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 		vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
102 	} else {
103 		msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
104 		vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
105 	}
106 
107 	msg->monitor_page1 = vmbus_connection.monitor_pages_pa[0];
108 	msg->monitor_page2 = vmbus_connection.monitor_pages_pa[1];
109 
110 	msg->target_vcpu = hv_cpu_number_to_vp_number(VMBUS_CONNECT_CPU);
111 
112 	/*
113 	 * Add to list before we send the request since we may
114 	 * receive the response before returning from this routine
115 	 */
116 	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
117 	list_add_tail(&msginfo->msglistentry,
118 		      &vmbus_connection.chn_msg_list);
119 
120 	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
121 
122 	ret = vmbus_post_msg(msg,
123 			     sizeof(struct vmbus_channel_initiate_contact),
124 			     true);
125 
126 	trace_vmbus_negotiate_version(msg, ret);
127 
128 	if (ret != 0) {
129 		spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
130 		list_del(&msginfo->msglistentry);
131 		spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
132 					flags);
133 		return ret;
134 	}
135 
136 	/* Wait for the connection response */
137 	wait_for_completion(&msginfo->waitevent);
138 
139 	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
140 	list_del(&msginfo->msglistentry);
141 	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
142 
143 	/* Check if successful */
144 	if (msginfo->response.version_response.version_supported) {
145 		vmbus_connection.conn_state = CONNECTED;
146 
147 		if (version >= VERSION_WIN10_V5)
148 			vmbus_connection.msg_conn_id =
149 				msginfo->response.version_response.msg_conn_id;
150 	} else {
151 		return -ECONNREFUSED;
152 	}
153 
154 	return ret;
155 }
156 
157 /*
158  * vmbus_connect - Sends a connect request on the partition service connection
159  */
vmbus_connect(void)160 int vmbus_connect(void)
161 {
162 	struct vmbus_channel_msginfo *msginfo = NULL;
163 	int i, ret = 0;
164 	__u32 version;
165 
166 	/* Initialize the vmbus connection */
167 	vmbus_connection.conn_state = CONNECTING;
168 	vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
169 	if (!vmbus_connection.work_queue) {
170 		ret = -ENOMEM;
171 		goto cleanup;
172 	}
173 
174 	vmbus_connection.handle_primary_chan_wq =
175 		create_workqueue("hv_pri_chan");
176 	if (!vmbus_connection.handle_primary_chan_wq) {
177 		ret = -ENOMEM;
178 		goto cleanup;
179 	}
180 
181 	vmbus_connection.handle_sub_chan_wq =
182 		create_workqueue("hv_sub_chan");
183 	if (!vmbus_connection.handle_sub_chan_wq) {
184 		ret = -ENOMEM;
185 		goto cleanup;
186 	}
187 
188 	INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
189 	spin_lock_init(&vmbus_connection.channelmsg_lock);
190 
191 	INIT_LIST_HEAD(&vmbus_connection.chn_list);
192 	mutex_init(&vmbus_connection.channel_mutex);
193 
194 	/*
195 	 * Setup the vmbus event connection for channel interrupt
196 	 * abstraction stuff
197 	 */
198 	vmbus_connection.int_page =
199 	(void *)hv_alloc_hyperv_zeroed_page();
200 	if (vmbus_connection.int_page == NULL) {
201 		ret = -ENOMEM;
202 		goto cleanup;
203 	}
204 
205 	vmbus_connection.recv_int_page = vmbus_connection.int_page;
206 	vmbus_connection.send_int_page =
207 		(void *)((unsigned long)vmbus_connection.int_page +
208 			(HV_HYP_PAGE_SIZE >> 1));
209 
210 	/*
211 	 * Setup the monitor notification facility. The 1st page for
212 	 * parent->child and the 2nd page for child->parent
213 	 */
214 	vmbus_connection.monitor_pages[0] = (void *)hv_alloc_hyperv_zeroed_page();
215 	vmbus_connection.monitor_pages[1] = (void *)hv_alloc_hyperv_zeroed_page();
216 	if ((vmbus_connection.monitor_pages[0] == NULL) ||
217 	    (vmbus_connection.monitor_pages[1] == NULL)) {
218 		ret = -ENOMEM;
219 		goto cleanup;
220 	}
221 
222 	vmbus_connection.monitor_pages_original[0]
223 		= vmbus_connection.monitor_pages[0];
224 	vmbus_connection.monitor_pages_original[1]
225 		= vmbus_connection.monitor_pages[1];
226 	vmbus_connection.monitor_pages_pa[0]
227 		= virt_to_phys(vmbus_connection.monitor_pages[0]);
228 	vmbus_connection.monitor_pages_pa[1]
229 		= virt_to_phys(vmbus_connection.monitor_pages[1]);
230 
231 	if (hv_is_isolation_supported()) {
232 		ret = set_memory_decrypted((unsigned long)
233 					   vmbus_connection.monitor_pages[0],
234 					   1);
235 		ret |= set_memory_decrypted((unsigned long)
236 					    vmbus_connection.monitor_pages[1],
237 					    1);
238 		if (ret)
239 			goto cleanup;
240 
241 		/*
242 		 * Isolation VM with AMD SNP needs to access monitor page via
243 		 * address space above shared gpa boundary.
244 		 */
245 		if (hv_isolation_type_snp()) {
246 			vmbus_connection.monitor_pages_pa[0] +=
247 				ms_hyperv.shared_gpa_boundary;
248 			vmbus_connection.monitor_pages_pa[1] +=
249 				ms_hyperv.shared_gpa_boundary;
250 
251 			vmbus_connection.monitor_pages[0]
252 				= memremap(vmbus_connection.monitor_pages_pa[0],
253 					   HV_HYP_PAGE_SIZE,
254 					   MEMREMAP_WB);
255 			if (!vmbus_connection.monitor_pages[0]) {
256 				ret = -ENOMEM;
257 				goto cleanup;
258 			}
259 
260 			vmbus_connection.monitor_pages[1]
261 				= memremap(vmbus_connection.monitor_pages_pa[1],
262 					   HV_HYP_PAGE_SIZE,
263 					   MEMREMAP_WB);
264 			if (!vmbus_connection.monitor_pages[1]) {
265 				ret = -ENOMEM;
266 				goto cleanup;
267 			}
268 		}
269 
270 		/*
271 		 * Set memory host visibility hvcall smears memory
272 		 * and so zero monitor pages here.
273 		 */
274 		memset(vmbus_connection.monitor_pages[0], 0x00,
275 		       HV_HYP_PAGE_SIZE);
276 		memset(vmbus_connection.monitor_pages[1], 0x00,
277 		       HV_HYP_PAGE_SIZE);
278 
279 	}
280 
281 	msginfo = kzalloc(sizeof(*msginfo) +
282 			  sizeof(struct vmbus_channel_initiate_contact),
283 			  GFP_KERNEL);
284 	if (msginfo == NULL) {
285 		ret = -ENOMEM;
286 		goto cleanup;
287 	}
288 
289 	/*
290 	 * Negotiate a compatible VMBUS version number with the
291 	 * host. We start with the highest number we can support
292 	 * and work our way down until we negotiate a compatible
293 	 * version.
294 	 */
295 
296 	for (i = 0; ; i++) {
297 		if (i == ARRAY_SIZE(vmbus_versions)) {
298 			ret = -EDOM;
299 			goto cleanup;
300 		}
301 
302 		version = vmbus_versions[i];
303 		if (version > max_version)
304 			continue;
305 
306 		ret = vmbus_negotiate_version(msginfo, version);
307 		if (ret == -ETIMEDOUT)
308 			goto cleanup;
309 
310 		if (vmbus_connection.conn_state == CONNECTED)
311 			break;
312 	}
313 
314 	if (hv_is_isolation_supported() && version < VERSION_WIN10_V5_2) {
315 		pr_err("Invalid VMBus version %d.%d (expected >= %d.%d) from the host supporting isolation\n",
316 		       version >> 16, version & 0xFFFF, VERSION_WIN10_V5_2 >> 16, VERSION_WIN10_V5_2 & 0xFFFF);
317 		ret = -EINVAL;
318 		goto cleanup;
319 	}
320 
321 	vmbus_proto_version = version;
322 	pr_info("Vmbus version:%d.%d\n",
323 		version >> 16, version & 0xFFFF);
324 
325 	vmbus_connection.channels = kcalloc(MAX_CHANNEL_RELIDS,
326 					    sizeof(struct vmbus_channel *),
327 					    GFP_KERNEL);
328 	if (vmbus_connection.channels == NULL) {
329 		ret = -ENOMEM;
330 		goto cleanup;
331 	}
332 
333 	kfree(msginfo);
334 	return 0;
335 
336 cleanup:
337 	pr_err("Unable to connect to host\n");
338 
339 	vmbus_connection.conn_state = DISCONNECTED;
340 	vmbus_disconnect();
341 
342 	kfree(msginfo);
343 
344 	return ret;
345 }
346 
vmbus_disconnect(void)347 void vmbus_disconnect(void)
348 {
349 	/*
350 	 * First send the unload request to the host.
351 	 */
352 	vmbus_initiate_unload(false);
353 
354 	if (vmbus_connection.handle_sub_chan_wq)
355 		destroy_workqueue(vmbus_connection.handle_sub_chan_wq);
356 
357 	if (vmbus_connection.handle_primary_chan_wq)
358 		destroy_workqueue(vmbus_connection.handle_primary_chan_wq);
359 
360 	if (vmbus_connection.work_queue)
361 		destroy_workqueue(vmbus_connection.work_queue);
362 
363 	if (vmbus_connection.int_page) {
364 		hv_free_hyperv_page((unsigned long)vmbus_connection.int_page);
365 		vmbus_connection.int_page = NULL;
366 	}
367 
368 	if (hv_is_isolation_supported()) {
369 		/*
370 		 * memunmap() checks input address is ioremap address or not
371 		 * inside. It doesn't unmap any thing in the non-SNP CVM and
372 		 * so not check CVM type here.
373 		 */
374 		memunmap(vmbus_connection.monitor_pages[0]);
375 		memunmap(vmbus_connection.monitor_pages[1]);
376 
377 		set_memory_encrypted((unsigned long)
378 			vmbus_connection.monitor_pages_original[0],
379 			1);
380 		set_memory_encrypted((unsigned long)
381 			vmbus_connection.monitor_pages_original[1],
382 			1);
383 	}
384 
385 	hv_free_hyperv_page((unsigned long)
386 		vmbus_connection.monitor_pages_original[0]);
387 	hv_free_hyperv_page((unsigned long)
388 		vmbus_connection.monitor_pages_original[1]);
389 	vmbus_connection.monitor_pages_original[0] =
390 		vmbus_connection.monitor_pages[0] = NULL;
391 	vmbus_connection.monitor_pages_original[1] =
392 		vmbus_connection.monitor_pages[1] = NULL;
393 }
394 
395 /*
396  * relid2channel - Get the channel object given its
397  * child relative id (ie channel id)
398  */
relid2channel(u32 relid)399 struct vmbus_channel *relid2channel(u32 relid)
400 {
401 	if (WARN_ON(relid >= MAX_CHANNEL_RELIDS))
402 		return NULL;
403 	return READ_ONCE(vmbus_connection.channels[relid]);
404 }
405 
406 /*
407  * vmbus_on_event - Process a channel event notification
408  *
409  * For batched channels (default) optimize host to guest signaling
410  * by ensuring:
411  * 1. While reading the channel, we disable interrupts from host.
412  * 2. Ensure that we process all posted messages from the host
413  *    before returning from this callback.
414  * 3. Once we return, enable signaling from the host. Once this
415  *    state is set we check to see if additional packets are
416  *    available to read. In this case we repeat the process.
417  *    If this tasklet has been running for a long time
418  *    then reschedule ourselves.
419  */
vmbus_on_event(unsigned long data)420 void vmbus_on_event(unsigned long data)
421 {
422 	struct vmbus_channel *channel = (void *) data;
423 	unsigned long time_limit = jiffies + 2;
424 
425 	trace_vmbus_on_event(channel);
426 
427 	hv_debug_delay_test(channel, INTERRUPT_DELAY);
428 	do {
429 		void (*callback_fn)(void *);
430 
431 		/* A channel once created is persistent even when
432 		 * there is no driver handling the device. An
433 		 * unloading driver sets the onchannel_callback to NULL.
434 		 */
435 		callback_fn = READ_ONCE(channel->onchannel_callback);
436 		if (unlikely(callback_fn == NULL))
437 			return;
438 
439 		(*callback_fn)(channel->channel_callback_context);
440 
441 		if (channel->callback_mode != HV_CALL_BATCHED)
442 			return;
443 
444 		if (likely(hv_end_read(&channel->inbound) == 0))
445 			return;
446 
447 		hv_begin_read(&channel->inbound);
448 	} while (likely(time_before(jiffies, time_limit)));
449 
450 	/* The time limit (2 jiffies) has been reached */
451 	tasklet_schedule(&channel->callback_event);
452 }
453 
454 /*
455  * vmbus_post_msg - Send a msg on the vmbus's message connection
456  */
vmbus_post_msg(void * buffer,size_t buflen,bool can_sleep)457 int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
458 {
459 	struct vmbus_channel_message_header *hdr;
460 	union hv_connection_id conn_id;
461 	int ret = 0;
462 	int retries = 0;
463 	u32 usec = 1;
464 
465 	conn_id.asu32 = 0;
466 	conn_id.u.id = vmbus_connection.msg_conn_id;
467 
468 	/*
469 	 * hv_post_message() can have transient failures because of
470 	 * insufficient resources. Retry the operation a couple of
471 	 * times before giving up.
472 	 */
473 	while (retries < 100) {
474 		ret = hv_post_message(conn_id, 1, buffer, buflen);
475 
476 		switch (ret) {
477 		case HV_STATUS_INVALID_CONNECTION_ID:
478 			/*
479 			 * See vmbus_negotiate_version(): VMBus protocol 5.0
480 			 * and higher require that we must use
481 			 * VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
482 			 * Contact message, but on old hosts that only
483 			 * support VMBus protocol 4.0 or lower, here we get
484 			 * HV_STATUS_INVALID_CONNECTION_ID and we should
485 			 * return an error immediately without retrying.
486 			 */
487 			hdr = buffer;
488 			if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
489 				return -EINVAL;
490 			/*
491 			 * We could get this if we send messages too
492 			 * frequently.
493 			 */
494 			ret = -EAGAIN;
495 			break;
496 		case HV_STATUS_INSUFFICIENT_MEMORY:
497 		case HV_STATUS_INSUFFICIENT_BUFFERS:
498 			ret = -ENOBUFS;
499 			break;
500 		case HV_STATUS_SUCCESS:
501 			return ret;
502 		default:
503 			pr_err("hv_post_msg() failed; error code:%d\n", ret);
504 			return -EINVAL;
505 		}
506 
507 		retries++;
508 		if (can_sleep && usec > 1000)
509 			msleep(usec / 1000);
510 		else if (usec < MAX_UDELAY_MS * 1000)
511 			udelay(usec);
512 		else
513 			mdelay(usec / 1000);
514 
515 		if (retries < 22)
516 			usec *= 2;
517 	}
518 	return ret;
519 }
520 
521 /*
522  * vmbus_set_event - Send an event notification to the parent
523  */
vmbus_set_event(struct vmbus_channel * channel)524 void vmbus_set_event(struct vmbus_channel *channel)
525 {
526 	u32 child_relid = channel->offermsg.child_relid;
527 
528 	if (!channel->is_dedicated_interrupt)
529 		vmbus_send_interrupt(child_relid);
530 
531 	++channel->sig_events;
532 
533 	if (hv_isolation_type_snp())
534 		hv_ghcb_hypercall(HVCALL_SIGNAL_EVENT, &channel->sig_event,
535 				NULL, sizeof(channel->sig_event));
536 	else
537 		hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
538 }
539 EXPORT_SYMBOL_GPL(vmbus_set_event);
540