1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Finite state machine for vfio-ccw device handling
4 *
5 * Copyright IBM Corp. 2017
6 * Copyright Red Hat, Inc. 2019
7 *
8 * Author(s): Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
9 * Cornelia Huck <cohuck@redhat.com>
10 */
11
12 #include <linux/vfio.h>
13 #include <linux/mdev.h>
14
15 #include "ioasm.h"
16 #include "vfio_ccw_private.h"
17
fsm_io_helper(struct vfio_ccw_private * private)18 static int fsm_io_helper(struct vfio_ccw_private *private)
19 {
20 struct subchannel *sch;
21 union orb *orb;
22 int ccode;
23 __u8 lpm;
24 unsigned long flags;
25 int ret;
26
27 sch = private->sch;
28
29 spin_lock_irqsave(sch->lock, flags);
30
31 orb = cp_get_orb(&private->cp, (u32)(addr_t)sch, sch->lpm);
32 if (!orb) {
33 ret = -EIO;
34 goto out;
35 }
36
37 VFIO_CCW_TRACE_EVENT(5, "stIO");
38 VFIO_CCW_TRACE_EVENT(5, dev_name(&sch->dev));
39
40 /* Issue "Start Subchannel" */
41 ccode = ssch(sch->schid, orb);
42
43 VFIO_CCW_HEX_EVENT(5, &ccode, sizeof(ccode));
44
45 switch (ccode) {
46 case 0:
47 /*
48 * Initialize device status information
49 */
50 sch->schib.scsw.cmd.actl |= SCSW_ACTL_START_PEND;
51 ret = 0;
52 private->state = VFIO_CCW_STATE_CP_PENDING;
53 break;
54 case 1: /* Status pending */
55 case 2: /* Busy */
56 ret = -EBUSY;
57 break;
58 case 3: /* Device/path not operational */
59 {
60 lpm = orb->cmd.lpm;
61 if (lpm != 0)
62 sch->lpm &= ~lpm;
63 else
64 sch->lpm = 0;
65
66 if (cio_update_schib(sch))
67 ret = -ENODEV;
68 else
69 ret = sch->lpm ? -EACCES : -ENODEV;
70 break;
71 }
72 default:
73 ret = ccode;
74 }
75 out:
76 spin_unlock_irqrestore(sch->lock, flags);
77 return ret;
78 }
79
fsm_do_halt(struct vfio_ccw_private * private)80 static int fsm_do_halt(struct vfio_ccw_private *private)
81 {
82 struct subchannel *sch;
83 unsigned long flags;
84 int ccode;
85 int ret;
86
87 sch = private->sch;
88
89 spin_lock_irqsave(sch->lock, flags);
90
91 VFIO_CCW_TRACE_EVENT(2, "haltIO");
92 VFIO_CCW_TRACE_EVENT(2, dev_name(&sch->dev));
93
94 /* Issue "Halt Subchannel" */
95 ccode = hsch(sch->schid);
96
97 VFIO_CCW_HEX_EVENT(2, &ccode, sizeof(ccode));
98
99 switch (ccode) {
100 case 0:
101 /*
102 * Initialize device status information
103 */
104 sch->schib.scsw.cmd.actl |= SCSW_ACTL_HALT_PEND;
105 ret = 0;
106 break;
107 case 1: /* Status pending */
108 case 2: /* Busy */
109 ret = -EBUSY;
110 break;
111 case 3: /* Device not operational */
112 ret = -ENODEV;
113 break;
114 default:
115 ret = ccode;
116 }
117 spin_unlock_irqrestore(sch->lock, flags);
118 return ret;
119 }
120
fsm_do_clear(struct vfio_ccw_private * private)121 static int fsm_do_clear(struct vfio_ccw_private *private)
122 {
123 struct subchannel *sch;
124 unsigned long flags;
125 int ccode;
126 int ret;
127
128 sch = private->sch;
129
130 spin_lock_irqsave(sch->lock, flags);
131
132 VFIO_CCW_TRACE_EVENT(2, "clearIO");
133 VFIO_CCW_TRACE_EVENT(2, dev_name(&sch->dev));
134
135 /* Issue "Clear Subchannel" */
136 ccode = csch(sch->schid);
137
138 VFIO_CCW_HEX_EVENT(2, &ccode, sizeof(ccode));
139
140 switch (ccode) {
141 case 0:
142 /*
143 * Initialize device status information
144 */
145 sch->schib.scsw.cmd.actl = SCSW_ACTL_CLEAR_PEND;
146 /* TODO: check what else we might need to clear */
147 ret = 0;
148 break;
149 case 3: /* Device not operational */
150 ret = -ENODEV;
151 break;
152 default:
153 ret = ccode;
154 }
155 spin_unlock_irqrestore(sch->lock, flags);
156 return ret;
157 }
158
fsm_notoper(struct vfio_ccw_private * private,enum vfio_ccw_event event)159 static void fsm_notoper(struct vfio_ccw_private *private,
160 enum vfio_ccw_event event)
161 {
162 struct subchannel *sch = private->sch;
163
164 VFIO_CCW_TRACE_EVENT(2, "notoper");
165 VFIO_CCW_TRACE_EVENT(2, dev_name(&sch->dev));
166
167 /*
168 * TODO:
169 * Probably we should send the machine check to the guest.
170 */
171 css_sched_sch_todo(sch, SCH_TODO_UNREG);
172 private->state = VFIO_CCW_STATE_NOT_OPER;
173 }
174
175 /*
176 * No operation action.
177 */
fsm_nop(struct vfio_ccw_private * private,enum vfio_ccw_event event)178 static void fsm_nop(struct vfio_ccw_private *private,
179 enum vfio_ccw_event event)
180 {
181 }
182
fsm_io_error(struct vfio_ccw_private * private,enum vfio_ccw_event event)183 static void fsm_io_error(struct vfio_ccw_private *private,
184 enum vfio_ccw_event event)
185 {
186 pr_err("vfio-ccw: FSM: I/O request from state:%d\n", private->state);
187 private->io_region->ret_code = -EIO;
188 }
189
fsm_io_busy(struct vfio_ccw_private * private,enum vfio_ccw_event event)190 static void fsm_io_busy(struct vfio_ccw_private *private,
191 enum vfio_ccw_event event)
192 {
193 private->io_region->ret_code = -EBUSY;
194 }
195
fsm_io_retry(struct vfio_ccw_private * private,enum vfio_ccw_event event)196 static void fsm_io_retry(struct vfio_ccw_private *private,
197 enum vfio_ccw_event event)
198 {
199 private->io_region->ret_code = -EAGAIN;
200 }
201
fsm_async_error(struct vfio_ccw_private * private,enum vfio_ccw_event event)202 static void fsm_async_error(struct vfio_ccw_private *private,
203 enum vfio_ccw_event event)
204 {
205 struct ccw_cmd_region *cmd_region = private->cmd_region;
206
207 pr_err("vfio-ccw: FSM: %s request from state:%d\n",
208 cmd_region->command == VFIO_CCW_ASYNC_CMD_HSCH ? "halt" :
209 cmd_region->command == VFIO_CCW_ASYNC_CMD_CSCH ? "clear" :
210 "<unknown>", private->state);
211 cmd_region->ret_code = -EIO;
212 }
213
fsm_async_retry(struct vfio_ccw_private * private,enum vfio_ccw_event event)214 static void fsm_async_retry(struct vfio_ccw_private *private,
215 enum vfio_ccw_event event)
216 {
217 private->cmd_region->ret_code = -EAGAIN;
218 }
219
fsm_disabled_irq(struct vfio_ccw_private * private,enum vfio_ccw_event event)220 static void fsm_disabled_irq(struct vfio_ccw_private *private,
221 enum vfio_ccw_event event)
222 {
223 struct subchannel *sch = private->sch;
224
225 /*
226 * An interrupt in a disabled state means a previous disable was not
227 * successful - should not happen, but we try to disable again.
228 */
229 cio_disable_subchannel(sch);
230 }
get_schid(struct vfio_ccw_private * p)231 inline struct subchannel_id get_schid(struct vfio_ccw_private *p)
232 {
233 return p->sch->schid;
234 }
235
236 /*
237 * Deal with the ccw command request from the userspace.
238 */
fsm_io_request(struct vfio_ccw_private * private,enum vfio_ccw_event event)239 static void fsm_io_request(struct vfio_ccw_private *private,
240 enum vfio_ccw_event event)
241 {
242 union orb *orb;
243 union scsw *scsw = &private->scsw;
244 struct ccw_io_region *io_region = private->io_region;
245 struct mdev_device *mdev = private->mdev;
246 char *errstr = "request";
247 struct subchannel_id schid = get_schid(private);
248
249 private->state = VFIO_CCW_STATE_CP_PROCESSING;
250 memcpy(scsw, io_region->scsw_area, sizeof(*scsw));
251
252 if (scsw->cmd.fctl & SCSW_FCTL_START_FUNC) {
253 orb = (union orb *)io_region->orb_area;
254
255 /* Don't try to build a cp if transport mode is specified. */
256 if (orb->tm.b) {
257 io_region->ret_code = -EOPNOTSUPP;
258 VFIO_CCW_MSG_EVENT(2,
259 "%pUl (%x.%x.%04x): transport mode\n",
260 mdev_uuid(mdev), schid.cssid,
261 schid.ssid, schid.sch_no);
262 errstr = "transport mode";
263 goto err_out;
264 }
265 io_region->ret_code = cp_init(&private->cp, mdev_dev(mdev),
266 orb);
267 if (io_region->ret_code) {
268 VFIO_CCW_MSG_EVENT(2,
269 "%pUl (%x.%x.%04x): cp_init=%d\n",
270 mdev_uuid(mdev), schid.cssid,
271 schid.ssid, schid.sch_no,
272 io_region->ret_code);
273 errstr = "cp init";
274 goto err_out;
275 }
276
277 io_region->ret_code = cp_prefetch(&private->cp);
278 if (io_region->ret_code) {
279 VFIO_CCW_MSG_EVENT(2,
280 "%pUl (%x.%x.%04x): cp_prefetch=%d\n",
281 mdev_uuid(mdev), schid.cssid,
282 schid.ssid, schid.sch_no,
283 io_region->ret_code);
284 errstr = "cp prefetch";
285 cp_free(&private->cp);
286 goto err_out;
287 }
288
289 /* Start channel program and wait for I/O interrupt. */
290 io_region->ret_code = fsm_io_helper(private);
291 if (io_region->ret_code) {
292 VFIO_CCW_MSG_EVENT(2,
293 "%pUl (%x.%x.%04x): fsm_io_helper=%d\n",
294 mdev_uuid(mdev), schid.cssid,
295 schid.ssid, schid.sch_no,
296 io_region->ret_code);
297 errstr = "cp fsm_io_helper";
298 cp_free(&private->cp);
299 goto err_out;
300 }
301 return;
302 } else if (scsw->cmd.fctl & SCSW_FCTL_HALT_FUNC) {
303 VFIO_CCW_MSG_EVENT(2,
304 "%pUl (%x.%x.%04x): halt on io_region\n",
305 mdev_uuid(mdev), schid.cssid,
306 schid.ssid, schid.sch_no);
307 /* halt is handled via the async cmd region */
308 io_region->ret_code = -EOPNOTSUPP;
309 goto err_out;
310 } else if (scsw->cmd.fctl & SCSW_FCTL_CLEAR_FUNC) {
311 VFIO_CCW_MSG_EVENT(2,
312 "%pUl (%x.%x.%04x): clear on io_region\n",
313 mdev_uuid(mdev), schid.cssid,
314 schid.ssid, schid.sch_no);
315 /* clear is handled via the async cmd region */
316 io_region->ret_code = -EOPNOTSUPP;
317 goto err_out;
318 }
319
320 err_out:
321 trace_vfio_ccw_fsm_io_request(scsw->cmd.fctl, schid,
322 io_region->ret_code, errstr);
323 }
324
325 /*
326 * Deal with an async request from userspace.
327 */
fsm_async_request(struct vfio_ccw_private * private,enum vfio_ccw_event event)328 static void fsm_async_request(struct vfio_ccw_private *private,
329 enum vfio_ccw_event event)
330 {
331 struct ccw_cmd_region *cmd_region = private->cmd_region;
332
333 switch (cmd_region->command) {
334 case VFIO_CCW_ASYNC_CMD_HSCH:
335 cmd_region->ret_code = fsm_do_halt(private);
336 break;
337 case VFIO_CCW_ASYNC_CMD_CSCH:
338 cmd_region->ret_code = fsm_do_clear(private);
339 break;
340 default:
341 /* should not happen? */
342 cmd_region->ret_code = -EINVAL;
343 }
344
345 trace_vfio_ccw_fsm_async_request(get_schid(private),
346 cmd_region->command,
347 cmd_region->ret_code);
348 }
349
350 /*
351 * Got an interrupt for a normal io (state busy).
352 */
fsm_irq(struct vfio_ccw_private * private,enum vfio_ccw_event event)353 static void fsm_irq(struct vfio_ccw_private *private,
354 enum vfio_ccw_event event)
355 {
356 struct irb *irb = this_cpu_ptr(&cio_irb);
357
358 VFIO_CCW_TRACE_EVENT(6, "IRQ");
359 VFIO_CCW_TRACE_EVENT(6, dev_name(&private->sch->dev));
360
361 memcpy(&private->irb, irb, sizeof(*irb));
362
363 queue_work(vfio_ccw_work_q, &private->io_work);
364
365 if (private->completion)
366 complete(private->completion);
367 }
368
369 /*
370 * Device statemachine
371 */
372 fsm_func_t *vfio_ccw_jumptable[NR_VFIO_CCW_STATES][NR_VFIO_CCW_EVENTS] = {
373 [VFIO_CCW_STATE_NOT_OPER] = {
374 [VFIO_CCW_EVENT_NOT_OPER] = fsm_nop,
375 [VFIO_CCW_EVENT_IO_REQ] = fsm_io_error,
376 [VFIO_CCW_EVENT_ASYNC_REQ] = fsm_async_error,
377 [VFIO_CCW_EVENT_INTERRUPT] = fsm_disabled_irq,
378 },
379 [VFIO_CCW_STATE_STANDBY] = {
380 [VFIO_CCW_EVENT_NOT_OPER] = fsm_notoper,
381 [VFIO_CCW_EVENT_IO_REQ] = fsm_io_error,
382 [VFIO_CCW_EVENT_ASYNC_REQ] = fsm_async_error,
383 [VFIO_CCW_EVENT_INTERRUPT] = fsm_irq,
384 },
385 [VFIO_CCW_STATE_IDLE] = {
386 [VFIO_CCW_EVENT_NOT_OPER] = fsm_notoper,
387 [VFIO_CCW_EVENT_IO_REQ] = fsm_io_request,
388 [VFIO_CCW_EVENT_ASYNC_REQ] = fsm_async_request,
389 [VFIO_CCW_EVENT_INTERRUPT] = fsm_irq,
390 },
391 [VFIO_CCW_STATE_CP_PROCESSING] = {
392 [VFIO_CCW_EVENT_NOT_OPER] = fsm_notoper,
393 [VFIO_CCW_EVENT_IO_REQ] = fsm_io_retry,
394 [VFIO_CCW_EVENT_ASYNC_REQ] = fsm_async_retry,
395 [VFIO_CCW_EVENT_INTERRUPT] = fsm_irq,
396 },
397 [VFIO_CCW_STATE_CP_PENDING] = {
398 [VFIO_CCW_EVENT_NOT_OPER] = fsm_notoper,
399 [VFIO_CCW_EVENT_IO_REQ] = fsm_io_busy,
400 [VFIO_CCW_EVENT_ASYNC_REQ] = fsm_async_request,
401 [VFIO_CCW_EVENT_INTERRUPT] = fsm_irq,
402 },
403 };
404