Merge tag 'char-misc-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

Pull char/misc and other driver subsystem updates from Greg KH:
 "Here is the big set of char/misc and other driver subsystem updates
  for 6.10-rc1. Nothing major here, just lots of new drivers and updates
  for apis and new hardware types. Included in here are:

   - big IIO driver updates with more devices and drivers added

   - fpga driver updates

   - hyper-v driver updates

   - uio_pruss driver removal, no one uses it, other drivers control the
     same hardware now

   - binder minor updates

   - mhi driver updates

   - excon driver updates

   - counter driver updates

   - accessability driver updates

   - coresight driver updates

   - other hwtracing driver updates

   - nvmem driver updates

   - slimbus driver updates

   - spmi driver updates

   - other smaller misc and char driver updates

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'char-misc-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (319 commits)
  misc: ntsync: mark driver as "broken" to prevent from building
  spmi: pmic-arb: Add multi bus support
  spmi: pmic-arb: Register controller for bus instead of arbiter
  spmi: pmic-arb: Make core resources acquiring a version operation
  spmi: pmic-arb: Make the APID init a version operation
  spmi: pmic-arb: Fix some compile warnings about members not being described
  dt-bindings: spmi: Deprecate qcom,bus-id
  dt-bindings: spmi: Add X1E80100 SPMI PMIC ARB schema
  spmi: pmic-arb: Replace three IS_ERR() calls by null pointer checks in spmi_pmic_arb_probe()
  spmi: hisi-spmi-controller: Do not override device identifier
  dt-bindings: spmi: hisilicon,hisi-spmi-controller: clean up example
  dt-bindings: spmi: hisilicon,hisi-spmi-controller: fix binding references
  spmi: make spmi_bus_type const
  extcon: adc-jack: Document missing struct members
  extcon: realtek: Remove unused of_gpio.h
  extcon: usbc-cros-ec: Convert to platform remove callback returning void
  extcon: usb-gpio: Convert to platform remove callback returning void
  extcon: max77843: Convert to platform remove callback returning void
  extcon: max3355: Convert to platform remove callback returning void
  extcon: intel-mrfld: Convert to platform remove callback returning void
  ...

6 files changed, 977 insertions, 272 deletions

diff --git a/tools/hv/Build b/tools/hv/Build
index 6cf51fa4b306..7d1f1698069b 100644
--- a/tools/hv/Build
+++ b/tools/hv/Build
@@ -1,3 +1,4 @@
 hv_kvp_daemon-y += hv_kvp_daemon.o
 hv_vss_daemon-y += hv_vss_daemon.o
-hv_fcopy_daemon-y += hv_fcopy_daemon.o
+hv_fcopy_uio_daemon-y += hv_fcopy_uio_daemon.o
+hv_fcopy_uio_daemon-y += vmbus_bufring.o
diff --git a/tools/hv/Makefile b/tools/hv/Makefile
index fe770e679ae8..bb52871da341 100644
--- a/tools/hv/Makefile
+++ b/tools/hv/Makefile
@@ -2,6 +2,7 @@
 # Makefile for Hyper-V tools
 include ../scripts/Makefile.include
 
+ARCH := $(shell uname -m 2>/dev/null)
 sbindir ?= /usr/sbin
 libexecdir ?= /usr/libexec
 sharedstatedir ?= /var/lib
@@ -17,7 +18,10 @@ MAKEFLAGS += -r
 
 override CFLAGS += -O2 -Wall -g -D_GNU_SOURCE -I$(OUTPUT)include
 
-ALL_TARGETS := hv_kvp_daemon hv_vss_daemon hv_fcopy_daemon
+ALL_TARGETS := hv_kvp_daemon hv_vss_daemon
+ifneq ($(ARCH), aarch64)
+ALL_TARGETS += hv_fcopy_uio_daemon
+endif
 ALL_PROGRAMS := $(patsubst %,$(OUTPUT)%,$(ALL_TARGETS))
 
 ALL_SCRIPTS := hv_get_dhcp_info.sh hv_get_dns_info.sh hv_set_ifconfig.sh
@@ -39,10 +43,10 @@ $(HV_VSS_DAEMON_IN): FORCE
 $(OUTPUT)hv_vss_daemon: $(HV_VSS_DAEMON_IN)
 	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $< -o $@
 
-HV_FCOPY_DAEMON_IN := $(OUTPUT)hv_fcopy_daemon-in.o
-$(HV_FCOPY_DAEMON_IN): FORCE
-	$(Q)$(MAKE) $(build)=hv_fcopy_daemon
-$(OUTPUT)hv_fcopy_daemon: $(HV_FCOPY_DAEMON_IN)
+HV_FCOPY_UIO_DAEMON_IN := $(OUTPUT)hv_fcopy_uio_daemon-in.o
+$(HV_FCOPY_UIO_DAEMON_IN): FORCE
+	$(Q)$(MAKE) $(build)=hv_fcopy_uio_daemon
+$(OUTPUT)hv_fcopy_uio_daemon: $(HV_FCOPY_UIO_DAEMON_IN)
 	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $< -o $@
 
 clean:
diff --git a/tools/hv/hv_fcopy_daemon.c b/tools/hv/hv_fcopy_daemon.c
deleted file mode 100644
index 16d629b22c25..000000000000
--- a/tools/hv/hv_fcopy_daemon.c
+++ /dev/null
@@ -1,266 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * An implementation of host to guest copy functionality for Linux.
- *
- * Copyright (C) 2014, Microsoft, Inc.
- *
- * Author : K. Y. Srinivasan <kys@microsoft.com>
- */
-
-
-#include <sys/types.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <string.h>
-#include <errno.h>
-#include <linux/hyperv.h>
-#include <linux/limits.h>
-#include <syslog.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <getopt.h>
-
-static int target_fd;
-static char target_fname[PATH_MAX];
-static unsigned long long filesize;
-
-static int hv_start_fcopy(struct hv_start_fcopy *smsg)
-{
-	int error = HV_E_FAIL;
-	char *q, *p;
-
-	filesize = 0;
-	p = (char *)smsg->path_name;
-	snprintf(target_fname, sizeof(target_fname), "%s/%s",
-		 (char *)smsg->path_name, (char *)smsg->file_name);
-
-	syslog(LOG_INFO, "Target file name: %s", target_fname);
-	/*
-	 * Check to see if the path is already in place; if not,
-	 * create if required.
-	 */
-	while ((q = strchr(p, '/')) != NULL) {
-		if (q == p) {
-			p++;
-			continue;
-		}
-		*q = '\0';
-		if (access((char *)smsg->path_name, F_OK)) {
-			if (smsg->copy_flags & CREATE_PATH) {
-				if (mkdir((char *)smsg->path_name, 0755)) {
-					syslog(LOG_ERR, "Failed to create %s",
-						(char *)smsg->path_name);
-					goto done;
-				}
-			} else {
-				syslog(LOG_ERR, "Invalid path: %s",
-					(char *)smsg->path_name);
-				goto done;
-			}
-		}
-		p = q + 1;
-		*q = '/';
-	}
-
-	if (!access(target_fname, F_OK)) {
-		syslog(LOG_INFO, "File: %s exists", target_fname);
-		if (!(smsg->copy_flags & OVER_WRITE)) {
-			error = HV_ERROR_ALREADY_EXISTS;
-			goto done;
-		}
-	}
-
-	target_fd = open(target_fname,
-			 O_RDWR | O_CREAT | O_TRUNC | O_CLOEXEC, 0744);
-	if (target_fd == -1) {
-		syslog(LOG_INFO, "Open Failed: %s", strerror(errno));
-		goto done;
-	}
-
-	error = 0;
-done:
-	if (error)
-		target_fname[0] = '\0';
-	return error;
-}
-
-static int hv_copy_data(struct hv_do_fcopy *cpmsg)
-{
-	ssize_t bytes_written;
-	int ret = 0;
-
-	bytes_written = pwrite(target_fd, cpmsg->data, cpmsg->size,
-				cpmsg->offset);
-
-	filesize += cpmsg->size;
-	if (bytes_written != cpmsg->size) {
-		switch (errno) {
-		case ENOSPC:
-			ret = HV_ERROR_DISK_FULL;
-			break;
-		default:
-			ret = HV_E_FAIL;
-			break;
-		}
-		syslog(LOG_ERR, "pwrite failed to write %llu bytes: %ld (%s)",
-		       filesize, (long)bytes_written, strerror(errno));
-	}
-
-	return ret;
-}
-
-/*
- * Reset target_fname to "" in the two below functions for hibernation: if
- * the fcopy operation is aborted by hibernation, the daemon should remove the
- * partially-copied file; to achieve this, the hv_utils driver always fakes a
- * CANCEL_FCOPY message upon suspend, and later when the VM resumes back,
- * the daemon calls hv_copy_cancel() to remove the file; if a file is copied
- * successfully before suspend, hv_copy_finished() must reset target_fname to
- * avoid that the file can be incorrectly removed upon resume, since the faked
- * CANCEL_FCOPY message is spurious in this case.
- */
-static int hv_copy_finished(void)
-{
-	close(target_fd);
-	target_fname[0] = '\0';
-	return 0;
-}
-static int hv_copy_cancel(void)
-{
-	close(target_fd);
-	if (strlen(target_fname) > 0) {
-		unlink(target_fname);
-		target_fname[0] = '\0';
-	}
-	return 0;
-
-}
-
-void print_usage(char *argv[])
-{
-	fprintf(stderr, "Usage: %s [options]\n"
-		"Options are:\n"
-		"  -n, --no-daemon        stay in foreground, don't daemonize\n"
-		"  -h, --help             print this help\n", argv[0]);
-}
-
-int main(int argc, char *argv[])
-{
-	int fcopy_fd = -1;
-	int error;
-	int daemonize = 1, long_index = 0, opt;
-	int version = FCOPY_CURRENT_VERSION;
-	union {
-		struct hv_fcopy_hdr hdr;
-		struct hv_start_fcopy start;
-		struct hv_do_fcopy copy;
-		__u32 kernel_modver;
-	} buffer = { };
-	int in_handshake;
-
-	static struct option long_options[] = {
-		{"help",	no_argument,	   0,  'h' },
-		{"no-daemon",	no_argument,	   0,  'n' },
-		{0,		0,		   0,  0   }
-	};
-
-	while ((opt = getopt_long(argc, argv, "hn", long_options,
-				  &long_index)) != -1) {
-		switch (opt) {
-		case 'n':
-			daemonize = 0;
-			break;
-		case 'h':
-		default:
-			print_usage(argv);
-			exit(EXIT_FAILURE);
-		}
-	}
-
-	if (daemonize && daemon(1, 0)) {
-		syslog(LOG_ERR, "daemon() failed; error: %s", strerror(errno));
-		exit(EXIT_FAILURE);
-	}
-
-	openlog("HV_FCOPY", 0, LOG_USER);
-	syslog(LOG_INFO, "starting; pid is:%d", getpid());
-
-reopen_fcopy_fd:
-	if (fcopy_fd != -1)
-		close(fcopy_fd);
-	/* Remove any possible partially-copied file on error */
-	hv_copy_cancel();
-	in_handshake = 1;
-	fcopy_fd = open("/dev/vmbus/hv_fcopy", O_RDWR);
-
-	if (fcopy_fd < 0) {
-		syslog(LOG_ERR, "open /dev/vmbus/hv_fcopy failed; error: %d %s",
-			errno, strerror(errno));
-		exit(EXIT_FAILURE);
-	}
-
-	/*
-	 * Register with the kernel.
-	 */
-	if ((write(fcopy_fd, &version, sizeof(int))) != sizeof(int)) {
-		syslog(LOG_ERR, "Registration failed: %s", strerror(errno));
-		exit(EXIT_FAILURE);
-	}
-
-	while (1) {
-		/*
-		 * In this loop we process fcopy messages after the
-		 * handshake is complete.
-		 */
-		ssize_t len;
-
-		len = pread(fcopy_fd, &buffer, sizeof(buffer), 0);
-		if (len < 0) {
-			syslog(LOG_ERR, "pread failed: %s", strerror(errno));
-			goto reopen_fcopy_fd;
-		}
-
-		if (in_handshake) {
-			if (len != sizeof(buffer.kernel_modver)) {
-				syslog(LOG_ERR, "invalid version negotiation");
-				exit(EXIT_FAILURE);
-			}
-			in_handshake = 0;
-			syslog(LOG_INFO, "kernel module version: %u",
-			       buffer.kernel_modver);
-			continue;
-		}
-
-		switch (buffer.hdr.operation) {
-		case START_FILE_COPY:
-			error = hv_start_fcopy(&buffer.start);
-			break;
-		case WRITE_TO_FILE:
-			error = hv_copy_data(&buffer.copy);
-			break;
-		case COMPLETE_FCOPY:
-			error = hv_copy_finished();
-			break;
-		case CANCEL_FCOPY:
-			error = hv_copy_cancel();
-			break;
-
-		default:
-			error = HV_E_FAIL;
-			syslog(LOG_ERR, "Unknown operation: %d",
-				buffer.hdr.operation);
-
-		}
-
-		/*
-		 * pwrite() may return an error due to the faked CANCEL_FCOPY
-		 * message upon hibernation. Ignore the error by resetting the
-		 * dev file, i.e. closing and re-opening it.
-		 */
-		if (pwrite(fcopy_fd, &error, sizeof(int), 0) != sizeof(int)) {
-			syslog(LOG_ERR, "pwrite failed: %s", strerror(errno));
-			goto reopen_fcopy_fd;
-		}
-	}
-}
diff --git a/tools/hv/hv_fcopy_uio_daemon.c b/tools/hv/hv_fcopy_uio_daemon.c
new file mode 100644
index 000000000000..3ce316cc9f97
--- /dev/null
+++ b/tools/hv/hv_fcopy_uio_daemon.c
@@ -0,0 +1,490 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * An implementation of host to guest copy functionality for Linux.
+ *
+ * Copyright (C) 2023, Microsoft, Inc.
+ *
+ * Author : K. Y. Srinivasan <kys@microsoft.com>
+ * Author : Saurabh Sengar <ssengar@microsoft.com>
+ *
+ */
+
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <locale.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <syslog.h>
+#include <unistd.h>
+#include <wchar.h>
+#include <sys/stat.h>
+#include <linux/hyperv.h>
+#include <linux/limits.h>
+#include "vmbus_bufring.h"
+
+#define ICMSGTYPE_NEGOTIATE	0
+#define ICMSGTYPE_FCOPY		7
+
+#define WIN8_SRV_MAJOR		1
+#define WIN8_SRV_MINOR		1
+#define WIN8_SRV_VERSION	(WIN8_SRV_MAJOR << 16 | WIN8_SRV_MINOR)
+
+#define MAX_FOLDER_NAME		15
+#define MAX_PATH_LEN		15
+#define FCOPY_UIO		"/sys/bus/vmbus/devices/eb765408-105f-49b6-b4aa-c123b64d17d4/uio"
+
+#define FCOPY_VER_COUNT		1
+static const int fcopy_versions[] = {
+	WIN8_SRV_VERSION
+};
+
+#define FW_VER_COUNT		1
+static const int fw_versions[] = {
+	UTIL_FW_VERSION
+};
+
+#define HV_RING_SIZE		0x4000 /* 16KB ring buffer size */
+
+unsigned char desc[HV_RING_SIZE];
+
+static int target_fd;
+static char target_fname[PATH_MAX];
+static unsigned long long filesize;
+
+static int hv_fcopy_create_file(char *file_name, char *path_name, __u32 flags)
+{
+	int error = HV_E_FAIL;
+	char *q, *p;
+
+	filesize = 0;
+	p = path_name;
+	snprintf(target_fname, sizeof(target_fname), "%s/%s",
+		 path_name, file_name);
+
+	/*
+	 * Check to see if the path is already in place; if not,
+	 * create if required.
+	 */
+	while ((q = strchr(p, '/')) != NULL) {
+		if (q == p) {
+			p++;
+			continue;
+		}
+		*q = '\0';
+		if (access(path_name, F_OK)) {
+			if (flags & CREATE_PATH) {
+				if (mkdir(path_name, 0755)) {
+					syslog(LOG_ERR, "Failed to create %s",
+					       path_name);
+					goto done;
+				}
+			} else {
+				syslog(LOG_ERR, "Invalid path: %s", path_name);
+				goto done;
+			}
+		}
+		p = q + 1;
+		*q = '/';
+	}
+
+	if (!access(target_fname, F_OK)) {
+		syslog(LOG_INFO, "File: %s exists", target_fname);
+		if (!(flags & OVER_WRITE)) {
+			error = HV_ERROR_ALREADY_EXISTS;
+			goto done;
+		}
+	}
+
+	target_fd = open(target_fname,
+			 O_RDWR | O_CREAT | O_TRUNC | O_CLOEXEC, 0744);
+	if (target_fd == -1) {
+		syslog(LOG_INFO, "Open Failed: %s", strerror(errno));
+		goto done;
+	}
+
+	error = 0;
+done:
+	if (error)
+		target_fname[0] = '\0';
+	return error;
+}
+
+/* copy the data into the file */
+static int hv_copy_data(struct hv_do_fcopy *cpmsg)
+{
+	ssize_t len;
+	int ret = 0;
+
+	len = pwrite(target_fd, cpmsg->data, cpmsg->size, cpmsg->offset);
+
+	filesize += cpmsg->size;
+	if (len != cpmsg->size) {
+		switch (errno) {
+		case ENOSPC:
+			ret = HV_ERROR_DISK_FULL;
+			break;
+		default:
+			ret = HV_E_FAIL;
+			break;
+		}
+		syslog(LOG_ERR, "pwrite failed to write %llu bytes: %ld (%s)",
+		       filesize, (long)len, strerror(errno));
+	}
+
+	return ret;
+}
+
+static int hv_copy_finished(void)
+{
+	close(target_fd);
+	target_fname[0] = '\0';
+
+	return 0;
+}
+
+static void print_usage(char *argv[])
+{
+	fprintf(stderr, "Usage: %s [options]\n"
+		"Options are:\n"
+		"  -n, --no-daemon        stay in foreground, don't daemonize\n"
+		"  -h, --help             print this help\n", argv[0]);
+}
+
+static bool vmbus_prep_negotiate_resp(struct icmsg_hdr *icmsghdrp, unsigned char *buf,
+				      unsigned int buflen, const int *fw_version, int fw_vercnt,
+				const int *srv_version, int srv_vercnt,
+				int *nego_fw_version, int *nego_srv_version)
+{
+	int icframe_major, icframe_minor;
+	int icmsg_major, icmsg_minor;
+	int fw_major, fw_minor;
+	int srv_major, srv_minor;
+	int i, j;
+	bool found_match = false;
+	struct icmsg_negotiate *negop;
+
+	/* Check that there's enough space for icframe_vercnt, icmsg_vercnt */
+	if (buflen < ICMSG_HDR + offsetof(struct icmsg_negotiate, reserved)) {
+		syslog(LOG_ERR, "Invalid icmsg negotiate");
+		return false;
+	}
+
+	icmsghdrp->icmsgsize = 0x10;
+	negop = (struct icmsg_negotiate *)&buf[ICMSG_HDR];
+
+	icframe_major = negop->icframe_vercnt;
+	icframe_minor = 0;
+
+	icmsg_major = negop->icmsg_vercnt;
+	icmsg_minor = 0;
+
+	/* Validate negop packet */
+	if (icframe_major > IC_VERSION_NEGOTIATION_MAX_VER_COUNT ||
+	    icmsg_major > IC_VERSION_NEGOTIATION_MAX_VER_COUNT ||
+	    ICMSG_NEGOTIATE_PKT_SIZE(icframe_major, icmsg_major) > buflen) {
+		syslog(LOG_ERR, "Invalid icmsg negotiate - icframe_major: %u, icmsg_major: %u\n",
+		       icframe_major, icmsg_major);
+		goto fw_error;
+	}
+
+	/*
+	 * Select the framework version number we will
+	 * support.
+	 */
+
+	for (i = 0; i < fw_vercnt; i++) {
+		fw_major = (fw_version[i] >> 16);
+		fw_minor = (fw_version[i] & 0xFFFF);
+
+		for (j = 0; j < negop->icframe_vercnt; j++) {
+			if (negop->icversion_data[j].major == fw_major &&
+			    negop->icversion_data[j].minor == fw_minor) {
+				icframe_major = negop->icversion_data[j].major;
+				icframe_minor = negop->icversion_data[j].minor;
+				found_match = true;
+				break;
+			}
+		}
+
+		if (found_match)
+			break;
+	}
+
+	if (!found_match)
+		goto fw_error;
+
+	found_match = false;
+
+	for (i = 0; i < srv_vercnt; i++) {
+		srv_major = (srv_version[i] >> 16);
+		srv_minor = (srv_version[i] & 0xFFFF);
+
+		for (j = negop->icframe_vercnt;
+			(j < negop->icframe_vercnt + negop->icmsg_vercnt);
+			j++) {
+			if (negop->icversion_data[j].major == srv_major &&
+			    negop->icversion_data[j].minor == srv_minor) {
+				icmsg_major = negop->icversion_data[j].major;
+				icmsg_minor = negop->icversion_data[j].minor;
+				found_match = true;
+				break;
+			}
+		}
+
+		if (found_match)
+			break;
+	}
+
+	/*
+	 * Respond with the framework and service
+	 * version numbers we can support.
+	 */
+fw_error:
+	if (!found_match) {
+		negop->icframe_vercnt = 0;
+		negop->icmsg_vercnt = 0;
+	} else {
+		negop->icframe_vercnt = 1;
+		negop->icmsg_vercnt = 1;
+	}
+
+	if (nego_fw_version)
+		*nego_fw_version = (icframe_major << 16) | icframe_minor;
+
+	if (nego_srv_version)
+		*nego_srv_version = (icmsg_major << 16) | icmsg_minor;
+
+	negop->icversion_data[0].major = icframe_major;
+	negop->icversion_data[0].minor = icframe_minor;
+	negop->icversion_data[1].major = icmsg_major;
+	negop->icversion_data[1].minor = icmsg_minor;
+
+	return found_match;
+}
+
+static void wcstoutf8(char *dest, const __u16 *src, size_t dest_size)
+{
+	size_t len = 0;
+
+	while (len < dest_size) {
+		if (src[len] < 0x80)
+			dest[len++] = (char)(*src++);
+		else
+			dest[len++] = 'X';
+	}
+
+	dest[len] = '\0';
+}
+
+static int hv_fcopy_start(struct hv_start_fcopy *smsg_in)
+{
+	setlocale(LC_ALL, "en_US.utf8");
+	size_t file_size, path_size;
+	char *file_name, *path_name;
+	char *in_file_name = (char *)smsg_in->file_name;
+	char *in_path_name = (char *)smsg_in->path_name;
+
+	file_size = wcstombs(NULL, (const wchar_t *restrict)in_file_name, 0) + 1;
+	path_size = wcstombs(NULL, (const wchar_t *restrict)in_path_name, 0) + 1;
+
+	file_name = (char *)malloc(file_size * sizeof(char));
+	path_name = (char *)malloc(path_size * sizeof(char));
+
+	wcstoutf8(file_name, (__u16 *)in_file_name, file_size);
+	wcstoutf8(path_name, (__u16 *)in_path_name, path_size);
+
+	return hv_fcopy_create_file(file_name, path_name, smsg_in->copy_flags);
+}
+
+static int hv_fcopy_send_data(struct hv_fcopy_hdr *fcopy_msg, int recvlen)
+{
+	int operation = fcopy_msg->operation;
+
+	/*
+	 * The  strings sent from the host are encoded in
+	 * utf16; convert it to utf8 strings.
+	 * The host assures us that the utf16 strings will not exceed
+	 * the max lengths specified. We will however, reserve room
+	 * for the string terminating character - in the utf16s_utf8s()
+	 * function we limit the size of the buffer where the converted
+	 * string is placed to W_MAX_PATH -1 to guarantee
+	 * that the strings can be properly terminated!
+	 */
+
+	switch (operation) {
+	case START_FILE_COPY:
+		return hv_fcopy_start((struct hv_start_fcopy *)fcopy_msg);
+	case WRITE_TO_FILE:
+		return hv_copy_data((struct hv_do_fcopy *)fcopy_msg);
+	case COMPLETE_FCOPY:
+		return hv_copy_finished();
+	}
+
+	return HV_E_FAIL;
+}
+
+/* process the packet recv from host */
+static int fcopy_pkt_process(struct vmbus_br *txbr)
+{
+	int ret, offset, pktlen;
+	int fcopy_srv_version;
+	const struct vmbus_chanpkt_hdr *pkt;
+	struct hv_fcopy_hdr *fcopy_msg;
+	struct icmsg_hdr *icmsghdr;
+
+	pkt = (const struct vmbus_chanpkt_hdr *)desc;
+	offset = pkt->hlen << 3;
+	pktlen = (pkt->tlen << 3) - offset;
+	icmsghdr = (struct icmsg_hdr *)&desc[offset + sizeof(struct vmbuspipe_hdr)];
+	icmsghdr->status = HV_E_FAIL;
+
+	if (icmsghdr->icmsgtype == ICMSGTYPE_NEGOTIATE) {
+		if (vmbus_prep_negotiate_resp(icmsghdr, desc + offset, pktlen, fw_versions,
+					      FW_VER_COUNT, fcopy_versions, FCOPY_VER_COUNT,
+					      NULL, &fcopy_srv_version)) {
+			syslog(LOG_INFO, "FCopy IC version %d.%d",
+			       fcopy_srv_version >> 16, fcopy_srv_version & 0xFFFF);
+			icmsghdr->status = 0;
+		}
+	} else if (icmsghdr->icmsgtype == ICMSGTYPE_FCOPY) {
+		/* Ensure recvlen is big enough to contain hv_fcopy_hdr */
+		if (pktlen < ICMSG_HDR + sizeof(struct hv_fcopy_hdr)) {
+			syslog(LOG_ERR, "Invalid Fcopy hdr. Packet length too small: %u",
+			       pktlen);
+			return -ENOBUFS;
+		}
+
+		fcopy_msg = (struct hv_fcopy_hdr *)&desc[offset + ICMSG_HDR];
+		icmsghdr->status = hv_fcopy_send_data(fcopy_msg, pktlen);
+	}
+
+	icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
+	ret = rte_vmbus_chan_send(txbr, 0x6, desc + offset, pktlen, 0);
+	if (ret) {
+		syslog(LOG_ERR, "Write to ringbuffer failed err: %d", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void fcopy_get_first_folder(char *path, char *chan_no)
+{
+	DIR *dir = opendir(path);
+	struct dirent *entry;
+
+	if (!dir) {
+		syslog(LOG_ERR, "Failed to open directory (errno=%s).\n", strerror(errno));
+		return;
+	}
+
+	while ((entry = readdir(dir)) != NULL) {
+		if (entry->d_type == DT_DIR && strcmp(entry->d_name, ".") != 0 &&
+		    strcmp(entry->d_name, "..") != 0) {
+			strcpy(chan_no, entry->d_name);
+			break;
+		}
+	}
+
+	closedir(dir);
+}
+
+int main(int argc, char *argv[])
+{
+	int fcopy_fd = -1, tmp = 1;
+	int daemonize = 1, long_index = 0, opt, ret = -EINVAL;
+	struct vmbus_br txbr, rxbr;
+	void *ring;
+	uint32_t len = HV_RING_SIZE;
+	char uio_name[MAX_FOLDER_NAME] = {0};
+	char uio_dev_path[MAX_PATH_LEN] = {0};
+
+	static struct option long_options[] = {
+		{"help",	no_argument,	   0,  'h' },
+		{"no-daemon",	no_argument,	   0,  'n' },
+		{0,		0,		   0,  0   }
+	};
+
+	while ((opt = getopt_long(argc, argv, "hn", long_options,
+				  &long_index)) != -1) {
+		switch (opt) {
+		case 'n':
+			daemonize = 0;
+			break;
+		case 'h':
+		default:
+			print_usage(argv);
+			goto exit;
+		}
+	}
+
+	if (daemonize && daemon(1, 0)) {
+		syslog(LOG_ERR, "daemon() failed; error: %s", strerror(errno));
+		goto exit;
+	}
+
+	openlog("HV_UIO_FCOPY", 0, LOG_USER);
+	syslog(LOG_INFO, "starting; pid is:%d", getpid());
+
+	fcopy_get_first_folder(FCOPY_UIO, uio_name);
+	snprintf(uio_dev_path, sizeof(uio_dev_path), "/dev/%s", uio_name);
+	fcopy_fd = open(uio_dev_path, O_RDWR);
+
+	if (fcopy_fd < 0) {
+		syslog(LOG_ERR, "open %s failed; error: %d %s",
+		       uio_dev_path, errno, strerror(errno));
+		ret = fcopy_fd;
+		goto exit;
+	}
+
+	ring = vmbus_uio_map(&fcopy_fd, HV_RING_SIZE);
+	if (!ring) {
+		ret = errno;
+		syslog(LOG_ERR, "mmap ringbuffer failed; error: %d %s", ret, strerror(ret));
+		goto close;
+	}
+	vmbus_br_setup(&txbr, ring, HV_RING_SIZE);
+	vmbus_br_setup(&rxbr, (char *)ring + HV_RING_SIZE, HV_RING_SIZE);
+
+	rxbr.vbr->imask = 0;
+
+	while (1) {
+		/*
+		 * In this loop we process fcopy messages after the
+		 * handshake is complete.
+		 */
+		ret = pread(fcopy_fd, &tmp, sizeof(int), 0);
+		if (ret < 0) {
+			syslog(LOG_ERR, "pread failed: %s", strerror(errno));
+			continue;
+		}
+
+		len = HV_RING_SIZE;
+		ret = rte_vmbus_chan_recv_raw(&rxbr, desc, &len);
+		if (unlikely(ret <= 0)) {
+			/* This indicates a failure to communicate (or worse) */
+			syslog(LOG_ERR, "VMBus channel recv error: %d", ret);
+		} else {
+			ret = fcopy_pkt_process(&txbr);
+			if (ret < 0)
+				goto close;
+
+			/* Signal host */
+			if ((write(fcopy_fd, &tmp, sizeof(int))) != sizeof(int)) {
+				ret = errno;
+				syslog(LOG_ERR, "Signal to host failed: %s\n", strerror(ret));
+				goto close;
+			}
+		}
+	}
+close:
+	close(fcopy_fd);
+exit:
+	return ret;
+}
diff --git a/tools/hv/vmbus_bufring.c b/tools/hv/vmbus_bufring.c
new file mode 100644
index 000000000000..bac32c1109df
--- /dev/null
+++ b/tools/hv/vmbus_bufring.c
@@ -0,0 +1,318 @@
+// SPDX-License-Identifier: BSD-3-Clause
+/*
+ * Copyright (c) 2009-2012,2016,2023 Microsoft Corp.
+ * Copyright (c) 2012 NetApp Inc.
+ * Copyright (c) 2012 Citrix Inc.
+ * All rights reserved.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <emmintrin.h>
+#include <linux/limits.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/uio.h>
+#include <unistd.h>
+#include "vmbus_bufring.h"
+
+/**
+ * Compiler barrier.
+ *
+ * Guarantees that operation reordering does not occur at compile time
+ * for operations directly before and after the barrier.
+ */
+#define	rte_compiler_barrier()		({ asm volatile ("" : : : "memory"); })
+
+#define VMBUS_RQST_ERROR	0xFFFFFFFFFFFFFFFF
+#define ALIGN(val, align)	((typeof(val))((val) & (~((typeof(val))((align) - 1)))))
+
+void *vmbus_uio_map(int *fd, int size)
+{
+	void *map;
+
+	map = mmap(NULL, 2 * size, PROT_READ | PROT_WRITE, MAP_SHARED, *fd, 0);
+	if (map == MAP_FAILED)
+		return NULL;
+
+	return map;
+}
+
+/* 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);
+}
+
+static inline __always_inline void
+rte_smp_mb(void)
+{
+	asm volatile("lock addl $0, -128(%%rsp); " ::: "memory");
+}
+
+static inline int
+rte_atomic32_cmpset(volatile uint32_t *dst, uint32_t exp, uint32_t src)
+{
+	uint8_t res;
+
+	asm volatile("lock ; "
+		     "cmpxchgl %[src], %[dst];"
+		     "sete %[res];"
+		     : [res] "=a" (res),     /* output */
+		     [dst] "=m" (*dst)
+		     : [src] "r" (src),      /* input */
+		     "a" (exp),
+		     "m" (*dst)
+		     : "memory");            /* no-clobber list */
+	return res;
+}
+
+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
+ */
+static int
+vmbus_txbr_write(struct vmbus_br *tbr, const struct iovec iov[], int iovlen)
+{
+	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 */
+	if (windex != next_windex)
+		return -EINVAL;
+
+	/* Ensure that data is available before updating host index */
+	rte_compiler_barrier();
+
+	/* Checkin for our reservation. wait for our turn to update host */
+	while (!rte_atomic32_cmpset(&vbr->windex, old_windex, next_windex))
+		_mm_pause();
+
+	return 0;
+}
+
+int rte_vmbus_chan_send(struct vmbus_br *txbr, uint16_t type, void *data,
+			uint32_t dlen, uint32_t flags)
+{
+	struct vmbus_chanpkt pkt;
+	unsigned int pktlen, pad_pktlen;
+	const uint32_t hlen = sizeof(pkt);
+	uint64_t pad = 0;
+	struct iovec iov[3];
+	int error;
+
+	pktlen = hlen + dlen;
+	pad_pktlen = 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 = VMBUS_RQST_ERROR;
+
+	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(txbr, iov, 3);
+
+	return error;
+}
+
+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 */
+static 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).
+ */
+static 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;
+}
+
+int rte_vmbus_chan_recv_raw(struct vmbus_br *rxbr,
+			    void *data, uint32_t *len)
+{
+	struct vmbus_chanpkt_hdr pkt;
+	uint32_t dlen, bufferlen = *len;
+	int error;
+
+	error = vmbus_rxbr_peek(rxbr, &pkt, sizeof(pkt));
+	if (error)
+		return error;
+
+	if (unlikely(pkt.hlen < VMBUS_CHANPKT_HLEN_MIN))
+		/* XXX this channel is dead actually. */
+		return -EIO;
+
+	if (unlikely(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(rxbr, data, dlen, 0);
+	if (error)
+		return error;
+
+	/* Return the number of bytes read */
+	return dlen + sizeof(uint64_t);
+}
diff --git a/tools/hv/vmbus_bufring.h b/tools/hv/vmbus_bufring.h
new file mode 100644
index 000000000000..6e7caacfff57
--- /dev/null
+++ b/tools/hv/vmbus_bufring.h
@@ -0,0 +1,158 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+
+#ifndef _VMBUS_BUF_H_
+#define _VMBUS_BUF_H_
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#define __packed   __attribute__((__packed__))
+#define unlikely(x)	__builtin_expect(!!(x), 0)
+
+#define ICMSGHDRFLAG_TRANSACTION	1
+#define ICMSGHDRFLAG_REQUEST		2
+#define ICMSGHDRFLAG_RESPONSE		4
+
+#define IC_VERSION_NEGOTIATION_MAX_VER_COUNT 100
+#define ICMSG_HDR (sizeof(struct vmbuspipe_hdr) + sizeof(struct icmsg_hdr))
+#define ICMSG_NEGOTIATE_PKT_SIZE(icframe_vercnt, icmsg_vercnt) \
+	(ICMSG_HDR + sizeof(struct icmsg_negotiate) + \
+	 (((icframe_vercnt) + (icmsg_vercnt)) * sizeof(struct ic_version)))
+
+/*
+ * 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	BIT(VMBUS_CHANPKT_SIZE_SHIFT)
+#define VMBUS_CHANPKT_HLEN_MIN		\
+	(sizeof(struct vmbus_chanpkt_hdr) >> VMBUS_CHANPKT_SIZE_SHIFT)
+
+/*
+ * 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 rte_mem_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[];
+} __packed;
+
+struct vmbus_br {
+	struct vmbus_bufring *vbr;
+	uint32_t	dsize;
+	uint32_t	windex; /* next available location */
+};
+
+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;
+} __packed;
+
+struct vmbus_chanpkt {
+	struct vmbus_chanpkt_hdr hdr;
+} __packed;
+
+struct vmbuspipe_hdr {
+	unsigned int flags;
+	unsigned int msgsize;
+} __packed;
+
+struct ic_version {
+	unsigned short major;
+	unsigned short minor;
+} __packed;
+
+struct icmsg_negotiate {
+	unsigned short icframe_vercnt;
+	unsigned short icmsg_vercnt;
+	unsigned int reserved;
+	struct ic_version icversion_data[]; /* any size array */
+} __packed;
+
+struct icmsg_hdr {
+	struct ic_version icverframe;
+	unsigned short icmsgtype;
+	struct ic_version icvermsg;
+	unsigned short icmsgsize;
+	unsigned int status;
+	unsigned char ictransaction_id;
+	unsigned char icflags;
+	unsigned char reserved[2];
+} __packed;
+
+int rte_vmbus_chan_recv_raw(struct vmbus_br *rxbr, void *data, uint32_t *len);
+int rte_vmbus_chan_send(struct vmbus_br *txbr, uint16_t type, void *data,
+			uint32_t dlen, uint32_t flags);
+void vmbus_br_setup(struct vmbus_br *br, void *buf, unsigned int blen);
+void *vmbus_uio_map(int *fd, int size);
+
+/* 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);
+}
+
+#endif	/* !_VMBUS_BUF_H_ */