1 files changed, 326 insertions, 148 deletions

diff --git a/drivers/hv/hv_snapshot.c b/drivers/hv/hv_snapshot.c
index 8ad5653ce447..2e7f537d53cf 100644
--- a/drivers/hv/hv_snapshot.c
+++ b/drivers/hv/hv_snapshot.c
@@ -1,20 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * An implementation of host initiated guest snapshot.
  *
- *
  * Copyright (C) 2013, Microsoft, Inc.
  * Author : K. Y. Srinivasan <kys@microsoft.com>
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
- * NON INFRINGEMENT.  See the GNU General Public License for more
- * details.
- *
  */
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
@@ -23,20 +12,49 @@
 #include <linux/connector.h>
 #include <linux/workqueue.h>
 #include <linux/hyperv.h>
+#include <hyperv/hvhdk.h>
+
+#include "hyperv_vmbus.h"
+#include "hv_utils_transport.h"
+
+#define VSS_MAJOR  5
+#define VSS_MINOR  0
+#define VSS_VERSION    (VSS_MAJOR << 16 | VSS_MINOR)
+
+#define VSS_VER_COUNT 1
+static const int vss_versions[] = {
+	VSS_VERSION
+};
+
+#define FW_VER_COUNT 1
+static const int fw_versions[] = {
+	UTIL_FW_VERSION
+};
 
+/* See comment with struct hv_vss_msg regarding the max VMbus packet size */
+#define VSS_MAX_PKT_SIZE (HV_HYP_PAGE_SIZE * 2)
 
+/*
+ * Timeout values are based on expecations from host
+ */
+#define VSS_FREEZE_TIMEOUT (15 * 60)
 
 /*
- * Global state maintained for transaction that is being processed.
- * Note that only one transaction can be active at any point in time.
+ * Global state maintained for transaction that is being processed. For a class
+ * of integration services, including the "VSS service", the specified protocol
+ * is a "request/response" protocol which means that there can only be single
+ * outstanding transaction from the host at any given point in time. We use
+ * this to simplify memory management in this driver - we cache and process
+ * only one message at a time.
  *
- * This state is set when we receive a request from the host; we
- * cleanup this state when the transaction is completed - when we respond
- * to the host with the key value.
+ * While the request/response protocol is guaranteed by the host, we further
+ * ensure this by serializing packet processing in this driver - we do not
+ * read additional packets from the VMBUs until the current packet is fully
+ * handled.
  */
 
 static struct {
-	bool active; /* transaction status - active or not */
+	int state;   /* hvutil_device_state */
 	int recv_len; /* number of bytes received. */
 	struct vmbus_channel *recv_channel; /* chn we got the request */
 	u64 recv_req_id; /* request ID. */
@@ -46,58 +64,184 @@ static struct {
 
 static void vss_respond_to_host(int error);
 
-static struct cb_id vss_id = { CN_VSS_IDX, CN_VSS_VAL };
-static const char vss_name[] = "vss_kernel_module";
+/*
+ * This state maintains the version number registered by the daemon.
+ */
+static int dm_reg_value;
+
+static const char vss_devname[] = "vmbus/hv_vss";
 static __u8 *recv_buffer;
+static struct hvutil_transport *hvt;
+
+static void vss_timeout_func(struct work_struct *dummy);
+static void vss_handle_request(struct work_struct *dummy);
 
-static void vss_send_op(struct work_struct *dummy);
-static DECLARE_WORK(vss_send_op_work, vss_send_op);
+static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
+static DECLARE_WORK(vss_handle_request_work, vss_handle_request);
+
+static void vss_poll_wrapper(void *channel)
+{
+	/* Transaction is finished, reset the state here to avoid races. */
+	vss_transaction.state = HVUTIL_READY;
+	tasklet_schedule(&((struct vmbus_channel *)channel)->callback_event);
+}
 
 /*
  * Callback when data is received from user mode.
  */
 
-static void
-vss_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
+static void vss_timeout_func(struct work_struct *dummy)
 {
-	struct hv_vss_msg *vss_msg;
+	/*
+	 * Timeout waiting for userspace component to reply happened.
+	 */
+	pr_warn("VSS: timeout waiting for daemon to reply\n");
+	vss_respond_to_host(HV_E_FAIL);
 
-	vss_msg = (struct hv_vss_msg *)msg->data;
+	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
+}
 
-	if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER) {
-		pr_info("VSS daemon registered\n");
-		vss_transaction.active = false;
-		if (vss_transaction.recv_channel != NULL)
-			hv_vss_onchannelcallback(vss_transaction.recv_channel);
-		return;
+static void vss_register_done(void)
+{
+	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
+	pr_debug("VSS: userspace daemon registered\n");
+}
 
+static int vss_handle_handshake(struct hv_vss_msg *vss_msg)
+{
+	u32 our_ver = VSS_OP_REGISTER1;
+
+	switch (vss_msg->vss_hdr.operation) {
+	case VSS_OP_REGISTER:
+		/* Daemon doesn't expect us to reply */
+		dm_reg_value = VSS_OP_REGISTER;
+		break;
+	case VSS_OP_REGISTER1:
+		/* Daemon expects us to reply with our own version */
+		if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver),
+					  vss_register_done))
+			return -EFAULT;
+		dm_reg_value = VSS_OP_REGISTER1;
+		break;
+	default:
+		return -EINVAL;
 	}
-	vss_respond_to_host(vss_msg->error);
+	pr_info("VSS: userspace daemon ver. %d connected\n", dm_reg_value);
+	return 0;
 }
 
+static int vss_on_msg(void *msg, int len)
+{
+	struct hv_vss_msg *vss_msg = (struct hv_vss_msg *)msg;
 
-static void vss_send_op(struct work_struct *dummy)
+	if (len != sizeof(*vss_msg)) {
+		pr_debug("VSS: Message size does not match length\n");
+		return -EINVAL;
+	}
+
+	if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER ||
+	    vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) {
+		/*
+		 * Don't process registration messages if we're in the middle
+		 * of a transaction processing.
+		 */
+		if (vss_transaction.state > HVUTIL_READY) {
+			pr_debug("VSS: Got unexpected registration request\n");
+			return -EINVAL;
+		}
+
+		return vss_handle_handshake(vss_msg);
+	} else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {
+		vss_transaction.state = HVUTIL_USERSPACE_RECV;
+
+		if (vss_msg->vss_hdr.operation == VSS_OP_HOT_BACKUP)
+			vss_transaction.msg->vss_cf.flags =
+				VSS_HBU_NO_AUTO_RECOVERY;
+
+		if (cancel_delayed_work_sync(&vss_timeout_work)) {
+			vss_respond_to_host(vss_msg->error);
+			/* Transaction is finished, reset the state. */
+			hv_poll_channel(vss_transaction.recv_channel,
+					vss_poll_wrapper);
+		}
+	} else {
+		/* This is a spurious call! */
+		pr_debug("VSS: Transaction not active\n");
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static void vss_send_op(void)
 {
 	int op = vss_transaction.msg->vss_hdr.operation;
-	struct cn_msg *msg;
+	int rc;
 	struct hv_vss_msg *vss_msg;
 
-	msg = kzalloc(sizeof(*msg) + sizeof(*vss_msg), GFP_ATOMIC);
-	if (!msg)
+	/* The transaction state is wrong. */
+	if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED) {
+		pr_debug("VSS: Unexpected attempt to send to daemon\n");
 		return;
+	}
 
-	vss_msg = (struct hv_vss_msg *)msg->data;
-
-	msg->id.idx =  CN_VSS_IDX;
-	msg->id.val = CN_VSS_VAL;
+	vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL);
+	if (!vss_msg)
+		return;
 
 	vss_msg->vss_hdr.operation = op;
-	msg->len = sizeof(struct hv_vss_msg);
 
-	cn_netlink_send(msg, 0, GFP_ATOMIC);
-	kfree(msg);
+	vss_transaction.state = HVUTIL_USERSPACE_REQ;
+
+	schedule_delayed_work(&vss_timeout_work, op == VSS_OP_FREEZE ?
+				secs_to_jiffies(VSS_FREEZE_TIMEOUT) :
+				secs_to_jiffies(HV_UTIL_TIMEOUT));
+
+	rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);
+	if (rc) {
+		pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
+		if (cancel_delayed_work_sync(&vss_timeout_work)) {
+			vss_respond_to_host(HV_E_FAIL);
+			vss_transaction.state = HVUTIL_READY;
+		}
+	}
 
-	return;
+	kfree(vss_msg);
+}
+
+static void vss_handle_request(struct work_struct *dummy)
+{
+	switch (vss_transaction.msg->vss_hdr.operation) {
+	/*
+	 * Initiate a "freeze/thaw" operation in the guest.
+	 * We respond to the host once the operation is complete.
+	 *
+	 * We send the message to the user space daemon and the operation is
+	 * performed in the daemon.
+	 */
+	case VSS_OP_THAW:
+	case VSS_OP_FREEZE:
+	case VSS_OP_HOT_BACKUP:
+		if (vss_transaction.state < HVUTIL_READY) {
+			/* Userspace is not registered yet */
+			pr_debug("VSS: Not ready for request.\n");
+			vss_respond_to_host(HV_E_FAIL);
+			return;
+		}
+
+		pr_debug("VSS: Received request for op code: %d\n",
+			vss_transaction.msg->vss_hdr.operation);
+		vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
+		vss_send_op();
+		return;
+	case VSS_OP_GET_DM_INFO:
+		vss_transaction.msg->dm_info.flags = 0;
+		break;
+	default:
+		break;
+	}
+
+	vss_respond_to_host(0);
+	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
 }
 
 /*
@@ -113,17 +257,6 @@ vss_respond_to_host(int error)
 	u64	req_id;
 
 	/*
-	 * If a transaction is not active; log and return.
-	 */
-
-	if (!vss_transaction.active) {
-		/*
-		 * This is a spurious call!
-		 */
-		pr_warn("VSS: Transaction not active\n");
-		return;
-	}
-	/*
 	 * Copy the global state for completing the transaction. Note that
 	 * only one transaction can be active at a time.
 	 */
@@ -131,7 +264,6 @@ vss_respond_to_host(int error)
 	buf_len = vss_transaction.recv_len;
 	channel = vss_transaction.recv_channel;
 	req_id = vss_transaction.recv_req_id;
-	vss_transaction.active = false;
 
 	icmsghdrp = (struct icmsg_hdr *)
 			&recv_buffer[sizeof(struct vmbuspipe_hdr)];
@@ -163,112 +295,91 @@ void hv_vss_onchannelcallback(void *context)
 	u32 recvlen;
 	u64 requestid;
 	struct hv_vss_msg *vss_msg;
-
+	int vss_srv_version;
 
 	struct icmsg_hdr *icmsghdrp;
-	struct icmsg_negotiate *negop = NULL;
 
-	if (vss_transaction.active) {
-		/*
-		 * We will defer processing this callback once
-		 * the current transaction is complete.
-		 */
-		vss_transaction.recv_channel = channel;
+	if (vss_transaction.state > HVUTIL_READY)
+		return;
+
+	if (vmbus_recvpacket(channel, recv_buffer, VSS_MAX_PKT_SIZE, &recvlen, &requestid)) {
+		pr_err_ratelimited("VSS request received. Could not read into recv buf\n");
 		return;
 	}
 
-	vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
-			 &requestid);
-
-	if (recvlen > 0) {
-		icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
-			sizeof(struct vmbuspipe_hdr)];
-
-		if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
-			vmbus_prep_negotiate_resp(icmsghdrp, negop,
-				 recv_buffer, MAX_SRV_VER, MAX_SRV_VER);
-			/*
-			 * We currently negotiate the highest number the
-			 * host has presented. If this version is not
-			 * atleast 5.0, reject.
-			 */
-			negop = (struct icmsg_negotiate *)&recv_buffer[
-				sizeof(struct vmbuspipe_hdr) +
-				sizeof(struct icmsg_hdr)];
-
-			if (negop->icversion_data[1].major < 5)
-				negop->icframe_vercnt = 0;
-		} else {
-			vss_msg = (struct hv_vss_msg *)&recv_buffer[
-				sizeof(struct vmbuspipe_hdr) +
-				sizeof(struct icmsg_hdr)];
-
-			/*
-			 * Stash away this global state for completing the
-			 * transaction; note transactions are serialized.
-			 */
-
-			vss_transaction.recv_len = recvlen;
-			vss_transaction.recv_channel = channel;
-			vss_transaction.recv_req_id = requestid;
-			vss_transaction.active = true;
-			vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
-
-			switch (vss_msg->vss_hdr.operation) {
-				/*
-				 * Initiate a "freeze/thaw"
-				 * operation in the guest.
-				 * We respond to the host once
-				 * the operation is complete.
-				 *
-				 * We send the message to the
-				 * user space daemon and the
-				 * operation is performed in
-				 * the daemon.
-				 */
-			case VSS_OP_FREEZE:
-			case VSS_OP_THAW:
-				schedule_work(&vss_send_op_work);
-				return;
-
-			case VSS_OP_HOT_BACKUP:
-				vss_msg->vss_cf.flags =
-					 VSS_HBU_NO_AUTO_RECOVERY;
-				vss_respond_to_host(0);
-				return;
-
-			case VSS_OP_GET_DM_INFO:
-				vss_msg->dm_info.flags = 0;
-				vss_respond_to_host(0);
-				return;
-
-			default:
-				vss_respond_to_host(0);
-				return;
-
-			}
+	if (!recvlen)
+		return;
+
+	/* Ensure recvlen is big enough to read header data */
+	if (recvlen < ICMSG_HDR) {
+		pr_err_ratelimited("VSS request received. Packet length too small: %d\n",
+				   recvlen);
+		return;
+	}
+
+	icmsghdrp = (struct icmsg_hdr *)&recv_buffer[sizeof(struct vmbuspipe_hdr)];
+
+	if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
+		if (vmbus_prep_negotiate_resp(icmsghdrp,
+				recv_buffer, recvlen,
+				fw_versions, FW_VER_COUNT,
+				vss_versions, VSS_VER_COUNT,
+				NULL, &vss_srv_version)) {
 
+			pr_info("VSS IC version %d.%d\n",
+				vss_srv_version >> 16,
+				vss_srv_version & 0xFFFF);
 		}
+	} else if (icmsghdrp->icmsgtype == ICMSGTYPE_VSS) {
+		/* Ensure recvlen is big enough to contain hv_vss_msg */
+		if (recvlen < ICMSG_HDR + sizeof(struct hv_vss_msg)) {
+			pr_err_ratelimited("Invalid VSS msg. Packet length too small: %u\n",
+					   recvlen);
+			return;
+		}
+		vss_msg = (struct hv_vss_msg *)&recv_buffer[ICMSG_HDR];
+
+		/*
+		 * Stash away this global state for completing the
+		 * transaction; note transactions are serialized.
+		 */
 
-		icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
-			| ICMSGHDRFLAG_RESPONSE;
+		vss_transaction.recv_len = recvlen;
+		vss_transaction.recv_req_id = requestid;
+		vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
 
-		vmbus_sendpacket(channel, recv_buffer,
-				       recvlen, requestid,
-				       VM_PKT_DATA_INBAND, 0);
+		schedule_work(&vss_handle_request_work);
+		return;
+	} else {
+		pr_err_ratelimited("VSS request received. Invalid msg type: %d\n",
+				   icmsghdrp->icmsgtype);
+		return;
 	}
 
+	icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION |
+		ICMSGHDRFLAG_RESPONSE;
+	vmbus_sendpacket(channel, recv_buffer, recvlen, requestid,
+			 VM_PKT_DATA_INBAND, 0);
+}
+
+static void vss_on_reset(void)
+{
+	if (cancel_delayed_work_sync(&vss_timeout_work))
+		vss_respond_to_host(HV_E_FAIL);
+	vss_transaction.state = HVUTIL_DEVICE_INIT;
 }
 
 int
 hv_vss_init(struct hv_util_service *srv)
 {
-	int err;
-
-	err = cn_add_callback(&vss_id, vss_name, vss_cn_callback);
-	if (err)
-		return err;
+	if (vmbus_proto_version < VERSION_WIN8_1) {
+		pr_warn("Integration service 'Backup (volume snapshot)'"
+			" not supported on this host version.\n");
+		return -ENOTSUPP;
+	}
 	recv_buffer = srv->recv_buffer;
+	vss_transaction.recv_channel = srv->channel;
+	vss_transaction.recv_channel->max_pkt_size = VSS_MAX_PKT_SIZE;
 
 	/*
 	 * When this driver loads, the user level daemon that
@@ -276,12 +387,79 @@ hv_vss_init(struct hv_util_service *srv)
 	 * Defer processing channel callbacks until the daemon
 	 * has registered.
 	 */
-	vss_transaction.active = true;
+	vss_transaction.state = HVUTIL_DEVICE_INIT;
+
+	return 0;
+}
+
+int
+hv_vss_init_transport(void)
+{
+	hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL,
+				    vss_on_msg, vss_on_reset);
+	if (!hvt) {
+		pr_warn("VSS: Failed to initialize transport\n");
+		return -EFAULT;
+	}
+
+	return 0;
+}
+
+static void hv_vss_cancel_work(void)
+{
+	cancel_delayed_work_sync(&vss_timeout_work);
+	cancel_work_sync(&vss_handle_request_work);
+}
+
+int hv_vss_pre_suspend(void)
+{
+	struct vmbus_channel *channel = vss_transaction.recv_channel;
+	struct hv_vss_msg *vss_msg;
+
+	/*
+	 * Fake a THAW message for the user space daemon in case the daemon
+	 * has frozen the file systems. It doesn't matter if there is already
+	 * a message pending to be delivered to the user space since we force
+	 * vss_transaction.state to be HVUTIL_READY, so the user space daemon's
+	 * write() will fail with EINVAL (see vss_on_msg()), and the daemon
+	 * will reset the device by closing and re-opening it.
+	 */
+	vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL);
+	if (!vss_msg)
+		return -ENOMEM;
+
+	tasklet_disable(&channel->callback_event);
+
+	vss_msg->vss_hdr.operation = VSS_OP_THAW;
+
+	/* Cancel any possible pending work. */
+	hv_vss_cancel_work();
+
+	/* We don't care about the return value. */
+	hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);
+
+	kfree(vss_msg);
+
+	vss_transaction.state = HVUTIL_READY;
+
+	/* tasklet_enable() will be called in hv_vss_pre_resume(). */
+	return 0;
+}
+
+int hv_vss_pre_resume(void)
+{
+	struct vmbus_channel *channel = vss_transaction.recv_channel;
+
+	tasklet_enable(&channel->callback_event);
+
 	return 0;
 }
 
 void hv_vss_deinit(void)
 {
-	cn_del_callback(&vss_id);
-	cancel_work_sync(&vss_send_op_work);
+	vss_transaction.state = HVUTIL_DEVICE_DYING;
+
+	hv_vss_cancel_work();
+
+	hvutil_transport_destroy(hvt);
 }