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
11 #include <linux/list.h>
12 #include <linux/slab.h>
13 #include <linux/pci.h>
14 #include <linux/mutex.h>
15 #include "pciback.h"
16
17 #define PCI_SLOT_MAX 32
18
19 struct vpci_dev_data {
20 /* Access to dev_list must be protected by lock */
21 struct list_head dev_list[PCI_SLOT_MAX];
22 struct mutex lock;
23 };
24
list_first(struct list_head * head)25 static inline struct list_head *list_first(struct list_head *head)
26 {
27 return head->next;
28 }
29
__xen_pcibk_get_pci_dev(struct xen_pcibk_device * pdev,unsigned int domain,unsigned int bus,unsigned int devfn)30 static struct pci_dev *__xen_pcibk_get_pci_dev(struct xen_pcibk_device *pdev,
31 unsigned int domain,
32 unsigned int bus,
33 unsigned int devfn)
34 {
35 struct pci_dev_entry *entry;
36 struct pci_dev *dev = NULL;
37 struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
38
39 if (domain != 0 || bus != 0)
40 return NULL;
41
42 if (PCI_SLOT(devfn) < PCI_SLOT_MAX) {
43 mutex_lock(&vpci_dev->lock);
44
45 list_for_each_entry(entry,
46 &vpci_dev->dev_list[PCI_SLOT(devfn)],
47 list) {
48 if (PCI_FUNC(entry->dev->devfn) == PCI_FUNC(devfn)) {
49 dev = entry->dev;
50 break;
51 }
52 }
53
54 mutex_unlock(&vpci_dev->lock);
55 }
56 return dev;
57 }
58
match_slot(struct pci_dev * l,struct pci_dev * r)59 static inline int match_slot(struct pci_dev *l, struct pci_dev *r)
60 {
61 if (pci_domain_nr(l->bus) == pci_domain_nr(r->bus)
62 && l->bus == r->bus && PCI_SLOT(l->devfn) == PCI_SLOT(r->devfn))
63 return 1;
64
65 return 0;
66 }
67
__xen_pcibk_add_pci_dev(struct xen_pcibk_device * pdev,struct pci_dev * dev,int devid,publish_pci_dev_cb publish_cb)68 static int __xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev,
69 struct pci_dev *dev, int devid,
70 publish_pci_dev_cb publish_cb)
71 {
72 int err = 0, slot, func = PCI_FUNC(dev->devfn);
73 struct pci_dev_entry *t, *dev_entry;
74 struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
75
76 if ((dev->class >> 24) == PCI_BASE_CLASS_BRIDGE) {
77 err = -EFAULT;
78 xenbus_dev_fatal(pdev->xdev, err,
79 "Can't export bridges on the virtual PCI bus");
80 goto out;
81 }
82
83 dev_entry = kmalloc(sizeof(*dev_entry), GFP_KERNEL);
84 if (!dev_entry) {
85 err = -ENOMEM;
86 xenbus_dev_fatal(pdev->xdev, err,
87 "Error adding entry to virtual PCI bus");
88 goto out;
89 }
90
91 dev_entry->dev = dev;
92
93 mutex_lock(&vpci_dev->lock);
94
95 /*
96 * Keep multi-function devices together on the virtual PCI bus, except
97 * that we want to keep virtual functions at func 0 on their own. They
98 * aren't multi-function devices and hence their presence at func 0
99 * may cause guests to not scan the other functions.
100 */
101 if (!dev->is_virtfn || func) {
102 for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
103 if (list_empty(&vpci_dev->dev_list[slot]))
104 continue;
105
106 t = list_entry(list_first(&vpci_dev->dev_list[slot]),
107 struct pci_dev_entry, list);
108 if (t->dev->is_virtfn && !PCI_FUNC(t->dev->devfn))
109 continue;
110
111 if (match_slot(dev, t->dev)) {
112 pr_info("vpci: %s: assign to virtual slot %d func %d\n",
113 pci_name(dev), slot,
114 func);
115 list_add_tail(&dev_entry->list,
116 &vpci_dev->dev_list[slot]);
117 goto unlock;
118 }
119 }
120 }
121
122 /* Assign to a new slot on the virtual PCI bus */
123 for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
124 if (list_empty(&vpci_dev->dev_list[slot])) {
125 pr_info("vpci: %s: assign to virtual slot %d\n",
126 pci_name(dev), slot);
127 list_add_tail(&dev_entry->list,
128 &vpci_dev->dev_list[slot]);
129 goto unlock;
130 }
131 }
132
133 err = -ENOMEM;
134 xenbus_dev_fatal(pdev->xdev, err,
135 "No more space on root virtual PCI bus");
136
137 unlock:
138 mutex_unlock(&vpci_dev->lock);
139
140 /* Publish this device. */
141 if (!err)
142 err = publish_cb(pdev, 0, 0, PCI_DEVFN(slot, func), devid);
143 else
144 kfree(dev_entry);
145
146 out:
147 return err;
148 }
149
__xen_pcibk_release_pci_dev(struct xen_pcibk_device * pdev,struct pci_dev * dev,bool lock)150 static void __xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev,
151 struct pci_dev *dev, bool lock)
152 {
153 int slot;
154 struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
155 struct pci_dev *found_dev = NULL;
156
157 mutex_lock(&vpci_dev->lock);
158
159 for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
160 struct pci_dev_entry *e;
161
162 list_for_each_entry(e, &vpci_dev->dev_list[slot], list) {
163 if (e->dev == dev) {
164 list_del(&e->list);
165 found_dev = e->dev;
166 kfree(e);
167 goto out;
168 }
169 }
170 }
171
172 out:
173 mutex_unlock(&vpci_dev->lock);
174
175 if (found_dev) {
176 if (lock)
177 device_lock(&found_dev->dev);
178 pcistub_put_pci_dev(found_dev);
179 if (lock)
180 device_unlock(&found_dev->dev);
181 }
182 }
183
__xen_pcibk_init_devices(struct xen_pcibk_device * pdev)184 static int __xen_pcibk_init_devices(struct xen_pcibk_device *pdev)
185 {
186 int slot;
187 struct vpci_dev_data *vpci_dev;
188
189 vpci_dev = kmalloc(sizeof(*vpci_dev), GFP_KERNEL);
190 if (!vpci_dev)
191 return -ENOMEM;
192
193 mutex_init(&vpci_dev->lock);
194
195 for (slot = 0; slot < PCI_SLOT_MAX; slot++)
196 INIT_LIST_HEAD(&vpci_dev->dev_list[slot]);
197
198 pdev->pci_dev_data = vpci_dev;
199
200 return 0;
201 }
202
__xen_pcibk_publish_pci_roots(struct xen_pcibk_device * pdev,publish_pci_root_cb publish_cb)203 static int __xen_pcibk_publish_pci_roots(struct xen_pcibk_device *pdev,
204 publish_pci_root_cb publish_cb)
205 {
206 /* The Virtual PCI bus has only one root */
207 return publish_cb(pdev, 0, 0);
208 }
209
__xen_pcibk_release_devices(struct xen_pcibk_device * pdev)210 static void __xen_pcibk_release_devices(struct xen_pcibk_device *pdev)
211 {
212 int slot;
213 struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
214
215 for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
216 struct pci_dev_entry *e, *tmp;
217 list_for_each_entry_safe(e, tmp, &vpci_dev->dev_list[slot],
218 list) {
219 struct pci_dev *dev = e->dev;
220 list_del(&e->list);
221 device_lock(&dev->dev);
222 pcistub_put_pci_dev(dev);
223 device_unlock(&dev->dev);
224 kfree(e);
225 }
226 }
227
228 kfree(vpci_dev);
229 pdev->pci_dev_data = NULL;
230 }
231
__xen_pcibk_get_pcifront_dev(struct pci_dev * pcidev,struct xen_pcibk_device * pdev,unsigned int * domain,unsigned int * bus,unsigned int * devfn)232 static int __xen_pcibk_get_pcifront_dev(struct pci_dev *pcidev,
233 struct xen_pcibk_device *pdev,
234 unsigned int *domain, unsigned int *bus,
235 unsigned int *devfn)
236 {
237 struct pci_dev_entry *entry;
238 struct pci_dev *dev = NULL;
239 struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
240 int found = 0, slot;
241
242 mutex_lock(&vpci_dev->lock);
243 for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
244 list_for_each_entry(entry,
245 &vpci_dev->dev_list[slot],
246 list) {
247 dev = entry->dev;
248 if (dev && dev->bus->number == pcidev->bus->number
249 && pci_domain_nr(dev->bus) ==
250 pci_domain_nr(pcidev->bus)
251 && dev->devfn == pcidev->devfn) {
252 found = 1;
253 *domain = 0;
254 *bus = 0;
255 *devfn = PCI_DEVFN(slot,
256 PCI_FUNC(pcidev->devfn));
257 }
258 }
259 }
260 mutex_unlock(&vpci_dev->lock);
261 return found;
262 }
263
264 const struct xen_pcibk_backend xen_pcibk_vpci_backend = {
265 .name = "vpci",
266 .init = __xen_pcibk_init_devices,
267 .free = __xen_pcibk_release_devices,
268 .find = __xen_pcibk_get_pcifront_dev,
269 .publish = __xen_pcibk_publish_pci_roots,
270 .release = __xen_pcibk_release_pci_dev,
271 .add = __xen_pcibk_add_pci_dev,
272 .get = __xen_pcibk_get_pci_dev,
273 };
274