KVM: SEV: Do cache maintenance on the source VM during intra-host migrationgrafted

Manually perform cache maintenance on the source VM during intra-host
migration to ensure no stale data is left in CPU caches after the VM is
destroyed.  Because the source VM is "converted" to a non-SEV VM, KVM's
memory reclaim flows won't trigger cache maintenance, e.g. when all guest
memory is reclaimed in response to detaching from the mmu_notifier.

Note, relying on the destination VM to do cache maintenance isn't an option
as KVM doesn't require identical guest memory configurations, i.e. the
source VM may have access to memory that the destination VM does not.
Enforcing equivalent memory configurations is infeasible, as it would
require a *deep* comparison of memslots, e.g. to verify that not only are
the memslot identical, but what the memslots point at is also identical.

Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration")
Cc: stable@vger.kernel.org
Reported-by: Stefan Teodorescu <fane@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260923163721.1584779-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 804 insertions, 0 deletions

diff --git a/net/qrtr/ns.c b/net/qrtr/ns.c
new file mode 100644
index 000000000..bcb090ee7
--- /dev/null
+++ b/net/qrtr/ns.c
@@ -0,0 +1,804 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+/*
+ * Copyright (c) 2015, Sony Mobile Communications Inc.
+ * Copyright (c) 2013, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2020, Linaro Ltd.
+ */
+
+#include <linux/module.h>
+#include <linux/qrtr.h>
+#include <linux/workqueue.h>
+#include <net/sock.h>
+
+#include "qrtr.h"
+
+#include <trace/events/sock.h>
+#define CREATE_TRACE_POINTS
+#include <trace/events/qrtr.h>
+
+static DEFINE_XARRAY(nodes);
+
+static struct {
+	struct socket *sock;
+	struct sockaddr_qrtr bcast_sq;
+	struct list_head lookups;
+	u32 lookup_count;
+	struct workqueue_struct *workqueue;
+	struct work_struct work;
+	void (*saved_data_ready)(struct sock *sk);
+	int local_node;
+} qrtr_ns;
+
+static const char * const qrtr_ctrl_pkt_strings[] = {
+	[QRTR_TYPE_HELLO]	= "hello",
+	[QRTR_TYPE_BYE]		= "bye",
+	[QRTR_TYPE_NEW_SERVER]	= "new-server",
+	[QRTR_TYPE_DEL_SERVER]	= "del-server",
+	[QRTR_TYPE_DEL_CLIENT]	= "del-client",
+	[QRTR_TYPE_RESUME_TX]	= "resume-tx",
+	[QRTR_TYPE_EXIT]	= "exit",
+	[QRTR_TYPE_PING]	= "ping",
+	[QRTR_TYPE_NEW_LOOKUP]	= "new-lookup",
+	[QRTR_TYPE_DEL_LOOKUP]	= "del-lookup",
+};
+
+struct qrtr_server_filter {
+	unsigned int service;
+	unsigned int instance;
+	unsigned int ifilter;
+};
+
+struct qrtr_lookup {
+	unsigned int service;
+	unsigned int instance;
+
+	struct sockaddr_qrtr sq;
+	struct list_head li;
+};
+
+struct qrtr_server {
+	unsigned int service;
+	unsigned int instance;
+
+	unsigned int node;
+	unsigned int port;
+
+	struct list_head qli;
+};
+
+struct qrtr_node {
+	unsigned int id;
+	struct xarray servers;
+	u32 server_count;
+};
+
+/* Max nodes, server, lookup limits are chosen based on the current platform
+ * requirements. If the requirement changes in the future, these values can be
+ * increased.
+ */
+#define QRTR_NS_MAX_NODES   512
+#define QRTR_NS_MAX_SERVERS 256
+#define QRTR_NS_MAX_LOOKUPS 128
+
+static u16 node_count;
+
+static struct qrtr_node *node_get(unsigned int node_id)
+{
+	struct qrtr_node *node;
+
+	node = xa_load(&nodes, node_id);
+	if (node)
+		return node;
+
+	if (node_count >= QRTR_NS_MAX_NODES) {
+		pr_err_ratelimited("QRTR clients exceed max node limit!\n");
+		return NULL;
+	}
+
+	/* If node didn't exist, allocate and insert it to the tree */
+	node = kzalloc_obj(*node);
+	if (!node)
+		return NULL;
+
+	node->id = node_id;
+	xa_init(&node->servers);
+
+	if (xa_store(&nodes, node_id, node, GFP_KERNEL)) {
+		kfree(node);
+		return NULL;
+	}
+
+	node_count++;
+
+	return node;
+}
+
+static int server_match(const struct qrtr_server *srv,
+			const struct qrtr_server_filter *f)
+{
+	unsigned int ifilter = f->ifilter;
+
+	if (f->service != 0 && srv->service != f->service)
+		return 0;
+	if (!ifilter && f->instance)
+		ifilter = ~0;
+
+	return (srv->instance & ifilter) == f->instance;
+}
+
+static int service_announce_new(struct sockaddr_qrtr *dest,
+				struct qrtr_server *srv)
+{
+	struct qrtr_ctrl_pkt pkt;
+	struct msghdr msg = { };
+	struct kvec iv;
+
+	trace_qrtr_ns_service_announce_new(srv->service, srv->instance,
+					   srv->node, srv->port);
+
+	iv.iov_base = &pkt;
+	iv.iov_len = sizeof(pkt);
+
+	memset(&pkt, 0, sizeof(pkt));
+	pkt.cmd = cpu_to_le32(QRTR_TYPE_NEW_SERVER);
+	pkt.server.service = cpu_to_le32(srv->service);
+	pkt.server.instance = cpu_to_le32(srv->instance);
+	pkt.server.node = cpu_to_le32(srv->node);
+	pkt.server.port = cpu_to_le32(srv->port);
+
+	msg.msg_name = (struct sockaddr *)dest;
+	msg.msg_namelen = sizeof(*dest);
+
+	return kernel_sendmsg(qrtr_ns.sock, &msg, &iv, 1, sizeof(pkt));
+}
+
+static void service_announce_del(struct sockaddr_qrtr *dest,
+				 struct qrtr_server *srv)
+{
+	struct qrtr_ctrl_pkt pkt;
+	struct msghdr msg = { };
+	struct kvec iv;
+	int ret;
+
+	trace_qrtr_ns_service_announce_del(srv->service, srv->instance,
+					   srv->node, srv->port);
+
+	iv.iov_base = &pkt;
+	iv.iov_len = sizeof(pkt);
+
+	memset(&pkt, 0, sizeof(pkt));
+	pkt.cmd = cpu_to_le32(QRTR_TYPE_DEL_SERVER);
+	pkt.server.service = cpu_to_le32(srv->service);
+	pkt.server.instance = cpu_to_le32(srv->instance);
+	pkt.server.node = cpu_to_le32(srv->node);
+	pkt.server.port = cpu_to_le32(srv->port);
+
+	msg.msg_name = (struct sockaddr *)dest;
+	msg.msg_namelen = sizeof(*dest);
+
+	ret = kernel_sendmsg(qrtr_ns.sock, &msg, &iv, 1, sizeof(pkt));
+	if (ret < 0 && ret != -ENODEV)
+		pr_err("failed to announce del service\n");
+
+	return;
+}
+
+static void lookup_notify(struct sockaddr_qrtr *to, struct qrtr_server *srv,
+			  bool new)
+{
+	struct qrtr_ctrl_pkt pkt;
+	struct msghdr msg = { };
+	struct kvec iv;
+	int ret;
+
+	iv.iov_base = &pkt;
+	iv.iov_len = sizeof(pkt);
+
+	memset(&pkt, 0, sizeof(pkt));
+	pkt.cmd = new ? cpu_to_le32(QRTR_TYPE_NEW_SERVER) :
+			cpu_to_le32(QRTR_TYPE_DEL_SERVER);
+	if (srv) {
+		pkt.server.service = cpu_to_le32(srv->service);
+		pkt.server.instance = cpu_to_le32(srv->instance);
+		pkt.server.node = cpu_to_le32(srv->node);
+		pkt.server.port = cpu_to_le32(srv->port);
+	}
+
+	msg.msg_name = (struct sockaddr *)to;
+	msg.msg_namelen = sizeof(*to);
+
+	ret = kernel_sendmsg(qrtr_ns.sock, &msg, &iv, 1, sizeof(pkt));
+	if (ret < 0 && ret != -ENODEV)
+		pr_err("failed to send lookup notification\n");
+}
+
+/* Announce the list of servers registered on the local node */
+static int announce_servers(struct sockaddr_qrtr *sq)
+{
+	struct qrtr_server *srv;
+	struct qrtr_node *node;
+	unsigned long index;
+	int ret;
+
+	node = node_get(qrtr_ns.local_node);
+	if (!node)
+		return 0;
+
+	/* Announce the list of servers registered in this node */
+	xa_for_each(&node->servers, index, srv) {
+		ret = service_announce_new(sq, srv);
+		if (ret < 0) {
+			if (ret == -ENODEV)
+				continue;
+
+			pr_err("failed to announce new service\n");
+			return ret;
+		}
+	}
+	return 0;
+}
+
+static struct qrtr_server *server_add(unsigned int service,
+				      unsigned int instance,
+				      unsigned int node_id,
+				      unsigned int port)
+{
+	struct qrtr_server *srv;
+	struct qrtr_server *old;
+	struct qrtr_node *node;
+
+	if (!service || !port)
+		return NULL;
+
+	node = node_get(node_id);
+	if (!node)
+		return NULL;
+
+	/* Make sure the new servers per port are capped at the maximum value */
+	old = xa_load(&node->servers, port);
+	if (!old && node->server_count >= QRTR_NS_MAX_SERVERS) {
+		pr_err_ratelimited("QRTR client node %u exceeds max server limit!\n", node_id);
+		return NULL;
+	}
+
+	srv = kzalloc_obj(*srv);
+	if (!srv)
+		return NULL;
+
+	srv->service = service;
+	srv->instance = instance;
+	srv->node = node_id;
+	srv->port = port;
+
+	/* Delete the old server on the same port */
+	old = xa_store(&node->servers, port, srv, GFP_KERNEL);
+	if (old) {
+		if (xa_is_err(old)) {
+			pr_err("failed to add server [0x%x:0x%x] ret:%d\n",
+			       srv->service, srv->instance, xa_err(old));
+			goto err;
+		} else {
+			kfree(old);
+		}
+	} else {
+		node->server_count++;
+	}
+
+	trace_qrtr_ns_server_add(srv->service, srv->instance,
+				 srv->node, srv->port);
+
+	return srv;
+
+err:
+	kfree(srv);
+	return NULL;
+}
+
+static int server_del(struct qrtr_node *node, unsigned int port, bool bcast)
+{
+	struct qrtr_lookup *lookup;
+	struct qrtr_server *srv;
+	struct list_head *li;
+
+	srv = xa_load(&node->servers, port);
+	if (!srv)
+		return -ENOENT;
+
+	xa_erase(&node->servers, port);
+
+	/* Broadcast the removal of local servers */
+	if (srv->node == qrtr_ns.local_node && bcast)
+		service_announce_del(&qrtr_ns.bcast_sq, srv);
+
+	/* Announce the service's disappearance to observers */
+	list_for_each(li, &qrtr_ns.lookups) {
+		lookup = container_of(li, struct qrtr_lookup, li);
+		if (lookup->service && lookup->service != srv->service)
+			continue;
+		if (lookup->instance && lookup->instance != srv->instance)
+			continue;
+
+		lookup_notify(&lookup->sq, srv, false);
+	}
+
+	kfree(srv);
+	node->server_count--;
+
+	return 0;
+}
+
+static int ctrl_cmd_hello(struct sockaddr_qrtr *sq)
+{
+	return announce_servers(sq);
+}
+
+static int ctrl_cmd_bye(struct sockaddr_qrtr *from)
+{
+	struct qrtr_node *local_node;
+	struct qrtr_ctrl_pkt pkt;
+	struct qrtr_server *srv;
+	struct sockaddr_qrtr sq;
+	struct msghdr msg = { };
+	struct qrtr_node *node;
+	unsigned long index;
+	struct kvec iv;
+	int ret = 0;
+
+	iv.iov_base = &pkt;
+	iv.iov_len = sizeof(pkt);
+
+	node = node_get(from->sq_node);
+	if (!node)
+		return 0;
+
+	/* Advertise removal of this client to all servers of remote node */
+	xa_for_each(&node->servers, index, srv)
+		server_del(node, srv->port, true);
+
+	/* Advertise the removal of this client to all local servers */
+	local_node = node_get(qrtr_ns.local_node);
+	if (!local_node) {
+		ret = 0;
+		goto delete_node;
+	}
+
+	memset(&pkt, 0, sizeof(pkt));
+	pkt.cmd = cpu_to_le32(QRTR_TYPE_BYE);
+	pkt.client.node = cpu_to_le32(from->sq_node);
+
+	xa_for_each(&local_node->servers, index, srv) {
+		sq.sq_family = AF_QIPCRTR;
+		sq.sq_node = srv->node;
+		sq.sq_port = srv->port;
+
+		msg.msg_name = (struct sockaddr *)&sq;
+		msg.msg_namelen = sizeof(sq);
+
+		ret = kernel_sendmsg(qrtr_ns.sock, &msg, &iv, 1, sizeof(pkt));
+		if (ret < 0 && ret != -ENODEV) {
+			pr_err("failed to send bye cmd\n");
+			goto delete_node;
+		}
+	}
+
+	/* Ignore -ENODEV */
+	ret = 0;
+
+delete_node:
+	xa_erase(&nodes, from->sq_node);
+	kfree(node);
+	node_count--;
+
+	return ret;
+}
+
+static int ctrl_cmd_del_client(struct sockaddr_qrtr *from,
+			       unsigned int node_id, unsigned int port)
+{
+	struct qrtr_node *local_node;
+	struct qrtr_lookup *lookup;
+	struct qrtr_ctrl_pkt pkt;
+	struct msghdr msg = { };
+	struct qrtr_server *srv;
+	struct sockaddr_qrtr sq;
+	struct qrtr_node *node;
+	struct list_head *tmp;
+	struct list_head *li;
+	unsigned long index;
+	struct kvec iv;
+	int ret;
+
+	iv.iov_base = &pkt;
+	iv.iov_len = sizeof(pkt);
+
+	/* Don't accept spoofed messages */
+	if (from->sq_node != node_id)
+		return -EINVAL;
+
+	/* Local DEL_CLIENT messages comes from the port being closed */
+	if (from->sq_node == qrtr_ns.local_node && from->sq_port != port)
+		return -EINVAL;
+
+	/* Remove any lookups by this client */
+	list_for_each_safe(li, tmp, &qrtr_ns.lookups) {
+		lookup = container_of(li, struct qrtr_lookup, li);
+		if (lookup->sq.sq_node != node_id)
+			continue;
+		if (lookup->sq.sq_port != port)
+			continue;
+
+		list_del(&lookup->li);
+		kfree(lookup);
+		qrtr_ns.lookup_count--;
+	}
+
+	/* Remove the server belonging to this port but don't broadcast
+	 * DEL_SERVER. Neighbours would've already removed the server belonging
+	 * to this port due to the DEL_CLIENT broadcast from qrtr_port_remove().
+	 */
+	node = node_get(node_id);
+	if (node)
+		server_del(node, port, false);
+
+	/* Advertise the removal of this client to all local servers */
+	local_node = node_get(qrtr_ns.local_node);
+	if (!local_node)
+		return 0;
+
+	memset(&pkt, 0, sizeof(pkt));
+	pkt.cmd = cpu_to_le32(QRTR_TYPE_DEL_CLIENT);
+	pkt.client.node = cpu_to_le32(node_id);
+	pkt.client.port = cpu_to_le32(port);
+
+	xa_for_each(&local_node->servers, index, srv) {
+		sq.sq_family = AF_QIPCRTR;
+		sq.sq_node = srv->node;
+		sq.sq_port = srv->port;
+
+		msg.msg_name = (struct sockaddr *)&sq;
+		msg.msg_namelen = sizeof(sq);
+
+		ret = kernel_sendmsg(qrtr_ns.sock, &msg, &iv, 1, sizeof(pkt));
+		if (ret < 0 && ret != -ENODEV) {
+			pr_err("failed to send del client cmd\n");
+			return ret;
+		}
+	}
+	return 0;
+}
+
+static int ctrl_cmd_new_server(struct sockaddr_qrtr *from,
+			       unsigned int service, unsigned int instance,
+			       unsigned int node_id, unsigned int port)
+{
+	struct qrtr_lookup *lookup;
+	struct qrtr_server *srv;
+	struct list_head *li;
+	int ret = 0;
+
+	/* Ignore specified node and port for local servers */
+	if (from->sq_node == qrtr_ns.local_node) {
+		node_id = from->sq_node;
+		port = from->sq_port;
+	}
+
+	srv = server_add(service, instance, node_id, port);
+	if (!srv)
+		return -EINVAL;
+
+	if (srv->node == qrtr_ns.local_node) {
+		ret = service_announce_new(&qrtr_ns.bcast_sq, srv);
+		if (ret < 0) {
+			pr_err("failed to announce new service\n");
+			return ret;
+		}
+	}
+
+	/* Notify any potential lookups about the new server */
+	list_for_each(li, &qrtr_ns.lookups) {
+		lookup = container_of(li, struct qrtr_lookup, li);
+		if (lookup->service && lookup->service != service)
+			continue;
+		if (lookup->instance && lookup->instance != instance)
+			continue;
+
+		lookup_notify(&lookup->sq, srv, true);
+	}
+
+	return ret;
+}
+
+static int ctrl_cmd_del_server(struct sockaddr_qrtr *from,
+			       unsigned int service, unsigned int instance,
+			       unsigned int node_id, unsigned int port)
+{
+	struct qrtr_node *node;
+
+	/* Ignore specified node and port for local servers*/
+	if (from->sq_node == qrtr_ns.local_node) {
+		node_id = from->sq_node;
+		port = from->sq_port;
+	}
+
+	/* Local servers may only unregister themselves */
+	if (from->sq_node == qrtr_ns.local_node && from->sq_port != port)
+		return -EINVAL;
+
+	node = node_get(node_id);
+	if (!node)
+		return -ENOENT;
+
+	server_del(node, port, true);
+
+	return 0;
+}
+
+static int ctrl_cmd_new_lookup(struct sockaddr_qrtr *from,
+			       unsigned int service, unsigned int instance)
+{
+	struct qrtr_server_filter filter;
+	struct qrtr_lookup *lookup;
+	struct qrtr_server *srv;
+	struct qrtr_node *node;
+	unsigned long node_idx;
+	unsigned long srv_idx;
+
+	/* Accept only local observers */
+	if (from->sq_node != qrtr_ns.local_node)
+		return -EINVAL;
+
+	if (qrtr_ns.lookup_count >= QRTR_NS_MAX_LOOKUPS) {
+		pr_err_ratelimited("QRTR client node exceeds max lookup limit!\n");
+		return -ENOSPC;
+	}
+
+	lookup = kzalloc_obj(*lookup);
+	if (!lookup)
+		return -ENOMEM;
+
+	lookup->sq = *from;
+	lookup->service = service;
+	lookup->instance = instance;
+	list_add_tail(&lookup->li, &qrtr_ns.lookups);
+	qrtr_ns.lookup_count++;
+
+	memset(&filter, 0, sizeof(filter));
+	filter.service = service;
+	filter.instance = instance;
+
+	xa_for_each(&nodes, node_idx, node) {
+		xa_for_each(&node->servers, srv_idx, srv) {
+			if (!server_match(srv, &filter))
+				continue;
+
+			lookup_notify(from, srv, true);
+		}
+	}
+
+	/* Empty notification, to indicate end of listing */
+	lookup_notify(from, NULL, true);
+
+	return 0;
+}
+
+static void ctrl_cmd_del_lookup(struct sockaddr_qrtr *from,
+				unsigned int service, unsigned int instance)
+{
+	struct qrtr_lookup *lookup;
+	struct list_head *tmp;
+	struct list_head *li;
+
+	list_for_each_safe(li, tmp, &qrtr_ns.lookups) {
+		lookup = container_of(li, struct qrtr_lookup, li);
+		if (lookup->sq.sq_node != from->sq_node)
+			continue;
+		if (lookup->sq.sq_port != from->sq_port)
+			continue;
+		if (lookup->service != service)
+			continue;
+		if (lookup->instance && lookup->instance != instance)
+			continue;
+
+		list_del(&lookup->li);
+		kfree(lookup);
+		qrtr_ns.lookup_count--;
+	}
+}
+
+static void qrtr_ns_worker(struct work_struct *work)
+{
+	const struct qrtr_ctrl_pkt *pkt;
+	size_t recv_buf_size = 4096;
+	struct sockaddr_qrtr sq;
+	struct msghdr msg = { };
+	unsigned int cmd;
+	ssize_t msglen;
+	void *recv_buf;
+	struct kvec iv;
+	int ret;
+
+	msg.msg_name = (struct sockaddr *)&sq;
+	msg.msg_namelen = sizeof(sq);
+
+	recv_buf = kzalloc(recv_buf_size, GFP_KERNEL);
+	if (!recv_buf)
+		return;
+
+	for (;;) {
+		iv.iov_base = recv_buf;
+		iv.iov_len = recv_buf_size;
+
+		msglen = kernel_recvmsg(qrtr_ns.sock, &msg, &iv, 1,
+					iv.iov_len, MSG_DONTWAIT);
+
+		if (msglen == -EAGAIN)
+			break;
+
+		if (msglen < 0) {
+			pr_err("error receiving packet: %zd\n", msglen);
+			break;
+		}
+
+		pkt = recv_buf;
+		cmd = le32_to_cpu(pkt->cmd);
+		if (cmd < ARRAY_SIZE(qrtr_ctrl_pkt_strings) &&
+		    qrtr_ctrl_pkt_strings[cmd])
+			trace_qrtr_ns_message(qrtr_ctrl_pkt_strings[cmd],
+					      sq.sq_node, sq.sq_port);
+
+		ret = 0;
+		switch (cmd) {
+		case QRTR_TYPE_HELLO:
+			ret = ctrl_cmd_hello(&sq);
+			break;
+		case QRTR_TYPE_BYE:
+			ret = ctrl_cmd_bye(&sq);
+			break;
+		case QRTR_TYPE_DEL_CLIENT:
+			ret = ctrl_cmd_del_client(&sq,
+					le32_to_cpu(pkt->client.node),
+					le32_to_cpu(pkt->client.port));
+			break;
+		case QRTR_TYPE_NEW_SERVER:
+			ret = ctrl_cmd_new_server(&sq,
+					le32_to_cpu(pkt->server.service),
+					le32_to_cpu(pkt->server.instance),
+					le32_to_cpu(pkt->server.node),
+					le32_to_cpu(pkt->server.port));
+			break;
+		case QRTR_TYPE_DEL_SERVER:
+			ret = ctrl_cmd_del_server(&sq,
+					 le32_to_cpu(pkt->server.service),
+					 le32_to_cpu(pkt->server.instance),
+					 le32_to_cpu(pkt->server.node),
+					 le32_to_cpu(pkt->server.port));
+			break;
+		case QRTR_TYPE_EXIT:
+		case QRTR_TYPE_PING:
+		case QRTR_TYPE_RESUME_TX:
+			break;
+		case QRTR_TYPE_NEW_LOOKUP:
+			ret = ctrl_cmd_new_lookup(&sq,
+					 le32_to_cpu(pkt->server.service),
+					 le32_to_cpu(pkt->server.instance));
+			break;
+		case QRTR_TYPE_DEL_LOOKUP:
+			ctrl_cmd_del_lookup(&sq,
+				    le32_to_cpu(pkt->server.service),
+				    le32_to_cpu(pkt->server.instance));
+			break;
+		}
+
+		if (ret < 0)
+			pr_err_ratelimited("failed while handling packet from %d:%d",
+			       sq.sq_node, sq.sq_port);
+	}
+
+	kfree(recv_buf);
+}
+
+static void qrtr_ns_data_ready(struct sock *sk)
+{
+	trace_sk_data_ready(sk);
+
+	queue_work(qrtr_ns.workqueue, &qrtr_ns.work);
+}
+
+int qrtr_ns_init(void)
+{
+	struct sockaddr_qrtr sq;
+	int ret;
+
+	INIT_LIST_HEAD(&qrtr_ns.lookups);
+	INIT_WORK(&qrtr_ns.work, qrtr_ns_worker);
+
+	ret = sock_create_kern(&init_net, AF_QIPCRTR, SOCK_DGRAM,
+			       PF_QIPCRTR, &qrtr_ns.sock);
+	if (ret < 0)
+		return ret;
+
+	ret = kernel_getsockname(qrtr_ns.sock, (struct sockaddr *)&sq);
+	if (ret < 0) {
+		pr_err("failed to get socket name\n");
+		goto err_sock;
+	}
+
+	qrtr_ns.workqueue = alloc_ordered_workqueue("qrtr_ns_handler", 0);
+	if (!qrtr_ns.workqueue) {
+		ret = -ENOMEM;
+		goto err_sock;
+	}
+
+	qrtr_ns.saved_data_ready = qrtr_ns.sock->sk->sk_data_ready;
+	qrtr_ns.sock->sk->sk_data_ready = qrtr_ns_data_ready;
+
+	sq.sq_port = QRTR_PORT_CTRL;
+	qrtr_ns.local_node = sq.sq_node;
+
+	ret = kernel_bind(qrtr_ns.sock, (struct sockaddr_unsized *)&sq, sizeof(sq));
+	if (ret < 0) {
+		pr_err("failed to bind to socket\n");
+		goto err_wq;
+	}
+
+	qrtr_ns.bcast_sq.sq_family = AF_QIPCRTR;
+	qrtr_ns.bcast_sq.sq_node = QRTR_NODE_BCAST;
+	qrtr_ns.bcast_sq.sq_port = QRTR_PORT_CTRL;
+
+	/* As the qrtr ns socket owner and creator is the same module, we have
+	 * to decrease the qrtr module reference count to guarantee that it
+	 * remains zero after the ns socket is created, otherwise, executing
+	 * "rmmod" command is unable to make the qrtr module deleted after the
+	 *  qrtr module is inserted successfully.
+	 *
+	 * However, the reference count is increased twice in
+	 * sock_create_kern(): one is to increase the reference count of owner
+	 * of qrtr socket's proto_ops struct; another is to increment the
+	 * reference count of owner of qrtr proto struct. Therefore, we must
+	 * decrement the module reference count twice to ensure that it keeps
+	 * zero after server's listening socket is created. Of course, we
+	 * must bump the module reference count twice as well before the socket
+	 * is closed.
+	 */
+	module_put(qrtr_ns.sock->ops->owner);
+	module_put(qrtr_ns.sock->sk->sk_prot_creator->owner);
+
+	return 0;
+
+err_wq:
+	write_lock_bh(&qrtr_ns.sock->sk->sk_callback_lock);
+	qrtr_ns.sock->sk->sk_data_ready = qrtr_ns.saved_data_ready;
+	write_unlock_bh(&qrtr_ns.sock->sk->sk_callback_lock);
+
+	destroy_workqueue(qrtr_ns.workqueue);
+err_sock:
+	sock_release(qrtr_ns.sock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(qrtr_ns_init);
+
+void qrtr_ns_remove(void)
+{
+	write_lock_bh(&qrtr_ns.sock->sk->sk_callback_lock);
+	qrtr_ns.sock->sk->sk_data_ready = qrtr_ns.saved_data_ready;
+	write_unlock_bh(&qrtr_ns.sock->sk->sk_callback_lock);
+
+	cancel_work_sync(&qrtr_ns.work);
+	synchronize_net();
+	destroy_workqueue(qrtr_ns.workqueue);
+
+	/* sock_release() expects the two references that were put during
+	 * qrtr_ns_init(). This function is only called during module remove,
+	 * so try_stop_module() has already set the refcnt to 0. Use
+	 * __module_get() instead of try_module_get() to successfully take two
+	 * references.
+	 */
+	__module_get(qrtr_ns.sock->ops->owner);
+	__module_get(qrtr_ns.sock->sk->sk_prot_creator->owner);
+	sock_release(qrtr_ns.sock);
+}
+EXPORT_SYMBOL_GPL(qrtr_ns_remove);
+
+MODULE_AUTHOR("Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>");
+MODULE_DESCRIPTION("Qualcomm IPC Router Nameservice");
+MODULE_LICENSE("Dual BSD/GPL");