1 files changed, 287 insertions, 0 deletions

diff --git a/drivers/hv/hv_snapshot.c b/drivers/hv/hv_snapshot.c
new file mode 100644
index 000000000000..8ad5653ce447
--- /dev/null
+++ b/drivers/hv/hv_snapshot.c
@@ -0,0 +1,287 @@
+/*
+ * 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>
+
+
+
+/*
+ * 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 DECLARE_WORK(vss_send_op_work, vss_send_op);
+
+/*
+ * Callback when data is received from user mode.
+ */
+
+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;
+
+        }
+        vss_respond_to_host(vss_msg->error);
+}
+
+
+static void vss_send_op(struct work_struct *dummy)
+{
+        int op = vss_transaction.msg->vss_hdr.operation;
+        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);
+
+        cn_netlink_send(msg, 0, GFP_ATOMIC);
+        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, 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;
+
+                        }
+
+                }
+
+                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_work_sync(&vss_send_op_work);
+}