root/drivers/xen/xen-pciback/pciback_ops.c

DEFINITIONS

1. xen_pcibk_control_isr
2. xen_pcibk_reset_device
3. xen_pcibk_enable_msi
4. xen_pcibk_disable_msi
5. xen_pcibk_enable_msix
6. xen_pcibk_disable_msix
7. xen_pcibk_test_and_schedule_op
8. xen_pcibk_do_op
9. xen_pcibk_handle_event
10. xen_pcibk_guest_interrupt

   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 
  10 #include <linux/moduleparam.h>
  11 #include <linux/wait.h>
  12 #include <linux/bitops.h>
  13 #include <xen/events.h>
  14 #include <linux/sched.h>
  15 #include "pciback.h"
  16 
  17 int verbose_request;
  18 module_param(verbose_request, int, 0644);
  19 
  20 static irqreturn_t xen_pcibk_guest_interrupt(int irq, void *dev_id);
  21 
  22 /* Ensure a device is has the fake IRQ handler "turned on/off" and is
  23  * ready to be exported. This MUST be run after xen_pcibk_reset_device
  24  * which does the actual PCI device enable/disable.
  25  */
  26 static void xen_pcibk_control_isr(struct pci_dev *dev, int reset)
  27 {
  28         struct xen_pcibk_dev_data *dev_data;
  29         int rc;
  30         int enable = 0;
  31 
  32         dev_data = pci_get_drvdata(dev);
  33         if (!dev_data)
  34                 return;
  35 
  36         /* We don't deal with bridges */
  37         if (dev->hdr_type != PCI_HEADER_TYPE_NORMAL)
  38                 return;
  39 
  40         if (reset) {
  41                 dev_data->enable_intx = 0;
  42                 dev_data->ack_intr = 0;
  43         }
  44         enable =  dev_data->enable_intx;
  45 
  46         /* Asked to disable, but ISR isn't runnig */
  47         if (!enable && !dev_data->isr_on)
  48                 return;
  49 
  50         /* Squirrel away the IRQs in the dev_data. We need this
  51          * b/c when device transitions to MSI, the dev->irq is
  52          * overwritten with the MSI vector.
  53          */
  54         if (enable)
  55                 dev_data->irq = dev->irq;
  56 
  57         /*
  58          * SR-IOV devices in all use MSI-X and have no legacy
  59          * interrupts, so inhibit creating a fake IRQ handler for them.
  60          */
  61         if (dev_data->irq == 0)
  62                 goto out;
  63 
  64         dev_dbg(&dev->dev, "%s: #%d %s %s%s %s-> %s\n",
  65                 dev_data->irq_name,
  66                 dev_data->irq,
  67                 pci_is_enabled(dev) ? "on" : "off",
  68                 dev->msi_enabled ? "MSI" : "",
  69                 dev->msix_enabled ? "MSI/X" : "",
  70                 dev_data->isr_on ? "enable" : "disable",
  71                 enable ? "enable" : "disable");
  72 
  73         if (enable) {
  74                 /*
  75                  * The MSI or MSI-X should not have an IRQ handler. Otherwise
  76                  * if the guest terminates we BUG_ON in free_msi_irqs.
  77                  */
  78                 if (dev->msi_enabled || dev->msix_enabled)
  79                         goto out;
  80 
  81                 rc = request_irq(dev_data->irq,
  82                                 xen_pcibk_guest_interrupt, IRQF_SHARED,
  83                                 dev_data->irq_name, dev);
  84                 if (rc) {
  85                         dev_err(&dev->dev, "%s: failed to install fake IRQ " \
  86                                 "handler for IRQ %d! (rc:%d)\n",
  87                                 dev_data->irq_name, dev_data->irq, rc);
  88                         goto out;
  89                 }
  90         } else {
  91                 free_irq(dev_data->irq, dev);
  92                 dev_data->irq = 0;
  93         }
  94         dev_data->isr_on = enable;
  95         dev_data->ack_intr = enable;
  96 out:
  97         dev_dbg(&dev->dev, "%s: #%d %s %s%s %s\n",
  98                 dev_data->irq_name,
  99                 dev_data->irq,
 100                 pci_is_enabled(dev) ? "on" : "off",
 101                 dev->msi_enabled ? "MSI" : "",
 102                 dev->msix_enabled ? "MSI/X" : "",
 103                 enable ? (dev_data->isr_on ? "enabled" : "failed to enable") :
 104                         (dev_data->isr_on ? "failed to disable" : "disabled"));
 105 }
 106 
 107 /* Ensure a device is "turned off" and ready to be exported.
 108  * (Also see xen_pcibk_config_reset to ensure virtual configuration space is
 109  * ready to be re-exported)
 110  */
 111 void xen_pcibk_reset_device(struct pci_dev *dev)
 112 {
 113         u16 cmd;
 114 
 115         xen_pcibk_control_isr(dev, 1 /* reset device */);
 116 
 117         /* Disable devices (but not bridges) */
 118         if (dev->hdr_type == PCI_HEADER_TYPE_NORMAL) {
 119 #ifdef CONFIG_PCI_MSI
 120                 /* The guest could have been abruptly killed without
 121                  * disabling MSI/MSI-X interrupts.*/
 122                 if (dev->msix_enabled)
 123                         pci_disable_msix(dev);
 124                 if (dev->msi_enabled)
 125                         pci_disable_msi(dev);
 126 #endif
 127                 if (pci_is_enabled(dev))
 128                         pci_disable_device(dev);
 129 
 130                 dev->is_busmaster = 0;
 131         } else {
 132                 pci_read_config_word(dev, PCI_COMMAND, &cmd);
 133                 if (cmd & (PCI_COMMAND_INVALIDATE)) {
 134                         cmd &= ~(PCI_COMMAND_INVALIDATE);
 135                         pci_write_config_word(dev, PCI_COMMAND, cmd);
 136 
 137                         dev->is_busmaster = 0;
 138                 }
 139         }
 140 }
 141 
 142 #ifdef CONFIG_PCI_MSI
 143 static
 144 int xen_pcibk_enable_msi(struct xen_pcibk_device *pdev,
 145                          struct pci_dev *dev, struct xen_pci_op *op)
 146 {
 147         struct xen_pcibk_dev_data *dev_data;
 148         int status;
 149 
 150         if (unlikely(verbose_request))
 151                 printk(KERN_DEBUG DRV_NAME ": %s: enable MSI\n", pci_name(dev));
 152 
 153         if (dev->msi_enabled)
 154                 status = -EALREADY;
 155         else if (dev->msix_enabled)
 156                 status = -ENXIO;
 157         else
 158                 status = pci_enable_msi(dev);
 159 
 160         if (status) {
 161                 pr_warn_ratelimited("%s: error enabling MSI for guest %u: err %d\n",
 162                                     pci_name(dev), pdev->xdev->otherend_id,
 163                                     status);
 164                 op->value = 0;
 165                 return XEN_PCI_ERR_op_failed;
 166         }
 167 
 168         /* The value the guest needs is actually the IDT vector, not the
 169          * the local domain's IRQ number. */
 170 
 171         op->value = dev->irq ? xen_pirq_from_irq(dev->irq) : 0;
 172         if (unlikely(verbose_request))
 173                 printk(KERN_DEBUG DRV_NAME ": %s: MSI: %d\n", pci_name(dev),
 174                         op->value);
 175 
 176         dev_data = pci_get_drvdata(dev);
 177         if (dev_data)
 178                 dev_data->ack_intr = 0;
 179 
 180         return 0;
 181 }
 182 
 183 static
 184 int xen_pcibk_disable_msi(struct xen_pcibk_device *pdev,
 185                           struct pci_dev *dev, struct xen_pci_op *op)
 186 {
 187         if (unlikely(verbose_request))
 188                 printk(KERN_DEBUG DRV_NAME ": %s: disable MSI\n",
 189                        pci_name(dev));
 190 
 191         if (dev->msi_enabled) {
 192                 struct xen_pcibk_dev_data *dev_data;
 193 
 194                 pci_disable_msi(dev);
 195 
 196                 dev_data = pci_get_drvdata(dev);
 197                 if (dev_data)
 198                         dev_data->ack_intr = 1;
 199         }
 200         op->value = dev->irq ? xen_pirq_from_irq(dev->irq) : 0;
 201         if (unlikely(verbose_request))
 202                 printk(KERN_DEBUG DRV_NAME ": %s: MSI: %d\n", pci_name(dev),
 203                         op->value);
 204         return 0;
 205 }
 206 
 207 static
 208 int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev,
 209                           struct pci_dev *dev, struct xen_pci_op *op)
 210 {
 211         struct xen_pcibk_dev_data *dev_data;
 212         int i, result;
 213         struct msix_entry *entries;
 214         u16 cmd;
 215 
 216         if (unlikely(verbose_request))
 217                 printk(KERN_DEBUG DRV_NAME ": %s: enable MSI-X\n",
 218                        pci_name(dev));
 219 
 220         if (op->value > SH_INFO_MAX_VEC)
 221                 return -EINVAL;
 222 
 223         if (dev->msix_enabled)
 224                 return -EALREADY;
 225 
 226         /*
 227          * PCI_COMMAND_MEMORY must be enabled, otherwise we may not be able
 228          * to access the BARs where the MSI-X entries reside.
 229          * But VF devices are unique in which the PF needs to be checked.
 230          */
 231         pci_read_config_word(pci_physfn(dev), PCI_COMMAND, &cmd);
 232         if (dev->msi_enabled || !(cmd & PCI_COMMAND_MEMORY))
 233                 return -ENXIO;
 234 
 235         entries = kmalloc_array(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                 schedule_work(&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 #ifdef CONFIG_PCI_MSI
 336         unsigned int nr = 0;
 337 #endif
 338 
 339         *op = pdev->sh_info->op;
 340         barrier();
 341         dev = xen_pcibk_get_pci_dev(pdev, op->domain, op->bus, op->devfn);
 342 
 343         if (dev == NULL)
 344                 op->err = XEN_PCI_ERR_dev_not_found;
 345         else {
 346                 dev_data = pci_get_drvdata(dev);
 347                 if (dev_data)
 348                         test_intx = dev_data->enable_intx;
 349                 switch (op->cmd) {
 350                 case XEN_PCI_OP_conf_read:
 351                         op->err = xen_pcibk_config_read(dev,
 352                                   op->offset, op->size, &op->value);
 353                         break;
 354                 case XEN_PCI_OP_conf_write:
 355                         op->err = xen_pcibk_config_write(dev,
 356                                   op->offset, op->size, op->value);
 357                         break;
 358 #ifdef CONFIG_PCI_MSI
 359                 case XEN_PCI_OP_enable_msi:
 360                         op->err = xen_pcibk_enable_msi(pdev, dev, op);
 361                         break;
 362                 case XEN_PCI_OP_disable_msi:
 363                         op->err = xen_pcibk_disable_msi(pdev, dev, op);
 364                         break;
 365                 case XEN_PCI_OP_enable_msix:
 366                         nr = op->value;
 367                         op->err = xen_pcibk_enable_msix(pdev, dev, op);
 368                         break;
 369                 case XEN_PCI_OP_disable_msix:
 370                         op->err = xen_pcibk_disable_msix(pdev, dev, op);
 371                         break;
 372 #endif
 373                 default:
 374                         op->err = XEN_PCI_ERR_not_implemented;
 375                         break;
 376                 }
 377         }
 378         if (!op->err && dev && dev_data) {
 379                 /* Transition detected */
 380                 if ((dev_data->enable_intx != test_intx))
 381                         xen_pcibk_control_isr(dev, 0 /* no reset */);
 382         }
 383         pdev->sh_info->op.err = op->err;
 384         pdev->sh_info->op.value = op->value;
 385 #ifdef CONFIG_PCI_MSI
 386         if (op->cmd == XEN_PCI_OP_enable_msix && op->err == 0) {
 387                 unsigned int i;
 388 
 389                 for (i = 0; i < nr; i++)
 390                         pdev->sh_info->op.msix_entries[i].vector =
 391                                 op->msix_entries[i].vector;
 392         }
 393 #endif
 394         /* Tell the driver domain that we're done. */
 395         wmb();
 396         clear_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags);
 397         notify_remote_via_irq(pdev->evtchn_irq);
 398 
 399         /* Mark that we're done. */
 400         smp_mb__before_atomic(); /* /after/ clearing PCIF_active */
 401         clear_bit(_PDEVF_op_active, &pdev->flags);
 402         smp_mb__after_atomic(); /* /before/ final check for work */
 403 
 404         /* Check to see if the driver domain tried to start another request in
 405          * between clearing _XEN_PCIF_active and clearing _PDEVF_op_active.
 406         */
 407         xen_pcibk_test_and_schedule_op(pdev);
 408 }
 409 
 410 irqreturn_t xen_pcibk_handle_event(int irq, void *dev_id)
 411 {
 412         struct xen_pcibk_device *pdev = dev_id;
 413 
 414         xen_pcibk_test_and_schedule_op(pdev);
 415 
 416         return IRQ_HANDLED;
 417 }
 418 static irqreturn_t xen_pcibk_guest_interrupt(int irq, void *dev_id)
 419 {
 420         struct pci_dev *dev = (struct pci_dev *)dev_id;
 421         struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
 422 
 423         if (dev_data->isr_on && dev_data->ack_intr) {
 424                 dev_data->handled++;
 425                 if ((dev_data->handled % 1000) == 0) {
 426                         if (xen_test_irq_shared(irq)) {
 427                                 pr_info("%s IRQ line is not shared "
 428                                         "with other domains. Turning ISR off\n",
 429                                          dev_data->irq_name);
 430                                 dev_data->ack_intr = 0;
 431                         }
 432                 }
 433                 return IRQ_HANDLED;
 434         }
 435         return IRQ_NONE;
 436 }