// SPDX-License-Identifier: GPL-2.0-only
/*
* An implementation of host initiated guest snapshot.
*
* Copyright (C) 2013, Microsoft, Inc.
* Author : K. Y. Srinivasan <[email protected]>
*/
#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>
#include <asm/hyperv-tlfs.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. 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.
*
* 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 {
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. */
struct hv_vss_msg *msg; /* current message */
} vss_transaction;
static void vss_respond_to_host(int error);
/*
* 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 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_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);
hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
}
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;
}
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;
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;
int rc;
struct hv_vss_msg *vss_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 = kzalloc(sizeof(*vss_msg), GFP_KERNEL);
if (!vss_msg)
return;
vss_msg->vss_hdr.operation = op;
vss_transaction.state = HVUTIL_USERSPACE_REQ;
schedule_delayed_work(&vss_timeout_work, op == VSS_OP_FREEZE ?
VSS_FREEZE_TIMEOUT * HZ : HV_UTIL_TIMEOUT * HZ);
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;
}
}
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);
}
/*
* 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;
/*
* 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;
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;
int vss_srv_version;
struct icmsg_hdr *icmsghdrp;
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;
}
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.
*/
vss_transaction.recv_len = recvlen;
vss_transaction.recv_req_id = requestid;
vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
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)
{
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
* processes the host requests may not yet be running.
* Defer processing channel callbacks until the daemon
* has registered.
*/
vss_transaction.state = HVUTIL_DEVICE_INIT;
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)
{
vss_transaction.state = HVUTIL_DEVICE_DYING;
hv_vss_cancel_work();
hvutil_transport_destroy(hvt);
}
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