/* * An implementation of host initiated guest snapshot. * * * Copyright (C) 2013, Microsoft, Inc. * Author : K. Y. Srinivasan * * 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 #include #include #include #include /* * 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); }