drivers/s390/cio/vfio_ccw_fsm.c

   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 <[email protected]>
   9  *            Cornelia Huck <[email protected]>
  10  */
  11
  12 #include <linux/vfio.h>
  13 #include <linux/mdev.h>
  14
  15 #include "ioasm.h"
  16 #include "vfio_ccw_private.h"
  17
  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
  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
 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
 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  */
 178 static void fsm_nop(struct vfio_ccw_private *private,
 179                     enum vfio_ccw_event event)
 180 {
 181 }
 182
 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
 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
 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
 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
 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
 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 }
 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  */
 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  */
 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  */
 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 };