linux/drivers/hv/hv_snapshot.c
K. Y. Srinivasan 3a4916050b Drivers: hv: util: Correctly support ws2008R2 and earlier
The current code does not correctly negotiate the version numbers for the util
driver when hosted on earlier hosts. The version numbers presented by this
driver were not compatible with the version numbers supported by Windows Server
2008. Fix this problem.

I would like to thank Olaf Hering (ohering@suse.com) for identifying the problem.

Reported-by: Olaf Hering <ohering@suse.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-26 14:20:21 -07:00

282 lines
6.5 KiB
C

/*
* 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)
/*
* 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, 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);
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);
}