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 }
439