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37c2578c0c
vmbus_process_offer() mustn't call channel->sc_creation_callback() directly for sub-channels, because sc_creation_callback() -> vmbus_open() may never get the host's response to the OPEN_CHANNEL message (the host may rescind a channel at any time, e.g. in the case of hot removing a NIC), and vmbus_onoffer_rescind() may not wake up the vmbus_open() as it's blocked due to a non-zero vmbus_connection.offer_in_progress, and finally we have a deadlock. The above is also true for primary channels, if the related device drivers use sync probing mode by default. And, usually the handling of primary channels and sub-channels can depend on each other, so we should offload them to different workqueues to avoid possible deadlock, e.g. in sync-probing mode, NIC1's netvsc_subchan_work() can race with NIC2's netvsc_probe() -> rtnl_lock(), and causes deadlock: the former gets the rtnl_lock and waits for all the sub-channels to appear, but the latter can't get the rtnl_lock and this blocks the handling of sub-channels. The patch can fix the multiple-NIC deadlock described above for v3.x kernels (e.g. RHEL 7.x) which don't support async-probing of devices, and v4.4, v4.9, v4.14 and v4.18 which support async-probing but don't enable async-probing for Hyper-V drivers (yet). The patch can also fix the hang issue in sub-channel's handling described above for all versions of kernels, including v4.19 and v4.20-rc4. So actually the patch should be applied to all the existing kernels, not only the kernels that have8195b1396e
. Fixes:8195b1396e
("hv_netvsc: fix deadlock on hotplug") Cc: stable@vger.kernel.org Cc: Stephen Hemminger <sthemmin@microsoft.com> Cc: K. Y. Srinivasan <kys@microsoft.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Signed-off-by: Dexuan Cui <decui@microsoft.com> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
481 lines
13 KiB
C
481 lines
13 KiB
C
/*
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*
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* Copyright (c) 2009, Microsoft Corporation.
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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 and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 59 Temple
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* Place - Suite 330, Boston, MA 02111-1307 USA.
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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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*/
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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/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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};
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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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static __u32 vmbus_get_next_version(__u32 current_version)
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{
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switch (current_version) {
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case (VERSION_WIN7):
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return VERSION_WS2008;
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case (VERSION_WIN8):
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return VERSION_WIN7;
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case (VERSION_WIN8_1):
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return VERSION_WIN8;
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case (VERSION_WIN10):
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return VERSION_WIN8_1;
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case (VERSION_WIN10_V5):
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return VERSION_WIN10;
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case (VERSION_WS2008):
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default:
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return VERSION_INVAL;
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}
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}
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static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
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__u32 version)
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{
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int ret = 0;
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unsigned int cur_cpu;
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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) requires that we must use
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* 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, we don't use msg->interrupt_page, but we tell
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* 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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/*
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* We want all channel messages to be delivered on CPU 0.
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* This has been the behavior pre-win8. This is not
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* perf issue and having all channel messages delivered on CPU 0
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* would be ok.
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* For post win8 hosts, we support receiving channel messagges on
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* all the CPUs. This is needed for kexec to work correctly where
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* the CPU attempting to connect may not be CPU 0.
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*/
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if (version >= VERSION_WIN8_1) {
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cur_cpu = get_cpu();
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msg->target_vcpu = hv_cpu_number_to_vp_number(cur_cpu);
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vmbus_connection.connect_cpu = cur_cpu;
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put_cpu();
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} else {
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msg->target_vcpu = 0;
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vmbus_connection.connect_cpu = 0;
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}
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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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int ret = 0;
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struct vmbus_channel_msginfo *msginfo = NULL;
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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 *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
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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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(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 *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
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vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
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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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version = VERSION_CURRENT;
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do {
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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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version = vmbus_get_next_version(version);
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} while (version != VERSION_INVAL);
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if (version == VERSION_INVAL)
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goto cleanup;
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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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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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free_pages((unsigned long)vmbus_connection.int_page, 0);
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vmbus_connection.int_page = NULL;
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}
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free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
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free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
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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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struct vmbus_channel *channel;
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struct vmbus_channel *found_channel = NULL;
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struct list_head *cur, *tmp;
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struct vmbus_channel *cur_sc;
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BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
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list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
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if (channel->offermsg.child_relid == relid) {
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found_channel = channel;
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break;
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} else if (!list_empty(&channel->sc_list)) {
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/*
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* Deal with sub-channels.
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*/
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list_for_each_safe(cur, tmp, &channel->sc_list) {
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cur_sc = list_entry(cur, struct vmbus_channel,
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sc_list);
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if (cur_sc->offermsg.child_relid == relid) {
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found_channel = cur_sc;
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break;
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}
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}
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}
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}
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return found_channel;
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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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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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* requires 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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