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
18static 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 */
24static 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(pdev: 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(irq: dev_data->irq,
80 handler: xen_pcibk_guest_interrupt, IRQF_SHARED,
81 name: 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;
94out:
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 */
109void xen_pcibk_reset_device(struct pci_dev *dev)
110{
111 u16 cmd;
112
113 xen_pcibk_control_isr(dev, reset: 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(pdev: dev))
126 pci_disable_device(dev);
127
128 dev->is_busmaster = 0;
129 } else {
130 pci_read_config_word(dev, PCI_COMMAND, val: &cmd);
131 if (cmd & (PCI_COMMAND_INVALIDATE)) {
132 cmd &= ~(PCI_COMMAND_INVALIDATE);
133 pci_write_config_word(dev, PCI_COMMAND, val: cmd);
134
135 dev->is_busmaster = 0;
136 }
137 }
138}
139
140#ifdef CONFIG_PCI_MSI
141static
142int 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(irq: dev->irq) : 0;
166
167 dev_dbg(&dev->dev, "MSI: %d\n", op->value);
168
169 dev_data = pci_get_drvdata(pdev: dev);
170 if (dev_data)
171 dev_data->ack_intr = 0;
172
173 return 0;
174}
175
176static
177int 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(pdev: dev);
186 if (dev_data)
187 dev_data->ack_intr = 1;
188 }
189 op->value = dev->irq ? xen_pirq_from_irq(irq: dev->irq) : 0;
190
191 dev_dbg(&dev->dev, "MSI: %d\n", op->value);
192
193 return 0;
194}
195
196static
197int 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(dev: pci_physfn(dev), PCI_COMMAND, val: &cmd);
219 if (dev->msi_enabled || !(cmd & PCI_COMMAND_MEMORY))
220 return -ENXIO;
221
222 entries = kmalloc_array(n: op->value, size: 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, nvec: 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(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(objp: entries);
246
247 op->value = result;
248 dev_data = pci_get_drvdata(pdev: dev);
249 if (dev_data)
250 dev_data->ack_intr = 0;
251
252 return result > 0 ? 0 : result;
253}
254
255static
256int 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(pdev: 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(irq: dev->irq) : 0;
273
274 dev_dbg(&dev->dev, "MSI-X: %d\n", op->value);
275
276 return 0;
277}
278#endif
279
280static 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, addr: &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*/
293static 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(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
321static 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, domain: op->domain, bus: op->bus, devfn: op->devfn);
334
335 if (dev == NULL)
336 op->err = XEN_PCI_ERR_dev_not_found;
337 else {
338 dev_data = pci_get_drvdata(pdev: 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 offset: op->offset, size: op->size, ret_val: &op->value);
345 break;
346 case XEN_PCI_OP_conf_write:
347 op->err = xen_pcibk_config_write(dev,
348 offset: op->offset, size: op->size, value: 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, reset: 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, addr: (unsigned long *)&pdev->sh_info->flags);
389 notify_remote_via_irq(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, addr: &pdev->flags);
394 smp_mb__after_atomic(); /* /before/ final check for work */
395}
396
397void 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, eoi_flag: 0);
407}
408
409irqreturn_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, addr: &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}
425static 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(pdev: 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}
444

source code of linux/drivers/xen/xen-pciback/pciback_ops.c