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![Andrea Parri (Microsoft)](/assets/img/avatar_default.png)
Restrict the protocol version(s) that will be negotiated with the host to be 5.2 or greater if the guest is running isolated. This reduces the footprint of the code that will be exercised by Confidential VMs and hence the exposure to bugs and vulnerabilities. Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/20210201144814.2701-4-parri.andrea@gmail.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
447 lines
12 KiB
C
447 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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*
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* Copyright (c) 2009, Microsoft Corporation.
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*
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* Authors:
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* Haiyang Zhang <haiyangz@microsoft.com>
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* Hank Janssen <hjanssen@microsoft.com>
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/wait.h>
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#include <linux/delay.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/vmalloc.h>
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#include <linux/hyperv.h>
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#include <linux/export.h>
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#include <asm/mshyperv.h>
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#include "hyperv_vmbus.h"
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struct vmbus_connection vmbus_connection = {
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.conn_state = DISCONNECTED,
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.next_gpadl_handle = ATOMIC_INIT(0xE1E10),
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.ready_for_suspend_event= COMPLETION_INITIALIZER(
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vmbus_connection.ready_for_suspend_event),
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.ready_for_resume_event = COMPLETION_INITIALIZER(
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vmbus_connection.ready_for_resume_event),
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};
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EXPORT_SYMBOL_GPL(vmbus_connection);
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/*
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* Negotiated protocol version with the host.
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*/
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__u32 vmbus_proto_version;
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EXPORT_SYMBOL_GPL(vmbus_proto_version);
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/*
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* Table of VMBus versions listed from newest to oldest.
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*/
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static __u32 vmbus_versions[] = {
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VERSION_WIN10_V5_2,
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VERSION_WIN10_V5_1,
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VERSION_WIN10_V5,
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VERSION_WIN10_V4_1,
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VERSION_WIN10,
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VERSION_WIN8_1,
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VERSION_WIN8,
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VERSION_WIN7,
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VERSION_WS2008
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};
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/*
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* Maximal VMBus protocol version guests can negotiate. Useful to cap the
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* VMBus version for testing and debugging purpose.
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*/
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static uint max_version = VERSION_WIN10_V5_2;
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module_param(max_version, uint, S_IRUGO);
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MODULE_PARM_DESC(max_version,
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"Maximal VMBus protocol version which can be negotiated");
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int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
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{
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int ret = 0;
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struct vmbus_channel_initiate_contact *msg;
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unsigned long flags;
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init_completion(&msginfo->waitevent);
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msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
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memset(msg, 0, sizeof(*msg));
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msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
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msg->vmbus_version_requested = version;
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/*
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* VMBus protocol 5.0 (VERSION_WIN10_V5) and higher require that we must
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* use VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
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* and for subsequent messages, we must use the Message Connection ID
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* field in the host-returned Version Response Message. And, with
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* VERSION_WIN10_V5 and higher, we don't use msg->interrupt_page, but we
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* tell the host explicitly that we still use VMBUS_MESSAGE_SINT(2) for
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* compatibility.
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*
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* On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
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*/
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if (version >= VERSION_WIN10_V5) {
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msg->msg_sint = VMBUS_MESSAGE_SINT;
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vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
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} else {
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msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
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vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
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}
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msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
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msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
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msg->target_vcpu = hv_cpu_number_to_vp_number(VMBUS_CONNECT_CPU);
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/*
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* Add to list before we send the request since we may
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* receive the response before returning from this routine
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*/
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spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
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list_add_tail(&msginfo->msglistentry,
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&vmbus_connection.chn_msg_list);
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spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
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ret = vmbus_post_msg(msg,
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sizeof(struct vmbus_channel_initiate_contact),
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true);
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trace_vmbus_negotiate_version(msg, ret);
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if (ret != 0) {
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spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
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list_del(&msginfo->msglistentry);
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spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
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flags);
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return ret;
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}
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/* Wait for the connection response */
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wait_for_completion(&msginfo->waitevent);
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spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
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list_del(&msginfo->msglistentry);
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spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
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/* Check if successful */
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if (msginfo->response.version_response.version_supported) {
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vmbus_connection.conn_state = CONNECTED;
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if (version >= VERSION_WIN10_V5)
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vmbus_connection.msg_conn_id =
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msginfo->response.version_response.msg_conn_id;
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} else {
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return -ECONNREFUSED;
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}
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return ret;
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}
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/*
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* vmbus_connect - Sends a connect request on the partition service connection
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*/
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int vmbus_connect(void)
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{
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struct vmbus_channel_msginfo *msginfo = NULL;
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int i, ret = 0;
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__u32 version;
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/* Initialize the vmbus connection */
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vmbus_connection.conn_state = CONNECTING;
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vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
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if (!vmbus_connection.work_queue) {
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ret = -ENOMEM;
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goto cleanup;
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}
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vmbus_connection.handle_primary_chan_wq =
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create_workqueue("hv_pri_chan");
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if (!vmbus_connection.handle_primary_chan_wq) {
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ret = -ENOMEM;
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goto cleanup;
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}
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vmbus_connection.handle_sub_chan_wq =
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create_workqueue("hv_sub_chan");
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if (!vmbus_connection.handle_sub_chan_wq) {
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ret = -ENOMEM;
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goto cleanup;
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}
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INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
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spin_lock_init(&vmbus_connection.channelmsg_lock);
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INIT_LIST_HEAD(&vmbus_connection.chn_list);
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mutex_init(&vmbus_connection.channel_mutex);
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/*
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* Setup the vmbus event connection for channel interrupt
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* abstraction stuff
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*/
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vmbus_connection.int_page =
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(void *)hv_alloc_hyperv_zeroed_page();
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if (vmbus_connection.int_page == NULL) {
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ret = -ENOMEM;
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goto cleanup;
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}
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vmbus_connection.recv_int_page = vmbus_connection.int_page;
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vmbus_connection.send_int_page =
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(void *)((unsigned long)vmbus_connection.int_page +
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(HV_HYP_PAGE_SIZE >> 1));
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/*
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* Setup the monitor notification facility. The 1st page for
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* parent->child and the 2nd page for child->parent
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*/
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vmbus_connection.monitor_pages[0] = (void *)hv_alloc_hyperv_zeroed_page();
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vmbus_connection.monitor_pages[1] = (void *)hv_alloc_hyperv_zeroed_page();
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if ((vmbus_connection.monitor_pages[0] == NULL) ||
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(vmbus_connection.monitor_pages[1] == NULL)) {
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ret = -ENOMEM;
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goto cleanup;
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}
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msginfo = kzalloc(sizeof(*msginfo) +
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sizeof(struct vmbus_channel_initiate_contact),
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GFP_KERNEL);
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if (msginfo == NULL) {
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ret = -ENOMEM;
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goto cleanup;
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}
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/*
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* Negotiate a compatible VMBUS version number with the
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* host. We start with the highest number we can support
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* and work our way down until we negotiate a compatible
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* version.
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*/
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for (i = 0; ; i++) {
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if (i == ARRAY_SIZE(vmbus_versions))
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goto cleanup;
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version = vmbus_versions[i];
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if (version > max_version)
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continue;
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ret = vmbus_negotiate_version(msginfo, version);
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if (ret == -ETIMEDOUT)
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goto cleanup;
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if (vmbus_connection.conn_state == CONNECTED)
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break;
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}
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if (hv_is_isolation_supported() && version < VERSION_WIN10_V5_2) {
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pr_err("Invalid VMBus version %d.%d (expected >= %d.%d) from the host supporting isolation\n",
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version >> 16, version & 0xFFFF, VERSION_WIN10_V5_2 >> 16, VERSION_WIN10_V5_2 & 0xFFFF);
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ret = -EINVAL;
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goto cleanup;
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}
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vmbus_proto_version = version;
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pr_info("Vmbus version:%d.%d\n",
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version >> 16, version & 0xFFFF);
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vmbus_connection.channels = kcalloc(MAX_CHANNEL_RELIDS,
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sizeof(struct vmbus_channel *),
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GFP_KERNEL);
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if (vmbus_connection.channels == NULL) {
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ret = -ENOMEM;
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goto cleanup;
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}
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kfree(msginfo);
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return 0;
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cleanup:
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pr_err("Unable to connect to host\n");
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vmbus_connection.conn_state = DISCONNECTED;
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vmbus_disconnect();
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kfree(msginfo);
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return ret;
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}
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void vmbus_disconnect(void)
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{
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/*
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* First send the unload request to the host.
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*/
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vmbus_initiate_unload(false);
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if (vmbus_connection.handle_sub_chan_wq)
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destroy_workqueue(vmbus_connection.handle_sub_chan_wq);
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if (vmbus_connection.handle_primary_chan_wq)
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destroy_workqueue(vmbus_connection.handle_primary_chan_wq);
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if (vmbus_connection.work_queue)
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destroy_workqueue(vmbus_connection.work_queue);
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if (vmbus_connection.int_page) {
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hv_free_hyperv_page((unsigned long)vmbus_connection.int_page);
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vmbus_connection.int_page = NULL;
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}
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hv_free_hyperv_page((unsigned long)vmbus_connection.monitor_pages[0]);
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hv_free_hyperv_page((unsigned long)vmbus_connection.monitor_pages[1]);
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vmbus_connection.monitor_pages[0] = NULL;
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vmbus_connection.monitor_pages[1] = NULL;
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}
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/*
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* relid2channel - Get the channel object given its
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* child relative id (ie channel id)
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*/
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struct vmbus_channel *relid2channel(u32 relid)
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{
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if (WARN_ON(relid >= MAX_CHANNEL_RELIDS))
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return NULL;
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return READ_ONCE(vmbus_connection.channels[relid]);
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}
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/*
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* vmbus_on_event - Process a channel event notification
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*
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* For batched channels (default) optimize host to guest signaling
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* by ensuring:
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* 1. While reading the channel, we disable interrupts from host.
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* 2. Ensure that we process all posted messages from the host
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* before returning from this callback.
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* 3. Once we return, enable signaling from the host. Once this
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* state is set we check to see if additional packets are
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* available to read. In this case we repeat the process.
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* If this tasklet has been running for a long time
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* then reschedule ourselves.
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*/
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void vmbus_on_event(unsigned long data)
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{
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struct vmbus_channel *channel = (void *) data;
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unsigned long time_limit = jiffies + 2;
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trace_vmbus_on_event(channel);
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hv_debug_delay_test(channel, INTERRUPT_DELAY);
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do {
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void (*callback_fn)(void *);
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/* A channel once created is persistent even when
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* there is no driver handling the device. An
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* unloading driver sets the onchannel_callback to NULL.
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*/
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callback_fn = READ_ONCE(channel->onchannel_callback);
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if (unlikely(callback_fn == NULL))
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return;
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(*callback_fn)(channel->channel_callback_context);
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if (channel->callback_mode != HV_CALL_BATCHED)
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return;
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if (likely(hv_end_read(&channel->inbound) == 0))
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return;
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hv_begin_read(&channel->inbound);
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} while (likely(time_before(jiffies, time_limit)));
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/* The time limit (2 jiffies) has been reached */
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tasklet_schedule(&channel->callback_event);
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}
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/*
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* vmbus_post_msg - Send a msg on the vmbus's message connection
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*/
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int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
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{
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struct vmbus_channel_message_header *hdr;
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union hv_connection_id conn_id;
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int ret = 0;
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int retries = 0;
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u32 usec = 1;
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conn_id.asu32 = 0;
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conn_id.u.id = vmbus_connection.msg_conn_id;
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/*
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* hv_post_message() can have transient failures because of
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* insufficient resources. Retry the operation a couple of
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* times before giving up.
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*/
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while (retries < 100) {
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ret = hv_post_message(conn_id, 1, buffer, buflen);
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switch (ret) {
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case HV_STATUS_INVALID_CONNECTION_ID:
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/*
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* See vmbus_negotiate_version(): VMBus protocol 5.0
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* and higher require that we must use
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* VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
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* Contact message, but on old hosts that only
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* support VMBus protocol 4.0 or lower, here we get
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* HV_STATUS_INVALID_CONNECTION_ID and we should
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* return an error immediately without retrying.
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*/
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hdr = buffer;
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if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
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return -EINVAL;
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/*
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* We could get this if we send messages too
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* frequently.
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*/
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ret = -EAGAIN;
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break;
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case HV_STATUS_INSUFFICIENT_MEMORY:
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case HV_STATUS_INSUFFICIENT_BUFFERS:
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ret = -ENOBUFS;
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break;
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case HV_STATUS_SUCCESS:
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return ret;
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default:
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pr_err("hv_post_msg() failed; error code:%d\n", ret);
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return -EINVAL;
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}
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retries++;
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if (can_sleep && usec > 1000)
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msleep(usec / 1000);
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else if (usec < MAX_UDELAY_MS * 1000)
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udelay(usec);
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else
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mdelay(usec / 1000);
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if (retries < 22)
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usec *= 2;
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}
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return ret;
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}
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/*
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* vmbus_set_event - Send an event notification to the parent
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*/
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void vmbus_set_event(struct vmbus_channel *channel)
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{
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u32 child_relid = channel->offermsg.child_relid;
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if (!channel->is_dedicated_interrupt)
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vmbus_send_interrupt(child_relid);
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++channel->sig_events;
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hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
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}
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EXPORT_SYMBOL_GPL(vmbus_set_event);
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