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281 lines
6.5 KiB
281 lines
6.5 KiB
/* |
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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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/* |
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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 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 |
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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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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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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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cn_netlink_send(msg, 0, 0, GFP_ATOMIC); |
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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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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_work_sync(&vss_send_op_work); |
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}
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