler reordering this with calculation */
+		rte_compiler_barrier();
+
+		avail = vmbus_br_availwrite(tbr, old_windex);
+
+		/* If not enough space in ring, then tell caller. */
+		if (avail <= total)
+			return -EAGAIN;
+
+		next_windex = vmbus_br_idxinc(old_windex, total, ring_size);
+
+		/* Atomic update of next write_index for other threads */
+	} while (!rte_atomic32_cmpset(&tbr->windex, old_windex, next_windex));
+
+	/* Space from old..new is now reserved */
+	windex = old_windex;
+	for (i = 0; i < iovlen; i++) {
+		windex = vmbus_txbr_copyto(tbr, windex,
+					   iov[i].iov_base, iov[i].iov_len);
+	}
+
+	/* Set the offset of the current channel packet. */
+	save_windex = ((uint64_t)old_windex) << 32;
+	windex = vmbus_txbr_copyto(tbr, windex, &save_windex,
+				   sizeof(save_windex));
+
+	/* The region reserved should match region used */
+	RTE_ASSERT(windex == next_windex);
+
+	/* Ensure that data is available before updating host index */
+	rte_smp_wmb();
+
+	/* Checkin for our reservation. wait for our turn to update host */
+	while (!rte_atomic32_cmpset(&vbr->windex, old_windex, next_windex))
+		rte_pause();
+
+	/* If host had read all data before this, then need to signal */
+	*need_sig |= vmbus_txbr_need_signal(tbr, old_windex);
+	return 0;
+}
+
+static inline uint32_t
+vmbus_rxbr_copyfrom(const struct vmbus_br *rbr, uint32_t rindex,
+		    void *dst0, size_t cplen)
+{
+	const uint8_t *br_data = rbr->vbr->data;
+	uint32_t br_dsize = rbr->dsize;
+	uint8_t *dst = dst0;
+
+	if (cplen > br_dsize - rindex) {
+		uint32_t fraglen = br_dsize - rindex;
+
+		/* Wrap-around detected. */
+		memcpy(dst, br_data + rindex, fraglen);
+		memcpy(dst + fraglen, br_data, cplen - fraglen);
+	} else {
+		memcpy(dst, br_data + rindex, cplen);
+	}
+
+	return vmbus_br_idxinc(rindex, cplen, br_dsize);
+}
+
+/* Copy data from receive ring but don't change index */
+int
+vmbus_rxbr_peek(const struct vmbus_br *rbr, void *data, size_t dlen)
+{
+	uint32_t avail;
+
+	/*
+	 * The requested data and the 64bits channel packet
+	 * offset should be there at least.
+	 */
+	avail = vmbus_br_availread(rbr);
+	if (avail < dlen + sizeof(uint64_t))
+		return -EAGAIN;
+
+	vmbus_rxbr_copyfrom(rbr, rbr->vbr->rindex, data, dlen);
+	return 0;
+}
+
+/*
+ * Copy data from receive ring and change index
+ * NOTE:
+ * We assume (dlen + skip) == sizeof(channel packet).
+ */
+int
+vmbus_rxbr_read(struct vmbus_br *rbr, void *data, size_t dlen, size_t skip)
+{
+	struct vmbus_bufring *vbr = rbr->vbr;
+	uint32_t br_dsize = rbr->dsize;
+	uint32_t rindex;
+
+	if (vmbus_br_availread(rbr) < dlen + skip + sizeof(uint64_t))
+		return -EAGAIN;
+
+	/* Record where host was when we started read (for debug) */
+	rbr->windex = rbr->vbr->windex;
+
+	/*
+	 * Copy channel packet from RX bufring.
+	 */
+	rindex = vmbus_br_idxinc(rbr->vbr->rindex, skip, br_dsize);
+	rindex = vmbus_rxbr_copyfrom(rbr, rindex, data, dlen);
+
+	/*
+	 * Discard this channel packet's 64bits offset, which is useless to us.
+	 */
+	rindex = vmbus_br_idxinc(rindex, sizeof(uint64_t), br_dsize);
+
+	/* Update the read index _after_ the channel packet is fetched.	 */
+	rte_compiler_barrier();
+
+	vbr->rindex = rindex;
+
+	return 0;
+}
diff --git a/drivers/bus/vmbus/vmbus_channel.c b/drivers/bus/vmbus/vmbus_channel.c
new file mode 100644
index 00000000..cc5f3e83
--- /dev/null
+++ b/drivers/bus/vmbus/vmbus_channel.c
@@ -0,0 +1,405 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright (c) 2018, Microsoft Corporation.
+ * All Rights Reserved.
+ */
+
+#include <unistd.h>
+#include <stdint.h>
+#include <string.h>
+#include <sys/uio.h>
+
+#include <rte_eal.h>
+#include <rte_tailq.h>
+#include <rte_log.h>
+#include <rte_malloc.h>
+#include <rte_bus.h>
+#include <rte_atomic.h>
+#include <rte_memory.h>
+#include <rte_bus_vmbus.h>
+
+#include "private.h"
+
+static inline void
+vmbus_sync_set_bit(volatile uint32_t *addr, uint32_t mask)
+{
+	/* Use GCC builtin which atomic does atomic OR operation */
+	__sync_or_and_fetch(addr, mask);
+}
+
+static inline void
+vmbus_send_interrupt(const struct rte_vmbus_device *dev, uint32_t relid)
+{
+	uint32_t *int_addr;
+	uint32_t int_mask;
+
+	int_addr = dev->int_page + relid / 32;
+	int_mask = 1u << (relid % 32);
+
+	vmbus_sync_set_bit(int_addr, int_mask);
+}
+
+static inline void
+vmbus_set_monitor(const struct rte_vmbus_device *dev, uint32_t monitor_id)
+{
+	uint32_t *monitor_addr, monitor_mask;
+	unsigned int trigger_index;
+
+	trigger_index = monitor_id / HV_MON_TRIG_LEN;
+	monitor_mask = 1u << (monitor_id % HV_MON_TRIG_LEN);
+
+	monitor_addr = &dev->monitor_page->trigs[trigger_index].pending;
+	vmbus_sync_set_bit(monitor_addr, monitor_mask);
+}
+
+static void
+vmbus_set_event(const struct rte_vmbus_device *dev,
+		const struct vmbus_channel *chan)
+{
+	vmbus_send_interrupt(dev, chan->relid);
+	vmbus_set_monitor(dev, chan->monitor_id);
+}
+
+/*
+ * Notify host that there are data pending on our TX bufring.
+ *
+ * Since this in userspace, rely on the monitor page.
+ * Can't do a hypercall from userspace.
+ */
+void
+rte_vmbus_chan_signal_tx(const struct vmbus_channel *chan)
+{
+	const struct rte_vmbus_device *dev = chan->device;
+	const struct vmbus_br *tbr = &chan->txbr;
+
+	/* Make sure all updates are done before signaling host */
+	rte_smp_wmb();
+
+	/* If host is ignoring interrupts? */
+	if (tbr->vbr->imask)
+		return;
+
+	vmbus_set_event(dev, chan);
+}
+
+
+/* Do a simple send directly using transmit ring. */
+int rte_vmbus_chan_send(struct vmbus_channel *chan, uint16_t type,
+			void *data, uint32_t dlen,
+			uint64_t xactid, uint32_t flags, bool *need_sig)
+{
+	struct vmbus_chanpkt pkt;
+	unsigned int pktlen, pad_pktlen;
+	const uint32_t hlen = sizeof(pkt);
+	bool send_evt = false;
+	uint64_t pad = 0;
+	struct iovec iov[3];
+	int error;
+
+	pktlen = hlen + dlen;
+	pad_pktlen = RTE_ALIGN(pktlen, sizeof(uint64_t));
+
+	pkt.hdr.type = type;
+	pkt.hdr.flags = flags;
+	pkt.hdr.hlen = hlen >> VMBUS_CHANPKT_SIZE_SHIFT;
+	pkt.hdr.tlen = pad_pktlen >> VMBUS_CHANPKT_SIZE_SHIFT;
+	pkt.hdr.xactid = xactid;
+
+	iov[0].iov_base = &pkt;
+	iov[0].iov_len = hlen;
+	iov[1].iov_base = data;
+	iov[1].iov_len = dlen;
+	iov[2].iov_base = &pad;
+	iov[2].iov_len = pad_pktlen - pktlen;
+
+	error = vmbus_txbr_write(&chan->txbr, iov, 3, &send_evt);
+
+	/*
+	 * caller sets need_sig to non-NULL if it will handle
+	 * signaling if required later.
+	 * if need_sig is NULL, signal now if needed.
+	 */
+	if (need_sig)
+		*need_sig |= send_evt;
+	else if (error == 0 && send_evt)
+		rte_vmbus_chan_signal_tx(chan);
+	return error;
+}
+
+/* Do a scatter/gather send where the descriptor points to data. */
+int rte_vmbus_chan_send_sglist(struct vmbus_channel *chan,
+			       struct vmbus_gpa sg[], uint32_t sglen,
+			       void *data, uint32_t dlen,
+			       uint64_t xactid, bool *need_sig)
+{
+	struct vmbus_chanpkt_sglist pkt;
+	unsigned int pktlen, pad_pktlen, hlen;
+	bool send_evt = false;
+	struct iovec iov[4];
+	uint64_t pad = 0;
+	int error;
+
+	hlen = offsetof(struct vmbus_chanpkt_sglist, gpa[sglen]);
+	pktlen = hlen + dlen;
+	pad_pktlen = RTE_ALIGN(pktlen, sizeof(uint64_t));
+
+	pkt.hdr.type = VMBUS_CHANPKT_TYPE_GPA;
+	pkt.hdr.flags = VMBUS_CHANPKT_FLAG_RC;
+	pkt.hdr.hlen = hlen >> VMBUS_CHANPKT_SIZE_SHIFT;
+	pkt.hdr.tlen = pad_pktlen >> VMBUS_CHANPKT_SIZE_SHIFT;
+	pkt.hdr.xactid = xactid;
+	pkt.rsvd = 0;
+	pkt.gpa_cnt = sglen;
+
+	iov[0].iov_base = &pkt;
+	iov[0].iov_len = sizeof(pkt);
+	iov[1].iov_base = sg;
+	iov[1].iov_len = sizeof(struct vmbus_gpa) * sglen;
+	iov[2].iov_base = data;
+	iov[2].iov_len = dlen;
+	iov[3].iov_base = &pad;
+	iov[3].iov_len = pad_pktlen - pktlen;
+
+	error = vmbus_txbr_write(&chan->txbr, iov, 4, &send_evt);
+
+	/* if caller is batching, just propagate the status */
+	if (need_sig)
+		*need_sig |= send_evt;
+	else if (error == 0 && send_evt)
+		rte_vmbus_chan_signal_tx(chan);
+	return error;
+}
+
+bool rte_vmbus_chan_rx_empty(const struct vmbus_channel *channel)
+{
+	const struct vmbus_br *br = &channel->rxbr;
+
+	return br->vbr->rindex == br->vbr->windex;
+}
+
+/* Signal host after reading N bytes */
+void rte_vmbus_chan_signal_read(struct vmbus_channel *chan, uint32_t bytes_read)
+{
+	struct vmbus_br *rbr = &chan->rxbr;
+	uint32_t write_sz, pending_sz;
+
+	/* No need for signaling on older versions */
+	if (!rbr->vbr->feature_bits.feat_pending_send_sz)
+		return;
+
+	/* Make sure reading of pending happens after new read index */
+	rte_mb();
+
+	pending_sz = rbr->vbr->pending_send;
+	if (!pending_sz)
+		return;
+
+	rte_smp_rmb();
+	write_sz = vmbus_br_availwrite(rbr, rbr->vbr->windex);
+
+	/* If there was space before then host was not blocked */
+	if (write_sz - bytes_read > pending_sz)
+		return;
+
+	/* If pending write will not fit */
+	if (write_sz <= pending_sz)
+		return;
+
+	vmbus_set_event(chan->device, chan);
+}
+
+int rte_vmbus_chan_recv(struct vmbus_channel *chan, void *data, uint32_t *len,
+			uint64_t *request_id)
+{
+	struct vmbus_chanpkt_hdr pkt;
+	uint32_t dlen, hlen, bufferlen = *len;
+	int error;
+
+	*len = 0;
+
+	error = vmbus_rxbr_peek(&chan->rxbr, &pkt, sizeof(pkt));
+	if (error)
+		return error;
+
+	if (unlikely(pkt.hlen < VMBUS_CHANPKT_HLEN_MIN)) {
+		VMBUS_LOG(ERR, "VMBUS recv, invalid hlen %u", pkt.hlen);
+		/* XXX this channel is dead actually. */
+		return -EIO;
+	}
+
+	if (unlikely(pkt.hlen > pkt.tlen)) {
+		VMBUS_LOG(ERR, "VMBUS recv,invalid hlen %u and tlen %u",
+			  pkt.hlen, pkt.tlen);
+		return -EIO;
+	}
+
+	/* Length are in quad words */
+	hlen = pkt.hlen << VMBUS_CHANPKT_SIZE_SHIFT;
+	dlen = (pkt.tlen << VMBUS_CHANPKT_SIZE_SHIFT) - hlen;
+	*len = dlen;
+
+	/* If caller buffer is not large enough */
+	if (unlikely(dlen > bufferlen))
+		return -ENOBUFS;
+
+	if (request_id)
+		*request_id = pkt.xactid;
+
+	/* Read data and skip packet header */
+	error = vmbus_rxbr_read(&chan->rxbr, data, dlen, hlen);
+	if (error)
+		return error;
+
+	rte_vmbus_chan_signal_read(chan, dlen + hlen + sizeof(uint64_t));
+	return 0;
+}
+
+/* TODO: replace this with inplace ring buffer (no copy) */
+int rte_vmbus_chan_recv_raw(struct vmbus_channel *chan,
+			    void *data, uint32_t *len)
+{
+	struct vmbus_chanpkt_hdr pkt;
+	uint32_t dlen, bufferlen = *len;
+	int error;
+
+	error = vmbus_rxbr_peek(&chan->rxbr, &pkt, sizeof(pkt));
+	if (error)
+		return error;
+
+	if (unlikely(pkt.hlen < VMBUS_CHANPKT_HLEN_MIN)) {
+		VMBUS_LOG(ERR, "VMBUS recv, invalid hlen %u", pkt.hlen);
+		/* XXX this channel is dead actually. */
+		return -EIO;
+	}
+
+	if (unlikely(pkt.hlen > pkt.tlen)) {
+		VMBUS_LOG(ERR, "VMBUS recv,invalid hlen %u and tlen %u",
+			pkt.hlen, pkt.tlen);
+		return -EIO;
+	}
+
+	/* Length are in quad words */
+	dlen = pkt.tlen << VMBUS_CHANPKT_SIZE_SHIFT;
+	*len = dlen;
+
+	/* If caller buffer is not large enough */
+	if (unlikely(dlen > bufferlen))
+		return -ENOBUFS;
+
+	/* Read data and skip packet header */
+	error = vmbus_rxbr_read(&chan->rxbr, data, dlen, 0);
+	if (error)
+		return error;
+
+	/* Return the number of bytes read */
+	return dlen + sizeof(uint64_t);
+}
+
+int vmbus_chan_create(const struct rte_vmbus_device *device,
+		      uint16_t relid, uint16_t subid, uint8_t monitor_id,
+		      struct vmbus_channel **new_chan)
+{
+	struct vmbus_channel *chan;
+	int err;
+
+	chan = rte_zmalloc_socket("VMBUS", sizeof(*chan), RTE_CACHE_LINE_SIZE,
+				  device->device.numa_node);
+	if (!chan)
+		return -ENOMEM;
+
+	STAILQ_INIT(&chan->subchannel_list);
+	chan->device = device;
+	chan->subchannel_id = subid;
+	chan->relid = relid;
+	chan->monitor_id = monitor_id;
+	*new_chan = chan;
+
+	err = vmbus_uio_map_rings(chan);
+	if (err) {
+		rte_free(chan);
+		return err;
+	}
+
+	return 0;
+}
+
+/* Setup the primary channel */
+int rte_vmbus_chan_open(struct rte_vmbus_device *device,
+			struct vmbus_channel **new_chan)
+{
+	int err;
+
+	err = vmbus_chan_create(device, device->relid, 0,
+				device->monitor_id, new_chan);
+	if (!err)
+		device->primary = *new_chan;
+
+	return err;
+}
+
+int rte_vmbus_max_channels(const struct rte_vmbus_device *device)
+{
+	if (vmbus_uio_subchannels_supported(device, device->primary))
+		return VMBUS_MAX_CHANNELS;
+	else
+		return 1;
+}
+
+/* Setup secondary channel */
+int rte_vmbus_subchan_open(struct vmbus_channel *primary,
+			   struct vmbus_channel **new_chan)
+{
+	struct vmbus_channel *chan;
+	int err;
+
+	err = vmbus_uio_get_subchan(primary, &chan);
+	if (err)
+		return err;
+
+	STAILQ_INSERT_TAIL(&primary->subchannel_list, chan, next);
+	*new_chan = chan;
+	return 0;
+}
+
+uint16_t rte_vmbus_sub_channel_index(const struct vmbus_channel *chan)
+{
+	return chan->subchannel_id;
+}
+
+void rte_vmbus_chan_close(struct vmbus_channel *chan)
+{
+	const struct rte_vmbus_device *device = chan->device;
+	struct vmbus_channel *primary = device->primary;
+
+	if (chan != primary)
+		STAILQ_REMOVE(&primary->subchannel_list, chan,
+			      vmbus_channel, next);
+
+	rte_free(chan);
+}
+
+static void vmbus_dump_ring(FILE *f, const char *id, const struct vmbus_br *br)
+{
+	const struct vmbus_bufring *vbr = br->vbr;
+	struct vmbus_chanpkt_hdr pkt;
+
+	fprintf(f, "%s windex=%u rindex=%u mask=%u pending=%u feature=%#x\n",
+		id, vbr->windex, vbr->rindex, vbr->imask,
+		vbr->pending_send, vbr->feature_bits.value);
+	fprintf(f, " size=%u avail write=%u read=%u\n",
+		br->dsize, vmbus_br_availwrite(br, vbr->windex),
+		vmbus_br_availread(br));
+
+	if (vmbus_rxbr_peek(br, &pkt, sizeof(pkt)) == 0)
+		fprintf(f, "  pkt type %#x len %u flags %#x xactid %#"PRIx64"\n",
+			pkt.type,
+			pkt.tlen << VMBUS_CHANPKT_SIZE_SHIFT,
+			pkt.flags, pkt.xactid);
+}
+
+void rte_vmbus_chan_dump(FILE *f, const struct vmbus_channel *chan)
+{
+	fprintf(f, "channel[%u] relid=%u monitor=%u\n",
+		chan->subchannel_id, chan->relid, chan->monitor_id);
+	vmbus_dump_ring(f, "rxbr", &chan->rxbr);
+	vmbus_dump_ring(f, "txbr", &chan->txbr);
+}
diff --git a/drivers/bus/vmbus/vmbus_common.c b/drivers/bus/vmbus/vmbus_common.c
new file mode 100644
index 00000000..c7165ad5
--- /dev/null
+++ b/drivers/bus/vmbus/vmbus_common.c
@@ -0,0 +1,286 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright (c) 2018, Microsoft Corporation.
+ * All Rights Reserved.
+ */
+
+#include <string.h>
+#include <unistd.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <sys/queue.h>
+#include <sys/mman.h>
+
+#include <rte_log.h>
+#include <rte_bus.h>
+#include <rte_eal.h>
+#include <rte_tailq.h>
+#include <rte_devargs.h>
+#include <rte_malloc.h>
+#include <rte_errno.h>
+#include <rte_memory.h>
+#include <rte_bus_vmbus.h>
+
+#include "private.h"
+
+int vmbus_logtype_bus;
+extern struct rte_vmbus_bus rte_vmbus_bus;
+
+/* map a particular resource from a file */
+void *
+vmbus_map_resource(void *requested_addr, int fd, off_t offset, size_t size,
+		   int flags)
+{
+	void *mapaddr;
+
+	/* Map the memory resource of device */
+	mapaddr = mmap(requested_addr, size, PROT_READ | PROT_WRITE,
+		       MAP_SHARED | flags, fd, offset);
+	if (mapaddr == MAP_FAILED) {
+		VMBUS_LOG(ERR,
+			  "mmap(%d, %p, %zu, %ld) failed: %s",
+			  fd, requested_addr, size, (long)offset,
+			  strerror(errno));
+	}
+	return mapaddr;
+}
+
+/* unmap a particular resource */
+void
+vmbus_unmap_resource(void *requested_addr, size_t size)
+{
+	if (requested_addr == NULL)
+		return;
+
+	/* Unmap the VMBUS memory resource of device */
+	if (munmap(requested_addr, size)) {
+		VMBUS_LOG(ERR, "munmap(%p, 0x%lx) failed: %s",
+			requested_addr, (unsigned long)size,
+			strerror(errno));
+	} else
+		VMBUS_LOG(DEBUG, "  VMBUS memory unmapped at %p",
+			  requested_addr);
+}
+
+/**
+ * Match the VMBUS driver and device using UUID table
+ *
+ * @param drv
+ *	VMBUS driver from which ID table would be extracted
+ * @param pci_dev
+ *	VMBUS device to match against the driver
+ * @return
+ *	true for successful match
+ *	false for unsuccessful match
+ */
+static bool
+vmbus_match(const struct rte_vmbus_driver *dr,
+	    const struct rte_vmbus_device *dev)
+{
+	const rte_uuid_t *id_table;
+
+	for (id_table = dr->id_table; !rte_uuid_is_null(*id_table); ++id_table) {
+		if (rte_uuid_compare(*id_table, dev->class_id) == 0)
+			return true;
+	}
+
+	return false;
+}
+
+/*
+ * If device ID match, call the devinit() function of the driver.
+ */
+static int
+vmbus_probe_one_driver(struct rte_vmbus_driver *dr,
+		       struct rte_vmbus_device *dev)
+{
+	char guid[RTE_UUID_STRLEN];
+	int ret;
+
+	if (!vmbus_match(dr, dev))
+		return 1;	 /* not supported */
+
+	rte_uuid_unparse(dev->device_id, guid, sizeof(guid));
+	VMBUS_LOG(INFO, "VMBUS device %s on NUMA socket %i",
+		  guid, dev->device.numa_node);
+
+	/* TODO add blacklisted */
+
+	/* map resources for device */
+	ret = rte_vmbus_map_device(dev);
+	if (ret != 0)
+		return ret;
+
+	/* reference driver structure */
+	dev->driver = dr;
+	dev->device.driver = &dr->driver;
+
+	if (dev->device.numa_node < 0) {
+		VMBUS_LOG(WARNING, "  Invalid NUMA socket, default to 0");
+		dev->device.numa_node = 0;
+	}
+
+	/* call the driver probe() function */
+	VMBUS_LOG(INFO, "  probe driver: %s", dr->driver.name);
+	ret = dr->probe(dr, dev);
+	if (ret) {
+		dev->driver = NULL;
+		rte_vmbus_unmap_device(dev);
+	}
+
+	return ret;
+}
+
+/*
+ * IF device class GUID mathces, call the probe function of
+ * registere drivers for the vmbus device.
+ * Return -1 if initialization failed,
+ * and 1 if no driver found for this device.
+ */
+static int
+vmbus_probe_all_drivers(struct rte_vmbus_device *dev)
+{
+	struct rte_vmbus_driver *dr;
+	int rc;
+
+	/* Check if a driver is already loaded */
+	if (dev->driver != NULL) {
+		VMBUS_LOG(DEBUG, "VMBUS driver already loaded");
+		return 0;
+	}
+
+	FOREACH_DRIVER_ON_VMBUS(dr) {
+		rc = vmbus_probe_one_driver(dr, dev);
+		if (rc < 0) /* negative is an error */
+			return -1;
+
+		if (rc > 0) /* positive driver doesn't support it */
+			continue;
+
+		return 0;
+	}
+	return 1;
+}
+
+/*
+ * Scan the vmbus, and call the devinit() function for
+ * all registered drivers that have a matching entry in its id_table
+ * for discovered devices.
+ */
+int
+rte_vmbus_probe(void)
+{
+	struct rte_vmbus_device *dev;
+	size_t probed = 0, failed = 0;
+	char ubuf[RTE_UUID_STRLEN];
+
+	FOREACH_DEVICE_ON_VMBUS(dev) {
+		probed++;
+
+		rte_uuid_unparse(dev->device_id, ubuf, sizeof(ubuf));
+
+		/* TODO: add whitelist/blacklist */
+
+		if (vmbus_probe_all_drivers(dev) < 0) {
+			VMBUS_LOG(NOTICE,
+				"Requested device %s cannot be used", ubuf);
+			rte_errno = errno;
+			failed++;
+		}
+	}
+
+	return (probed && probed == failed) ? -1 : 0;
+}
+
+static int
+vmbus_parse(const char *name, void *addr)
+{
+	rte_uuid_t guid;
+	int ret;
+
+	ret = rte_uuid_parse(name, guid);
+	if (ret == 0 && addr)
+		memcpy(addr, &guid, sizeof(guid));
+
+	return ret;
+}
+
+/* register vmbus driver */
+void
+rte_vmbus_register(struct rte_vmbus_driver *driver)
+{
+	VMBUS_LOG(DEBUG,
+		"Registered driver %s", driver->driver.name);
+
+	TAILQ_INSERT_TAIL(&rte_vmbus_bus.driver_list, driver, next);
+	driver->bus = &rte_vmbus_bus;
+}
+
+/* unregister vmbus driver */
+void
+rte_vmbus_unregister(struct rte_vmbus_driver *driver)
+{
+	TAILQ_REMOVE(&rte_vmbus_bus.driver_list, driver, next);
+	driver->bus = NULL;
+}
+
+/* Add a device to VMBUS bus */
+void
+vmbus_add_device(struct rte_vmbus_device *vmbus_dev)
+{
+	TAILQ_INSERT_TAIL(&rte_vmbus_bus.device_list, vmbus_dev, next);
+}
+
+/* Insert a device into a predefined position in VMBUS bus */
+void
+vmbus_insert_device(struct rte_vmbus_device *exist_vmbus_dev,
+		      struct rte_vmbus_device *new_vmbus_dev)
+{
+	TAILQ_INSERT_BEFORE(exist_vmbus_dev, new_vmbus_dev, next);
+}
+
+/* Remove a device from VMBUS bus */
+void
+vmbus_remove_device(struct rte_vmbus_device *vmbus_dev)
+{
+	TAILQ_REMOVE(&rte_vmbus_bus.device_list, vmbus_dev, next);
+}
+
+/* VMBUS doesn't support hotplug */
+static struct rte_device *
+vmbus_find_device(const struct rte_device *start, rte_dev_cmp_t cmp,
+		  const void *data)
+{
+	struct rte_vmbus_device *dev;
+
+	FOREACH_DEVICE_ON_VMBUS(dev) {
+		if (start && &dev->device == start) {
+			start = NULL;
+			continue;
+		}
+		if (cmp(&dev->device, data) == 0)
+			return &dev->device;
+	}
+
+	return NULL;
+}
+
+
+struct rte_vmbus_bus rte_vmbus_bus = {
+	.bus = {
+		.scan = rte_vmbus_scan,
+		.probe = rte_vmbus_probe,
+		.find_device = vmbus_find_device,
+		.parse = vmbus_parse,
+	},
+	.device_list = TAILQ_HEAD_INITIALIZER(rte_vmbus_bus.device_list),
+	.driver_list = TAILQ_HEAD_INITIALIZER(rte_vmbus_bus.driver_list),
+};
+
+RTE_REGISTER_BUS(vmbus, rte_vmbus_bus.bus);
+
+RTE_INIT(vmbus_init_log)
+{
+	vmbus_logtype_bus = rte_log_register("bus.vmbus");
+	if (vmbus_logtype_bus >= 0)
+		rte_log_set_level(vmbus_logtype_bus, RTE_LOG_NOTICE);
+}
diff --git a/drivers/bus/vmbus/vmbus_common_uio.c b/drivers/bus/vmbus/vmbus_common_uio.c
new file mode 100644
index 00000000..5ddd36ab
--- /dev/null
+++ b/drivers/bus/vmbus/vmbus_common_uio.c
@@ -0,0 +1,232 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright (c) 2018, Microsoft Corporation.
+ * All Rights Reserved.
+ */
+
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/mman.h>
+
+#include <rte_eal.h>
+#include <rte_tailq.h>
+#include <rte_log.h>
+#include <rte_malloc.h>
+#include <rte_bus.h>
+#include <rte_bus_vmbus.h>
+
+#include "private.h"
+
+static struct rte_tailq_elem vmbus_tailq = {
+	.name = "VMBUS_RESOURCE_LIST",
+};
+EAL_REGISTER_TAILQ(vmbus_tailq)
+
+static int
+vmbus_uio_map_secondary(struct rte_vmbus_device *dev)
+{
+	int fd, i;
+	struct mapped_vmbus_resource *uio_res;
+	struct mapped_vmbus_res_list *uio_res_list
+		= RTE_TAILQ_CAST(vmbus_tailq.head, mapped_vmbus_res_list);
+
+	TAILQ_FOREACH(uio_res, uio_res_list, next) {
+
+		/* skip this element if it doesn't match our UUID */
+		if (rte_uuid_compare(uio_res->id, dev->device_id) != 0)
+			continue;
+
+		/* open /dev/uioX */
+		fd = open(uio_res->path, O_RDWR);
+		if (fd < 0) {
+			VMBUS_LOG(ERR, "Cannot open %s: %s",
+				  uio_res->path, strerror(errno));
+			return -1;
+		}
+
+		for (i = 0; i != uio_res->nb_maps; i++) {
+			void *mapaddr;
+
+			mapaddr = vmbus_map_resource(uio_res->maps[i].addr,
+						     fd, 0,
+						     uio_res->maps[i].size, 0);
+
+			if (mapaddr == uio_res->maps[i].addr)
+				continue;
+
+			VMBUS_LOG(ERR,
+				  "Cannot mmap device resource file %s to address: %p",
+				  uio_res->path, uio_res->maps[i].addr);
+
+			if (mapaddr != MAP_FAILED)
+				/* unmap addr wrongly mapped */
+				vmbus_unmap_resource(mapaddr,
+						     (size_t)uio_res->maps[i].size);
+
+			/* unmap addrs correctly mapped */
+			while (--i >= 0)
+				vmbus_unmap_resource(uio_res->maps[i].addr,
+						     (size_t)uio_res->maps[i].size);
+
+			close(fd);
+			return -1;
+		}
+
+		/* fd is not needed in slave process, close it */
+		close(fd);
+		return 0;
+	}
+
+	VMBUS_LOG(ERR,  "Cannot find resource for device");
+	return 1;
+}
+
+static int
+vmbus_uio_map_primary(struct rte_vmbus_device *dev)
+{
+	int i, ret;
+	struct mapped_vmbus_resource *uio_res = NULL;
+	struct mapped_vmbus_res_list *uio_res_list =
+		RTE_TAILQ_CAST(vmbus_tailq.head, mapped_vmbus_res_list);
+
+	/* allocate uio resource */
+	ret = vmbus_uio_alloc_resource(dev, &uio_res);
+	if (ret)
+		return ret;
+
+	/* Map the resources */
+	for (i = 0; i < VMBUS_MAX_RESOURCE; i++) {
+		/* skip empty BAR */
+		if (dev->resource[i].len == 0)
+			continue;
+
+		ret = vmbus_uio_map_resource_by_index(dev, i, uio_res, 0);
+		if (ret)
+			goto error;
+	}
+
+	uio_res->nb_maps = i;
+
+	TAILQ_INSERT_TAIL(uio_res_list, uio_res, next);
+
+	return 0;
+error:
+	while (--i >= 0) {
+		vmbus_unmap_resource(uio_res->maps[i].addr,
+				(size_t)uio_res->maps[i].size);
+	}
+	vmbus_uio_free_resource(dev, uio_res);
+	return -1;
+}
+
+
+struct mapped_vmbus_resource *
+vmbus_uio_find_resource(const struct rte_vmbus_device *dev)
+{
+	struct mapped_vmbus_resource *uio_res;
+	struct mapped_vmbus_res_list *uio_res_list =
+			RTE_TAILQ_CAST(vmbus_tailq.head, mapped_vmbus_res_list);
+
+	if (dev == NULL)
+		return NULL;
+
+	TAILQ_FOREACH(uio_res, uio_res_list, next) {
+		/* skip this element if it doesn't match our VMBUS address */
+		if (rte_uuid_compare(uio_res->id, dev->device_id) == 0)
+			return uio_res;
+	}
+	return NULL;
+}
+
+/* map the VMBUS resource of a VMBUS device in virtual memory */
+int
+vmbus_uio_map_resource(struct rte_vmbus_device *dev)
+{
+	struct mapped_vmbus_resource *uio_res;
+	int ret;
+
+	/* TODO: handle rescind */
+	dev->intr_handle.fd = -1;
+	dev->intr_handle.uio_cfg_fd = -1;
+	dev->intr_handle.type = RTE_INTR_HANDLE_UNKNOWN;
+
+	/* secondary processes - use already recorded details */
+	if (rte_eal_process_type() != RTE_PROC_PRIMARY)
+		ret = vmbus_uio_map_secondary(dev);
+	else
+		ret = vmbus_uio_map_primary(dev);
+
+	if (ret != 0)
+		return ret;
+
+	uio_res = vmbus_uio_find_resource(dev);
+	if (!uio_res) {
+		VMBUS_LOG(ERR, "can not find resources!");
+		return -EIO;
+	}
+
+	if (uio_res->nb_maps <= HV_MON_PAGE_MAP) {
+		VMBUS_LOG(ERR, "VMBUS: only %u resources found!",
+			uio_res->nb_maps);
+		return -EINVAL;
+	}
+
+	dev->int_page = (uint32_t *)((char *)uio_res->maps[HV_INT_PAGE_MAP].addr
+				     + (PAGE_SIZE >> 1));
+	dev->monitor_page = uio_res->maps[HV_MON_PAGE_MAP].addr;
+	return 0;
+}
+
+static void
+vmbus_uio_unmap(struct mapped_vmbus_resource *uio_res)
+{
+	int i;
+
+	if (uio_res == NULL)
+		return;
+
+	for (i = 0; i != uio_res->nb_maps; i++) {
+		vmbus_unmap_resource(uio_res->maps[i].addr,
+				     (size_t)uio_res->maps[i].size);
+	}
+}
+
+/* unmap the VMBUS resource of a VMBUS device in virtual memory */
+void
+vmbus_uio_unmap_resource(struct rte_vmbus_device *dev)
+{
+	struct mapped_vmbus_resource *uio_res;
+	struct mapped_vmbus_res_list *uio_res_list =
+			RTE_TAILQ_CAST(vmbus_tailq.head, mapped_vmbus_res_list);
+
+	if (dev == NULL)
+		return;
+
+	/* find an entry for the device */
+	uio_res = vmbus_uio_find_resource(dev);
+	if (uio_res == NULL)
+		return;
+
+	/* secondary processes - just free maps */
+	if (rte_eal_process_type() != RTE_PROC_PRIMARY)
+		return vmbus_uio_unmap(uio_res);
+
+	TAILQ_REMOVE(uio_res_list, uio_res, next);
+
+	/* unmap all resources */
+	vmbus_uio_unmap(uio_res);
+
+	/* free uio resource */
+	rte_free(uio_res);
+
+	/* close fd if in primary process */
+	close(dev->intr_handle.fd);
+	if (dev->intr_handle.uio_cfg_fd >= 0) {
+		close(dev->intr_handle.uio_cfg_fd);
+		dev->intr_handle.uio_cfg_fd = -1;
+	}
+
+	dev->intr_handle.fd = -1;
+	dev->intr_handle.type = RTE_INTR_HANDLE_UNKNOWN;
+}