Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
[linux-2.6-microblaze.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         /*
87          * We want all channel messages to be delivered on CPU 0.
88          * This has been the behavior pre-win8. This is not
89          * perf issue and having all channel messages delivered on CPU 0
90          * would be ok.
91          * For post win8 hosts, we support receiving channel messagges on
92          * all the CPUs. This is needed for kexec to work correctly where
93          * the CPU attempting to connect may not be CPU 0.
94          */
95         if (version >= VERSION_WIN8_1) {
96                 msg->target_vcpu = hv_context.vp_index[get_cpu()];
97                 put_cpu();
98         } else {
99                 msg->target_vcpu = 0;
100         }
101
102         /*
103          * Add to list before we send the request since we may
104          * receive the response before returning from this routine
105          */
106         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
107         list_add_tail(&msginfo->msglistentry,
108                       &vmbus_connection.chn_msg_list);
109
110         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
111
112         ret = vmbus_post_msg(msg,
113                                sizeof(struct vmbus_channel_initiate_contact));
114         if (ret != 0) {
115                 spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
116                 list_del(&msginfo->msglistentry);
117                 spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
118                                         flags);
119                 return ret;
120         }
121
122         /* Wait for the connection response */
123         wait_for_completion(&msginfo->waitevent);
124
125         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
126         list_del(&msginfo->msglistentry);
127         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
128
129         /* Check if successful */
130         if (msginfo->response.version_response.version_supported) {
131                 vmbus_connection.conn_state = CONNECTED;
132         } else {
133                 return -ECONNREFUSED;
134         }
135
136         return ret;
137 }
138
139 /*
140  * vmbus_connect - Sends a connect request on the partition service connection
141  */
142 int vmbus_connect(void)
143 {
144         int ret = 0;
145         struct vmbus_channel_msginfo *msginfo = NULL;
146         __u32 version;
147
148         /* Initialize the vmbus connection */
149         vmbus_connection.conn_state = CONNECTING;
150         vmbus_connection.work_queue = create_workqueue("hv_vmbus_con");
151         if (!vmbus_connection.work_queue) {
152                 ret = -ENOMEM;
153                 goto cleanup;
154         }
155
156         INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
157         spin_lock_init(&vmbus_connection.channelmsg_lock);
158
159         INIT_LIST_HEAD(&vmbus_connection.chn_list);
160         mutex_init(&vmbus_connection.channel_mutex);
161
162         /*
163          * Setup the vmbus event connection for channel interrupt
164          * abstraction stuff
165          */
166         vmbus_connection.int_page =
167         (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
168         if (vmbus_connection.int_page == NULL) {
169                 ret = -ENOMEM;
170                 goto cleanup;
171         }
172
173         vmbus_connection.recv_int_page = vmbus_connection.int_page;
174         vmbus_connection.send_int_page =
175                 (void *)((unsigned long)vmbus_connection.int_page +
176                         (PAGE_SIZE >> 1));
177
178         /*
179          * Setup the monitor notification facility. The 1st page for
180          * parent->child and the 2nd page for child->parent
181          */
182         vmbus_connection.monitor_pages[0] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
183         vmbus_connection.monitor_pages[1] = (void *)__get_free_pages((GFP_KERNEL|__GFP_ZERO), 0);
184         if ((vmbus_connection.monitor_pages[0] == NULL) ||
185             (vmbus_connection.monitor_pages[1] == NULL)) {
186                 ret = -ENOMEM;
187                 goto cleanup;
188         }
189
190         msginfo = kzalloc(sizeof(*msginfo) +
191                           sizeof(struct vmbus_channel_initiate_contact),
192                           GFP_KERNEL);
193         if (msginfo == NULL) {
194                 ret = -ENOMEM;
195                 goto cleanup;
196         }
197
198         /*
199          * Negotiate a compatible VMBUS version number with the
200          * host. We start with the highest number we can support
201          * and work our way down until we negotiate a compatible
202          * version.
203          */
204
205         version = VERSION_CURRENT;
206
207         do {
208                 ret = vmbus_negotiate_version(msginfo, version);
209                 if (ret == -ETIMEDOUT)
210                         goto cleanup;
211
212                 if (vmbus_connection.conn_state == CONNECTED)
213                         break;
214
215                 version = vmbus_get_next_version(version);
216         } while (version != VERSION_INVAL);
217
218         if (version == VERSION_INVAL)
219                 goto cleanup;
220
221         vmbus_proto_version = version;
222         pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d; Vmbus version:%d.%d\n",
223                     host_info_eax, host_info_ebx >> 16,
224                     host_info_ebx & 0xFFFF, host_info_ecx,
225                     host_info_edx >> 24, host_info_edx & 0xFFFFFF,
226                     version >> 16, version & 0xFFFF);
227
228         kfree(msginfo);
229         return 0;
230
231 cleanup:
232         pr_err("Unable to connect to host\n");
233
234         vmbus_connection.conn_state = DISCONNECTED;
235         vmbus_disconnect();
236
237         kfree(msginfo);
238
239         return ret;
240 }
241
242 void vmbus_disconnect(void)
243 {
244         /*
245          * First send the unload request to the host.
246          */
247         vmbus_initiate_unload(false);
248
249         if (vmbus_connection.work_queue) {
250                 drain_workqueue(vmbus_connection.work_queue);
251                 destroy_workqueue(vmbus_connection.work_queue);
252         }
253
254         if (vmbus_connection.int_page) {
255                 free_pages((unsigned long)vmbus_connection.int_page, 0);
256                 vmbus_connection.int_page = NULL;
257         }
258
259         free_pages((unsigned long)vmbus_connection.monitor_pages[0], 0);
260         free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
261         vmbus_connection.monitor_pages[0] = NULL;
262         vmbus_connection.monitor_pages[1] = NULL;
263 }
264
265 /*
266  * Map the given relid to the corresponding channel based on the
267  * per-cpu list of channels that have been affinitized to this CPU.
268  * This will be used in the channel callback path as we can do this
269  * mapping in a lock-free fashion.
270  */
271 static struct vmbus_channel *pcpu_relid2channel(u32 relid)
272 {
273         struct vmbus_channel *channel;
274         struct vmbus_channel *found_channel  = NULL;
275         int cpu = smp_processor_id();
276         struct list_head *pcpu_head = &hv_context.percpu_list[cpu];
277
278         list_for_each_entry(channel, pcpu_head, percpu_list) {
279                 if (channel->offermsg.child_relid == relid) {
280                         found_channel = channel;
281                         break;
282                 }
283         }
284
285         return found_channel;
286 }
287
288 /*
289  * relid2channel - Get the channel object given its
290  * child relative id (ie channel id)
291  */
292 struct vmbus_channel *relid2channel(u32 relid)
293 {
294         struct vmbus_channel *channel;
295         struct vmbus_channel *found_channel  = NULL;
296         struct list_head *cur, *tmp;
297         struct vmbus_channel *cur_sc;
298
299         BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
300
301         list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
302                 if (channel->offermsg.child_relid == relid) {
303                         found_channel = channel;
304                         break;
305                 } else if (!list_empty(&channel->sc_list)) {
306                         /*
307                          * Deal with sub-channels.
308                          */
309                         list_for_each_safe(cur, tmp, &channel->sc_list) {
310                                 cur_sc = list_entry(cur, struct vmbus_channel,
311                                                         sc_list);
312                                 if (cur_sc->offermsg.child_relid == relid) {
313                                         found_channel = cur_sc;
314                                         break;
315                                 }
316                         }
317                 }
318         }
319
320         return found_channel;
321 }
322
323 /*
324  * process_chn_event - Process a channel event notification
325  */
326 static void process_chn_event(u32 relid)
327 {
328         struct vmbus_channel *channel;
329         void *arg;
330         bool read_state;
331         u32 bytes_to_read;
332
333         /*
334          * Find the channel based on this relid and invokes the
335          * channel callback to process the event
336          */
337         channel = pcpu_relid2channel(relid);
338
339         if (!channel)
340                 return;
341
342         /*
343          * A channel once created is persistent even when there
344          * is no driver handling the device. An unloading driver
345          * sets the onchannel_callback to NULL on the same CPU
346          * as where this interrupt is handled (in an interrupt context).
347          * Thus, checking and invoking the driver specific callback takes
348          * care of orderly unloading of the driver.
349          */
350
351         if (channel->onchannel_callback != NULL) {
352                 arg = channel->channel_callback_context;
353                 read_state = channel->batched_reading;
354                 /*
355                  * This callback reads the messages sent by the host.
356                  * We can optimize host to guest signaling by ensuring:
357                  * 1. While reading the channel, we disable interrupts from
358                  *    host.
359                  * 2. Ensure that we process all posted messages from the host
360                  *    before returning from this callback.
361                  * 3. Once we return, enable signaling from the host. Once this
362                  *    state is set we check to see if additional packets are
363                  *    available to read. In this case we repeat the process.
364                  */
365
366                 do {
367                         if (read_state)
368                                 hv_begin_read(&channel->inbound);
369                         channel->onchannel_callback(arg);
370                         if (read_state)
371                                 bytes_to_read = hv_end_read(&channel->inbound);
372                         else
373                                 bytes_to_read = 0;
374                 } while (read_state && (bytes_to_read != 0));
375         }
376 }
377
378 /*
379  * vmbus_on_event - Handler for events
380  */
381 void vmbus_on_event(unsigned long data)
382 {
383         u32 dword;
384         u32 maxdword;
385         int bit;
386         u32 relid;
387         u32 *recv_int_page = NULL;
388         void *page_addr;
389         int cpu = smp_processor_id();
390         union hv_synic_event_flags *event;
391
392         if (vmbus_proto_version < VERSION_WIN8) {
393                 maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
394                 recv_int_page = vmbus_connection.recv_int_page;
395         } else {
396                 /*
397                  * When the host is win8 and beyond, the event page
398                  * can be directly checked to get the id of the channel
399                  * that has the interrupt pending.
400                  */
401                 maxdword = HV_EVENT_FLAGS_DWORD_COUNT;
402                 page_addr = hv_context.synic_event_page[cpu];
403                 event = (union hv_synic_event_flags *)page_addr +
404                                                  VMBUS_MESSAGE_SINT;
405                 recv_int_page = event->flags32;
406         }
407
408
409
410         /* Check events */
411         if (!recv_int_page)
412                 return;
413         for (dword = 0; dword < maxdword; dword++) {
414                 if (!recv_int_page[dword])
415                         continue;
416                 for (bit = 0; bit < 32; bit++) {
417                         if (sync_test_and_clear_bit(bit,
418                                 (unsigned long *)&recv_int_page[dword])) {
419                                 relid = (dword << 5) + bit;
420
421                                 if (relid == 0)
422                                         /*
423                                          * Special case - vmbus
424                                          * channel protocol msg
425                                          */
426                                         continue;
427
428                                 process_chn_event(relid);
429                         }
430                 }
431         }
432 }
433
434 /*
435  * vmbus_post_msg - Send a msg on the vmbus's message connection
436  */
437 int vmbus_post_msg(void *buffer, size_t buflen)
438 {
439         union hv_connection_id conn_id;
440         int ret = 0;
441         int retries = 0;
442         u32 msec = 1;
443
444         conn_id.asu32 = 0;
445         conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
446
447         /*
448          * hv_post_message() can have transient failures because of
449          * insufficient resources. Retry the operation a couple of
450          * times before giving up.
451          */
452         while (retries < 20) {
453                 ret = hv_post_message(conn_id, 1, buffer, buflen);
454
455                 switch (ret) {
456                 case HV_STATUS_INVALID_CONNECTION_ID:
457                         /*
458                          * We could get this if we send messages too
459                          * frequently.
460                          */
461                         ret = -EAGAIN;
462                         break;
463                 case HV_STATUS_INSUFFICIENT_MEMORY:
464                 case HV_STATUS_INSUFFICIENT_BUFFERS:
465                         ret = -ENOMEM;
466                         break;
467                 case HV_STATUS_SUCCESS:
468                         return ret;
469                 default:
470                         pr_err("hv_post_msg() failed; error code:%d\n", ret);
471                         return -EINVAL;
472                 }
473
474                 retries++;
475                 msleep(msec);
476                 if (msec < 2048)
477                         msec *= 2;
478         }
479         return ret;
480 }
481
482 /*
483  * vmbus_set_event - Send an event notification to the parent
484  */
485 void vmbus_set_event(struct vmbus_channel *channel)
486 {
487         u32 child_relid = channel->offermsg.child_relid;
488
489         if (!channel->is_dedicated_interrupt) {
490                 /* Each u32 represents 32 channels */
491                 sync_set_bit(child_relid & 31,
492                         (unsigned long *)vmbus_connection.send_int_page +
493                         (child_relid >> 5));
494         }
495
496         hv_do_hypercall(HVCALL_SIGNAL_EVENT, channel->sig_event, NULL);
497 }
498 EXPORT_SYMBOL_GPL(vmbus_set_event);