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(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;
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, 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
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(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
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(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
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(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
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(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
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, &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(&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, 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
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, 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, &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(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