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