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(&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(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(vmbus_connection.monitor_pages[0]) |
113				ms_hyperv.shared_gpa_boundary;
114	msg->monitor_page2 = virt_to_phys(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(&msginfo->msglistentry,
125		      &vmbus_connection.chn_msg_list);
126
127	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
128
129	ret = vmbus_post_msg(msg,
130			     sizeof(struct vmbus_channel_initiate_contact),
131			     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(&msginfo->msglistentry);
138		spin_unlock_irqrestore(&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(&msginfo->msglistentry);
148	spin_unlock_irqrestore(&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(&vmbus_connection.chn_msg_list);
204	spin_lock_init(&vmbus_connection.channelmsg_lock);
205
206	INIT_LIST_HEAD(&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((unsigned long)
237				vmbus_connection.monitor_pages[0], 1);
238	ret |= set_memory_decrypted((unsigned long)
239				vmbus_connection.monitor_pages[1], 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(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					    sizeof(struct vmbus_channel *),
305					    GFP_KERNEL);
306	if (vmbus_connection.channels == NULL) {
307		ret = -ENOMEM;
308		goto cleanup;
309	}
310
311	kfree(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(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(false);
331
332	if (vmbus_connection.handle_sub_chan_wq)
333		destroy_workqueue(vmbus_connection.handle_sub_chan_wq);
334
335	if (vmbus_connection.handle_primary_chan_wq)
336		destroy_workqueue(vmbus_connection.handle_primary_chan_wq);
337
338	if (vmbus_connection.rescind_work_queue)
339		destroy_workqueue(vmbus_connection.rescind_work_queue);
340
341	if (vmbus_connection.work_queue)
342		destroy_workqueue(vmbus_connection.work_queue);
343
344	if (vmbus_connection.int_page) {
345		hv_free_hyperv_page(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			(unsigned long)vmbus_connection.monitor_pages[0], 1))
352			hv_free_hyperv_page(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			(unsigned long)vmbus_connection.monitor_pages[1], 1))
359			hv_free_hyperv_page(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, 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(&channel->inbound);
419	tasklet_schedule(&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(conn_id, 1, buffer, 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(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(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, &channel->sig_event,
504					  NULL, sizeof(channel->sig_event));
505		else if (hv_isolation_type_tdx())
506			hv_tdx_hypercall(HVCALL_SIGNAL_EVENT | HV_HYPERCALL_FAST_BIT,
507					 channel->sig_event, 0);
508		else
509			WARN_ON_ONCE(1);
510	} else {
511		hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
512	}
513}
514EXPORT_SYMBOL_GPL(vmbus_set_event);
515