1 #include <linux/virtio_ring.h> 2 #include <linux/types.h> 3 #include <sys/uio.h> 4 #include <stdlib.h> 5 6 #include "kvm/guest_compat.h" 7 #include "kvm/barrier.h" 8 #include "kvm/virtio.h" 9 #include "kvm/virtio-pci.h" 10 #include "kvm/virtio-mmio.h" 11 #include "kvm/util.h" 12 #include "kvm/kvm.h" 13 14 15 const char* virtio_trans_name(enum virtio_trans trans) 16 { 17 if (trans == VIRTIO_PCI) 18 return "pci"; 19 else if (trans == VIRTIO_MMIO) 20 return "mmio"; 21 return "unknown"; 22 } 23 24 void virt_queue__used_idx_advance(struct virt_queue *queue, u16 jump) 25 { 26 u16 idx = virtio_guest_to_host_u16(queue, queue->vring.used->idx); 27 28 /* 29 * Use wmb to assure that used elem was updated with head and len. 30 * We need a wmb here since we can't advance idx unless we're ready 31 * to pass the used element to the guest. 32 */ 33 wmb(); 34 idx += jump; 35 queue->vring.used->idx = virtio_host_to_guest_u16(queue, idx); 36 } 37 38 struct vring_used_elem * 39 virt_queue__set_used_elem_no_update(struct virt_queue *queue, u32 head, 40 u32 len, u16 offset) 41 { 42 struct vring_used_elem *used_elem; 43 u16 idx = virtio_guest_to_host_u16(queue, queue->vring.used->idx); 44 45 idx += offset; 46 used_elem = &queue->vring.used->ring[idx % queue->vring.num]; 47 used_elem->id = virtio_host_to_guest_u32(queue, head); 48 used_elem->len = virtio_host_to_guest_u32(queue, len); 49 50 return used_elem; 51 } 52 53 struct vring_used_elem *virt_queue__set_used_elem(struct virt_queue *queue, u32 head, u32 len) 54 { 55 struct vring_used_elem *used_elem; 56 57 used_elem = virt_queue__set_used_elem_no_update(queue, head, len, 0); 58 virt_queue__used_idx_advance(queue, 1); 59 60 return used_elem; 61 } 62 63 static inline bool virt_desc__test_flag(struct virt_queue *vq, 64 struct vring_desc *desc, u16 flag) 65 { 66 return !!(virtio_guest_to_host_u16(vq, desc->flags) & flag); 67 } 68 69 /* 70 * Each buffer in the virtqueues is actually a chain of descriptors. This 71 * function returns the next descriptor in the chain, or max if we're at the 72 * end. 73 */ 74 static unsigned next_desc(struct virt_queue *vq, struct vring_desc *desc, 75 unsigned int i, unsigned int max) 76 { 77 unsigned int next; 78 79 /* If this descriptor says it doesn't chain, we're done. */ 80 if (!virt_desc__test_flag(vq, &desc[i], VRING_DESC_F_NEXT)) 81 return max; 82 83 next = virtio_guest_to_host_u16(vq, desc[i].next); 84 85 /* Ensure they're not leading us off end of descriptors. */ 86 return min(next, max); 87 } 88 89 u16 virt_queue__get_head_iov(struct virt_queue *vq, struct iovec iov[], u16 *out, u16 *in, u16 head, struct kvm *kvm) 90 { 91 struct vring_desc *desc; 92 u16 idx; 93 u16 max; 94 95 idx = head; 96 *out = *in = 0; 97 max = vq->vring.num; 98 desc = vq->vring.desc; 99 100 if (virt_desc__test_flag(vq, &desc[idx], VRING_DESC_F_INDIRECT)) { 101 max = virtio_guest_to_host_u32(vq, desc[idx].len) / sizeof(struct vring_desc); 102 desc = guest_flat_to_host(kvm, virtio_guest_to_host_u64(vq, desc[idx].addr)); 103 idx = 0; 104 } 105 106 do { 107 /* Grab the first descriptor, and check it's OK. */ 108 iov[*out + *in].iov_len = virtio_guest_to_host_u32(vq, desc[idx].len); 109 iov[*out + *in].iov_base = guest_flat_to_host(kvm, 110 virtio_guest_to_host_u64(vq, desc[idx].addr)); 111 /* If this is an input descriptor, increment that count. */ 112 if (virt_desc__test_flag(vq, &desc[idx], VRING_DESC_F_WRITE)) 113 (*in)++; 114 else 115 (*out)++; 116 } while ((idx = next_desc(vq, desc, idx, max)) != max); 117 118 return head; 119 } 120 121 u16 virt_queue__get_iov(struct virt_queue *vq, struct iovec iov[], u16 *out, u16 *in, struct kvm *kvm) 122 { 123 u16 head; 124 125 head = virt_queue__pop(vq); 126 127 return virt_queue__get_head_iov(vq, iov, out, in, head, kvm); 128 } 129 130 /* in and out are relative to guest */ 131 u16 virt_queue__get_inout_iov(struct kvm *kvm, struct virt_queue *queue, 132 struct iovec in_iov[], struct iovec out_iov[], 133 u16 *in, u16 *out) 134 { 135 struct vring_desc *desc; 136 u16 head, idx; 137 138 idx = head = virt_queue__pop(queue); 139 *out = *in = 0; 140 do { 141 u64 addr; 142 desc = virt_queue__get_desc(queue, idx); 143 addr = virtio_guest_to_host_u64(queue, desc->addr); 144 if (virt_desc__test_flag(queue, desc, VRING_DESC_F_WRITE)) { 145 in_iov[*in].iov_base = guest_flat_to_host(kvm, addr); 146 in_iov[*in].iov_len = virtio_guest_to_host_u32(queue, desc->len); 147 (*in)++; 148 } else { 149 out_iov[*out].iov_base = guest_flat_to_host(kvm, addr); 150 out_iov[*out].iov_len = virtio_guest_to_host_u32(queue, desc->len); 151 (*out)++; 152 } 153 if (virt_desc__test_flag(queue, desc, VRING_DESC_F_NEXT)) 154 idx = virtio_guest_to_host_u16(queue, desc->next); 155 else 156 break; 157 } while (1); 158 159 return head; 160 } 161 162 void virtio_exit_vq(struct kvm *kvm, struct virtio_device *vdev, 163 void *dev, int num) 164 { 165 struct virt_queue *vq = vdev->ops->get_vq(kvm, dev, num); 166 167 if (vq->enabled && vdev->ops->exit_vq) 168 vdev->ops->exit_vq(kvm, dev, num); 169 memset(vq, 0, sizeof(*vq)); 170 } 171 172 int virtio__get_dev_specific_field(int offset, bool msix, u32 *config_off) 173 { 174 if (msix) { 175 if (offset < 4) 176 return VIRTIO_PCI_O_MSIX; 177 else 178 offset -= 4; 179 } 180 181 *config_off = offset; 182 183 return VIRTIO_PCI_O_CONFIG; 184 } 185 186 bool virtio_queue__should_signal(struct virt_queue *vq) 187 { 188 u16 old_idx, new_idx, event_idx; 189 190 /* 191 * Use mb to assure used idx has been increased before we signal the 192 * guest, and we don't read a stale value for used_event. Without a mb 193 * here we might not send a notification that we need to send, or the 194 * guest may ignore the queue since it won't see an updated idx. 195 */ 196 mb(); 197 198 if (!vq->use_event_idx) { 199 /* 200 * When VIRTIO_RING_F_EVENT_IDX isn't negotiated, interrupt the 201 * guest if it didn't explicitly request to be left alone. 202 */ 203 return !(virtio_guest_to_host_u16(vq, vq->vring.avail->flags) & 204 VRING_AVAIL_F_NO_INTERRUPT); 205 } 206 207 old_idx = vq->last_used_signalled; 208 new_idx = virtio_guest_to_host_u16(vq, vq->vring.used->idx); 209 event_idx = virtio_guest_to_host_u16(vq, vring_used_event(&vq->vring)); 210 211 if (vring_need_event(event_idx, new_idx, old_idx)) { 212 vq->last_used_signalled = new_idx; 213 return true; 214 } 215 216 return false; 217 } 218 219 void virtio_set_guest_features(struct kvm *kvm, struct virtio_device *vdev, 220 void *dev, u32 features) 221 { 222 /* TODO: fail negotiation if features & ~host_features */ 223 224 vdev->features = features; 225 vdev->ops->set_guest_features(kvm, dev, features); 226 } 227 228 void virtio_notify_status(struct kvm *kvm, struct virtio_device *vdev, 229 void *dev, u8 status) 230 { 231 u32 ext_status = status; 232 233 vdev->status &= ~VIRTIO_CONFIG_S_MASK; 234 vdev->status |= status; 235 236 /* Add a few hints to help devices */ 237 if ((status & VIRTIO_CONFIG_S_DRIVER_OK) && 238 !(vdev->status & VIRTIO__STATUS_START)) { 239 vdev->status |= VIRTIO__STATUS_START; 240 ext_status |= VIRTIO__STATUS_START; 241 242 } else if (!status && (vdev->status & VIRTIO__STATUS_START)) { 243 vdev->status &= ~VIRTIO__STATUS_START; 244 ext_status |= VIRTIO__STATUS_STOP; 245 246 /* 247 * Reset virtqueues and stop all traffic now, so that the device 248 * can safely reset the backend in notify_status(). 249 */ 250 if (ext_status & VIRTIO__STATUS_STOP) 251 vdev->ops->reset(kvm, vdev); 252 } 253 254 if (vdev->ops->notify_status) 255 vdev->ops->notify_status(kvm, dev, ext_status); 256 } 257 258 int virtio_init(struct kvm *kvm, void *dev, struct virtio_device *vdev, 259 struct virtio_ops *ops, enum virtio_trans trans, 260 int device_id, int subsys_id, int class) 261 { 262 void *virtio; 263 int r; 264 265 switch (trans) { 266 case VIRTIO_PCI: 267 virtio = calloc(sizeof(struct virtio_pci), 1); 268 if (!virtio) 269 return -ENOMEM; 270 vdev->virtio = virtio; 271 vdev->ops = ops; 272 vdev->ops->signal_vq = virtio_pci__signal_vq; 273 vdev->ops->signal_config = virtio_pci__signal_config; 274 vdev->ops->init = virtio_pci__init; 275 vdev->ops->exit = virtio_pci__exit; 276 vdev->ops->reset = virtio_pci__reset; 277 r = vdev->ops->init(kvm, dev, vdev, device_id, subsys_id, class); 278 break; 279 case VIRTIO_MMIO: 280 virtio = calloc(sizeof(struct virtio_mmio), 1); 281 if (!virtio) 282 return -ENOMEM; 283 vdev->virtio = virtio; 284 vdev->ops = ops; 285 vdev->ops->signal_vq = virtio_mmio_signal_vq; 286 vdev->ops->signal_config = virtio_mmio_signal_config; 287 vdev->ops->init = virtio_mmio_init; 288 vdev->ops->exit = virtio_mmio_exit; 289 vdev->ops->reset = virtio_mmio_reset; 290 r = vdev->ops->init(kvm, dev, vdev, device_id, subsys_id, class); 291 break; 292 default: 293 r = -1; 294 }; 295 296 return r; 297 } 298 299 int virtio_compat_add_message(const char *device, const char *config) 300 { 301 int len = 1024; 302 int compat_id; 303 char *title; 304 char *desc; 305 306 title = malloc(len); 307 if (!title) 308 return -ENOMEM; 309 310 desc = malloc(len); 311 if (!desc) { 312 free(title); 313 return -ENOMEM; 314 } 315 316 snprintf(title, len, "%s device was not detected.", device); 317 snprintf(desc, len, "While you have requested a %s device, " 318 "the guest kernel did not initialize it.\n" 319 "\tPlease make sure that the guest kernel was " 320 "compiled with %s=y enabled in .config.", 321 device, config); 322 323 compat_id = compat__add_message(title, desc); 324 325 free(desc); 326 free(title); 327 328 return compat_id; 329 } 330