xref: /openbmc/linux/drivers/hv/connection.c (revision 6123a4e8)
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 
29 struct 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 };
40 EXPORT_SYMBOL_GPL(vmbus_connection);
41 
42 /*
43  * Negotiated protocol version with the host.
44  */
45 __u32 vmbus_proto_version;
46 EXPORT_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  */
53 static __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  */
68 static uint max_version = VERSION_WIN10_V5_3;
69 
70 module_param(max_version, uint, S_IRUGO);
71 MODULE_PARM_DESC(max_version,
72 		 "Maximal VMBus protocol version which can be negotiated");
73 
vmbus_negotiate_version(struct vmbus_channel_msginfo * msginfo,u32 version)74 int 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  */
vmbus_connect(void)167 int 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 
314 cleanup:
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 
vmbus_disconnect(void)325 void 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  */
relid2channel(u32 relid)368 struct 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  */
vmbus_on_event(unsigned long data)393 void 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  */
vmbus_post_msg(void * buffer,size_t buflen,bool can_sleep)425 int 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  */
vmbus_set_event(struct vmbus_channel * channel)492 void 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 }
514 EXPORT_SYMBOL_GPL(vmbus_set_event);
515