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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * An implementation of host initiated guest snapshot.4 *5 * Copyright (C) 2013, Microsoft, Inc.6 * Author : K. Y. Srinivasan <kys@microsoft.com>7 */8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt9 10#include <linux/net.h>11#include <linux/nls.h>12#include <linux/connector.h>13#include <linux/workqueue.h>14#include <linux/hyperv.h>15#include <asm/hyperv-tlfs.h>16 17#include "hyperv_vmbus.h"18#include "hv_utils_transport.h"19 20#define VSS_MAJOR 521#define VSS_MINOR 022#define VSS_VERSION (VSS_MAJOR << 16 | VSS_MINOR)23 24#define VSS_VER_COUNT 125static const int vss_versions[] = {26 VSS_VERSION27};28 29#define FW_VER_COUNT 130static const int fw_versions[] = {31 UTIL_FW_VERSION32};33 34/* See comment with struct hv_vss_msg regarding the max VMbus packet size */35#define VSS_MAX_PKT_SIZE (HV_HYP_PAGE_SIZE * 2)36 37/*38 * Timeout values are based on expecations from host39 */40#define VSS_FREEZE_TIMEOUT (15 * 60)41 42/*43 * Global state maintained for transaction that is being processed. For a class44 * of integration services, including the "VSS service", the specified protocol45 * is a "request/response" protocol which means that there can only be single46 * outstanding transaction from the host at any given point in time. We use47 * this to simplify memory management in this driver - we cache and process48 * only one message at a time.49 *50 * While the request/response protocol is guaranteed by the host, we further51 * ensure this by serializing packet processing in this driver - we do not52 * read additional packets from the VMBUs until the current packet is fully53 * handled.54 */55 56static struct {57 int state; /* hvutil_device_state */58 int recv_len; /* number of bytes received. */59 struct vmbus_channel *recv_channel; /* chn we got the request */60 u64 recv_req_id; /* request ID. */61 struct hv_vss_msg *msg; /* current message */62} vss_transaction;63 64 65static void vss_respond_to_host(int error);66 67/*68 * This state maintains the version number registered by the daemon.69 */70static int dm_reg_value;71 72static const char vss_devname[] = "vmbus/hv_vss";73static __u8 *recv_buffer;74static struct hvutil_transport *hvt;75 76static void vss_timeout_func(struct work_struct *dummy);77static void vss_handle_request(struct work_struct *dummy);78 79static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);80static DECLARE_WORK(vss_handle_request_work, vss_handle_request);81 82static void vss_poll_wrapper(void *channel)83{84 /* Transaction is finished, reset the state here to avoid races. */85 vss_transaction.state = HVUTIL_READY;86 tasklet_schedule(&((struct vmbus_channel *)channel)->callback_event);87}88 89/*90 * Callback when data is received from user mode.91 */92 93static void vss_timeout_func(struct work_struct *dummy)94{95 /*96 * Timeout waiting for userspace component to reply happened.97 */98 pr_warn("VSS: timeout waiting for daemon to reply\n");99 vss_respond_to_host(HV_E_FAIL);100 101 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);102}103 104static void vss_register_done(void)105{106 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);107 pr_debug("VSS: userspace daemon registered\n");108}109 110static int vss_handle_handshake(struct hv_vss_msg *vss_msg)111{112 u32 our_ver = VSS_OP_REGISTER1;113 114 switch (vss_msg->vss_hdr.operation) {115 case VSS_OP_REGISTER:116 /* Daemon doesn't expect us to reply */117 dm_reg_value = VSS_OP_REGISTER;118 break;119 case VSS_OP_REGISTER1:120 /* Daemon expects us to reply with our own version */121 if (hvutil_transport_send(hvt, &our_ver, sizeof(our_ver),122 vss_register_done))123 return -EFAULT;124 dm_reg_value = VSS_OP_REGISTER1;125 break;126 default:127 return -EINVAL;128 }129 pr_info("VSS: userspace daemon ver. %d connected\n", dm_reg_value);130 return 0;131}132 133static int vss_on_msg(void *msg, int len)134{135 struct hv_vss_msg *vss_msg = (struct hv_vss_msg *)msg;136 137 if (len != sizeof(*vss_msg)) {138 pr_debug("VSS: Message size does not match length\n");139 return -EINVAL;140 }141 142 if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER ||143 vss_msg->vss_hdr.operation == VSS_OP_REGISTER1) {144 /*145 * Don't process registration messages if we're in the middle146 * of a transaction processing.147 */148 if (vss_transaction.state > HVUTIL_READY) {149 pr_debug("VSS: Got unexpected registration request\n");150 return -EINVAL;151 }152 153 return vss_handle_handshake(vss_msg);154 } else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {155 vss_transaction.state = HVUTIL_USERSPACE_RECV;156 157 if (vss_msg->vss_hdr.operation == VSS_OP_HOT_BACKUP)158 vss_transaction.msg->vss_cf.flags =159 VSS_HBU_NO_AUTO_RECOVERY;160 161 if (cancel_delayed_work_sync(&vss_timeout_work)) {162 vss_respond_to_host(vss_msg->error);163 /* Transaction is finished, reset the state. */164 hv_poll_channel(vss_transaction.recv_channel,165 vss_poll_wrapper);166 }167 } else {168 /* This is a spurious call! */169 pr_debug("VSS: Transaction not active\n");170 return -EINVAL;171 }172 return 0;173}174 175static void vss_send_op(void)176{177 int op = vss_transaction.msg->vss_hdr.operation;178 int rc;179 struct hv_vss_msg *vss_msg;180 181 /* The transaction state is wrong. */182 if (vss_transaction.state != HVUTIL_HOSTMSG_RECEIVED) {183 pr_debug("VSS: Unexpected attempt to send to daemon\n");184 return;185 }186 187 vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL);188 if (!vss_msg)189 return;190 191 vss_msg->vss_hdr.operation = op;192 193 vss_transaction.state = HVUTIL_USERSPACE_REQ;194 195 schedule_delayed_work(&vss_timeout_work, op == VSS_OP_FREEZE ?196 VSS_FREEZE_TIMEOUT * HZ : HV_UTIL_TIMEOUT * HZ);197 198 rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);199 if (rc) {200 pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);201 if (cancel_delayed_work_sync(&vss_timeout_work)) {202 vss_respond_to_host(HV_E_FAIL);203 vss_transaction.state = HVUTIL_READY;204 }205 }206 207 kfree(vss_msg);208}209 210static void vss_handle_request(struct work_struct *dummy)211{212 switch (vss_transaction.msg->vss_hdr.operation) {213 /*214 * Initiate a "freeze/thaw" operation in the guest.215 * We respond to the host once the operation is complete.216 *217 * We send the message to the user space daemon and the operation is218 * performed in the daemon.219 */220 case VSS_OP_THAW:221 case VSS_OP_FREEZE:222 case VSS_OP_HOT_BACKUP:223 if (vss_transaction.state < HVUTIL_READY) {224 /* Userspace is not registered yet */225 pr_debug("VSS: Not ready for request.\n");226 vss_respond_to_host(HV_E_FAIL);227 return;228 }229 230 pr_debug("VSS: Received request for op code: %d\n",231 vss_transaction.msg->vss_hdr.operation);232 vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;233 vss_send_op();234 return;235 case VSS_OP_GET_DM_INFO:236 vss_transaction.msg->dm_info.flags = 0;237 break;238 default:239 break;240 }241 242 vss_respond_to_host(0);243 hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);244}245 246/*247 * Send a response back to the host.248 */249 250static void251vss_respond_to_host(int error)252{253 struct icmsg_hdr *icmsghdrp;254 u32 buf_len;255 struct vmbus_channel *channel;256 u64 req_id;257 258 /*259 * Copy the global state for completing the transaction. Note that260 * only one transaction can be active at a time.261 */262 263 buf_len = vss_transaction.recv_len;264 channel = vss_transaction.recv_channel;265 req_id = vss_transaction.recv_req_id;266 267 icmsghdrp = (struct icmsg_hdr *)268 &recv_buffer[sizeof(struct vmbuspipe_hdr)];269 270 if (channel->onchannel_callback == NULL)271 /*272 * We have raced with util driver being unloaded;273 * silently return.274 */275 return;276 277 icmsghdrp->status = error;278 279 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;280 281 vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,282 VM_PKT_DATA_INBAND, 0);283 284}285 286/*287 * This callback is invoked when we get a VSS message from the host.288 * The host ensures that only one VSS transaction can be active at a time.289 */290 291void hv_vss_onchannelcallback(void *context)292{293 struct vmbus_channel *channel = context;294 u32 recvlen;295 u64 requestid;296 struct hv_vss_msg *vss_msg;297 int vss_srv_version;298 299 struct icmsg_hdr *icmsghdrp;300 301 if (vss_transaction.state > HVUTIL_READY)302 return;303 304 if (vmbus_recvpacket(channel, recv_buffer, VSS_MAX_PKT_SIZE, &recvlen, &requestid)) {305 pr_err_ratelimited("VSS request received. Could not read into recv buf\n");306 return;307 }308 309 if (!recvlen)310 return;311 312 /* Ensure recvlen is big enough to read header data */313 if (recvlen < ICMSG_HDR) {314 pr_err_ratelimited("VSS request received. Packet length too small: %d\n",315 recvlen);316 return;317 }318 319 icmsghdrp = (struct icmsg_hdr *)&recv_buffer[sizeof(struct vmbuspipe_hdr)];320 321 if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {322 if (vmbus_prep_negotiate_resp(icmsghdrp,323 recv_buffer, recvlen,324 fw_versions, FW_VER_COUNT,325 vss_versions, VSS_VER_COUNT,326 NULL, &vss_srv_version)) {327 328 pr_info("VSS IC version %d.%d\n",329 vss_srv_version >> 16,330 vss_srv_version & 0xFFFF);331 }332 } else if (icmsghdrp->icmsgtype == ICMSGTYPE_VSS) {333 /* Ensure recvlen is big enough to contain hv_vss_msg */334 if (recvlen < ICMSG_HDR + sizeof(struct hv_vss_msg)) {335 pr_err_ratelimited("Invalid VSS msg. Packet length too small: %u\n",336 recvlen);337 return;338 }339 vss_msg = (struct hv_vss_msg *)&recv_buffer[ICMSG_HDR];340 341 /*342 * Stash away this global state for completing the343 * transaction; note transactions are serialized.344 */345 346 vss_transaction.recv_len = recvlen;347 vss_transaction.recv_req_id = requestid;348 vss_transaction.msg = (struct hv_vss_msg *)vss_msg;349 350 schedule_work(&vss_handle_request_work);351 return;352 } else {353 pr_err_ratelimited("VSS request received. Invalid msg type: %d\n",354 icmsghdrp->icmsgtype);355 return;356 }357 358 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION |359 ICMSGHDRFLAG_RESPONSE;360 vmbus_sendpacket(channel, recv_buffer, recvlen, requestid,361 VM_PKT_DATA_INBAND, 0);362}363 364static void vss_on_reset(void)365{366 if (cancel_delayed_work_sync(&vss_timeout_work))367 vss_respond_to_host(HV_E_FAIL);368 vss_transaction.state = HVUTIL_DEVICE_INIT;369}370 371int372hv_vss_init(struct hv_util_service *srv)373{374 if (vmbus_proto_version < VERSION_WIN8_1) {375 pr_warn("Integration service 'Backup (volume snapshot)'"376 " not supported on this host version.\n");377 return -ENOTSUPP;378 }379 recv_buffer = srv->recv_buffer;380 vss_transaction.recv_channel = srv->channel;381 vss_transaction.recv_channel->max_pkt_size = VSS_MAX_PKT_SIZE;382 383 /*384 * When this driver loads, the user level daemon that385 * processes the host requests may not yet be running.386 * Defer processing channel callbacks until the daemon387 * has registered.388 */389 vss_transaction.state = HVUTIL_DEVICE_INIT;390 391 hvt = hvutil_transport_init(vss_devname, CN_VSS_IDX, CN_VSS_VAL,392 vss_on_msg, vss_on_reset);393 if (!hvt) {394 pr_warn("VSS: Failed to initialize transport\n");395 return -EFAULT;396 }397 398 return 0;399}400 401static void hv_vss_cancel_work(void)402{403 cancel_delayed_work_sync(&vss_timeout_work);404 cancel_work_sync(&vss_handle_request_work);405}406 407int hv_vss_pre_suspend(void)408{409 struct vmbus_channel *channel = vss_transaction.recv_channel;410 struct hv_vss_msg *vss_msg;411 412 /*413 * Fake a THAW message for the user space daemon in case the daemon414 * has frozen the file systems. It doesn't matter if there is already415 * a message pending to be delivered to the user space since we force416 * vss_transaction.state to be HVUTIL_READY, so the user space daemon's417 * write() will fail with EINVAL (see vss_on_msg()), and the daemon418 * will reset the device by closing and re-opening it.419 */420 vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL);421 if (!vss_msg)422 return -ENOMEM;423 424 tasklet_disable(&channel->callback_event);425 426 vss_msg->vss_hdr.operation = VSS_OP_THAW;427 428 /* Cancel any possible pending work. */429 hv_vss_cancel_work();430 431 /* We don't care about the return value. */432 hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);433 434 kfree(vss_msg);435 436 vss_transaction.state = HVUTIL_READY;437 438 /* tasklet_enable() will be called in hv_vss_pre_resume(). */439 return 0;440}441 442int hv_vss_pre_resume(void)443{444 struct vmbus_channel *channel = vss_transaction.recv_channel;445 446 tasklet_enable(&channel->callback_event);447 448 return 0;449}450 451void hv_vss_deinit(void)452{453 vss_transaction.state = HVUTIL_DEVICE_DYING;454 455 hv_vss_cancel_work();456 457 hvutil_transport_destroy(hvt);458}459