drivers/xen/xen-pciback/pciback_ops.c

   1 /*
   2  * PCI Backend Operations - respond to PCI requests from Frontend
   3  *
   4  *   Author: Ryan Wilson <hap9@epoch.ncsc.mil>
   5  */
   6
   7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   8
   9 #include <linux/module.h>
  10 #include <linux/wait.h>
  11 #include <linux/bitops.h>
  12 #include <xen/events.h>
  13 #include <linux/sched.h>
  14 #include "pciback.h"
  15
  16 int verbose_request;
  17 module_param(verbose_request, int, 0644);
  18
  19 static irqreturn_t xen_pcibk_guest_interrupt(int irq, void *dev_id);
  20
  21 /* Ensure a device is has the fake IRQ handler "turned on/off" and is
  22  * ready to be exported. This MUST be run after xen_pcibk_reset_device
  23  * which does the actual PCI device enable/disable.
  24  */
  25 static void xen_pcibk_control_isr(struct pci_dev *dev, int reset)
  26 {
  27         struct xen_pcibk_dev_data *dev_data;
  28         int rc;
  29         int enable = 0;
  30
  31         dev_data = pci_get_drvdata(dev);
  32         if (!dev_data)
  33                 return;
  34
  35         /* We don't deal with bridges */
  36         if (dev->hdr_type != PCI_HEADER_TYPE_NORMAL)
  37                 return;
  38
  39         if (reset) {
  40                 dev_data->enable_intx = 0;
  41                 dev_data->ack_intr = 0;
  42         }
  43         enable =  dev_data->enable_intx;
  44
  45         /* Asked to disable, but ISR isn't runnig */
  46         if (!enable && !dev_data->isr_on)
  47                 return;
  48
  49         /* Squirrel away the IRQs in the dev_data. We need this
  50          * b/c when device transitions to MSI, the dev->irq is
  51          * overwritten with the MSI vector.
  52          */
  53         if (enable)
  54                 dev_data->irq = dev->irq;
  55
  56         /*
  57          * SR-IOV devices in all use MSI-X and have no legacy
  58          * interrupts, so inhibit creating a fake IRQ handler for them.
  59          */
  60         if (dev_data->irq == 0)
  61                 goto out;
  62
  63         dev_dbg(&dev->dev, "%s: #%d %s %s%s %s-> %s\n",
  64                 dev_data->irq_name,
  65                 dev_data->irq,
  66                 pci_is_enabled(dev) ? "on" : "off",
  67                 dev->msi_enabled ? "MSI" : "",
  68                 dev->msix_enabled ? "MSI/X" : "",
  69                 dev_data->isr_on ? "enable" : "disable",
  70                 enable ? "enable" : "disable");
  71
  72         if (enable) {
  73                 /*
  74                  * The MSI or MSI-X should not have an IRQ handler. Otherwise
  75                  * if the guest terminates we BUG_ON in free_msi_irqs.
  76                  */
  77                 if (dev->msi_enabled || dev->msix_enabled)
  78                         goto out;
  79
  80                 rc = request_irq(dev_data->irq,
  81                                 xen_pcibk_guest_interrupt, IRQF_SHARED,
  82                                 dev_data->irq_name, dev);
  83                 if (rc) {
  84                         dev_err(&dev->dev, "%s: failed to install fake IRQ " \
  85                                 "handler for IRQ %d! (rc:%d)\n",
  86                                 dev_data->irq_name, dev_data->irq, rc);
  87                         goto out;
  88                 }
  89         } else {
  90                 free_irq(dev_data->irq, dev);
  91                 dev_data->irq = 0;
  92         }
  93         dev_data->isr_on = enable;
  94         dev_data->ack_intr = enable;
  95 out:
  96         dev_dbg(&dev->dev, "%s: #%d %s %s%s %s\n",
  97                 dev_data->irq_name,
  98                 dev_data->irq,
  99                 pci_is_enabled(dev) ? "on" : "off",
 100                 dev->msi_enabled ? "MSI" : "",
 101                 dev->msix_enabled ? "MSI/X" : "",
 102                 enable ? (dev_data->isr_on ? "enabled" : "failed to enable") :
 103                         (dev_data->isr_on ? "failed to disable" : "disabled"));
 104 }
 105
 106 /* Ensure a device is "turned off" and ready to be exported.
 107  * (Also see xen_pcibk_config_reset to ensure virtual configuration space is
 108  * ready to be re-exported)
 109  */
 110 void xen_pcibk_reset_device(struct pci_dev *dev)
 111 {
 112         u16 cmd;
 113
 114         xen_pcibk_control_isr(dev, 1 /* reset device */);
 115
 116         /* Disable devices (but not bridges) */
 117         if (dev->hdr_type == PCI_HEADER_TYPE_NORMAL) {
 118 #ifdef CONFIG_PCI_MSI
 119                 /* The guest could have been abruptly killed without
 120                  * disabling MSI/MSI-X interrupts.*/
 121                 if (dev->msix_enabled)
 122                         pci_disable_msix(dev);
 123                 if (dev->msi_enabled)
 124                         pci_disable_msi(dev);
 125 #endif
 126                 if (pci_is_enabled(dev))
 127                         pci_disable_device(dev);
 128
 129                 pci_write_config_word(dev, PCI_COMMAND, 0);
 130
 131                 dev->is_busmaster = 0;
 132         } else {
 133                 pci_read_config_word(dev, PCI_COMMAND, &cmd);
 134                 if (cmd & (PCI_COMMAND_INVALIDATE)) {
 135                         cmd &= ~(PCI_COMMAND_INVALIDATE);
 136                         pci_write_config_word(dev, PCI_COMMAND, cmd);
 137
 138                         dev->is_busmaster = 0;
 139                 }
 140         }
 141 }
 142
 143 #ifdef CONFIG_PCI_MSI
 144 static
 145 int xen_pcibk_enable_msi(struct xen_pcibk_device *pdev,
 146                          struct pci_dev *dev, struct xen_pci_op *op)
 147 {
 148         struct xen_pcibk_dev_data *dev_data;
 149         int status;
 150
 151         if (unlikely(verbose_request))
 152                 printk(KERN_DEBUG DRV_NAME ": %s: enable MSI\n", pci_name(dev));
 153
 154         if (dev->msi_enabled)
 155                 status = -EALREADY;
 156         else if (dev->msix_enabled)
 157                 status = -ENXIO;
 158         else
 159                 status = pci_enable_msi(dev);
 160
 161         if (status) {
 162                 pr_warn_ratelimited("%s: error enabling MSI for guest %u: err %d\n",
 163                                     pci_name(dev), pdev->xdev->otherend_id,
 164                                     status);
 165                 op->value = 0;
 166                 return XEN_PCI_ERR_op_failed;
 167         }
 168
 169         /* The value the guest needs is actually the IDT vector, not the
 170          * the local domain's IRQ number. */
 171
 172         op->value = dev->irq ? xen_pirq_from_irq(dev->irq) : 0;
 173         if (unlikely(verbose_request))
 174                 printk(KERN_DEBUG DRV_NAME ": %s: MSI: %d\n", pci_name(dev),
 175                         op->value);
 176
 177         dev_data = pci_get_drvdata(dev);
 178         if (dev_data)
 179                 dev_data->ack_intr = 0;
 180
 181         return 0;
 182 }
 183
 184 static
 185 int xen_pcibk_disable_msi(struct xen_pcibk_device *pdev,
 186                           struct pci_dev *dev, struct xen_pci_op *op)
 187 {
 188         if (unlikely(verbose_request))
 189                 printk(KERN_DEBUG DRV_NAME ": %s: disable MSI\n",
 190                        pci_name(dev));
 191
 192         if (dev->msi_enabled) {
 193                 struct xen_pcibk_dev_data *dev_data;
 194
 195                 pci_disable_msi(dev);
 196
 197                 dev_data = pci_get_drvdata(dev);
 198                 if (dev_data)
 199                         dev_data->ack_intr = 1;
 200         }
 201         op->value = dev->irq ? xen_pirq_from_irq(dev->irq) : 0;
 202         if (unlikely(verbose_request))
 203                 printk(KERN_DEBUG DRV_NAME ": %s: MSI: %d\n", pci_name(dev),
 204                         op->value);
 205         return 0;
 206 }
 207
 208 static
 209 int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev,
 210                           struct pci_dev *dev, struct xen_pci_op *op)
 211 {
 212         struct xen_pcibk_dev_data *dev_data;
 213         int i, result;
 214         struct msix_entry *entries;
 215         u16 cmd;
 216
 217         if (unlikely(verbose_request))
 218                 printk(KERN_DEBUG DRV_NAME ": %s: enable MSI-X\n",
 219                        pci_name(dev));
 220
 221         if (op->value > SH_INFO_MAX_VEC)
 222                 return -EINVAL;
 223
 224         if (dev->msix_enabled)
 225                 return -EALREADY;
 226
 227         /*
 228          * PCI_COMMAND_MEMORY must be enabled, otherwise we may not be able
 229          * to access the BARs where the MSI-X entries reside.
 230          */
 231         pci_read_config_word(dev, PCI_COMMAND, &cmd);
 232         if (dev->msi_enabled || !(cmd & PCI_COMMAND_MEMORY))
 233                 return -ENXIO;
 234
 235         entries = kmalloc(op->value * sizeof(*entries), GFP_KERNEL);
 236         if (entries == NULL)
 237                 return -ENOMEM;
 238
 239         for (i = 0; i < op->value; i++) {
 240                 entries[i].entry = op->msix_entries[i].entry;
 241                 entries[i].vector = op->msix_entries[i].vector;
 242         }
 243
 244         result = pci_enable_msix_exact(dev, entries, op->value);
 245         if (result == 0) {
 246                 for (i = 0; i < op->value; i++) {
 247                         op->msix_entries[i].entry = entries[i].entry;
 248                         if (entries[i].vector) {
 249                                 op->msix_entries[i].vector =
 250                                         xen_pirq_from_irq(entries[i].vector);
 251                                 if (unlikely(verbose_request))
 252                                         printk(KERN_DEBUG DRV_NAME ": %s: " \
 253                                                 "MSI-X[%d]: %d\n",
 254                                                 pci_name(dev), i,
 255                                                 op->msix_entries[i].vector);
 256                         }
 257                 }
 258         } else
 259                 pr_warn_ratelimited("%s: error enabling MSI-X for guest %u: err %d!\n",
 260                                     pci_name(dev), pdev->xdev->otherend_id,
 261                                     result);
 262         kfree(entries);
 263
 264         op->value = result;
 265         dev_data = pci_get_drvdata(dev);
 266         if (dev_data)
 267                 dev_data->ack_intr = 0;
 268
 269         return result > 0 ? 0 : result;
 270 }
 271
 272 static
 273 int xen_pcibk_disable_msix(struct xen_pcibk_device *pdev,
 274                            struct pci_dev *dev, struct xen_pci_op *op)
 275 {
 276         if (unlikely(verbose_request))
 277                 printk(KERN_DEBUG DRV_NAME ": %s: disable MSI-X\n",
 278                         pci_name(dev));
 279
 280         if (dev->msix_enabled) {
 281                 struct xen_pcibk_dev_data *dev_data;
 282
 283                 pci_disable_msix(dev);
 284
 285                 dev_data = pci_get_drvdata(dev);
 286                 if (dev_data)
 287                         dev_data->ack_intr = 1;
 288         }
 289         /*
 290          * SR-IOV devices (which don't have any legacy IRQ) have
 291          * an undefined IRQ value of zero.
 292          */
 293         op->value = dev->irq ? xen_pirq_from_irq(dev->irq) : 0;
 294         if (unlikely(verbose_request))
 295                 printk(KERN_DEBUG DRV_NAME ": %s: MSI-X: %d\n",
 296                        pci_name(dev), op->value);
 297         return 0;
 298 }
 299 #endif
 300 /*
 301 * Now the same evtchn is used for both pcifront conf_read_write request
 302 * as well as pcie aer front end ack. We use a new work_queue to schedule
 303 * xen_pcibk conf_read_write service for avoiding confict with aer_core
 304 * do_recovery job which also use the system default work_queue
 305 */
 306 void xen_pcibk_test_and_schedule_op(struct xen_pcibk_device *pdev)
 307 {
 308         /* Check that frontend is requesting an operation and that we are not
 309          * already processing a request */
 310         if (test_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags)
 311             && !test_and_set_bit(_PDEVF_op_active, &pdev->flags)) {
 312                 queue_work(xen_pcibk_wq, &pdev->op_work);
 313         }
 314         /*_XEN_PCIB_active should have been cleared by pcifront. And also make
 315         sure xen_pcibk is waiting for ack by checking _PCIB_op_pending*/
 316         if (!test_bit(_XEN_PCIB_active, (unsigned long *)&pdev->sh_info->flags)
 317             && test_bit(_PCIB_op_pending, &pdev->flags)) {
 318                 wake_up(&xen_pcibk_aer_wait_queue);
 319         }
 320 }
 321
 322 /* Performing the configuration space reads/writes must not be done in atomic
 323  * context because some of the pci_* functions can sleep (mostly due to ACPI
 324  * use of semaphores). This function is intended to be called from a work
 325  * queue in process context taking a struct xen_pcibk_device as a parameter */
 326
 327 void xen_pcibk_do_op(struct work_struct *data)
 328 {
 329         struct xen_pcibk_device *pdev =
 330                 container_of(data, struct xen_pcibk_device, op_work);
 331         struct pci_dev *dev;
 332         struct xen_pcibk_dev_data *dev_data = NULL;
 333         struct xen_pci_op *op = &pdev->op;
 334         int test_intx = 0;
 335
 336         *op = pdev->sh_info->op;
 337         barrier();
 338         dev = xen_pcibk_get_pci_dev(pdev, op->domain, op->bus, op->devfn);
 339
 340         if (dev == NULL)
 341                 op->err = XEN_PCI_ERR_dev_not_found;
 342         else {
 343                 dev_data = pci_get_drvdata(dev);
 344                 if (dev_data)
 345                         test_intx = dev_data->enable_intx;
 346                 switch (op->cmd) {
 347                 case XEN_PCI_OP_conf_read:
 348                         op->err = xen_pcibk_config_read(dev,
 349                                   op->offset, op->size, &op->value);
 350                         break;
 351                 case XEN_PCI_OP_conf_write:
 352                         op->err = xen_pcibk_config_write(dev,
 353                                   op->offset, op->size, op->value);
 354                         break;
 355 #ifdef CONFIG_PCI_MSI
 356                 case XEN_PCI_OP_enable_msi:
 357                         op->err = xen_pcibk_enable_msi(pdev, dev, op);
 358                         break;
 359                 case XEN_PCI_OP_disable_msi:
 360                         op->err = xen_pcibk_disable_msi(pdev, dev, op);
 361                         break;
 362                 case XEN_PCI_OP_enable_msix:
 363                         op->err = xen_pcibk_enable_msix(pdev, dev, op);
 364                         break;
 365                 case XEN_PCI_OP_disable_msix:
 366                         op->err = xen_pcibk_disable_msix(pdev, dev, op);
 367                         break;
 368 #endif
 369                 default:
 370                         op->err = XEN_PCI_ERR_not_implemented;
 371                         break;
 372                 }
 373         }
 374         if (!op->err && dev && dev_data) {
 375                 /* Transition detected */
 376                 if ((dev_data->enable_intx != test_intx))
 377                         xen_pcibk_control_isr(dev, 0 /* no reset */);
 378         }
 379         pdev->sh_info->op.err = op->err;
 380         pdev->sh_info->op.value = op->value;
 381 #ifdef CONFIG_PCI_MSI
 382         if (op->cmd == XEN_PCI_OP_enable_msix && op->err == 0) {
 383                 unsigned int i;
 384
 385                 for (i = 0; i < op->value; i++)
 386                         pdev->sh_info->op.msix_entries[i].vector =
 387                                 op->msix_entries[i].vector;
 388         }
 389 #endif
 390         /* Tell the driver domain that we're done. */
 391         wmb();
 392         clear_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags);
 393         notify_remote_via_irq(pdev->evtchn_irq);
 394
 395         /* Mark that we're done. */
 396         smp_mb__before_atomic(); /* /after/ clearing PCIF_active */
 397         clear_bit(_PDEVF_op_active, &pdev->flags);
 398         smp_mb__after_atomic(); /* /before/ final check for work */
 399
 400         /* Check to see if the driver domain tried to start another request in
 401          * between clearing _XEN_PCIF_active and clearing _PDEVF_op_active.
 402         */
 403         xen_pcibk_test_and_schedule_op(pdev);
 404 }
 405
 406 irqreturn_t xen_pcibk_handle_event(int irq, void *dev_id)
 407 {
 408         struct xen_pcibk_device *pdev = dev_id;
 409
 410         xen_pcibk_test_and_schedule_op(pdev);
 411
 412         return IRQ_HANDLED;
 413 }
 414 static irqreturn_t xen_pcibk_guest_interrupt(int irq, void *dev_id)
 415 {
 416         struct pci_dev *dev = (struct pci_dev *)dev_id;
 417         struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
 418
 419         if (dev_data->isr_on && dev_data->ack_intr) {
 420                 dev_data->handled++;
 421                 if ((dev_data->handled % 1000) == 0) {
 422                         if (xen_test_irq_shared(irq)) {
 423                                 pr_info("%s IRQ line is not shared "
 424                                         "with other domains. Turning ISR off\n",
 425                                          dev_data->irq_name);
 426                                 dev_data->ack_intr = 0;
 427                         }
 428                 }
 429                 return IRQ_HANDLED;
 430         }
 431         return IRQ_NONE;
 432 }