GNU Linux-libre 4.4.289-gnu1
[releases.git] / drivers / hv / connection.c
1 /*
2  *
3  * Copyright (c) 2009, Microsoft Corporation.
4  *
5  * This program is free software; you can redistribute it and/or modify it
6  * under the terms and conditions of the GNU General Public License,
7  * version 2, as published by the Free Software Foundation.
8  *
9  * This program is distributed in the hope it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
12  * more details.
13  *
14  * You should have received a copy of the GNU General Public License along with
15  * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
16  * Place - Suite 330, Boston, MA 02111-1307 USA.
17  *
18  * Authors:
19  *   Haiyang Zhang <haiyangz@microsoft.com>
20  *   Hank Janssen  <hjanssen@microsoft.com>
21  *
22  */
23 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
24
25 #include <linux/kernel.h>
26 #include <linux/sched.h>
27 #include <linux/wait.h>
28 #include <linux/delay.h>
29 #include <linux/mm.h>
30 #include <linux/slab.h>
31 #include <linux/vmalloc.h>
32 #include <linux/hyperv.h>
33 #include <linux/export.h>
34 #include <asm/hyperv.h>
35 #include "hyperv_vmbus.h"
36
37
38 struct vmbus_connection vmbus_connection = {
39         .conn_state             = DISCONNECTED,
40         .next_gpadl_handle      = ATOMIC_INIT(0xE1E10),
41 };
42
43 /*
44  * Negotiated protocol version with the host.
45  */
46 __u32 vmbus_proto_version;
47 EXPORT_SYMBOL_GPL(vmbus_proto_version);
48
49 static __u32 vmbus_get_next_version(__u32 current_version)
50 {
51         switch (current_version) {
52         case (VERSION_WIN7):
53                 return VERSION_WS2008;
54
55         case (VERSION_WIN8):
56                 return VERSION_WIN7;
57
58         case (VERSION_WIN8_1):
59                 return VERSION_WIN8;
60
61         case (VERSION_WIN10):
62                 return VERSION_WIN8_1;
63
64         case (VERSION_WS2008):
65         default:
66                 return VERSION_INVAL;
67         }
68 }
69
70 static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
71                                         __u32 version)
72 {
73         int ret = 0;
74         struct vmbus_channel_initiate_contact *msg;
75         unsigned long flags;
76
77         init_completion(&msginfo->waitevent);
78
79         msg = (struct vmbus_channel_initiate_contact *)msginfo->msg;
80
81         msg->header.msgtype = CHANNELMSG_INITIATE_CONTACT;
82         msg->vmbus_version_requested = version;
83         msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
84         msg->monitor_page1 = virt_to_phys(vmbus_connection.monitor_pages[0]);
85         msg->monitor_page2 = virt_to_phys(vmbus_connection.monitor_pages[1]);
86         if (version >= VERSION_WIN8_1) {
87                 msg->target_vcpu = hv_context.vp_index[get_cpu()];
88                 put_cpu();
89         }
90
91         /*
92          * Add to list before we send the request since we may
93          * receive the response before returning from this routine
94          */
95         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
96         list_add_tail(&msginfo->msglistentry,
97                       &vmbus_connection.chn_msg_list);
98
99         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
100
101         ret = vmbus_post_msg(msg,
102                                sizeof(struct vmbus_channel_initiate_contact));
103         if (ret != 0) {
104                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
105                 list_del(&msginfo->msglistentry);
106                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
107                                         flags);
108                 return ret;
109         }
110
111         /* Wait for the connection response */
112         wait_for_completion(&msginfo->waitevent);
113
114         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
115         list_del(&msginfo->msglistentry);
116         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
117
118         /* Check if successful */
119         if (msginfo->response.version_response.version_supported) {
120                 vmbus_connection.conn_state = CONNECTED;
121         } else {
122                 return -ECONNREFUSED;
123         }
124
125         return ret;
126 }
127
128 /*
129  * vmbus_connect - Sends a connect request on the partition service connection
130  */
131 int vmbus_connect(void)
132 {
133         int ret = 0;
134         struct vmbus_channel_msginfo *msginfo = NULL;
135         __u32 version;
136
137         /* Initialize the vmbus connection */
138         vmbus_connection.conn_state = CONNECTING;
139         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
140         if (!vmbus_connection.work_queue) {
141                 ret = -ENOMEM;
142                 goto cleanup;
143         }
144
145         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
146         spin_lock_init(&vmbus_connection.channelmsg_lock);
147
148         INIT_LIST_HEAD(&vmbus_connection.chn_list);
149         spin_lock_init(&vmbus_connection.channel_lock);
150
151         /*
152          * Setup the vmbus event connection for channel interrupt
153          * abstraction stuff
154          */
155         vmbus_connection.int_page =
156         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
157         if (vmbus_connection.int_page == NULL) {
158                 ret = -ENOMEM;
159                 goto cleanup;
160         }
161
162         vmbus_connection.recv_int_page = vmbus_connection.int_page;
163         vmbus_connection.send_int_page =
164                 (void *)((unsigned long)vmbus_connection.int_page +
165                         (PAGE_SIZE >> 1));
166
167         /*
168          * Setup the monitor notification facility. The 1st page for
169          * parent->child and the 2nd page for child->parent
170          */
171         vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
172         vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
173         if ((vmbus_connection.monitor_pages[0] == NULL) ||
174             (vmbus_connection.monitor_pages[1] == NULL)) {
175                 ret = -ENOMEM;
176                 goto cleanup;
177         }
178
179         msginfo = kzalloc(sizeof(*msginfo) +
180                           sizeof(struct vmbus_channel_initiate_contact),
181                           GFP_KERNEL);
182         if (msginfo == NULL) {
183                 ret = -ENOMEM;
184                 goto cleanup;
185         }
186
187         /*
188          * Negotiate a compatible VMBUS version number with the
189          * host. We start with the highest number we can support
190          * and work our way down until we negotiate a compatible
191          * version.
192          */
193
194         version = VERSION_CURRENT;
195
196         do {
197                 ret = vmbus_negotiate_version(msginfo, version);
198                 if (ret == -ETIMEDOUT)
199                         goto cleanup;
200
201                 if (vmbus_connection.conn_state == CONNECTED)
202                         break;
203
204                 version = vmbus_get_next_version(version);
205         } while (version != VERSION_INVAL);
206
207         if (version == VERSION_INVAL)
208                 goto cleanup;
209
210         vmbus_proto_version = version;
211         pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
212                     host_info_eax, host_info_ebx >> 16,
213                     host_info_ebx & 0xFFFF, host_info_ecx,
214                     host_info_edx >> 24, host_info_edx & 0xFFFFFF,
215                     version >> 16, version & 0xFFFF);
216
217         kfree(msginfo);
218         return 0;
219
220 cleanup:
221         pr_err("Unable to connect to host\n");
222
223         vmbus_connection.conn_state = DISCONNECTED;
224         vmbus_disconnect();
225
226         kfree(msginfo);
227
228         return ret;
229 }
230
231 void vmbus_disconnect(void)
232 {
233         /*
234          * First send the unload request to the host.
235          */
236         vmbus_initiate_unload();
237
238         if (vmbus_connection.work_queue) {
239                 drain_workqueue(vmbus_connection.work_queue);
240                 destroy_workqueue(vmbus_connection.work_queue);
241         }
242
243         if (vmbus_connection.int_page) {
244                 free_pages((unsigned long)vmbus_connection.int_page, 0);
245                 vmbus_connection.int_page = NULL;
246         }
247
248         free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
249         free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
250         vmbus_connection.monitor_pages[0] = NULL;
251         vmbus_connection.monitor_pages[1] = NULL;
252 }
253
254 /*
255  * Map the given relid to the corresponding channel based on the
256  * per-cpu list of channels that have been affinitized to this CPU.
257  * This will be used in the channel callback path as we can do this
258  * mapping in a lock-free fashion.
259  */
260 static struct vmbus_channel *pcpu_relid2channel(u32 relid)
261 {
262         struct vmbus_channel *channel;
263         struct vmbus_channel *found_channel  = NULL;
264         int cpu = smp_processor_id();
265         struct list_head *pcpu_head = &hv_context.percpu_list[cpu];
266
267         list_for_each_entry(channel, pcpu_head, percpu_list) {
268                 if (channel->offermsg.child_relid == relid) {
269                         found_channel = channel;
270                         break;
271                 }
272         }
273
274         return found_channel;
275 }
276
277 /*
278  * relid2channel - Get the channel object given its
279  * child relative id (ie channel id)
280  */
281 struct vmbus_channel *relid2channel(u32 relid)
282 {
283         struct vmbus_channel *channel;
284         struct vmbus_channel *found_channel  = NULL;
285         unsigned long flags;
286         struct list_head *cur, *tmp;
287         struct vmbus_channel *cur_sc;
288
289         spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
290         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
291                 if (channel->offermsg.child_relid == relid) {
292                         found_channel = channel;
293                         break;
294                 } else if (!list_empty(&channel->sc_list)) {
295                         /*
296                          * Deal with sub-channels.
297                          */
298                         list_for_each_safe(cur, tmp, &channel->sc_list) {
299                                 cur_sc = list_entry(cur, struct vmbus_channel,
300                                                         sc_list);
301                                 if (cur_sc->offermsg.child_relid == relid) {
302                                         found_channel = cur_sc;
303                                         break;
304                                 }
305                         }
306                 }
307         }
308         spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
309
310         return found_channel;
311 }
312
313 /*
314  * process_chn_event - Process a channel event notification
315  */
316 static void process_chn_event(u32 relid)
317 {
318         struct vmbus_channel *channel;
319         void *arg;
320         bool read_state;
321         u32 bytes_to_read;
322
323         /*
324          * Find the channel based on this relid and invokes the
325          * channel callback to process the event
326          */
327         channel = pcpu_relid2channel(relid);
328
329         if (!channel)
330                 return;
331
332         /*
333          * A channel once created is persistent even when there
334          * is no driver handling the device. An unloading driver
335          * sets the onchannel_callback to NULL on the same CPU
336          * as where this interrupt is handled (in an interrupt context).
337          * Thus, checking and invoking the driver specific callback takes
338          * care of orderly unloading of the driver.
339          */
340
341         if (channel->onchannel_callback != NULL) {
342                 arg = channel->channel_callback_context;
343                 read_state = channel->batched_reading;
344                 /*
345                  * This callback reads the messages sent by the host.
346                  * We can optimize host to guest signaling by ensuring:
347                  * 1. While reading the channel, we disable interrupts from
348                  *    host.
349                  * 2. Ensure that we process all posted messages from the host
350                  *    before returning from this callback.
351                  * 3. Once we return, enable signaling from the host. Once this
352                  *    state is set we check to see if additional packets are
353                  *    available to read. In this case we repeat the process.
354                  */
355
356                 do {
357                         if (read_state)
358                                 hv_begin_read(&channel->inbound);
359                         channel->onchannel_callback(arg);
360                         if (read_state)
361                                 bytes_to_read = hv_end_read(&channel->inbound);
362                         else
363                                 bytes_to_read = 0;
364                 } while (read_state && (bytes_to_read != 0));
365         }
366 }
367
368 /*
369  * vmbus_on_event - Handler for events
370  */
371 void vmbus_on_event(unsigned long data)
372 {
373         u32 dword;
374         u32 maxdword;
375         int bit;
376         u32 relid;
377         u32 *recv_int_page = NULL;
378         void *page_addr;
379         int cpu = smp_processor_id();
380         union hv_synic_event_flags *event;
381
382         if (vmbus_proto_version < VERSION_WIN8) {
383                 maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
384                 recv_int_page = vmbus_connection.recv_int_page;
385         } else {
386                 /*
387                  * When the host is win8 and beyond, the event page
388                  * can be directly checked to get the id of the channel
389                  * that has the interrupt pending.
390                  */
391                 maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
392                 page_addr = hv_context.synic_event_page[cpu];
393                 event = (union hv_synic_event_flags *)page_addr +
394                                                  VMBUS_MESSAGE_SINT;
395                 recv_int_page = event->flags32;
396         }
397
398
399
400         /* Check events */
401         if (!recv_int_page)
402                 return;
403         for (dword = 0; dword < maxdword; dword++) {
404                 if (!recv_int_page[dword])
405                         continue;
406                 for (bit = 0; bit < 32; bit++) {
407                         if (sync_test_and_clear_bit(bit,
408                                 (unsigned long *)&recv_int_page[dword])) {
409                                 relid = (dword << 5) + bit;
410
411                                 if (relid == 0)
412                                         /*
413                                          * Special case - vmbus
414                                          * channel protocol msg
415                                          */
416                                         continue;
417
418                                 process_chn_event(relid);
419                         }
420                 }
421         }
422 }
423
424 /*
425  * vmbus_post_msg - Send a msg on the vmbus's message connection
426  */
427 int vmbus_post_msg(void *buffer, size_t buflen)
428 {
429         union hv_connection_id conn_id;
430         int ret = 0;
431         int retries = 0;
432         u32 usec = 1;
433
434         conn_id.asu32 = 0;
435         conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
436
437         /*
438          * hv_post_message() can have transient failures because of
439          * insufficient resources. Retry the operation a couple of
440          * times before giving up.
441          */
442         while (retries < 20) {
443                 ret = hv_post_message(conn_id, 1, buffer, buflen);
444
445                 switch (ret) {
446                 case HV_STATUS_INVALID_CONNECTION_ID:
447                         /*
448                          * We could get this if we send messages too
449                          * frequently.
450                          */
451                         ret = -EAGAIN;
452                         break;
453                 case HV_STATUS_INSUFFICIENT_MEMORY:
454                 case HV_STATUS_INSUFFICIENT_BUFFERS:
455                         ret = -ENOMEM;
456                         break;
457                 case HV_STATUS_SUCCESS:
458                         return ret;
459                 default:
460                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
461                         return -EINVAL;
462                 }
463
464                 retries++;
465                 udelay(usec);
466                 if (usec < 2048)
467                         usec *= 2;
468         }
469         return ret;
470 }
471
472 /*
473  * vmbus_set_event - Send an event notification to the parent
474  */
475 int vmbus_set_event(struct vmbus_channel *channel)
476 {
477         u32 child_relid = channel->offermsg.child_relid;
478
479         if (!channel->is_dedicated_interrupt) {
480                 /* Each u32 represents 32 channels */
481                 sync_set_bit(child_relid & 31,
482                         (unsigned long *)vmbus_connection.send_int_page +
483                         (child_relid >> 5));
484         }
485
486         return hv_signal_event(channel->sig_event);
487 }