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
  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                 pci_write_config_word(dev, PCI_COMMAND, 0);
 131
 132                 dev->is_busmaster = 0;
 133         } else {
 134                 pci_read_config_word(dev, PCI_COMMAND, &cmd);
 135                 if (cmd & (PCI_COMMAND_INVALIDATE)) {
 136                         cmd &= ~(PCI_COMMAND_INVALIDATE);
 137                         pci_write_config_word(dev, PCI_COMMAND, cmd);
 138
 139                         dev->is_busmaster = 0;
 140                 }
 141         }
 142 }
 143
 144 #ifdef CONFIG_PCI_MSI
 145 static
 146 int xen_pcibk_enable_msi(struct xen_pcibk_device *pdev,
 147                          struct pci_dev *dev, struct xen_pci_op *op)
 148 {
 149         struct xen_pcibk_dev_data *dev_data;
 150         int status;
 151
 152         if (unlikely(verbose_request))
 153                 printk(KERN_DEBUG DRV_NAME ": %s: enable MSI\n", pci_name(dev));
 154
 155         if (dev->msi_enabled)
 156                 status = -EALREADY;
 157         else if (dev->msix_enabled)
 158                 status = -ENXIO;
 159         else
 160                 status = pci_enable_msi(dev);
 161
 162         if (status) {
 163                 pr_warn_ratelimited("%s: error enabling MSI for guest %u: err %d\n",
 164                                     pci_name(dev), pdev->xdev->otherend_id,
 165                                     status);
 166                 op->value = 0;
 167                 return XEN_PCI_ERR_op_failed;
 168         }
 169
 170         /* The value the guest needs is actually the IDT vector, not the
 171          * the local domain's IRQ number. */
 172
 173         op->value = dev->irq ? xen_pirq_from_irq(dev->irq) : 0;
 174         if (unlikely(verbose_request))
 175                 printk(KERN_DEBUG DRV_NAME ": %s: MSI: %d\n", pci_name(dev),
 176                         op->value);
 177
 178         dev_data = pci_get_drvdata(dev);
 179         if (dev_data)
 180                 dev_data->ack_intr = 0;
 181
 182         return 0;
 183 }
 184
 185 static
 186 int xen_pcibk_disable_msi(struct xen_pcibk_device *pdev,
 187                           struct pci_dev *dev, struct xen_pci_op *op)
 188 {
 189         if (unlikely(verbose_request))
 190                 printk(KERN_DEBUG DRV_NAME ": %s: disable MSI\n",
 191                        pci_name(dev));
 192
 193         if (dev->msi_enabled) {
 194                 struct xen_pcibk_dev_data *dev_data;
 195
 196                 pci_disable_msi(dev);
 197
 198                 dev_data = pci_get_drvdata(dev);
 199                 if (dev_data)
 200                         dev_data->ack_intr = 1;
 201         }
 202         op->value = dev->irq ? xen_pirq_from_irq(dev->irq) : 0;
 203         if (unlikely(verbose_request))
 204                 printk(KERN_DEBUG DRV_NAME ": %s: MSI: %d\n", pci_name(dev),
 205                         op->value);
 206         return 0;
 207 }
 208
 209 static
 210 int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev,
 211                           struct pci_dev *dev, struct xen_pci_op *op)
 212 {
 213         struct xen_pcibk_dev_data *dev_data;
 214         int i, result;
 215         struct msix_entry *entries;
 216         u16 cmd;
 217
 218         if (unlikely(verbose_request))
 219                 printk(KERN_DEBUG DRV_NAME ": %s: enable MSI-X\n",
 220                        pci_name(dev));
 221
 222         if (op->value > SH_INFO_MAX_VEC)
 223                 return -EINVAL;
 224
 225         if (dev->msix_enabled)
 226                 return -EALREADY;
 227
 228         /*
 229          * PCI_COMMAND_MEMORY must be enabled, otherwise we may not be able
 230          * to access the BARs where the MSI-X entries reside.
 231          * But VF devices are unique in which the PF needs to be checked.
 232          */
 233         pci_read_config_word(pci_physfn(dev), PCI_COMMAND, &cmd);
 234         if (dev->msi_enabled || !(cmd & PCI_COMMAND_MEMORY))
 235                 return -ENXIO;
 236
 237         entries = kmalloc(op->value * sizeof(*entries), GFP_KERNEL);
 238         if (entries == NULL)
 239                 return -ENOMEM;
 240
 241         for (i = 0; i < op->value; i++) {
 242                 entries[i].entry = op->msix_entries[i].entry;
 243                 entries[i].vector = op->msix_entries[i].vector;
 244         }
 245
 246         result = pci_enable_msix_exact(dev, entries, op->value);
 247         if (result == 0) {
 248                 for (i = 0; i < op->value; i++) {
 249                         op->msix_entries[i].entry = entries[i].entry;
 250                         if (entries[i].vector) {
 251                                 op->msix_entries[i].vector =
 252                                         xen_pirq_from_irq(entries[i].vector);
 253                                 if (unlikely(verbose_request))
 254                                         printk(KERN_DEBUG DRV_NAME ": %s: " \
 255                                                 "MSI-X[%d]: %d\n",
 256                                                 pci_name(dev), i,
 257                                                 op->msix_entries[i].vector);
 258                         }
 259                 }
 260         } else
 261                 pr_warn_ratelimited("%s: error enabling MSI-X for guest %u: err %d!\n",
 262                                     pci_name(dev), pdev->xdev->otherend_id,
 263                                     result);
 264         kfree(entries);
 265
 266         op->value = result;
 267         dev_data = pci_get_drvdata(dev);
 268         if (dev_data)
 269                 dev_data->ack_intr = 0;
 270
 271         return result > 0 ? 0 : result;
 272 }
 273
 274 static
 275 int xen_pcibk_disable_msix(struct xen_pcibk_device *pdev,
 276                            struct pci_dev *dev, struct xen_pci_op *op)
 277 {
 278         if (unlikely(verbose_request))
 279                 printk(KERN_DEBUG DRV_NAME ": %s: disable MSI-X\n",
 280                         pci_name(dev));
 281
 282         if (dev->msix_enabled) {
 283                 struct xen_pcibk_dev_data *dev_data;
 284
 285                 pci_disable_msix(dev);
 286
 287                 dev_data = pci_get_drvdata(dev);
 288                 if (dev_data)
 289                         dev_data->ack_intr = 1;
 290         }
 291         /*
 292          * SR-IOV devices (which don't have any legacy IRQ) have
 293          * an undefined IRQ value of zero.
 294          */
 295         op->value = dev->irq ? xen_pirq_from_irq(dev->irq) : 0;
 296         if (unlikely(verbose_request))
 297                 printk(KERN_DEBUG DRV_NAME ": %s: MSI-X: %d\n",
 298                        pci_name(dev), op->value);
 299         return 0;
 300 }
 301 #endif
 302 /*
 303 * Now the same evtchn is used for both pcifront conf_read_write request
 304 * as well as pcie aer front end ack. We use a new work_queue to schedule
 305 * xen_pcibk conf_read_write service for avoiding confict with aer_core
 306 * do_recovery job which also use the system default work_queue
 307 */
 308 void xen_pcibk_test_and_schedule_op(struct xen_pcibk_device *pdev)
 309 {
 310         /* Check that frontend is requesting an operation and that we are not
 311          * already processing a request */
 312         if (test_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags)
 313             && !test_and_set_bit(_PDEVF_op_active, &pdev->flags)) {
 314                 schedule_work(&pdev->op_work);
 315         }
 316         /*_XEN_PCIB_active should have been cleared by pcifront. And also make
 317         sure xen_pcibk is waiting for ack by checking _PCIB_op_pending*/
 318         if (!test_bit(_XEN_PCIB_active, (unsigned long *)&pdev->sh_info->flags)
 319             && test_bit(_PCIB_op_pending, &pdev->flags)) {
 320                 wake_up(&xen_pcibk_aer_wait_queue);
 321         }
 322 }
 323
 324 /* Performing the configuration space reads/writes must not be done in atomic
 325  * context because some of the pci_* functions can sleep (mostly due to ACPI
 326  * use of semaphores). This function is intended to be called from a work
 327  * queue in process context taking a struct xen_pcibk_device as a parameter */
 328
 329 void xen_pcibk_do_op(struct work_struct *data)
 330 {
 331         struct xen_pcibk_device *pdev =
 332                 container_of(data, struct xen_pcibk_device, op_work);
 333         struct pci_dev *dev;
 334         struct xen_pcibk_dev_data *dev_data = NULL;
 335         struct xen_pci_op *op = &pdev->op;
 336         int test_intx = 0;
 337 #ifdef CONFIG_PCI_MSI
 338         unsigned int nr = 0;
 339 #endif
 340
 341         *op = pdev->sh_info->op;
 342         barrier();
 343         dev = xen_pcibk_get_pci_dev(pdev, op->domain, op->bus, op->devfn);
 344
 345         if (dev == NULL)
 346                 op->err = XEN_PCI_ERR_dev_not_found;
 347         else {
 348                 dev_data = pci_get_drvdata(dev);
 349                 if (dev_data)
 350                         test_intx = dev_data->enable_intx;
 351                 switch (op->cmd) {
 352                 case XEN_PCI_OP_conf_read:
 353                         op->err = xen_pcibk_config_read(dev,
 354                                   op->offset, op->size, &op->value);
 355                         break;
 356                 case XEN_PCI_OP_conf_write:
 357                         op->err = xen_pcibk_config_write(dev,
 358                                   op->offset, op->size, op->value);
 359                         break;
 360 #ifdef CONFIG_PCI_MSI
 361                 case XEN_PCI_OP_enable_msi:
 362                         op->err = xen_pcibk_enable_msi(pdev, dev, op);
 363                         break;
 364                 case XEN_PCI_OP_disable_msi:
 365                         op->err = xen_pcibk_disable_msi(pdev, dev, op);
 366                         break;
 367                 case XEN_PCI_OP_enable_msix:
 368                         nr = op->value;
 369                         op->err = xen_pcibk_enable_msix(pdev, dev, op);
 370                         break;
 371                 case XEN_PCI_OP_disable_msix:
 372                         op->err = xen_pcibk_disable_msix(pdev, dev, op);
 373                         break;
 374 #endif
 375                 default:
 376                         op->err = XEN_PCI_ERR_not_implemented;
 377                         break;
 378                 }
 379         }
 380         if (!op->err && dev && dev_data) {
 381                 /* Transition detected */
 382                 if ((dev_data->enable_intx != test_intx))
 383                         xen_pcibk_control_isr(dev, 0 /* no reset */);
 384         }
 385         pdev->sh_info->op.err = op->err;
 386         pdev->sh_info->op.value = op->value;
 387 #ifdef CONFIG_PCI_MSI
 388         if (op->cmd == XEN_PCI_OP_enable_msix && op->err == 0) {
 389                 unsigned int i;
 390
 391                 for (i = 0; i < nr; i++)
 392                         pdev->sh_info->op.msix_entries[i].vector =
 393                                 op->msix_entries[i].vector;
 394         }
 395 #endif
 396         /* Tell the driver domain that we're done. */
 397         wmb();
 398         clear_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags);
 399         notify_remote_via_irq(pdev->evtchn_irq);
 400
 401         /* Mark that we're done. */
 402         smp_mb__before_atomic(); /* /after/ clearing PCIF_active */
 403         clear_bit(_PDEVF_op_active, &pdev->flags);
 404         smp_mb__after_atomic(); /* /before/ final check for work */
 405
 406         /* Check to see if the driver domain tried to start another request in
 407          * between clearing _XEN_PCIF_active and clearing _PDEVF_op_active.
 408         */
 409         xen_pcibk_test_and_schedule_op(pdev);
 410 }
 411
 412 irqreturn_t xen_pcibk_handle_event(int irq, void *dev_id)
 413 {
 414         struct xen_pcibk_device *pdev = dev_id;
 415
 416         xen_pcibk_test_and_schedule_op(pdev);
 417
 418         return IRQ_HANDLED;
 419 }
 420 static irqreturn_t xen_pcibk_guest_interrupt(int irq, void *dev_id)
 421 {
 422         struct pci_dev *dev = (struct pci_dev *)dev_id;
 423         struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
 424
 425         if (dev_data->isr_on && dev_data->ack_intr) {
 426                 dev_data->handled++;
 427                 if ((dev_data->handled % 1000) == 0) {
 428                         if (xen_test_irq_shared(irq)) {
 429                                 pr_info("%s IRQ line is not shared "
 430                                         "with other domains. Turning ISR off\n",
 431                                          dev_data->irq_name);
 432                                 dev_data->ack_intr = 0;
 433                         }
 434                 }
 435                 return IRQ_HANDLED;
 436         }
 437         return IRQ_NONE;
 438 }