drivers/xen/xen-pciback/pciback_ops.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * PCI Backend Operations - respond to PCI requests from Frontend
   4  *
   5  *   Author: Ryan Wilson <hap9@epoch.ncsc.mil>
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9 #define dev_fmt pr_fmt
  10
  11 #include <linux/moduleparam.h>
  12 #include <linux/wait.h>
  13 #include <linux/bitops.h>
  14 #include <xen/events.h>
  15 #include <linux/sched.h>
  16 #include "pciback.h"
  17
  18 static irqreturn_t xen_pcibk_guest_interrupt(int irq, void *dev_id);
  19
  20 /* Ensure a device is has the fake IRQ handler "turned on/off" and is
  21  * ready to be exported. This MUST be run after xen_pcibk_reset_device
  22  * which does the actual PCI device enable/disable.
  23  */
  24 static void xen_pcibk_control_isr(struct pci_dev *dev, int reset)
  25 {
  26         struct xen_pcibk_dev_data *dev_data;
  27         int rc;
  28         int enable = 0;
  29
  30         dev_data = pci_get_drvdata(dev);
  31         if (!dev_data)
  32                 return;
  33
  34         /* We don't deal with bridges */
  35         if (dev->hdr_type != PCI_HEADER_TYPE_NORMAL)
  36                 return;
  37
  38         if (reset) {
  39                 dev_data->enable_intx = 0;
  40                 dev_data->ack_intr = 0;
  41         }
  42         enable =  dev_data->enable_intx;
  43
  44         /* Asked to disable, but ISR isn't runnig */
  45         if (!enable && !dev_data->isr_on)
  46                 return;
  47
  48         /* Squirrel away the IRQs in the dev_data. We need this
  49          * b/c when device transitions to MSI, the dev->irq is
  50          * overwritten with the MSI vector.
  51          */
  52         if (enable)
  53                 dev_data->irq = dev->irq;
  54
  55         /*
  56          * SR-IOV devices in all use MSI-X and have no legacy
  57          * interrupts, so inhibit creating a fake IRQ handler for them.
  58          */
  59         if (dev_data->irq == 0)
  60                 goto out;
  61
  62         dev_dbg(&dev->dev, "%s: #%d %s %s%s %s-> %s\n",
  63                 dev_data->irq_name,
  64                 dev_data->irq,
  65                 pci_is_enabled(dev) ? "on" : "off",
  66                 dev->msi_enabled ? "MSI" : "",
  67                 dev->msix_enabled ? "MSI/X" : "",
  68                 dev_data->isr_on ? "enable" : "disable",
  69                 enable ? "enable" : "disable");
  70
  71         if (enable) {
  72                 /*
  73                  * The MSI or MSI-X should not have an IRQ handler. Otherwise
  74                  * if the guest terminates we BUG_ON in free_msi_irqs.
  75                  */
  76                 if (dev->msi_enabled || dev->msix_enabled)
  77                         goto out;
  78
  79                 rc = request_irq(dev_data->irq,
  80                                 xen_pcibk_guest_interrupt, IRQF_SHARED,
  81                                 dev_data->irq_name, dev);
  82                 if (rc) {
  83                         dev_err(&dev->dev, "%s: failed to install fake IRQ " \
  84                                 "handler for IRQ %d! (rc:%d)\n",
  85                                 dev_data->irq_name, dev_data->irq, rc);
  86                         goto out;
  87                 }
  88         } else {
  89                 free_irq(dev_data->irq, dev);
  90                 dev_data->irq = 0;
  91         }
  92         dev_data->isr_on = enable;
  93         dev_data->ack_intr = enable;
  94 out:
  95         dev_dbg(&dev->dev, "%s: #%d %s %s%s %s\n",
  96                 dev_data->irq_name,
  97                 dev_data->irq,
  98                 pci_is_enabled(dev) ? "on" : "off",
  99                 dev->msi_enabled ? "MSI" : "",
 100                 dev->msix_enabled ? "MSI/X" : "",
 101                 enable ? (dev_data->isr_on ? "enabled" : "failed to enable") :
 102                         (dev_data->isr_on ? "failed to disable" : "disabled"));
 103 }
 104
 105 /* Ensure a device is "turned off" and ready to be exported.
 106  * (Also see xen_pcibk_config_reset to ensure virtual configuration space is
 107  * ready to be re-exported)
 108  */
 109 void xen_pcibk_reset_device(struct pci_dev *dev)
 110 {
 111         u16 cmd;
 112
 113         xen_pcibk_control_isr(dev, 1 /* reset device */);
 114
 115         /* Disable devices (but not bridges) */
 116         if (dev->hdr_type == PCI_HEADER_TYPE_NORMAL) {
 117 #ifdef CONFIG_PCI_MSI
 118                 /* The guest could have been abruptly killed without
 119                  * disabling MSI/MSI-X interrupts.*/
 120                 if (dev->msix_enabled)
 121                         pci_disable_msix(dev);
 122                 if (dev->msi_enabled)
 123                         pci_disable_msi(dev);
 124 #endif
 125                 if (pci_is_enabled(dev))
 126                         pci_disable_device(dev);
 127
 128                 dev->is_busmaster = 0;
 129         } else {
 130                 pci_read_config_word(dev, PCI_COMMAND, &cmd);
 131                 if (cmd & (PCI_COMMAND_INVALIDATE)) {
 132                         cmd &= ~(PCI_COMMAND_INVALIDATE);
 133                         pci_write_config_word(dev, PCI_COMMAND, cmd);
 134
 135                         dev->is_busmaster = 0;
 136                 }
 137         }
 138 }
 139
 140 #ifdef CONFIG_PCI_MSI
 141 static
 142 int xen_pcibk_enable_msi(struct xen_pcibk_device *pdev,
 143                          struct pci_dev *dev, struct xen_pci_op *op)
 144 {
 145         struct xen_pcibk_dev_data *dev_data;
 146         int status;
 147
 148         if (dev->msi_enabled)
 149                 status = -EALREADY;
 150         else if (dev->msix_enabled)
 151                 status = -ENXIO;
 152         else
 153                 status = pci_enable_msi(dev);
 154
 155         if (status) {
 156                 dev_warn_ratelimited(&dev->dev, "error enabling MSI for guest %u: err %d\n",
 157                                      pdev->xdev->otherend_id, status);
 158                 op->value = 0;
 159                 return XEN_PCI_ERR_op_failed;
 160         }
 161
 162         /* The value the guest needs is actually the IDT vector, not
 163          * the local domain's IRQ number. */
 164
 165         op->value = dev->irq ? xen_pirq_from_irq(dev->irq) : 0;
 166
 167         dev_dbg(&dev->dev, "MSI: %d\n", op->value);
 168
 169         dev_data = pci_get_drvdata(dev);
 170         if (dev_data)
 171                 dev_data->ack_intr = 0;
 172
 173         return 0;
 174 }
 175
 176 static
 177 int xen_pcibk_disable_msi(struct xen_pcibk_device *pdev,
 178                           struct pci_dev *dev, struct xen_pci_op *op)
 179 {
 180         if (dev->msi_enabled) {
 181                 struct xen_pcibk_dev_data *dev_data;
 182
 183                 pci_disable_msi(dev);
 184
 185                 dev_data = pci_get_drvdata(dev);
 186                 if (dev_data)
 187                         dev_data->ack_intr = 1;
 188         }
 189         op->value = dev->irq ? xen_pirq_from_irq(dev->irq) : 0;
 190
 191         dev_dbg(&dev->dev, "MSI: %d\n", op->value);
 192
 193         return 0;
 194 }
 195
 196 static
 197 int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev,
 198                           struct pci_dev *dev, struct xen_pci_op *op)
 199 {
 200         struct xen_pcibk_dev_data *dev_data;
 201         int i, result;
 202         struct msix_entry *entries;
 203         u16 cmd;
 204
 205         dev_dbg(&dev->dev, "enable MSI-X\n");
 206
 207         if (op->value > SH_INFO_MAX_VEC)
 208                 return -EINVAL;
 209
 210         if (dev->msix_enabled)
 211                 return -EALREADY;
 212
 213         /*
 214          * PCI_COMMAND_MEMORY must be enabled, otherwise we may not be able
 215          * to access the BARs where the MSI-X entries reside.
 216          * But VF devices are unique in which the PF needs to be checked.
 217          */
 218         pci_read_config_word(pci_physfn(dev), PCI_COMMAND, &cmd);
 219         if (dev->msi_enabled || !(cmd & PCI_COMMAND_MEMORY))
 220                 return -ENXIO;
 221
 222         entries = kmalloc_array(op->value, sizeof(*entries), GFP_KERNEL);
 223         if (entries == NULL)
 224                 return -ENOMEM;
 225
 226         for (i = 0; i < op->value; i++) {
 227                 entries[i].entry = op->msix_entries[i].entry;
 228                 entries[i].vector = op->msix_entries[i].vector;
 229         }
 230
 231         result = pci_enable_msix_exact(dev, entries, op->value);
 232         if (result == 0) {
 233                 for (i = 0; i < op->value; i++) {
 234                         op->msix_entries[i].entry = entries[i].entry;
 235                         if (entries[i].vector) {
 236                                 op->msix_entries[i].vector =
 237                                         xen_pirq_from_irq(entries[i].vector);
 238                                 dev_dbg(&dev->dev, "MSI-X[%d]: %d\n", i,
 239                                         op->msix_entries[i].vector);
 240                         }
 241                 }
 242         } else
 243                 dev_warn_ratelimited(&dev->dev, "error enabling MSI-X for guest %u: err %d!\n",
 244                                      pdev->xdev->otherend_id, result);
 245         kfree(entries);
 246
 247         op->value = result;
 248         dev_data = pci_get_drvdata(dev);
 249         if (dev_data)
 250                 dev_data->ack_intr = 0;
 251
 252         return result > 0 ? 0 : result;
 253 }
 254
 255 static
 256 int xen_pcibk_disable_msix(struct xen_pcibk_device *pdev,
 257                            struct pci_dev *dev, struct xen_pci_op *op)
 258 {
 259         if (dev->msix_enabled) {
 260                 struct xen_pcibk_dev_data *dev_data;
 261
 262                 pci_disable_msix(dev);
 263
 264                 dev_data = pci_get_drvdata(dev);
 265                 if (dev_data)
 266                         dev_data->ack_intr = 1;
 267         }
 268         /*
 269          * SR-IOV devices (which don't have any legacy IRQ) have
 270          * an undefined IRQ value of zero.
 271          */
 272         op->value = dev->irq ? xen_pirq_from_irq(dev->irq) : 0;
 273
 274         dev_dbg(&dev->dev, "MSI-X: %d\n", op->value);
 275
 276         return 0;
 277 }
 278 #endif
 279
 280 static inline bool xen_pcibk_test_op_pending(struct xen_pcibk_device *pdev)
 281 {
 282         return test_bit(_XEN_PCIF_active,
 283                         (unsigned long *)&pdev->sh_info->flags) &&
 284                !test_and_set_bit(_PDEVF_op_active, &pdev->flags);
 285 }
 286
 287 /*
 288 * Now the same evtchn is used for both pcifront conf_read_write request
 289 * as well as pcie aer front end ack. We use a new work_queue to schedule
 290 * xen_pcibk conf_read_write service for avoiding confict with aer_core
 291 * do_recovery job which also use the system default work_queue
 292 */
 293 static void xen_pcibk_test_and_schedule_op(struct xen_pcibk_device *pdev)
 294 {
 295         bool eoi = true;
 296
 297         /* Check that frontend is requesting an operation and that we are not
 298          * already processing a request */
 299         if (xen_pcibk_test_op_pending(pdev)) {
 300                 schedule_work(&pdev->op_work);
 301                 eoi = false;
 302         }
 303         /*_XEN_PCIB_active should have been cleared by pcifront. And also make
 304         sure xen_pcibk is waiting for ack by checking _PCIB_op_pending*/
 305         if (!test_bit(_XEN_PCIB_active, (unsigned long *)&pdev->sh_info->flags)
 306             && test_bit(_PCIB_op_pending, &pdev->flags)) {
 307                 wake_up(&xen_pcibk_aer_wait_queue);
 308                 eoi = false;
 309         }
 310
 311         /* EOI if there was nothing to do. */
 312         if (eoi)
 313                 xen_pcibk_lateeoi(pdev, XEN_EOI_FLAG_SPURIOUS);
 314 }
 315
 316 /* Performing the configuration space reads/writes must not be done in atomic
 317  * context because some of the pci_* functions can sleep (mostly due to ACPI
 318  * use of semaphores). This function is intended to be called from a work
 319  * queue in process context taking a struct xen_pcibk_device as a parameter */
 320
 321 static void xen_pcibk_do_one_op(struct xen_pcibk_device *pdev)
 322 {
 323         struct pci_dev *dev;
 324         struct xen_pcibk_dev_data *dev_data = NULL;
 325         struct xen_pci_op *op = &pdev->op;
 326         int test_intx = 0;
 327 #ifdef CONFIG_PCI_MSI
 328         unsigned int nr = 0;
 329 #endif
 330
 331         *op = pdev->sh_info->op;
 332         barrier();
 333         dev = xen_pcibk_get_pci_dev(pdev, op->domain, op->bus, op->devfn);
 334
 335         if (dev == NULL)
 336                 op->err = XEN_PCI_ERR_dev_not_found;
 337         else {
 338                 dev_data = pci_get_drvdata(dev);
 339                 if (dev_data)
 340                         test_intx = dev_data->enable_intx;
 341                 switch (op->cmd) {
 342                 case XEN_PCI_OP_conf_read:
 343                         op->err = xen_pcibk_config_read(dev,
 344                                   op->offset, op->size, &op->value);
 345                         break;
 346                 case XEN_PCI_OP_conf_write:
 347                         op->err = xen_pcibk_config_write(dev,
 348                                   op->offset, op->size, op->value);
 349                         break;
 350 #ifdef CONFIG_PCI_MSI
 351                 case XEN_PCI_OP_enable_msi:
 352                         op->err = xen_pcibk_enable_msi(pdev, dev, op);
 353                         break;
 354                 case XEN_PCI_OP_disable_msi:
 355                         op->err = xen_pcibk_disable_msi(pdev, dev, op);
 356                         break;
 357                 case XEN_PCI_OP_enable_msix:
 358                         nr = op->value;
 359                         op->err = xen_pcibk_enable_msix(pdev, dev, op);
 360                         break;
 361                 case XEN_PCI_OP_disable_msix:
 362                         op->err = xen_pcibk_disable_msix(pdev, dev, op);
 363                         break;
 364 #endif
 365                 default:
 366                         op->err = XEN_PCI_ERR_not_implemented;
 367                         break;
 368                 }
 369         }
 370         if (!op->err && dev && dev_data) {
 371                 /* Transition detected */
 372                 if ((dev_data->enable_intx != test_intx))
 373                         xen_pcibk_control_isr(dev, 0 /* no reset */);
 374         }
 375         pdev->sh_info->op.err = op->err;
 376         pdev->sh_info->op.value = op->value;
 377 #ifdef CONFIG_PCI_MSI
 378         if (op->cmd == XEN_PCI_OP_enable_msix && op->err == 0) {
 379                 unsigned int i;
 380
 381                 for (i = 0; i < nr; i++)
 382                         pdev->sh_info->op.msix_entries[i].vector =
 383                                 op->msix_entries[i].vector;
 384         }
 385 #endif
 386         /* Tell the driver domain that we're done. */
 387         wmb();
 388         clear_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags);
 389         notify_remote_via_irq(pdev->evtchn_irq);
 390
 391         /* Mark that we're done. */
 392         smp_mb__before_atomic(); /* /after/ clearing PCIF_active */
 393         clear_bit(_PDEVF_op_active, &pdev->flags);
 394         smp_mb__after_atomic(); /* /before/ final check for work */
 395 }
 396
 397 void xen_pcibk_do_op(struct work_struct *data)
 398 {
 399         struct xen_pcibk_device *pdev =
 400                 container_of(data, struct xen_pcibk_device, op_work);
 401
 402         do {
 403                 xen_pcibk_do_one_op(pdev);
 404         } while (xen_pcibk_test_op_pending(pdev));
 405
 406         xen_pcibk_lateeoi(pdev, 0);
 407 }
 408
 409 irqreturn_t xen_pcibk_handle_event(int irq, void *dev_id)
 410 {
 411         struct xen_pcibk_device *pdev = dev_id;
 412         bool eoi;
 413
 414         /* IRQs might come in before pdev->evtchn_irq is written. */
 415         if (unlikely(pdev->evtchn_irq != irq))
 416                 pdev->evtchn_irq = irq;
 417
 418         eoi = test_and_set_bit(_EOI_pending, &pdev->flags);
 419         WARN(eoi, "IRQ while EOI pending\n");
 420
 421         xen_pcibk_test_and_schedule_op(pdev);
 422
 423         return IRQ_HANDLED;
 424 }
 425 static irqreturn_t xen_pcibk_guest_interrupt(int irq, void *dev_id)
 426 {
 427         struct pci_dev *dev = (struct pci_dev *)dev_id;
 428         struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
 429
 430         if (dev_data->isr_on && dev_data->ack_intr) {
 431                 dev_data->handled++;
 432                 if ((dev_data->handled % 1000) == 0) {
 433                         if (xen_test_irq_shared(irq)) {
 434                                 dev_info(&dev->dev, "%s IRQ line is not shared "
 435                                         "with other domains. Turning ISR off\n",
 436                                          dev_data->irq_name);
 437                                 dev_data->ack_intr = 0;
 438                         }
 439                 }
 440                 return IRQ_HANDLED;
 441         }
 442         return IRQ_NONE;
 443 }