1 /*
2  * PCI Backend Operations - respond to PCI requests from Frontend
3  *
4  *   Author: Ryan Wilson <hap9@epoch.ncsc.mil>
5  */
6 
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8 
9 #include <linux/moduleparam.h>
10 #include <linux/wait.h>
11 #include <linux/bitops.h>
12 #include <xen/events.h>
13 #include <linux/sched.h>
14 #include "pciback.h"
15 
16 int verbose_request;
17 module_param(verbose_request, int, 0644);
18 
19 static irqreturn_t xen_pcibk_guest_interrupt(int irq, void *dev_id);
20 
21 /* Ensure a device is has the fake IRQ handler "turned on/off" and is
22  * ready to be exported. This MUST be run after xen_pcibk_reset_device
23  * which does the actual PCI device enable/disable.
24  */
25 static void xen_pcibk_control_isr(struct pci_dev *dev, int reset)
26 {
27 	struct xen_pcibk_dev_data *dev_data;
28 	int rc;
29 	int enable = 0;
30 
31 	dev_data = pci_get_drvdata(dev);
32 	if (!dev_data)
33 		return;
34 
35 	/* We don't deal with bridges */
36 	if (dev->hdr_type != PCI_HEADER_TYPE_NORMAL)
37 		return;
38 
39 	if (reset) {
40 		dev_data->enable_intx = 0;
41 		dev_data->ack_intr = 0;
42 	}
43 	enable =  dev_data->enable_intx;
44 
45 	/* Asked to disable, but ISR isn't runnig */
46 	if (!enable && !dev_data->isr_on)
47 		return;
48 
49 	/* Squirrel away the IRQs in the dev_data. We need this
50 	 * b/c when device transitions to MSI, the dev->irq is
51 	 * overwritten with the MSI vector.
52 	 */
53 	if (enable)
54 		dev_data->irq = dev->irq;
55 
56 	/*
57 	 * SR-IOV devices in all use MSI-X and have no legacy
58 	 * interrupts, so inhibit creating a fake IRQ handler for them.
59 	 */
60 	if (dev_data->irq == 0)
61 		goto out;
62 
63 	dev_dbg(&dev->dev, "%s: #%d %s %s%s %s-> %s\n",
64 		dev_data->irq_name,
65 		dev_data->irq,
66 		pci_is_enabled(dev) ? "on" : "off",
67 		dev->msi_enabled ? "MSI" : "",
68 		dev->msix_enabled ? "MSI/X" : "",
69 		dev_data->isr_on ? "enable" : "disable",
70 		enable ? "enable" : "disable");
71 
72 	if (enable) {
73 		/*
74 		 * The MSI or MSI-X should not have an IRQ handler. Otherwise
75 		 * if the guest terminates we BUG_ON in free_msi_irqs.
76 		 */
77 		if (dev->msi_enabled || dev->msix_enabled)
78 			goto out;
79 
80 		rc = request_irq(dev_data->irq,
81 				xen_pcibk_guest_interrupt, IRQF_SHARED,
82 				dev_data->irq_name, dev);
83 		if (rc) {
84 			dev_err(&dev->dev, "%s: failed to install fake IRQ " \
85 				"handler for IRQ %d! (rc:%d)\n",
86 				dev_data->irq_name, dev_data->irq, rc);
87 			goto out;
88 		}
89 	} else {
90 		free_irq(dev_data->irq, dev);
91 		dev_data->irq = 0;
92 	}
93 	dev_data->isr_on = enable;
94 	dev_data->ack_intr = enable;
95 out:
96 	dev_dbg(&dev->dev, "%s: #%d %s %s%s %s\n",
97 		dev_data->irq_name,
98 		dev_data->irq,
99 		pci_is_enabled(dev) ? "on" : "off",
100 		dev->msi_enabled ? "MSI" : "",
101 		dev->msix_enabled ? "MSI/X" : "",
102 		enable ? (dev_data->isr_on ? "enabled" : "failed to enable") :
103 			(dev_data->isr_on ? "failed to disable" : "disabled"));
104 }
105 
106 /* Ensure a device is "turned off" and ready to be exported.
107  * (Also see xen_pcibk_config_reset to ensure virtual configuration space is
108  * ready to be re-exported)
109  */
110 void xen_pcibk_reset_device(struct pci_dev *dev)
111 {
112 	u16 cmd;
113 
114 	xen_pcibk_control_isr(dev, 1 /* reset device */);
115 
116 	/* Disable devices (but not bridges) */
117 	if (dev->hdr_type == PCI_HEADER_TYPE_NORMAL) {
118 #ifdef CONFIG_PCI_MSI
119 		/* The guest could have been abruptly killed without
120 		 * disabling MSI/MSI-X interrupts.*/
121 		if (dev->msix_enabled)
122 			pci_disable_msix(dev);
123 		if (dev->msi_enabled)
124 			pci_disable_msi(dev);
125 #endif
126 		if (pci_is_enabled(dev))
127 			pci_disable_device(dev);
128 
129 		pci_write_config_word(dev, PCI_COMMAND, 0);
130 
131 		dev->is_busmaster = 0;
132 	} else {
133 		pci_read_config_word(dev, PCI_COMMAND, &cmd);
134 		if (cmd & (PCI_COMMAND_INVALIDATE)) {
135 			cmd &= ~(PCI_COMMAND_INVALIDATE);
136 			pci_write_config_word(dev, PCI_COMMAND, cmd);
137 
138 			dev->is_busmaster = 0;
139 		}
140 	}
141 }
142 
143 #ifdef CONFIG_PCI_MSI
144 static
145 int xen_pcibk_enable_msi(struct xen_pcibk_device *pdev,
146 			 struct pci_dev *dev, struct xen_pci_op *op)
147 {
148 	struct xen_pcibk_dev_data *dev_data;
149 	int status;
150 
151 	if (unlikely(verbose_request))
152 		printk(KERN_DEBUG DRV_NAME ": %s: enable MSI\n", pci_name(dev));
153 
154 	if (dev->msi_enabled)
155 		status = -EALREADY;
156 	else if (dev->msix_enabled)
157 		status = -ENXIO;
158 	else
159 		status = pci_enable_msi(dev);
160 
161 	if (status) {
162 		pr_warn_ratelimited("%s: error enabling MSI for guest %u: err %d\n",
163 				    pci_name(dev), pdev->xdev->otherend_id,
164 				    status);
165 		op->value = 0;
166 		return XEN_PCI_ERR_op_failed;
167 	}
168 
169 	/* The value the guest needs is actually the IDT vector, not the
170 	 * the local domain's IRQ number. */
171 
172 	op->value = dev->irq ? xen_pirq_from_irq(dev->irq) : 0;
173 	if (unlikely(verbose_request))
174 		printk(KERN_DEBUG DRV_NAME ": %s: MSI: %d\n", pci_name(dev),
175 			op->value);
176 
177 	dev_data = pci_get_drvdata(dev);
178 	if (dev_data)
179 		dev_data->ack_intr = 0;
180 
181 	return 0;
182 }
183 
184 static
185 int xen_pcibk_disable_msi(struct xen_pcibk_device *pdev,
186 			  struct pci_dev *dev, struct xen_pci_op *op)
187 {
188 	if (unlikely(verbose_request))
189 		printk(KERN_DEBUG DRV_NAME ": %s: disable MSI\n",
190 		       pci_name(dev));
191 
192 	if (dev->msi_enabled) {
193 		struct xen_pcibk_dev_data *dev_data;
194 
195 		pci_disable_msi(dev);
196 
197 		dev_data = pci_get_drvdata(dev);
198 		if (dev_data)
199 			dev_data->ack_intr = 1;
200 	}
201 	op->value = dev->irq ? xen_pirq_from_irq(dev->irq) : 0;
202 	if (unlikely(verbose_request))
203 		printk(KERN_DEBUG DRV_NAME ": %s: MSI: %d\n", pci_name(dev),
204 			op->value);
205 	return 0;
206 }
207 
208 static
209 int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev,
210 			  struct pci_dev *dev, struct xen_pci_op *op)
211 {
212 	struct xen_pcibk_dev_data *dev_data;
213 	int i, result;
214 	struct msix_entry *entries;
215 	u16 cmd;
216 
217 	if (unlikely(verbose_request))
218 		printk(KERN_DEBUG DRV_NAME ": %s: enable MSI-X\n",
219 		       pci_name(dev));
220 
221 	if (op->value > SH_INFO_MAX_VEC)
222 		return -EINVAL;
223 
224 	if (dev->msix_enabled)
225 		return -EALREADY;
226 
227 	/*
228 	 * PCI_COMMAND_MEMORY must be enabled, otherwise we may not be able
229 	 * to access the BARs where the MSI-X entries reside.
230 	 * But VF devices are unique in which the PF needs to be checked.
231 	 */
232 	pci_read_config_word(pci_physfn(dev), PCI_COMMAND, &cmd);
233 	if (dev->msi_enabled || !(cmd & PCI_COMMAND_MEMORY))
234 		return -ENXIO;
235 
236 	entries = kmalloc(op->value * sizeof(*entries), GFP_KERNEL);
237 	if (entries == NULL)
238 		return -ENOMEM;
239 
240 	for (i = 0; i < op->value; i++) {
241 		entries[i].entry = op->msix_entries[i].entry;
242 		entries[i].vector = op->msix_entries[i].vector;
243 	}
244 
245 	result = pci_enable_msix_exact(dev, entries, op->value);
246 	if (result == 0) {
247 		for (i = 0; i < op->value; i++) {
248 			op->msix_entries[i].entry = entries[i].entry;
249 			if (entries[i].vector) {
250 				op->msix_entries[i].vector =
251 					xen_pirq_from_irq(entries[i].vector);
252 				if (unlikely(verbose_request))
253 					printk(KERN_DEBUG DRV_NAME ": %s: " \
254 						"MSI-X[%d]: %d\n",
255 						pci_name(dev), i,
256 						op->msix_entries[i].vector);
257 			}
258 		}
259 	} else
260 		pr_warn_ratelimited("%s: error enabling MSI-X for guest %u: err %d!\n",
261 				    pci_name(dev), pdev->xdev->otherend_id,
262 				    result);
263 	kfree(entries);
264 
265 	op->value = result;
266 	dev_data = pci_get_drvdata(dev);
267 	if (dev_data)
268 		dev_data->ack_intr = 0;
269 
270 	return result > 0 ? 0 : result;
271 }
272 
273 static
274 int xen_pcibk_disable_msix(struct xen_pcibk_device *pdev,
275 			   struct pci_dev *dev, struct xen_pci_op *op)
276 {
277 	if (unlikely(verbose_request))
278 		printk(KERN_DEBUG DRV_NAME ": %s: disable MSI-X\n",
279 			pci_name(dev));
280 
281 	if (dev->msix_enabled) {
282 		struct xen_pcibk_dev_data *dev_data;
283 
284 		pci_disable_msix(dev);
285 
286 		dev_data = pci_get_drvdata(dev);
287 		if (dev_data)
288 			dev_data->ack_intr = 1;
289 	}
290 	/*
291 	 * SR-IOV devices (which don't have any legacy IRQ) have
292 	 * an undefined IRQ value of zero.
293 	 */
294 	op->value = dev->irq ? xen_pirq_from_irq(dev->irq) : 0;
295 	if (unlikely(verbose_request))
296 		printk(KERN_DEBUG DRV_NAME ": %s: MSI-X: %d\n",
297 		       pci_name(dev), op->value);
298 	return 0;
299 }
300 #endif
301 /*
302 * Now the same evtchn is used for both pcifront conf_read_write request
303 * as well as pcie aer front end ack. We use a new work_queue to schedule
304 * xen_pcibk conf_read_write service for avoiding confict with aer_core
305 * do_recovery job which also use the system default work_queue
306 */
307 void xen_pcibk_test_and_schedule_op(struct xen_pcibk_device *pdev)
308 {
309 	/* Check that frontend is requesting an operation and that we are not
310 	 * already processing a request */
311 	if (test_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags)
312 	    && !test_and_set_bit(_PDEVF_op_active, &pdev->flags)) {
313 		schedule_work(&pdev->op_work);
314 	}
315 	/*_XEN_PCIB_active should have been cleared by pcifront. And also make
316 	sure xen_pcibk is waiting for ack by checking _PCIB_op_pending*/
317 	if (!test_bit(_XEN_PCIB_active, (unsigned long *)&pdev->sh_info->flags)
318 	    && test_bit(_PCIB_op_pending, &pdev->flags)) {
319 		wake_up(&xen_pcibk_aer_wait_queue);
320 	}
321 }
322 
323 /* Performing the configuration space reads/writes must not be done in atomic
324  * context because some of the pci_* functions can sleep (mostly due to ACPI
325  * use of semaphores). This function is intended to be called from a work
326  * queue in process context taking a struct xen_pcibk_device as a parameter */
327 
328 void xen_pcibk_do_op(struct work_struct *data)
329 {
330 	struct xen_pcibk_device *pdev =
331 		container_of(data, struct xen_pcibk_device, op_work);
332 	struct pci_dev *dev;
333 	struct xen_pcibk_dev_data *dev_data = NULL;
334 	struct xen_pci_op *op = &pdev->op;
335 	int test_intx = 0;
336 #ifdef CONFIG_PCI_MSI
337 	unsigned int nr = 0;
338 #endif
339 
340 	*op = pdev->sh_info->op;
341 	barrier();
342 	dev = xen_pcibk_get_pci_dev(pdev, op->domain, op->bus, op->devfn);
343 
344 	if (dev == NULL)
345 		op->err = XEN_PCI_ERR_dev_not_found;
346 	else {
347 		dev_data = pci_get_drvdata(dev);
348 		if (dev_data)
349 			test_intx = dev_data->enable_intx;
350 		switch (op->cmd) {
351 		case XEN_PCI_OP_conf_read:
352 			op->err = xen_pcibk_config_read(dev,
353 				  op->offset, op->size, &op->value);
354 			break;
355 		case XEN_PCI_OP_conf_write:
356 			op->err = xen_pcibk_config_write(dev,
357 				  op->offset, op->size,	op->value);
358 			break;
359 #ifdef CONFIG_PCI_MSI
360 		case XEN_PCI_OP_enable_msi:
361 			op->err = xen_pcibk_enable_msi(pdev, dev, op);
362 			break;
363 		case XEN_PCI_OP_disable_msi:
364 			op->err = xen_pcibk_disable_msi(pdev, dev, op);
365 			break;
366 		case XEN_PCI_OP_enable_msix:
367 			nr = op->value;
368 			op->err = xen_pcibk_enable_msix(pdev, dev, op);
369 			break;
370 		case XEN_PCI_OP_disable_msix:
371 			op->err = xen_pcibk_disable_msix(pdev, dev, op);
372 			break;
373 #endif
374 		default:
375 			op->err = XEN_PCI_ERR_not_implemented;
376 			break;
377 		}
378 	}
379 	if (!op->err && dev && dev_data) {
380 		/* Transition detected */
381 		if ((dev_data->enable_intx != test_intx))
382 			xen_pcibk_control_isr(dev, 0 /* no reset */);
383 	}
384 	pdev->sh_info->op.err = op->err;
385 	pdev->sh_info->op.value = op->value;
386 #ifdef CONFIG_PCI_MSI
387 	if (op->cmd == XEN_PCI_OP_enable_msix && op->err == 0) {
388 		unsigned int i;
389 
390 		for (i = 0; i < nr; i++)
391 			pdev->sh_info->op.msix_entries[i].vector =
392 				op->msix_entries[i].vector;
393 	}
394 #endif
395 	/* Tell the driver domain that we're done. */
396 	wmb();
397 	clear_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags);
398 	notify_remote_via_irq(pdev->evtchn_irq);
399 
400 	/* Mark that we're done. */
401 	smp_mb__before_atomic(); /* /after/ clearing PCIF_active */
402 	clear_bit(_PDEVF_op_active, &pdev->flags);
403 	smp_mb__after_atomic(); /* /before/ final check for work */
404 
405 	/* Check to see if the driver domain tried to start another request in
406 	 * between clearing _XEN_PCIF_active and clearing _PDEVF_op_active.
407 	*/
408 	xen_pcibk_test_and_schedule_op(pdev);
409 }
410 
411 irqreturn_t xen_pcibk_handle_event(int irq, void *dev_id)
412 {
413 	struct xen_pcibk_device *pdev = dev_id;
414 
415 	xen_pcibk_test_and_schedule_op(pdev);
416 
417 	return IRQ_HANDLED;
418 }
419 static irqreturn_t xen_pcibk_guest_interrupt(int irq, void *dev_id)
420 {
421 	struct pci_dev *dev = (struct pci_dev *)dev_id;
422 	struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
423 
424 	if (dev_data->isr_on && dev_data->ack_intr) {
425 		dev_data->handled++;
426 		if ((dev_data->handled % 1000) == 0) {
427 			if (xen_test_irq_shared(irq)) {
428 				pr_info("%s IRQ line is not shared "
429 					"with other domains. Turning ISR off\n",
430 					 dev_data->irq_name);
431 				dev_data->ack_intr = 0;
432 			}
433 		}
434 		return IRQ_HANDLED;
435 	}
436 	return IRQ_NONE;
437 }
438