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 }
444