1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *
4 * Copyright (c) 2009, Microsoft Corporation.
5 *
6 * Authors:
7 * Haiyang Zhang <haiyangz@microsoft.com>
8 * Hank Janssen <hjanssen@microsoft.com>
9 */
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12#include <linux/kernel.h>
13#include <linux/sched.h>
14#include <linux/wait.h>
15#include <linux/delay.h>
16#include <linux/mm.h>
17#include <linux/module.h>
18#include <linux/slab.h>
19#include <linux/vmalloc.h>
20#include <linux/hyperv.h>
21#include <linux/export.h>
22#include <linux/io.h>
23#include <linux/set_memory.h>
24#include <asm/mshyperv.h>
25
26#include "hyperv_vmbus.h"
27
28
29struct vmbus_connection vmbus_connection = {
30 .conn_state = DISCONNECTED,
31 .unload_event = COMPLETION_INITIALIZER(
32 vmbus_connection.unload_event),
33 .next_gpadl_handle = ATOMIC_INIT(0xE1E10),
34
35 .ready_for_suspend_event = COMPLETION_INITIALIZER(
36 vmbus_connection.ready_for_suspend_event),
37 .ready_for_resume_event = COMPLETION_INITIALIZER(
38 vmbus_connection.ready_for_resume_event),
39};
40EXPORT_SYMBOL_GPL(vmbus_connection);
41
42/*
43 * Negotiated protocol version with the host.
44 */
45__u32 vmbus_proto_version;
46EXPORT_SYMBOL_GPL(vmbus_proto_version);
47
48/*
49 * Table of VMBus versions listed from newest to oldest.
50 * VERSION_WIN7 and VERSION_WS2008 are no longer supported in
51 * Linux guests and are not listed.
52 */
53static __u32 vmbus_versions[] = {
54 VERSION_WIN10_V5_3,
55 VERSION_WIN10_V5_2,
56 VERSION_WIN10_V5_1,
57 VERSION_WIN10_V5,
58 VERSION_WIN10_V4_1,
59 VERSION_WIN10,
60 VERSION_WIN8_1,
61 VERSION_WIN8
62};
63
64/*
65 * Maximal VMBus protocol version guests can negotiate. Useful to cap the
66 * VMBus version for testing and debugging purpose.
67 */
68static uint max_version = VERSION_WIN10_V5_3;
69
70module_param(max_version, uint, S_IRUGO);
71MODULE_PARM_DESC(max_version,
72 "Maximal VMBus protocol version which can be negotiated");
73
74int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
75{
76 int ret = 0;
77 struct vmbus_channel_initiate_contact *msg;
78 unsigned long flags;
79
80 init_completion(x: &msginfo->waitevent);
81
82 msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
83
84 memset(msg, 0, sizeof(*msg));
85 msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
86 msg->vmbus_version_requested = version;
87
88 /*
89 * VMBus protocol 5.0 (VERSION_WIN10_V5) and higher require that we must
90 * use VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
91 * and for subsequent messages, we must use the Message Connection ID
92 * field in the host-returned Version Response Message. And, with
93 * VERSION_WIN10_V5 and higher, we don't use msg->interrupt_page, but we
94 * tell the host explicitly that we still use VMBUS_MESSAGE_SINT(2) for
95 * compatibility.
96 *
97 * On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
98 */
99 if (version >= VERSION_WIN10_V5) {
100 msg->msg_sint = VMBUS_MESSAGE_SINT;
101 msg->msg_vtl = ms_hyperv.vtl;
102 vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
103 } else {
104 msg->interrupt_page = virt_to_phys(address: vmbus_connection.int_page);
105 vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
106 }
107
108 /*
109 * shared_gpa_boundary is zero in non-SNP VMs, so it's safe to always
110 * bitwise OR it
111 */
112 msg->monitor_page1 = virt_to_phys(address: vmbus_connection.monitor_pages[0]) |
113 ms_hyperv.shared_gpa_boundary;
114 msg->monitor_page2 = virt_to_phys(address: vmbus_connection.monitor_pages[1]) |
115 ms_hyperv.shared_gpa_boundary;
116
117 msg->target_vcpu = hv_cpu_number_to_vp_number(VMBUS_CONNECT_CPU);
118
119 /*
120 * Add to list before we send the request since we may
121 * receive the response before returning from this routine
122 */
123 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
124 list_add_tail(new: &msginfo->msglistentry,
125 head: &vmbus_connection.chn_msg_list);
126
127 spin_unlock_irqrestore(lock: &vmbus_connection.channelmsg_lock, flags);
128
129 ret = vmbus_post_msg(buffer: msg,
130 buflen: sizeof(struct vmbus_channel_initiate_contact),
131 can_sleep: true);
132
133 trace_vmbus_negotiate_version(msg, ret);
134
135 if (ret != 0) {
136 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
137 list_del(entry: &msginfo->msglistentry);
138 spin_unlock_irqrestore(lock: &vmbus_connection.channelmsg_lock,
139 flags);
140 return ret;
141 }
142
143 /* Wait for the connection response */
144 wait_for_completion(&msginfo->waitevent);
145
146 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
147 list_del(entry: &msginfo->msglistentry);
148 spin_unlock_irqrestore(lock: &vmbus_connection.channelmsg_lock, flags);
149
150 /* Check if successful */
151 if (msginfo->response.version_response.version_supported) {
152 vmbus_connection.conn_state = CONNECTED;
153
154 if (version >= VERSION_WIN10_V5)
155 vmbus_connection.msg_conn_id =
156 msginfo->response.version_response.msg_conn_id;
157 } else {
158 return -ECONNREFUSED;
159 }
160
161 return ret;
162}
163
164/*
165 * vmbus_connect - Sends a connect request on the partition service connection
166 */
167int vmbus_connect(void)
168{
169 struct vmbus_channel_msginfo *msginfo = NULL;
170 int i, ret = 0;
171 __u32 version;
172
173 /* Initialize the vmbus connection */
174 vmbus_connection.conn_state = CONNECTING;
175 vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
176 if (!vmbus_connection.work_queue) {
177 ret = -ENOMEM;
178 goto cleanup;
179 }
180
181 vmbus_connection.rescind_work_queue =
182 create_workqueue("hv_vmbus_rescind");
183 if (!vmbus_connection.rescind_work_queue) {
184 ret = -ENOMEM;
185 goto cleanup;
186 }
187 vmbus_connection.ignore_any_offer_msg = false;
188
189 vmbus_connection.handle_primary_chan_wq =
190 create_workqueue("hv_pri_chan");
191 if (!vmbus_connection.handle_primary_chan_wq) {
192 ret = -ENOMEM;
193 goto cleanup;
194 }
195
196 vmbus_connection.handle_sub_chan_wq =
197 create_workqueue("hv_sub_chan");
198 if (!vmbus_connection.handle_sub_chan_wq) {
199 ret = -ENOMEM;
200 goto cleanup;
201 }
202
203 INIT_LIST_HEAD(list: &vmbus_connection.chn_msg_list);
204 spin_lock_init(&vmbus_connection.channelmsg_lock);
205
206 INIT_LIST_HEAD(list: &vmbus_connection.chn_list);
207 mutex_init(&vmbus_connection.channel_mutex);
208
209 /*
210 * Setup the vmbus event connection for channel interrupt
211 * abstraction stuff
212 */
213 vmbus_connection.int_page = hv_alloc_hyperv_zeroed_page();
214 if (vmbus_connection.int_page == NULL) {
215 ret = -ENOMEM;
216 goto cleanup;
217 }
218
219 vmbus_connection.recv_int_page = vmbus_connection.int_page;
220 vmbus_connection.send_int_page =
221 (void *)((unsigned long)vmbus_connection.int_page +
222 (HV_HYP_PAGE_SIZE >> 1));
223
224 /*
225 * Setup the monitor notification facility. The 1st page for
226 * parent->child and the 2nd page for child->parent
227 */
228 vmbus_connection.monitor_pages[0] = hv_alloc_hyperv_page();
229 vmbus_connection.monitor_pages[1] = hv_alloc_hyperv_page();
230 if ((vmbus_connection.monitor_pages[0] == NULL) ||
231 (vmbus_connection.monitor_pages[1] == NULL)) {
232 ret = -ENOMEM;
233 goto cleanup;
234 }
235
236 ret = set_memory_decrypted(addr: (unsigned long)
237 vmbus_connection.monitor_pages[0], numpages: 1);
238 ret |= set_memory_decrypted(addr: (unsigned long)
239 vmbus_connection.monitor_pages[1], numpages: 1);
240 if (ret) {
241 /*
242 * If set_memory_decrypted() fails, the encryption state
243 * of the memory is unknown. So leak the memory instead
244 * of risking returning decrypted memory to the free list.
245 * For simplicity, always handle both pages the same.
246 */
247 vmbus_connection.monitor_pages[0] = NULL;
248 vmbus_connection.monitor_pages[1] = NULL;
249 goto cleanup;
250 }
251
252 /*
253 * Set_memory_decrypted() will change the memory contents if
254 * decryption occurs, so zero monitor pages here.
255 */
256 memset(vmbus_connection.monitor_pages[0], 0x00, HV_HYP_PAGE_SIZE);
257 memset(vmbus_connection.monitor_pages[1], 0x00, HV_HYP_PAGE_SIZE);
258
259 msginfo = kzalloc(size: sizeof(*msginfo) +
260 sizeof(struct vmbus_channel_initiate_contact),
261 GFP_KERNEL);
262 if (msginfo == NULL) {
263 ret = -ENOMEM;
264 goto cleanup;
265 }
266
267 /*
268 * Negotiate a compatible VMBUS version number with the
269 * host. We start with the highest number we can support
270 * and work our way down until we negotiate a compatible
271 * version.
272 */
273
274 for (i = 0; ; i++) {
275 if (i == ARRAY_SIZE(vmbus_versions)) {
276 ret = -EDOM;
277 goto cleanup;
278 }
279
280 version = vmbus_versions[i];
281 if (version > max_version)
282 continue;
283
284 ret = vmbus_negotiate_version(msginfo, version);
285 if (ret == -ETIMEDOUT)
286 goto cleanup;
287
288 if (vmbus_connection.conn_state == CONNECTED)
289 break;
290 }
291
292 if (hv_is_isolation_supported() && version < VERSION_WIN10_V5_2) {
293 pr_err("Invalid VMBus version %d.%d (expected >= %d.%d) from the host supporting isolation\n",
294 version >> 16, version & 0xFFFF, VERSION_WIN10_V5_2 >> 16, VERSION_WIN10_V5_2 & 0xFFFF);
295 ret = -EINVAL;
296 goto cleanup;
297 }
298
299 vmbus_proto_version = version;
300 pr_info("Vmbus version:%d.%d\n",
301 version >> 16, version & 0xFFFF);
302
303 vmbus_connection.channels = kcalloc(MAX_CHANNEL_RELIDS,
304 size: sizeof(struct vmbus_channel *),
305 GFP_KERNEL);
306 if (vmbus_connection.channels == NULL) {
307 ret = -ENOMEM;
308 goto cleanup;
309 }
310
311 kfree(objp: msginfo);
312 return 0;
313
314cleanup:
315 pr_err("Unable to connect to host\n");
316
317 vmbus_connection.conn_state = DISCONNECTED;
318 vmbus_disconnect();
319
320 kfree(objp: msginfo);
321
322 return ret;
323}
324
325void vmbus_disconnect(void)
326{
327 /*
328 * First send the unload request to the host.
329 */
330 vmbus_initiate_unload(crash: false);
331
332 if (vmbus_connection.handle_sub_chan_wq)
333 destroy_workqueue(wq: vmbus_connection.handle_sub_chan_wq);
334
335 if (vmbus_connection.handle_primary_chan_wq)
336 destroy_workqueue(wq: vmbus_connection.handle_primary_chan_wq);
337
338 if (vmbus_connection.rescind_work_queue)
339 destroy_workqueue(wq: vmbus_connection.rescind_work_queue);
340
341 if (vmbus_connection.work_queue)
342 destroy_workqueue(wq: vmbus_connection.work_queue);
343
344 if (vmbus_connection.int_page) {
345 hv_free_hyperv_page(addr: vmbus_connection.int_page);
346 vmbus_connection.int_page = NULL;
347 }
348
349 if (vmbus_connection.monitor_pages[0]) {
350 if (!set_memory_encrypted(
351 addr: (unsigned long)vmbus_connection.monitor_pages[0], numpages: 1))
352 hv_free_hyperv_page(addr: vmbus_connection.monitor_pages[0]);
353 vmbus_connection.monitor_pages[0] = NULL;
354 }
355
356 if (vmbus_connection.monitor_pages[1]) {
357 if (!set_memory_encrypted(
358 addr: (unsigned long)vmbus_connection.monitor_pages[1], numpages: 1))
359 hv_free_hyperv_page(addr: vmbus_connection.monitor_pages[1]);
360 vmbus_connection.monitor_pages[1] = NULL;
361 }
362}
363
364/*
365 * relid2channel - Get the channel object given its
366 * child relative id (ie channel id)
367 */
368struct vmbus_channel *relid2channel(u32 relid)
369{
370 if (vmbus_connection.channels == NULL) {
371 pr_warn_once("relid2channel: relid=%d: No channels mapped!\n", relid);
372 return NULL;
373 }
374 if (WARN_ON(relid >= MAX_CHANNEL_RELIDS))
375 return NULL;
376 return READ_ONCE(vmbus_connection.channels[relid]);
377}
378
379/*
380 * vmbus_on_event - Process a channel event notification
381 *
382 * For batched channels (default) optimize host to guest signaling
383 * by ensuring:
384 * 1. While reading the channel, we disable interrupts from host.
385 * 2. Ensure that we process all posted messages from the host
386 * before returning from this callback.
387 * 3. Once we return, enable signaling from the host. Once this
388 * state is set we check to see if additional packets are
389 * available to read. In this case we repeat the process.
390 * If this tasklet has been running for a long time
391 * then reschedule ourselves.
392 */
393void vmbus_on_event(unsigned long data)
394{
395 struct vmbus_channel *channel = (void *) data;
396 void (*callback_fn)(void *context);
397
398 trace_vmbus_on_event(channel);
399
400 hv_debug_delay_test(channel, delay_type: INTERRUPT_DELAY);
401
402 /* A channel once created is persistent even when
403 * there is no driver handling the device. An
404 * unloading driver sets the onchannel_callback to NULL.
405 */
406 callback_fn = READ_ONCE(channel->onchannel_callback);
407 if (unlikely(!callback_fn))
408 return;
409
410 (*callback_fn)(channel->channel_callback_context);
411
412 if (channel->callback_mode != HV_CALL_BATCHED)
413 return;
414
415 if (likely(hv_end_read(&channel->inbound) == 0))
416 return;
417
418 hv_begin_read(rbi: &channel->inbound);
419 tasklet_schedule(t: &channel->callback_event);
420}
421
422/*
423 * vmbus_post_msg - Send a msg on the vmbus's message connection
424 */
425int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
426{
427 struct vmbus_channel_message_header *hdr;
428 union hv_connection_id conn_id;
429 int ret = 0;
430 int retries = 0;
431 u32 usec = 1;
432
433 conn_id.asu32 = 0;
434 conn_id.u.id = vmbus_connection.msg_conn_id;
435
436 /*
437 * hv_post_message() can have transient failures because of
438 * insufficient resources. Retry the operation a couple of
439 * times before giving up.
440 */
441 while (retries < 100) {
442 ret = hv_post_message(connection_id: conn_id, message_type: 1, payload: buffer, payload_size: buflen);
443
444 switch (ret) {
445 case HV_STATUS_INVALID_CONNECTION_ID:
446 /*
447 * See vmbus_negotiate_version(): VMBus protocol 5.0
448 * and higher require that we must use
449 * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
450 * Contact message, but on old hosts that only
451 * support VMBus protocol 4.0 or lower, here we get
452 * HV_STATUS_INVALID_CONNECTION_ID and we should
453 * return an error immediately without retrying.
454 */
455 hdr = buffer;
456 if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
457 return -EINVAL;
458 /*
459 * We could get this if we send messages too
460 * frequently.
461 */
462 ret = -EAGAIN;
463 break;
464 case HV_STATUS_INSUFFICIENT_MEMORY:
465 case HV_STATUS_INSUFFICIENT_BUFFERS:
466 ret = -ENOBUFS;
467 break;
468 case HV_STATUS_SUCCESS:
469 return ret;
470 default:
471 pr_err("hv_post_msg() failed; error code:%d\n", ret);
472 return -EINVAL;
473 }
474
475 retries++;
476 if (can_sleep && usec > 1000)
477 msleep(msecs: usec / 1000);
478 else if (usec < MAX_UDELAY_MS * 1000)
479 udelay(usec);
480 else
481 mdelay(usec / 1000);
482
483 if (retries < 22)
484 usec *= 2;
485 }
486 return ret;
487}
488
489/*
490 * vmbus_set_event - Send an event notification to the parent
491 */
492void vmbus_set_event(struct vmbus_channel *channel)
493{
494 u32 child_relid = channel->offermsg.child_relid;
495
496 if (!channel->is_dedicated_interrupt)
497 vmbus_send_interrupt(relid: child_relid);
498
499 ++channel->sig_events;
500
501 if (ms_hyperv.paravisor_present) {
502 if (hv_isolation_type_snp())
503 hv_ghcb_hypercall(HVCALL_SIGNAL_EVENT, input: &channel->sig_event,
504 NULL, input_size: sizeof(channel->sig_event));
505 else if (hv_isolation_type_tdx())
506 hv_tdx_hypercall(HVCALL_SIGNAL_EVENT | HV_HYPERCALL_FAST_BIT,
507 param1: channel->sig_event, param2: 0);
508 else
509 WARN_ON_ONCE(1);
510 } else {
511 hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, input8: channel->sig_event);
512 }
513}
514EXPORT_SYMBOL_GPL(vmbus_set_event);
515

source code of linux/drivers/hv/connection.c