--- /dev/null
+/*
+ * 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
+
+#include <linux/net.h>
+#include <linux/nls.h>
+#include <linux/connector.h>
+#include <linux/workqueue.h>
+#include <linux/hyperv.h>
+
+#define VSS_MAJOR 5
+#define VSS_MINOR 0
+#define VSS_VERSION (VSS_MAJOR << 16 | VSS_MINOR)
+
+#define VSS_USERSPACE_TIMEOUT (msecs_to_jiffies(10 * 1000))
+
+/*
+ * Global state maintained for transaction that is being processed.
+ * Note that only one transaction can be active at any point in 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.
+ */
+
+static struct {
+ bool active; /* transaction status - active or not */
+ int recv_len; /* number of bytes received. */
+ struct vmbus_channel *recv_channel; /* chn we got the request */
+ u64 recv_req_id; /* request ID. */
+ struct hv_vss_msg *msg; /* current message */
+} vss_transaction;
+
+
+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";
+static __u8 *recv_buffer;
+
+static void vss_send_op(struct work_struct *dummy);
+static void vss_timeout_func(struct work_struct *dummy);
+
+static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
+static DECLARE_WORK(vss_send_op_work, vss_send_op);
+
+/*
+ * Callback when data is received from user mode.
+ */
+
+static void vss_timeout_func(struct work_struct *dummy)
+{
+ /*
+ * 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);
+}
+
+static void
+vss_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
+{
+ struct hv_vss_msg *vss_msg;
+
+ vss_msg = (struct hv_vss_msg *)msg->data;
+
+ 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;
+
+ }
+ if (cancel_delayed_work_sync(&vss_timeout_work))
+ vss_respond_to_host(vss_msg->error);
+}
+
+
+static void vss_send_op(struct work_struct *dummy)
+{
+ int op = vss_transaction.msg->vss_hdr.operation;
+ int rc;
+ struct cn_msg *msg;
+ struct hv_vss_msg *vss_msg;
+
+ msg = kzalloc(sizeof(*msg) + sizeof(*vss_msg), GFP_ATOMIC);
+ if (!msg)
+ return;
+
+ vss_msg = (struct hv_vss_msg *)msg->data;
+
+ msg->id.idx = CN_VSS_IDX;
+ msg->id.val = CN_VSS_VAL;
+
+ vss_msg->vss_hdr.operation = op;
+ msg->len = sizeof(struct hv_vss_msg);
+
+ rc = cn_netlink_send(msg, 0, 0, GFP_ATOMIC);
+ 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);
+ }
+ kfree(msg);
+
+ return;
+}
+
+/*
+ * Send a response back to the host.
+ */
+
+static void
+vss_respond_to_host(int error)
+{
+ struct icmsg_hdr *icmsghdrp;
+ u32 buf_len;
+ struct vmbus_channel *channel;
+ 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.
+ */
+
+ 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)];
+
+ if (channel->onchannel_callback == NULL)
+ /*
+ * We have raced with util driver being unloaded;
+ * silently return.
+ */
+ return;
+
+ icmsghdrp->status = error;
+
+ icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
+
+ vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
+ VM_PKT_DATA_INBAND, 0);
+
+}
+
+/*
+ * This callback is invoked when we get a VSS message from the host.
+ * The host ensures that only one VSS transaction can be active at a time.
+ */
+
+void hv_vss_onchannelcallback(void *context)
+{
+ struct vmbus_channel *channel = context;
+ u32 recvlen;
+ u64 requestid;
+ struct hv_vss_msg *vss_msg;
+
+
+ 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;
+ 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, UTIL_FW_VERSION,
+ VSS_VERSION);
+ } 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);
+ schedule_delayed_work(&vss_timeout_work,
+ VSS_USERSPACE_TIMEOUT);
+ 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;
+
+ }
+
+ }
+
+ icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
+ | ICMSGHDRFLAG_RESPONSE;
+
+ vmbus_sendpacket(channel, recv_buffer,
+ recvlen, requestid,
+ VM_PKT_DATA_INBAND, 0);
+ }
+
+}
+
+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;
+ recv_buffer = srv->recv_buffer;
+
+ /*
+ * When this driver loads, the user level daemon that
+ * processes the host requests may not yet be running.
+ * Defer processing channel callbacks until the daemon
+ * has registered.
+ */
+ vss_transaction.active = true;
+ return 0;
+}
+
+void hv_vss_deinit(void)
+{
+ cn_del_callback(&vss_id);
+ cancel_delayed_work_sync(&vss_timeout_work);
+ cancel_work_sync(&vss_send_op_work);
+}
Code Review / kvmfornfv.git / blobdiff