[RESEND PATCH v2 10/18] xen: Port Xen bus driver from mini-os

[Anastasiia Lukianenko <vicooodin@gmail.com>]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

Make required updates to run on u-boot and strip test code.

Signed-off-by: Anastasiia Lukianenko <anastasiia_lukianenko@epam.com>
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
---

Changes since v1:
 - add comments
 - correct code style

 arch/arm/Kconfig                          |   1 +
 board/xen/xenguest_arm64/xenguest_arm64.c |  16 +-
 drivers/xen/Makefile                      |   1 +
 drivers/xen/hypervisor.c                  |   2 +
 drivers/xen/xenbus.c                      | 557 ++++++++++++++++++++++
 include/xen.h                             |   2 +-
 include/xen/xenbus.h                      | 116 +++++
 7 files changed, 693 insertions(+), 2 deletions(-)
 create mode 100644 drivers/xen/xenbus.c
 create mode 100644 include/xen/xenbus.h

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 124d3eb3aa..497f540019 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1746,6 +1746,7 @@ config TARGET_XENGUEST_ARM64
 	select OF_CONTROL
 	select LINUX_KERNEL_IMAGE_HEADER
 	select XEN_SERIAL
+	select SSCANF
 endchoice
 
 config ARCH_SUPPORT_TFABOOT
diff --git a/board/xen/xenguest_arm64/xenguest_arm64.c b/board/xen/xenguest_arm64/xenguest_arm64.c
index 488b238f02..18e12c404e 100644
--- a/board/xen/xenguest_arm64/xenguest_arm64.c
+++ b/board/xen/xenguest_arm64/xenguest_arm64.c
@@ -66,7 +66,7 @@ static int setup_mem_map(void)
 
 	/*
 	 * Add "magic" region which is used by Xen to provide some essentials
-	 * for the guest: we need console.
+	 * for the guest: we need console and xenstore.
 	 */
 	ret = hvm_get_parameter_maintain_dcache(HVM_PARAM_CONSOLE_PFN, &gfn);
 	if (ret < 0) {
@@ -82,6 +82,20 @@ static int setup_mem_map(void)
 				PTE_BLOCK_INNER_SHARE);
 	i++;
 
+	ret = hvm_get_parameter_maintain_dcache(HVM_PARAM_STORE_PFN, &gfn);
+	if (ret < 0) {
+		printf("%s: Can't get HVM_PARAM_STORE_PFN, ret %d\n",
+		       __func__, ret);
+		return -EINVAL;
+	}
+
+	xen_mem_map[i].virt = PFN_PHYS(gfn);
+	xen_mem_map[i].phys = PFN_PHYS(gfn);
+	xen_mem_map[i].size = PAGE_SIZE;
+	xen_mem_map[i].attrs = (PTE_BLOCK_MEMTYPE(MT_NORMAL) |
+				PTE_BLOCK_INNER_SHARE);
+	i++;
+
 	mem = get_next_memory_node(blob, -1);
 	if (mem < 0) {
 		printf("%s: Missing /memory node\n", __func__);
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 0ad35edefb..9d0f604aaa 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -4,3 +4,4 @@
 
 obj-y += hypervisor.o
 obj-y += events.o
+obj-y += xenbus.o
diff --git a/drivers/xen/hypervisor.c b/drivers/xen/hypervisor.c
index 63fed6074f..1c7ae94bdf 100644
--- a/drivers/xen/hypervisor.c
+++ b/drivers/xen/hypervisor.c
@@ -21,6 +21,7 @@
 
 #include <xen/hvm.h>
 #include <xen/events.h>
+#include <xen/xenbus.h>
 #include <xen/interface/memory.h>
 
 #define active_evtchns(cpu, sh, idx)	\
@@ -236,5 +237,6 @@ void xen_init(void)
 
 	map_shared_info(NULL);
 	init_events();
+	init_xenbus();
 }
 
diff --git a/drivers/xen/xenbus.c b/drivers/xen/xenbus.c
new file mode 100644
index 0000000000..177d144723
--- /dev/null
+++ b/drivers/xen/xenbus.c
@@ -0,0 +1,557 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * (C) 2006 - Cambridge University
+ * (C) 2020 - EPAM Systems Inc.
+ *
+ * File: xenbus.c [1]
+ * Author: Steven Smith (sos22 at cam.ac.uk)
+ * Changes: Grzegorz Milos (gm281 at cam.ac.uk)
+ * Changes: John D. Ramsdell
+ *
+ * Date: Jun 2006, changes Aug 2006
+ *
+ * Description: Minimal implementation of xenbus
+ *
+ * [1] - http://xenbits.xen.org/gitweb/?p=mini-os.git;a=summary
+ */
+
+#include <common.h>
+#include <log.h>
+
+#include <asm/armv8/mmu.h>
+#include <asm/io.h>
+#include <asm/xen/system.h>
+
+#include <linux/bug.h>
+#include <linux/compat.h>
+
+#include <xen/events.h>
+#include <xen/hvm.h>
+#include <xen/xenbus.h>
+
+#include <xen/interface/io/xs_wire.h>
+
+#define map_frame_virt(v)	(v << PAGE_SHIFT)
+
+#define SCNd16			"d"
+
+/* Wait for reply time out, ms */
+#define WAIT_XENBUS_TO_MS	5000
+/* Polling time out, ms */
+#define WAIT_XENBUS_POLL_TO_MS	1
+
+static struct xenstore_domain_interface *xenstore_buf;
+
+static char *errmsg(struct xsd_sockmsg *rep);
+
+u32 xenbus_evtchn;
+
+struct write_req {
+	const void *data;
+	unsigned int len;
+};
+
+static void memcpy_from_ring(const void *r, void *d, int off, int len)
+{
+	int c1, c2;
+	const char *ring = r;
+	char *dest = d;
+
+	c1 = min(len, XENSTORE_RING_SIZE - off);
+	c2 = len - c1;
+	memcpy(dest, ring + off, c1);
+	memcpy(dest + c1, ring, c2);
+}
+
+/**
+ * xenbus_get_reply() - Receive reply from xenbus
+ * @req_reply: reply message structure
+ *
+ * Wait for reply message event from the ring and copy received message
+ * to input xsd_sockmsg structure. Repeat until full reply is
+ * proceeded.
+ *
+ * Return: false - timeout
+ *	   true - reply is received
+ */
+static bool xenbus_get_reply(struct xsd_sockmsg **req_reply)
+{
+	struct xsd_sockmsg msg;
+	unsigned int prod = xenstore_buf->rsp_prod;
+
+again:
+	if (!wait_event_timeout(NULL, prod != xenstore_buf->rsp_prod,
+				WAIT_XENBUS_TO_MS)) {
+		printk("%s: wait_event timeout\n", __func__);
+		return false;
+	}
+
+	prod = xenstore_buf->rsp_prod;
+	if (xenstore_buf->rsp_prod - xenstore_buf->rsp_cons < sizeof(msg))
+		goto again;
+
+	rmb();
+	memcpy_from_ring(xenstore_buf->rsp, &msg,
+			 MASK_XENSTORE_IDX(xenstore_buf->rsp_cons),
+			 sizeof(msg));
+
+	if (xenstore_buf->rsp_prod - xenstore_buf->rsp_cons < sizeof(msg) + msg.len)
+		goto again;
+
+	/* We do not support and expect any Xen bus wathes. */
+	BUG_ON(msg.type == XS_WATCH_EVENT);
+
+	*req_reply = malloc(sizeof(msg) + msg.len);
+	memcpy_from_ring(xenstore_buf->rsp, *req_reply,
+			 MASK_XENSTORE_IDX(xenstore_buf->rsp_cons),
+			 msg.len + sizeof(msg));
+	mb();
+	xenstore_buf->rsp_cons += msg.len + sizeof(msg);
+
+	wmb();
+	notify_remote_via_evtchn(xenbus_evtchn);
+	return true;
+}
+
+char *xenbus_switch_state(xenbus_transaction_t xbt, const char *path,
+			  XenbusState state)
+{
+	char *current_state;
+	char *msg = NULL;
+	char *msg2 = NULL;
+	char value[2];
+	XenbusState rs;
+	int xbt_flag = 0;
+	int retry = 0;
+
+	do {
+		if (xbt == XBT_NIL) {
+			msg = xenbus_transaction_start(&xbt);
+			if (msg)
+				goto exit;
+			xbt_flag = 1;
+		}
+
+		msg = xenbus_read(xbt, path, &current_state);
+		if (msg)
+			goto exit;
+
+		rs = (XenbusState)(current_state[0] - '0');
+		free(current_state);
+		if (rs == state) {
+			msg = NULL;
+			goto exit;
+		}
+
+		snprintf(value, 2, "%d", state);
+		msg = xenbus_write(xbt, path, value);
+
+exit:
+		if (xbt_flag) {
+			msg2 = xenbus_transaction_end(xbt, 0, &retry);
+			xbt = XBT_NIL;
+		}
+		if (msg == NULL && msg2 != NULL)
+			msg = msg2;
+		else
+			free(msg2);
+	} while (retry);
+
+	return msg;
+}
+
+char *xenbus_wait_for_state_change(const char *path, XenbusState *state)
+{
+	for (;;) {
+		char *res, *msg;
+		XenbusState rs;
+
+		msg = xenbus_read(XBT_NIL, path, &res);
+		if (msg)
+			return msg;
+
+		rs = (XenbusState)(res[0] - 48);
+		free(res);
+
+		if (rs == *state) {
+			wait_event_timeout(NULL, false, WAIT_XENBUS_POLL_TO_MS);
+		} else {
+			*state = rs;
+			break;
+		}
+	}
+	return NULL;
+}
+
+/* Send data to xenbus.  This can block.  All of the requests are seen
+ * by xenbus as if sent atomically.  The header is added
+ * automatically, using type %type, req_id %req_id, and trans_id
+ * %trans_id.
+ */
+static void xb_write(int type, int req_id, xenbus_transaction_t trans_id,
+		     const struct write_req *req, int nr_reqs)
+{
+	XENSTORE_RING_IDX prod;
+	int r;
+	int len = 0;
+	const struct write_req *cur_req;
+	int req_off;
+	int total_off;
+	int this_chunk;
+	struct xsd_sockmsg m = {
+		.type = type,
+		.req_id = req_id,
+		.tx_id = trans_id
+	};
+	struct write_req header_req = {
+		&m,
+		sizeof(m)
+	};
+
+	for (r = 0; r < nr_reqs; r++)
+		len += req[r].len;
+	m.len = len;
+	len += sizeof(m);
+
+	cur_req = &header_req;
+
+	BUG_ON(len > XENSTORE_RING_SIZE);
+	prod = xenstore_buf->req_prod;
+	/* We are running synchronously, so it is a bug if we do not
+	 * have enough room to send a message: please note that a message
+	 * can occupy multiple slots in the ring buffer.
+	 */
+	BUG_ON(prod + len - xenstore_buf->req_cons > XENSTORE_RING_SIZE);
+
+	total_off = 0;
+	req_off = 0;
+	while (total_off < len) {
+		this_chunk = min(cur_req->len - req_off,
+				 XENSTORE_RING_SIZE - MASK_XENSTORE_IDX(prod));
+		memcpy((char *)xenstore_buf->req + MASK_XENSTORE_IDX(prod),
+		       (char *)cur_req->data + req_off, this_chunk);
+		prod += this_chunk;
+		req_off += this_chunk;
+		total_off += this_chunk;
+		if (req_off == cur_req->len) {
+			req_off = 0;
+			if (cur_req == &header_req)
+				cur_req = req;
+			else
+				cur_req++;
+		}
+	}
+
+	BUG_ON(req_off != 0);
+	BUG_ON(total_off != len);
+	BUG_ON(prod > xenstore_buf->req_cons + XENSTORE_RING_SIZE);
+
+	/* Remote must see entire message before updating indexes */
+	wmb();
+
+	xenstore_buf->req_prod += len;
+
+	/* Send evtchn to notify remote */
+	notify_remote_via_evtchn(xenbus_evtchn);
+}
+
+/* Send a message to xenbus, in the same fashion as xb_write, and
+ * block waiting for a reply.  The reply is malloced and should be
+ * freed by the caller.
+ */
+struct xsd_sockmsg *xenbus_msg_reply(int type,
+				     xenbus_transaction_t trans,
+				     struct write_req *io,
+				     int nr_reqs)
+{
+	struct xsd_sockmsg *rep;
+
+	/* We do not use request identifier which is echoed in daemon's response. */
+	xb_write(type, 0, trans, io, nr_reqs);
+	/* Now wait for the message to arrive. */
+	if (!xenbus_get_reply(&rep))
+		return NULL;
+	return rep;
+}
+
+static char *errmsg(struct xsd_sockmsg *rep)
+{
+	char *res;
+
+	if (!rep) {
+		char msg[] = "No reply";
+		size_t len = strlen(msg) + 1;
+
+		return memcpy(malloc(len), msg, len);
+	}
+	if (rep->type != XS_ERROR)
+		return NULL;
+	res = malloc(rep->len + 1);
+	memcpy(res, rep + 1, rep->len);
+	res[rep->len] = 0;
+	free(rep);
+	return res;
+}
+
+/* List the contents of a directory.  Returns a malloc()ed array of
+ * pointers to malloc()ed strings.  The array is NULL terminated.  May
+ * block.
+ */
+char *xenbus_ls(xenbus_transaction_t xbt, const char *pre, char ***contents)
+{
+	struct xsd_sockmsg *reply, *repmsg;
+	struct write_req req[] = { { pre, strlen(pre) + 1 } };
+	int nr_elems, x, i;
+	char **res, *msg;
+
+	repmsg = xenbus_msg_reply(XS_DIRECTORY, xbt, req, ARRAY_SIZE(req));
+	msg = errmsg(repmsg);
+	if (msg) {
+		*contents = NULL;
+		return msg;
+	}
+	reply = repmsg + 1;
+	for (x = nr_elems = 0; x < repmsg->len; x++)
+		nr_elems += (((char *)reply)[x] == 0);
+	res = malloc(sizeof(res[0]) * (nr_elems + 1));
+	for (x = i = 0; i < nr_elems; i++) {
+		int l = strlen((char *)reply + x);
+
+		res[i] = malloc(l + 1);
+		memcpy(res[i], (char *)reply + x, l + 1);
+		x += l + 1;
+	}
+	res[i] = NULL;
+	free(repmsg);
+	*contents = res;
+	return NULL;
+}
+
+char *xenbus_read(xenbus_transaction_t xbt, const char *path, char **value)
+{
+	struct write_req req[] = { {path, strlen(path) + 1} };
+	struct xsd_sockmsg *rep;
+	char *res, *msg;
+
+	rep = xenbus_msg_reply(XS_READ, xbt, req, ARRAY_SIZE(req));
+	msg = errmsg(rep);
+	if (msg) {
+		*value = NULL;
+		return msg;
+	}
+	res = malloc(rep->len + 1);
+	memcpy(res, rep + 1, rep->len);
+	res[rep->len] = 0;
+	free(rep);
+	*value = res;
+	return NULL;
+}
+
+char *xenbus_write(xenbus_transaction_t xbt, const char *path,
+				   const char *value)
+{
+	struct write_req req[] = {
+		{path, strlen(path) + 1},
+		{value, strlen(value)},
+	};
+	struct xsd_sockmsg *rep;
+	char *msg;
+
+	rep = xenbus_msg_reply(XS_WRITE, xbt, req, ARRAY_SIZE(req));
+	msg = errmsg(rep);
+	if (msg)
+		return msg;
+	free(rep);
+	return NULL;
+}
+
+char *xenbus_rm(xenbus_transaction_t xbt, const char *path)
+{
+	struct write_req req[] = { {path, strlen(path) + 1} };
+	struct xsd_sockmsg *rep;
+	char *msg;
+
+	rep = xenbus_msg_reply(XS_RM, xbt, req, ARRAY_SIZE(req));
+	msg = errmsg(rep);
+	if (msg)
+		return msg;
+	free(rep);
+	return NULL;
+}
+
+char *xenbus_get_perms(xenbus_transaction_t xbt, const char *path, char **value)
+{
+	struct write_req req[] = { {path, strlen(path) + 1} };
+	struct xsd_sockmsg *rep;
+	char *res, *msg;
+
+	rep = xenbus_msg_reply(XS_GET_PERMS, xbt, req, ARRAY_SIZE(req));
+	msg = errmsg(rep);
+	if (msg) {
+		*value = NULL;
+		return msg;
+	}
+	res = malloc(rep->len + 1);
+	memcpy(res, rep + 1, rep->len);
+	res[rep->len] = 0;
+	free(rep);
+	*value = res;
+	return NULL;
+}
+
+#define PERM_MAX_SIZE 32
+char *xenbus_set_perms(xenbus_transaction_t xbt, const char *path,
+		       domid_t dom, char perm)
+{
+	char value[PERM_MAX_SIZE];
+	struct write_req req[] = {
+		{path, strlen(path) + 1},
+		{value, 0},
+	};
+	struct xsd_sockmsg *rep;
+	char *msg;
+
+	snprintf(value, PERM_MAX_SIZE, "%c%hu", perm, dom);
+	req[1].len = strlen(value) + 1;
+	rep = xenbus_msg_reply(XS_SET_PERMS, xbt, req, ARRAY_SIZE(req));
+	msg = errmsg(rep);
+	if (msg)
+		return msg;
+	free(rep);
+	return NULL;
+}
+
+char *xenbus_transaction_start(xenbus_transaction_t *xbt)
+{
+	/* Xenstored becomes angry if you send a length 0 message, so just
+	 * shove a nul terminator on the end
+	 */
+	struct write_req req = { "", 1};
+	struct xsd_sockmsg *rep;
+	char *err;
+
+	rep = xenbus_msg_reply(XS_TRANSACTION_START, 0, &req, 1);
+	err = errmsg(rep);
+	if (err)
+		return err;
+	sscanf((char *)(rep + 1), "%lu", xbt);
+	free(rep);
+	return NULL;
+}
+
+char *xenbus_transaction_end(xenbus_transaction_t t, int abort, int *retry)
+{
+	struct xsd_sockmsg *rep;
+	struct write_req req;
+	char *err;
+
+	*retry = 0;
+
+	req.data = abort ? "F" : "T";
+	req.len = 2;
+	rep = xenbus_msg_reply(XS_TRANSACTION_END, t, &req, 1);
+	err = errmsg(rep);
+	if (err) {
+		if (!strcmp(err, "EAGAIN")) {
+			*retry = 1;
+			free(err);
+			return NULL;
+		} else {
+			return err;
+		}
+	}
+	free(rep);
+	return NULL;
+}
+
+int xenbus_read_integer(const char *path)
+{
+	char *res, *buf;
+	int t;
+
+	res = xenbus_read(XBT_NIL, path, &buf);
+	if (res) {
+		printk("Failed to read %s.\n", path);
+		free(res);
+		return -1;
+	}
+	sscanf(buf, "%d", &t);
+	free(buf);
+	return t;
+}
+
+int xenbus_read_uuid(const char *path, unsigned char uuid[16])
+{
+	char *res, *buf;
+
+	res = xenbus_read(XBT_NIL, path, &buf);
+	if (res) {
+		printk("Failed to read %s.\n", path);
+		free(res);
+		return 0;
+	}
+	if (strlen(buf) != ((2 * 16) + 4) /* 16 hex bytes and 4 hyphens */
+	    || sscanf(buf,
+		      "%2hhx%2hhx%2hhx%2hhx-"
+		      "%2hhx%2hhx-"
+		      "%2hhx%2hhx-"
+		      "%2hhx%2hhx-"
+		      "%2hhx%2hhx%2hhx%2hhx%2hhx%2hhx",
+		      uuid, uuid + 1, uuid + 2, uuid + 3,
+		      uuid + 4, uuid + 5, uuid + 6, uuid + 7,
+		      uuid + 8, uuid + 9, uuid + 10, uuid + 11,
+		      uuid + 12, uuid + 13, uuid + 14, uuid + 15) != 16) {
+		printk("Xenbus path %s value %s is not a uuid!\n", path, buf);
+		free(buf);
+		return 0;
+	}
+	free(buf);
+	return 1;
+}
+
+char *xenbus_printf(xenbus_transaction_t xbt,
+		    const char *node, const char *path,
+		    const char *fmt, ...)
+{
+#define BUFFER_SIZE 256
+	char fullpath[BUFFER_SIZE];
+	char val[BUFFER_SIZE];
+	va_list args;
+
+	BUG_ON(strlen(node) + strlen(path) + 1 >= BUFFER_SIZE);
+	sprintf(fullpath, "%s/%s", node, path);
+	va_start(args, fmt);
+	vsprintf(val, fmt, args);
+	va_end(args);
+	return xenbus_write(xbt, fullpath, val);
+}
+
+domid_t xenbus_get_self_id(void)
+{
+	char *dom_id;
+	domid_t ret;
+
+	BUG_ON(xenbus_read(XBT_NIL, "domid", &dom_id));
+	sscanf(dom_id, "%"SCNd16, &ret);
+
+	return ret;
+}
+
+void init_xenbus(void)
+{
+	u64 v;
+
+	debug("%s\n", __func__);
+	if (hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v))
+		BUG();
+	xenbus_evtchn = v;
+
+	if (hvm_get_parameter(HVM_PARAM_STORE_PFN, &v))
+		BUG();
+	xenstore_buf = (struct xenstore_domain_interface *)map_frame_virt(v);
+}
+
+void fini_xenbus(void)
+{
+	debug("%s\n", __func__);
+}
diff --git a/include/xen.h b/include/xen.h
index 64ed3f0654..6fe30b83a2 100644
--- a/include/xen.h
+++ b/include/xen.h
@@ -8,7 +8,7 @@
 /**
  * xen_init() - Xen initialization
  *
- * Map Xen memory pages, initialize event handler.
+ * Map Xen memory pages, initialize event handler and xenbus.
  */
 void xen_init(void);
 
diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
new file mode 100644
index 0000000000..3ed7fd5733
--- /dev/null
+++ b/include/xen/xenbus.h
@@ -0,0 +1,116 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef XENBUS_H__
+#define XENBUS_H__
+
+#include <xen/interface/xen.h>
+#include <xen/interface/io/xenbus.h>
+
+typedef unsigned long xenbus_transaction_t;
+#define XBT_NIL ((xenbus_transaction_t)0)
+
+extern u32 xenbus_evtchn;
+
+/* Initialize the XenBus system. */
+void init_xenbus(void);
+/* Finalize the XenBus system. */
+void fini_xenbus(void);
+
+/**
+ * xenbus_read() - Read the value associated with a path.
+ *
+ * Returns a malloc'd error string on failure and sets *value to NULL.
+ * On success, *value is set to a malloc'd copy of the value.
+ */
+char *xenbus_read(xenbus_transaction_t xbt, const char *path, char **value);
+
+char *xenbus_wait_for_state_change(const char *path, XenbusState *state);
+char *xenbus_switch_state(xenbus_transaction_t xbt, const char *path,
+			  XenbusState state);
+
+/**
+ * xenbus_write() - Associates a value with a path.
+ *
+ * Returns a malloc'd error string on failure.
+ */
+char *xenbus_write(xenbus_transaction_t xbt, const char *path,
+		   const char *value);
+
+/**
+ * xenbus_rm() - Removes the value associated with a path.
+ *
+ * Returns a malloc'd error string on failure.
+ */
+char *xenbus_rm(xenbus_transaction_t xbt, const char *path);
+
+/**
+ * xenbus_ls() - List the contents of a directory.
+ *
+ * Returns a malloc'd error string on failure and sets *contents to NULL.
+ * On success, *contents is set to a malloc'd array of pointers to malloc'd
+ * strings. The array is NULL terminated. May block.
+ */
+char *xenbus_ls(xenbus_transaction_t xbt, const char *prefix, char ***contents);
+
+/**
+ * xenbus_get_perms() - Reads permissions associated with a path.
+ *
+ * Returns a malloc'd error string on failure and sets *value to NULL.
+ * On success, *value is set to a malloc'd copy of the value.
+ */
+char *xenbus_get_perms(xenbus_transaction_t xbt, const char *path, char **value);
+
+/**
+ * xenbus_set_perms() - Sets the permissions associated with a path.
+ *
+ * Returns a malloc'd error string on failure.
+ */
+char *xenbus_set_perms(xenbus_transaction_t xbt, const char *path, domid_t dom,
+		       char perm);
+
+/**
+ * xenbus_transaction_start() - Start a xenbus transaction.
+ *
+ * Returns the transaction in xbt on success or a malloc'd error string
+ * otherwise.
+ */
+char *xenbus_transaction_start(xenbus_transaction_t *xbt);
+
+/**
+ * xenbus_transaction_end() - End a xenbus transaction.
+ *
+ * Returns a malloc'd error string if it fails. Abort says whether the
+ * transaction should be aborted.
+ * Returns 1 in *retry if the transaction should be retried.
+ */
+char *xenbus_transaction_end(xenbus_transaction_t xbt, int abort,
+			     int *retry);
+
+/**
+ * xenbus_read_integer() - Read path and parse it as an integer.
+ *
+ * Returns -1 on error.
+ */
+int xenbus_read_integer(const char *path);
+
+/**
+ * xenbus_read_uuid() - Read path and parse it as 16 byte uuid.
+ *
+ * Returns 1 if read and parsing were successful, 0 if not
+ */
+int xenbus_read_uuid(const char *path, unsigned char uuid[16]);
+
+/**
+ * xenbus_printf() - Contraction of snprintf and xenbus_write(path/node).
+ */
+char *xenbus_printf(xenbus_transaction_t xbt,
+		    const char *node, const char *path,
+		    const char *fmt, ...)
+	__attribute__((__format__(printf, 4, 5)));
+
+/**
+ * xenbus_get_self_id() - Utility function to figure out our domain id
+ */
+domid_t xenbus_get_self_id(void);
+
+#endif /* XENBUS_H__ */
-- 
2.17.1