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 26 static inline struct list_head *list_first(struct list_head *head) 27 { 28 return head->next; 29 } 30 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 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 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 = PCI_FUNC(dev->devfn); 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 * that we want to keep virtual functions at func 0 on their own. They 99 * aren't multi-function devices and hence their presence at func 0 100 * may cause guests to not scan the other functions. 101 */ 102 if (!dev->is_virtfn || func) { 103 for (slot = 0; slot < PCI_SLOT_MAX; slot++) { 104 if (list_empty(&vpci_dev->dev_list[slot])) 105 continue; 106 107 t = list_entry(list_first(&vpci_dev->dev_list[slot]), 108 struct pci_dev_entry, list); 109 if (t->dev->is_virtfn && !PCI_FUNC(t->dev->devfn)) 110 continue; 111 112 if (match_slot(dev, t->dev)) { 113 dev_info(&dev->dev, "vpci: assign to virtual slot %d func %d\n", 114 slot, 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 dev_info(&dev->dev, "vpci: assign to virtual slot %d\n", 126 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 } 149 150 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 } 183 184 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 } 202 203 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 } 209 210 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 } 231 232 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 vpci_dev_data *vpci_dev = pdev->pci_dev_data; 239 int found = 0, slot; 240 241 mutex_lock(&vpci_dev->lock); 242 for (slot = 0; slot < PCI_SLOT_MAX; slot++) { 243 list_for_each_entry(entry, 244 &vpci_dev->dev_list[slot], 245 list) { 246 if (entry->dev == pcidev) { 247 found = 1; 248 *domain = 0; 249 *bus = 0; 250 *devfn = PCI_DEVFN(slot, 251 PCI_FUNC(pcidev->devfn)); 252 } 253 } 254 } 255 mutex_unlock(&vpci_dev->lock); 256 return found; 257 } 258 259 const struct xen_pcibk_backend xen_pcibk_vpci_backend = { 260 .name = "vpci", 261 .init = __xen_pcibk_init_devices, 262 .free = __xen_pcibk_release_devices, 263 .find = __xen_pcibk_get_pcifront_dev, 264 .publish = __xen_pcibk_publish_pci_roots, 265 .release = __xen_pcibk_release_pci_dev, 266 .add = __xen_pcibk_add_pci_dev, 267 .get = __xen_pcibk_get_pci_dev, 268 }; 269