/*
* 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);
}
