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