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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *
4 * Copyright (c) 2009, Microsoft Corporation.
5 *
6 * Authors:
7 * Haiyang Zhang <[email protected]>
8 * Hank Janssen <[email protected]>
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 .all_offers_delivered_event = COMPLETION_INITIALIZER(
38 vmbus_connection.all_offers_delivered_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,VERSION_WS2008, VERSION_WIN8 (which is
51 * Windows Server 2012) and VERSION_WIN8_1 (which is
52 * Windows Server 2012 R2) are no longer supported in
53 * Linux guests and are not listed.
54 */
55static __u32 vmbus_versions[] = {
56 VERSION_WIN10_V6_0,
57 VERSION_WIN10_V5_3,
58 VERSION_WIN10_V5_2,
59 VERSION_WIN10_V5_1,
60 VERSION_WIN10_V5,
61 VERSION_WIN10_V4_1,
62 VERSION_WIN10
63};
64
65/*
66 * Maximal VMBus protocol version guests can negotiate. Useful to cap the
67 * VMBus version for testing and debugging purpose.
68 */
69static uint max_version = VERSION_WIN10_V6_0;
70
71module_param(max_version, uint, S_IRUGO);
72MODULE_PARM_DESC(max_version,
73 "Maximal VMBus protocol version which can be negotiated");
74
75static int vmbus_try_connection_id(struct vmbus_channel_msginfo *msginfo,
76 u32 version, u32 connection_id)
77{
78 int ret = 0;
79 struct vmbus_channel_initiate_contact *msg;
80 unsigned long flags;
81
82 init_completion(&msginfo->waitevent);
83
84 msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
85
86 memset(msg, 0, sizeof(*msg));
87 msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
88 msg->vmbus_version_requested = version;
89
90 /*
91 * For VMBus protocol 5.0 (VERSION_WIN10_V5) and higher, use the
92 * caller-supplied connection_id for the Initiate Contact message so
93 * the caller can implement the required retry scheme. For subsequent
94 * messages, use the Message Connection ID field in the host-returned
95 * Version Response message. With VERSION_WIN10_V5 and higher, we don't
96 * use msg->interrupt_page, but tell the host explicitly that we still
97 * use VMBUS_MESSAGE_SINT(2) for compatibility.
98 *
99 * On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
100 */
101 if (version >= VERSION_WIN10_V5) {
102 msg->msg_sint = VMBUS_MESSAGE_SINT;
103 msg->msg_vtl = ms_hyperv.vtl;
104 vmbus_connection.msg_conn_id = connection_id;
105 } else {
106 msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
107 vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
108 }
109
110 if (vmbus_is_confidential() && version >= VERSION_WIN10_V6_0)
111 msg->feature_flags = VMBUS_FEATURE_FLAG_CONFIDENTIAL_CHANNELS;
112
113 /*
114 * shared_gpa_boundary is zero in non-SNP VMs, so it's safe to always
115 * bitwise OR it
116 */
117 msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]) |
118 ms_hyperv.shared_gpa_boundary;
119 msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]) |
120 ms_hyperv.shared_gpa_boundary;
121
122 msg->target_vcpu = hv_cpu_number_to_vp_number(VMBUS_CONNECT_CPU);
123
124 /*
125 * Add to list before we send the request since we may
126 * receive the response before returning from this routine
127 */
128 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
129 list_add_tail(&msginfo->msglistentry,
130 &vmbus_connection.chn_msg_list);
131
132 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
133
134 ret = vmbus_post_msg(msg,
135 sizeof(struct vmbus_channel_initiate_contact),
136 true);
137
138 trace_vmbus_negotiate_version(msg, ret);
139
140 if (ret != 0) {
141 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
142 list_del(&msginfo->msglistentry);
143 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
144 flags);
145 return ret;
146 }
147
148 /* Wait for the connection response */
149 wait_for_completion(&msginfo->waitevent);
150
151 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
152 list_del(&msginfo->msglistentry);
153 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
154
155 /* Check if successful */
156 if (msginfo->response.version_response.version_supported) {
157 vmbus_connection.conn_state = CONNECTED;
158
159 if (version >= VERSION_WIN10_V5)
160 vmbus_connection.msg_conn_id =
161 msginfo->response.version_response.msg_conn_id;
162 } else {
163 return -ECONNREFUSED;
164 }
165
166 return ret;
167}
168
169int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
170{
171 int ret;
172
173 /* Try the redirect ID first for VTL2 with VMBus protocol 5.0+. */
174 if (version >= VERSION_WIN10_V5 && ms_hyperv.vtl == 2) {
175 ret = vmbus_try_connection_id(msginfo, version,
176 VMBUS_MESSAGE_CONNECTION_ID_REDIRECT);
177 if (ret != -ENXIO)
178 return ret;
179 }
180
181 return vmbus_try_connection_id(msginfo, version,
182 VMBUS_MESSAGE_CONNECTION_ID_4);
183}
184
185/*
186 * vmbus_connect - Sends a connect request on the partition service connection
187 */
188int vmbus_connect(void)
189{
190 struct vmbus_channel_msginfo *msginfo = NULL;
191 int i, ret = 0;
192 __u32 version;
193
194 /* Initialize the vmbus connection */
195 vmbus_connection.conn_state = CONNECTING;
196 vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
197 if (!vmbus_connection.work_queue) {
198 ret = -ENOMEM;
199 goto cleanup;
200 }
201
202 vmbus_connection.rescind_work_queue =
203 create_workqueue("hv_vmbus_rescind");
204 if (!vmbus_connection.rescind_work_queue) {
205 ret = -ENOMEM;
206 goto cleanup;
207 }
208 vmbus_connection.ignore_any_offer_msg = false;
209
210 vmbus_connection.handle_primary_chan_wq =
211 create_workqueue("hv_pri_chan");
212 if (!vmbus_connection.handle_primary_chan_wq) {
213 ret = -ENOMEM;
214 goto cleanup;
215 }
216
217 vmbus_connection.handle_sub_chan_wq =
218 create_workqueue("hv_sub_chan");
219 if (!vmbus_connection.handle_sub_chan_wq) {
220 ret = -ENOMEM;
221 goto cleanup;
222 }
223
224 INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
225 spin_lock_init(&vmbus_connection.channelmsg_lock);
226
227 INIT_LIST_HEAD(&vmbus_connection.chn_list);
228 mutex_init(&vmbus_connection.channel_mutex);
229
230 /*
231 * The following Hyper-V interrupt and monitor pages can be used by
232 * UIO for mapping to user-space, so they should always be allocated on
233 * system page boundaries. The system page size must be >= the Hyper-V
234 * page size.
235 */
236 BUILD_BUG_ON(PAGE_SIZE < HV_HYP_PAGE_SIZE);
237
238 /*
239 * Setup the vmbus event connection for channel interrupt
240 * abstraction stuff
241 */
242 vmbus_connection.int_page =
243 (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
244 if (vmbus_connection.int_page == NULL) {
245 ret = -ENOMEM;
246 goto cleanup;
247 }
248
249 vmbus_connection.recv_int_page = vmbus_connection.int_page;
250 vmbus_connection.send_int_page =
251 (void *)((unsigned long)vmbus_connection.int_page +
252 (HV_HYP_PAGE_SIZE >> 1));
253
254 /*
255 * Setup the monitor notification facility. The 1st page for
256 * parent->child and the 2nd page for child->parent
257 */
258 vmbus_connection.monitor_pages[0] = (void *)__get_free_page(GFP_KERNEL);
259 vmbus_connection.monitor_pages[1] = (void *)__get_free_page(GFP_KERNEL);
260 if ((vmbus_connection.monitor_pages[0] == NULL) ||
261 (vmbus_connection.monitor_pages[1] == NULL)) {
262 ret = -ENOMEM;
263 goto cleanup;
264 }
265
266 ret = set_memory_decrypted((unsigned long)
267 vmbus_connection.monitor_pages[0], 1);
268 ret |= set_memory_decrypted((unsigned long)
269 vmbus_connection.monitor_pages[1], 1);
270 if (ret) {
271 /*
272 * If set_memory_decrypted() fails, the encryption state
273 * of the memory is unknown. So leak the memory instead
274 * of risking returning decrypted memory to the free list.
275 * For simplicity, always handle both pages the same.
276 */
277 vmbus_connection.monitor_pages[0] = NULL;
278 vmbus_connection.monitor_pages[1] = NULL;
279 goto cleanup;
280 }
281
282 /*
283 * Set_memory_decrypted() will change the memory contents if
284 * decryption occurs, so zero monitor pages here.
285 */
286 memset(vmbus_connection.monitor_pages[0], 0x00, HV_HYP_PAGE_SIZE);
287 memset(vmbus_connection.monitor_pages[1], 0x00, HV_HYP_PAGE_SIZE);
288
289 msginfo = kzalloc(sizeof(*msginfo) +
290 sizeof(struct vmbus_channel_initiate_contact),
291 GFP_KERNEL);
292 if (msginfo == NULL) {
293 ret = -ENOMEM;
294 goto cleanup;
295 }
296
297 /*
298 * Negotiate a compatible VMBUS version number with the
299 * host. We start with the highest number we can support
300 * and work our way down until we negotiate a compatible
301 * version.
302 */
303
304 for (i = 0; ; i++) {
305 if (i == ARRAY_SIZE(vmbus_versions)) {
306 ret = -EDOM;
307 pr_err("Hyper-V host does not support VMBus version %d.%d or higher;\n\
308 the host may be an older version no longer supported by Linux\n",
309 vmbus_versions[i-1] >> 16, vmbus_versions[i-1] & 0xFFFF);
310 goto cleanup;
311 }
312
313 version = vmbus_versions[i];
314 if (version > max_version)
315 continue;
316
317 ret = vmbus_negotiate_version(msginfo, version);
318 if (ret == -ETIMEDOUT)
319 goto cleanup;
320
321 if (vmbus_connection.conn_state == CONNECTED)
322 break;
323 }
324
325 if (hv_is_isolation_supported() && version < VERSION_WIN10_V5_2) {
326 pr_err("Invalid VMBus version %d.%d (expected >= %d.%d) from the host supporting isolation\n",
327 version >> 16, version & 0xFFFF, VERSION_WIN10_V5_2 >> 16, VERSION_WIN10_V5_2 & 0xFFFF);
328 ret = -EINVAL;
329 goto cleanup;
330 }
331
332 vmbus_proto_version = version;
333 pr_info("Vmbus version:%d.%d\n",
334 version >> 16, version & 0xFFFF);
335
336 vmbus_connection.channels = kzalloc_objs(struct vmbus_channel *,
337 MAX_CHANNEL_RELIDS);
338 if (vmbus_connection.channels == NULL) {
339 ret = -ENOMEM;
340 goto cleanup;
341 }
342
343 kfree(msginfo);
344 return 0;
345
346cleanup:
347 pr_err("Unable to connect to host\n");
348
349 vmbus_disconnect();
350
351 kfree(msginfo);
352
353 return ret;
354}
355
356void vmbus_disconnect(void)
357{
358 /*
359 * First send the unload request to the host.
360 */
361 vmbus_initiate_unload(false);
362
363 if (vmbus_connection.handle_sub_chan_wq)
364 destroy_workqueue(vmbus_connection.handle_sub_chan_wq);
365
366 if (vmbus_connection.handle_primary_chan_wq)
367 destroy_workqueue(vmbus_connection.handle_primary_chan_wq);
368
369 if (vmbus_connection.rescind_work_queue)
370 destroy_workqueue(vmbus_connection.rescind_work_queue);
371
372 if (vmbus_connection.work_queue)
373 destroy_workqueue(vmbus_connection.work_queue);
374
375 if (vmbus_connection.int_page) {
376 free_page((unsigned long)vmbus_connection.int_page);
377 vmbus_connection.int_page = NULL;
378 }
379
380 if (vmbus_connection.monitor_pages[0]) {
381 if (!set_memory_encrypted(
382 (unsigned long)vmbus_connection.monitor_pages[0], 1))
383 free_page((unsigned long)
384 vmbus_connection.monitor_pages[0]);
385 vmbus_connection.monitor_pages[0] = NULL;
386 }
387
388 if (vmbus_connection.monitor_pages[1]) {
389 if (!set_memory_encrypted(
390 (unsigned long)vmbus_connection.monitor_pages[1], 1))
391 free_page((unsigned long)
392 vmbus_connection.monitor_pages[1]);
393 vmbus_connection.monitor_pages[1] = NULL;
394 }
395}
396
397/*
398 * relid2channel - Get the channel object given its
399 * child relative id (ie channel id)
400 */
401struct vmbus_channel *relid2channel(u32 relid)
402{
403 if (vmbus_connection.channels == NULL) {
404 pr_warn_once("relid2channel: relid=%d: No channels mapped!\n", relid);
405 return NULL;
406 }
407 if (WARN_ON(relid >= MAX_CHANNEL_RELIDS))
408 return NULL;
409 return READ_ONCE(vmbus_connection.channels[relid]);
410}
411
412/*
413 * vmbus_on_event - Process a channel event notification
414 *
415 * For batched channels (default) optimize host to guest signaling
416 * by ensuring:
417 * 1. While reading the channel, we disable interrupts from host.
418 * 2. Ensure that we process all posted messages from the host
419 * before returning from this callback.
420 * 3. Once we return, enable signaling from the host. Once this
421 * state is set we check to see if additional packets are
422 * available to read. In this case we repeat the process.
423 * If this tasklet has been running for a long time
424 * then reschedule ourselves.
425 */
426void vmbus_on_event(unsigned long data)
427{
428 struct vmbus_channel *channel = (void *) data;
429 void (*callback_fn)(void *context);
430
431 trace_vmbus_on_event(channel);
432
433 hv_debug_delay_test(channel, INTERRUPT_DELAY);
434
435 /* A channel once created is persistent even when
436 * there is no driver handling the device. An
437 * unloading driver sets the onchannel_callback to NULL.
438 */
439 callback_fn = READ_ONCE(channel->onchannel_callback);
440 if (unlikely(!callback_fn))
441 return;
442
443 (*callback_fn)(channel->channel_callback_context);
444
445 if (channel->callback_mode != HV_CALL_BATCHED)
446 return;
447
448 if (likely(hv_end_read(&channel->inbound) == 0))
449 return;
450
451 hv_begin_read(&channel->inbound);
452 tasklet_schedule(&channel->callback_event);
453}
454
455/*
456 * vmbus_post_msg - Send a msg on the vmbus's message connection
457 */
458int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
459{
460 struct vmbus_channel_message_header *hdr;
461 union hv_connection_id conn_id;
462 int ret = 0;
463 int retries = 0;
464 u32 usec = 1;
465
466 conn_id.asu32 = 0;
467 conn_id.u.id = vmbus_connection.msg_conn_id;
468
469 /*
470 * hv_post_message() can have transient failures because of
471 * insufficient resources. Retry the operation a couple of
472 * times before giving up.
473 */
474 while (retries < 100) {
475 ret = hv_post_message(conn_id, 1, buffer, buflen);
476
477 switch (ret) {
478 case HV_STATUS_INVALID_CONNECTION_ID:
479 /* Allow INITIATE_CONTACT to try another connection ID. */
480 hdr = buffer;
481 if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
482 return -ENXIO;
483 /*
484 * We could get this if we send messages too
485 * frequently.
486 */
487 ret = -EAGAIN;
488 break;
489 case HV_STATUS_INSUFFICIENT_MEMORY:
490 case HV_STATUS_INSUFFICIENT_BUFFERS:
491 ret = -ENOBUFS;
492 break;
493 case HV_STATUS_SUCCESS:
494 return ret;
495 default:
496 pr_err("hv_post_msg() failed; error code:%d\n", ret);
497 return -EINVAL;
498 }
499
500 retries++;
501 if (can_sleep && usec > 1000)
502 msleep(usec / 1000);
503 else if (usec < MAX_UDELAY_MS * 1000)
504 udelay(usec);
505 else
506 mdelay(usec / 1000);
507
508 if (retries < 22)
509 usec *= 2;
510 }
511 return ret;
512}
513
514/*
515 * vmbus_set_event - Send an event notification to the parent
516 */
517void vmbus_set_event(struct vmbus_channel *channel)
518{
519 u32 child_relid = channel->offermsg.child_relid;
520
521 if (!channel->is_dedicated_interrupt)
522 vmbus_send_interrupt(child_relid);
523
524 ++channel->sig_events;
525
526 if (ms_hyperv.paravisor_present) {
527 if (hv_isolation_type_snp())
528 hv_ghcb_hypercall(HVCALL_SIGNAL_EVENT, &channel->sig_event,
529 NULL, sizeof(channel->sig_event));
530 else if (hv_isolation_type_tdx())
531 hv_tdx_hypercall(HVCALL_SIGNAL_EVENT | HV_HYPERCALL_FAST_BIT,
532 channel->sig_event, 0);
533 else
534 WARN_ON_ONCE(1);
535 } else {
536 u64 control = HVCALL_SIGNAL_EVENT;
537
538 control |= hv_nested ? HV_HYPERCALL_NESTED : 0;
539 hv_do_fast_hypercall8(control, channel->sig_event);
540 }
541}
542EXPORT_SYMBOL_GPL(vmbus_set_event);