1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * PCI Backend - Provides a Virtual PCI bus (with real devices)
4 * to the frontend
5 *
6 * Author: Ryan Wilson <hap9@epoch.ncsc.mil>
7 */
8
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10 #define dev_fmt pr_fmt
11
12 #include <linux/list.h>
13 #include <linux/slab.h>
14 #include <linux/pci.h>
15 #include <linux/mutex.h>
16 #include "pciback.h"
17
18 #define PCI_SLOT_MAX 32
19
20 struct vpci_dev_data {
21 /* Access to dev_list must be protected by lock */
22 struct list_head dev_list[PCI_SLOT_MAX];
23 struct mutex lock;
24 };
25
list_first(struct list_head * head)26 static inline struct list_head *list_first(struct list_head *head)
27 {
28 return head->next;
29 }
30
__xen_pcibk_get_pci_dev(struct xen_pcibk_device * pdev,unsigned int domain,unsigned int bus,unsigned int devfn)31 static struct pci_dev *__xen_pcibk_get_pci_dev(struct xen_pcibk_device *pdev,
32 unsigned int domain,
33 unsigned int bus,
34 unsigned int devfn)
35 {
36 struct pci_dev_entry *entry;
37 struct pci_dev *dev = NULL;
38 struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
39
40 if (domain != 0 || bus != 0)
41 return NULL;
42
43 if (PCI_SLOT(devfn) < PCI_SLOT_MAX) {
44 mutex_lock(&vpci_dev->lock);
45
46 list_for_each_entry(entry,
47 &vpci_dev->dev_list[PCI_SLOT(devfn)],
48 list) {
49 if (PCI_FUNC(entry->dev->devfn) == PCI_FUNC(devfn)) {
50 dev = entry->dev;
51 break;
52 }
53 }
54
55 mutex_unlock(&vpci_dev->lock);
56 }
57 return dev;
58 }
59
match_slot(struct pci_dev * l,struct pci_dev * r)60 static inline int match_slot(struct pci_dev *l, struct pci_dev *r)
61 {
62 if (pci_domain_nr(l->bus) == pci_domain_nr(r->bus)
63 && l->bus == r->bus && PCI_SLOT(l->devfn) == PCI_SLOT(r->devfn))
64 return 1;
65
66 return 0;
67 }
68
__xen_pcibk_add_pci_dev(struct xen_pcibk_device * pdev,struct pci_dev * dev,int devid,publish_pci_dev_cb publish_cb)69 static int __xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev,
70 struct pci_dev *dev, int devid,
71 publish_pci_dev_cb publish_cb)
72 {
73 int err = 0, slot, func = -1;
74 struct pci_dev_entry *t, *dev_entry;
75 struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
76
77 if ((dev->class >> 24) == PCI_BASE_CLASS_BRIDGE) {
78 err = -EFAULT;
79 xenbus_dev_fatal(pdev->xdev, err,
80 "Can't export bridges on the virtual PCI bus");
81 goto out;
82 }
83
84 dev_entry = kmalloc(sizeof(*dev_entry), GFP_KERNEL);
85 if (!dev_entry) {
86 err = -ENOMEM;
87 xenbus_dev_fatal(pdev->xdev, err,
88 "Error adding entry to virtual PCI bus");
89 goto out;
90 }
91
92 dev_entry->dev = dev;
93
94 mutex_lock(&vpci_dev->lock);
95
96 /*
97 * Keep multi-function devices together on the virtual PCI bus, except
98 * virtual functions.
99 */
100 if (!dev->is_virtfn) {
101 for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
102 if (list_empty(&vpci_dev->dev_list[slot]))
103 continue;
104
105 t = list_entry(list_first(&vpci_dev->dev_list[slot]),
106 struct pci_dev_entry, list);
107
108 if (match_slot(dev, t->dev)) {
109 dev_info(&dev->dev, "vpci: assign to virtual slot %d func %d\n",
110 slot, PCI_FUNC(dev->devfn));
111 list_add_tail(&dev_entry->list,
112 &vpci_dev->dev_list[slot]);
113 func = PCI_FUNC(dev->devfn);
114 goto unlock;
115 }
116 }
117 }
118
119 /* Assign to a new slot on the virtual PCI bus */
120 for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
121 if (list_empty(&vpci_dev->dev_list[slot])) {
122 dev_info(&dev->dev, "vpci: assign to virtual slot %d\n",
123 slot);
124 list_add_tail(&dev_entry->list,
125 &vpci_dev->dev_list[slot]);
126 func = dev->is_virtfn ? 0 : PCI_FUNC(dev->devfn);
127 goto unlock;
128 }
129 }
130
131 err = -ENOMEM;
132 xenbus_dev_fatal(pdev->xdev, err,
133 "No more space on root virtual PCI bus");
134
135 unlock:
136 mutex_unlock(&vpci_dev->lock);
137
138 /* Publish this device. */
139 if (!err)
140 err = publish_cb(pdev, 0, 0, PCI_DEVFN(slot, func), devid);
141 else
142 kfree(dev_entry);
143
144 out:
145 return err;
146 }
147
__xen_pcibk_release_pci_dev(struct xen_pcibk_device * pdev,struct pci_dev * dev,bool lock)148 static void __xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev,
149 struct pci_dev *dev, bool lock)
150 {
151 int slot;
152 struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
153 struct pci_dev *found_dev = NULL;
154
155 mutex_lock(&vpci_dev->lock);
156
157 for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
158 struct pci_dev_entry *e;
159
160 list_for_each_entry(e, &vpci_dev->dev_list[slot], list) {
161 if (e->dev == dev) {
162 list_del(&e->list);
163 found_dev = e->dev;
164 kfree(e);
165 goto out;
166 }
167 }
168 }
169
170 out:
171 mutex_unlock(&vpci_dev->lock);
172
173 if (found_dev) {
174 if (lock)
175 device_lock(&found_dev->dev);
176 pcistub_put_pci_dev(found_dev);
177 if (lock)
178 device_unlock(&found_dev->dev);
179 }
180 }
181
__xen_pcibk_init_devices(struct xen_pcibk_device * pdev)182 static int __xen_pcibk_init_devices(struct xen_pcibk_device *pdev)
183 {
184 int slot;
185 struct vpci_dev_data *vpci_dev;
186
187 vpci_dev = kmalloc(sizeof(*vpci_dev), GFP_KERNEL);
188 if (!vpci_dev)
189 return -ENOMEM;
190
191 mutex_init(&vpci_dev->lock);
192
193 for (slot = 0; slot < PCI_SLOT_MAX; slot++)
194 INIT_LIST_HEAD(&vpci_dev->dev_list[slot]);
195
196 pdev->pci_dev_data = vpci_dev;
197
198 return 0;
199 }
200
__xen_pcibk_publish_pci_roots(struct xen_pcibk_device * pdev,publish_pci_root_cb publish_cb)201 static int __xen_pcibk_publish_pci_roots(struct xen_pcibk_device *pdev,
202 publish_pci_root_cb publish_cb)
203 {
204 /* The Virtual PCI bus has only one root */
205 return publish_cb(pdev, 0, 0);
206 }
207
__xen_pcibk_release_devices(struct xen_pcibk_device * pdev)208 static void __xen_pcibk_release_devices(struct xen_pcibk_device *pdev)
209 {
210 int slot;
211 struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
212
213 for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
214 struct pci_dev_entry *e, *tmp;
215 list_for_each_entry_safe(e, tmp, &vpci_dev->dev_list[slot],
216 list) {
217 struct pci_dev *dev = e->dev;
218 list_del(&e->list);
219 device_lock(&dev->dev);
220 pcistub_put_pci_dev(dev);
221 device_unlock(&dev->dev);
222 kfree(e);
223 }
224 }
225
226 kfree(vpci_dev);
227 pdev->pci_dev_data = NULL;
228 }
229
__xen_pcibk_get_pcifront_dev(struct pci_dev * pcidev,struct xen_pcibk_device * pdev,unsigned int * domain,unsigned int * bus,unsigned int * devfn)230 static int __xen_pcibk_get_pcifront_dev(struct pci_dev *pcidev,
231 struct xen_pcibk_device *pdev,
232 unsigned int *domain, unsigned int *bus,
233 unsigned int *devfn)
234 {
235 struct pci_dev_entry *entry;
236 struct pci_dev *dev = NULL;
237 struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
238 int found = 0, slot;
239
240 mutex_lock(&vpci_dev->lock);
241 for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
242 list_for_each_entry(entry,
243 &vpci_dev->dev_list[slot],
244 list) {
245 dev = entry->dev;
246 if (dev && dev->bus->number == pcidev->bus->number
247 && pci_domain_nr(dev->bus) ==
248 pci_domain_nr(pcidev->bus)
249 && dev->devfn == pcidev->devfn) {
250 found = 1;
251 *domain = 0;
252 *bus = 0;
253 *devfn = PCI_DEVFN(slot,
254 PCI_FUNC(pcidev->devfn));
255 }
256 }
257 }
258 mutex_unlock(&vpci_dev->lock);
259 return found;
260 }
261
262 const struct xen_pcibk_backend xen_pcibk_vpci_backend = {
263 .name = "vpci",
264 .init = __xen_pcibk_init_devices,
265 .free = __xen_pcibk_release_devices,
266 .find = __xen_pcibk_get_pcifront_dev,
267 .publish = __xen_pcibk_publish_pci_roots,
268 .release = __xen_pcibk_release_pci_dev,
269 .add = __xen_pcibk_add_pci_dev,
270 .get = __xen_pcibk_get_pci_dev,
271 };
272
