304 lines
7.2 KiB
C
304 lines
7.2 KiB
C
/*
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* An implementation of host initiated guest snapshot.
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*
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*
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* Copyright (C) 2013, Microsoft, Inc.
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* Author : K. Y. Srinivasan <kys@microsoft.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published
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* by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
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* NON INFRINGEMENT. See the GNU General Public License for more
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* details.
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*
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/net.h>
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#include <linux/nls.h>
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#include <linux/connector.h>
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#include <linux/workqueue.h>
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#include <linux/hyperv.h>
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#define VSS_MAJOR 5
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#define VSS_MINOR 0
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#define VSS_VERSION (VSS_MAJOR << 16 | VSS_MINOR)
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#define VSS_USERSPACE_TIMEOUT (msecs_to_jiffies(10 * 1000))
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/*
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* Global state maintained for transaction that is being processed.
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* Note that only one transaction can be active at any point in time.
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*
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* This state is set when we receive a request from the host; we
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* cleanup this state when the transaction is completed - when we respond
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* to the host with the key value.
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*/
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static struct {
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bool active; /* transaction status - active or not */
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int recv_len; /* number of bytes received. */
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struct vmbus_channel *recv_channel; /* chn we got the request */
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u64 recv_req_id; /* request ID. */
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struct hv_vss_msg *msg; /* current message */
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} vss_transaction;
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static void vss_respond_to_host(int error);
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static struct cb_id vss_id = { CN_VSS_IDX, CN_VSS_VAL };
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static const char vss_name[] = "vss_kernel_module";
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static __u8 *recv_buffer;
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static void vss_send_op(struct work_struct *dummy);
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static void vss_timeout_func(struct work_struct *dummy);
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static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
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static DECLARE_WORK(vss_send_op_work, vss_send_op);
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/*
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* Callback when data is received from user mode.
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*/
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static void vss_timeout_func(struct work_struct *dummy)
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{
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/*
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* Timeout waiting for userspace component to reply happened.
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*/
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pr_warn("VSS: timeout waiting for daemon to reply\n");
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vss_respond_to_host(HV_E_FAIL);
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}
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static void
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vss_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
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{
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struct hv_vss_msg *vss_msg;
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vss_msg = (struct hv_vss_msg *)msg->data;
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if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER) {
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pr_info("VSS daemon registered\n");
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vss_transaction.active = false;
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if (vss_transaction.recv_channel != NULL)
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hv_vss_onchannelcallback(vss_transaction.recv_channel);
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return;
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}
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if (cancel_delayed_work_sync(&vss_timeout_work))
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vss_respond_to_host(vss_msg->error);
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}
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static void vss_send_op(struct work_struct *dummy)
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{
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int op = vss_transaction.msg->vss_hdr.operation;
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int rc;
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struct cn_msg *msg;
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struct hv_vss_msg *vss_msg;
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msg = kzalloc(sizeof(*msg) + sizeof(*vss_msg), GFP_ATOMIC);
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if (!msg)
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return;
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vss_msg = (struct hv_vss_msg *)msg->data;
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msg->id.idx = CN_VSS_IDX;
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msg->id.val = CN_VSS_VAL;
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vss_msg->vss_hdr.operation = op;
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msg->len = sizeof(struct hv_vss_msg);
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rc = cn_netlink_send(msg, 0, 0, GFP_ATOMIC);
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if (rc) {
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pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
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if (cancel_delayed_work_sync(&vss_timeout_work))
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vss_respond_to_host(HV_E_FAIL);
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}
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kfree(msg);
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return;
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}
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/*
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* Send a response back to the host.
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*/
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static void
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vss_respond_to_host(int error)
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{
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struct icmsg_hdr *icmsghdrp;
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u32 buf_len;
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struct vmbus_channel *channel;
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u64 req_id;
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/*
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* If a transaction is not active; log and return.
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*/
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if (!vss_transaction.active) {
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/*
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* This is a spurious call!
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*/
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pr_warn("VSS: Transaction not active\n");
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return;
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}
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/*
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* Copy the global state for completing the transaction. Note that
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* only one transaction can be active at a time.
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*/
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buf_len = vss_transaction.recv_len;
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channel = vss_transaction.recv_channel;
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req_id = vss_transaction.recv_req_id;
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vss_transaction.active = false;
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icmsghdrp = (struct icmsg_hdr *)
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&recv_buffer[sizeof(struct vmbuspipe_hdr)];
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if (channel->onchannel_callback == NULL)
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/*
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* We have raced with util driver being unloaded;
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* silently return.
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*/
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return;
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icmsghdrp->status = error;
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icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
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vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
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VM_PKT_DATA_INBAND, 0);
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}
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/*
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* This callback is invoked when we get a VSS message from the host.
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* The host ensures that only one VSS transaction can be active at a time.
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*/
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void hv_vss_onchannelcallback(void *context)
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{
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struct vmbus_channel *channel = context;
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u32 recvlen;
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u64 requestid;
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struct hv_vss_msg *vss_msg;
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struct icmsg_hdr *icmsghdrp;
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struct icmsg_negotiate *negop = NULL;
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if (vss_transaction.active) {
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/*
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* We will defer processing this callback once
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* the current transaction is complete.
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*/
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vss_transaction.recv_channel = channel;
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return;
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}
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vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
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&requestid);
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if (recvlen > 0) {
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icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
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sizeof(struct vmbuspipe_hdr)];
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if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
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vmbus_prep_negotiate_resp(icmsghdrp, negop,
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recv_buffer, UTIL_FW_VERSION,
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VSS_VERSION);
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} else {
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vss_msg = (struct hv_vss_msg *)&recv_buffer[
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sizeof(struct vmbuspipe_hdr) +
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sizeof(struct icmsg_hdr)];
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/*
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* Stash away this global state for completing the
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* transaction; note transactions are serialized.
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*/
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vss_transaction.recv_len = recvlen;
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vss_transaction.recv_channel = channel;
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vss_transaction.recv_req_id = requestid;
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vss_transaction.active = true;
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vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
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switch (vss_msg->vss_hdr.operation) {
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/*
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* Initiate a "freeze/thaw"
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* operation in the guest.
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* We respond to the host once
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* the operation is complete.
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*
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* We send the message to the
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* user space daemon and the
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* operation is performed in
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* the daemon.
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*/
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case VSS_OP_FREEZE:
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case VSS_OP_THAW:
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schedule_work(&vss_send_op_work);
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schedule_delayed_work(&vss_timeout_work,
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VSS_USERSPACE_TIMEOUT);
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return;
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case VSS_OP_HOT_BACKUP:
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vss_msg->vss_cf.flags =
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VSS_HBU_NO_AUTO_RECOVERY;
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vss_respond_to_host(0);
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return;
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case VSS_OP_GET_DM_INFO:
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vss_msg->dm_info.flags = 0;
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vss_respond_to_host(0);
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return;
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default:
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vss_respond_to_host(0);
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return;
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}
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}
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icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
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| ICMSGHDRFLAG_RESPONSE;
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vmbus_sendpacket(channel, recv_buffer,
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recvlen, requestid,
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VM_PKT_DATA_INBAND, 0);
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}
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}
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int
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hv_vss_init(struct hv_util_service *srv)
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{
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int err;
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err = cn_add_callback(&vss_id, vss_name, vss_cn_callback);
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if (err)
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return err;
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recv_buffer = srv->recv_buffer;
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/*
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* When this driver loads, the user level daemon that
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* processes the host requests may not yet be running.
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* Defer processing channel callbacks until the daemon
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* has registered.
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*/
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vss_transaction.active = true;
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return 0;
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}
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void hv_vss_deinit(void)
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{
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cn_del_callback(&vss_id);
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cancel_delayed_work_sync(&vss_timeout_work);
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cancel_work_sync(&vss_send_op_work);
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}
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