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e976a2b9 CB |
1 | /* |
2 | * kvm_virtio.c - virtio for kvm on s390 | |
3 | * | |
4 | * Copyright IBM Corp. 2008 | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License (version 2 only) | |
8 | * as published by the Free Software Foundation. | |
9 | * | |
10 | * Author(s): Christian Borntraeger <borntraeger@de.ibm.com> | |
11 | */ | |
12 | ||
13 | #include <linux/init.h> | |
14 | #include <linux/bootmem.h> | |
15 | #include <linux/err.h> | |
16 | #include <linux/virtio.h> | |
17 | #include <linux/virtio_config.h> | |
faeba830 | 18 | #include <linux/virtio_console.h> |
e976a2b9 CB |
19 | #include <linux/interrupt.h> |
20 | #include <linux/virtio_ring.h> | |
17f34580 | 21 | #include <linux/pfn.h> |
e976a2b9 CB |
22 | #include <asm/io.h> |
23 | #include <asm/kvm_para.h> | |
24 | #include <asm/kvm_virtio.h> | |
25 | #include <asm/setup.h> | |
26 | #include <asm/s390_ext.h> | |
27 | ||
28 | #define VIRTIO_SUBCODE_64 0x0D00 | |
29 | ||
30 | /* | |
31 | * The pointer to our (page) of device descriptions. | |
32 | */ | |
33 | static void *kvm_devices; | |
34 | ||
e976a2b9 CB |
35 | struct kvm_device { |
36 | struct virtio_device vdev; | |
37 | struct kvm_device_desc *desc; | |
38 | }; | |
39 | ||
40 | #define to_kvmdev(vd) container_of(vd, struct kvm_device, vdev) | |
41 | ||
42 | /* | |
43 | * memory layout: | |
44 | * - kvm_device_descriptor | |
45 | * struct kvm_device_desc | |
46 | * - configuration | |
47 | * struct kvm_vqconfig | |
48 | * - feature bits | |
49 | * - config space | |
50 | */ | |
51 | static struct kvm_vqconfig *kvm_vq_config(const struct kvm_device_desc *desc) | |
52 | { | |
53 | return (struct kvm_vqconfig *)(desc + 1); | |
54 | } | |
55 | ||
56 | static u8 *kvm_vq_features(const struct kvm_device_desc *desc) | |
57 | { | |
58 | return (u8 *)(kvm_vq_config(desc) + desc->num_vq); | |
59 | } | |
60 | ||
61 | static u8 *kvm_vq_configspace(const struct kvm_device_desc *desc) | |
62 | { | |
63 | return kvm_vq_features(desc) + desc->feature_len * 2; | |
64 | } | |
65 | ||
66 | /* | |
67 | * The total size of the config page used by this device (incl. desc) | |
68 | */ | |
69 | static unsigned desc_size(const struct kvm_device_desc *desc) | |
70 | { | |
71 | return sizeof(*desc) | |
72 | + desc->num_vq * sizeof(struct kvm_vqconfig) | |
73 | + desc->feature_len * 2 | |
74 | + desc->config_len; | |
75 | } | |
76 | ||
5ca9fd54 HC |
77 | /* This gets the device's feature bits. */ |
78 | static u32 kvm_get_features(struct virtio_device *vdev) | |
e976a2b9 | 79 | { |
5ca9fd54 HC |
80 | unsigned int i; |
81 | u32 features = 0; | |
e976a2b9 | 82 | struct kvm_device_desc *desc = to_kvmdev(vdev)->desc; |
5ca9fd54 | 83 | u8 *in_features = kvm_vq_features(desc); |
e976a2b9 | 84 | |
5ca9fd54 HC |
85 | for (i = 0; i < min(desc->feature_len * 8, 32); i++) |
86 | if (in_features[i / 8] & (1 << (i % 8))) | |
87 | features |= (1 << i); | |
88 | return features; | |
89 | } | |
e976a2b9 | 90 | |
5ca9fd54 HC |
91 | static void kvm_set_features(struct virtio_device *vdev, u32 features) |
92 | { | |
93 | unsigned int i; | |
94 | struct kvm_device_desc *desc = to_kvmdev(vdev)->desc; | |
95 | /* Second half of bitmap is features we accept. */ | |
96 | u8 *out_features = kvm_vq_features(desc) + desc->feature_len; | |
e976a2b9 | 97 | |
5ca9fd54 HC |
98 | memset(out_features, 0, desc->feature_len); |
99 | for (i = 0; i < min(desc->feature_len * 8, 32); i++) { | |
100 | if (features & (1 << i)) | |
101 | out_features[i / 8] |= (1 << (i % 8)); | |
102 | } | |
e976a2b9 CB |
103 | } |
104 | ||
105 | /* | |
106 | * Reading and writing elements in config space | |
107 | */ | |
108 | static void kvm_get(struct virtio_device *vdev, unsigned int offset, | |
109 | void *buf, unsigned len) | |
110 | { | |
111 | struct kvm_device_desc *desc = to_kvmdev(vdev)->desc; | |
112 | ||
113 | BUG_ON(offset + len > desc->config_len); | |
114 | memcpy(buf, kvm_vq_configspace(desc) + offset, len); | |
115 | } | |
116 | ||
117 | static void kvm_set(struct virtio_device *vdev, unsigned int offset, | |
118 | const void *buf, unsigned len) | |
119 | { | |
120 | struct kvm_device_desc *desc = to_kvmdev(vdev)->desc; | |
121 | ||
122 | BUG_ON(offset + len > desc->config_len); | |
123 | memcpy(kvm_vq_configspace(desc) + offset, buf, len); | |
124 | } | |
125 | ||
126 | /* | |
127 | * The operations to get and set the status word just access | |
128 | * the status field of the device descriptor. set_status will also | |
129 | * make a hypercall to the host, to tell about status changes | |
130 | */ | |
131 | static u8 kvm_get_status(struct virtio_device *vdev) | |
132 | { | |
133 | return to_kvmdev(vdev)->desc->status; | |
134 | } | |
135 | ||
136 | static void kvm_set_status(struct virtio_device *vdev, u8 status) | |
137 | { | |
138 | BUG_ON(!status); | |
139 | to_kvmdev(vdev)->desc->status = status; | |
140 | kvm_hypercall1(KVM_S390_VIRTIO_SET_STATUS, | |
141 | (unsigned long) to_kvmdev(vdev)->desc); | |
142 | } | |
143 | ||
144 | /* | |
145 | * To reset the device, we use the KVM_VIRTIO_RESET hypercall, using the | |
146 | * descriptor address. The Host will zero the status and all the | |
147 | * features. | |
148 | */ | |
149 | static void kvm_reset(struct virtio_device *vdev) | |
150 | { | |
151 | kvm_hypercall1(KVM_S390_VIRTIO_RESET, | |
152 | (unsigned long) to_kvmdev(vdev)->desc); | |
153 | } | |
154 | ||
155 | /* | |
156 | * When the virtio_ring code wants to notify the Host, it calls us here and we | |
157 | * make a hypercall. We hand the address of the virtqueue so the Host | |
158 | * knows which virtqueue we're talking about. | |
159 | */ | |
160 | static void kvm_notify(struct virtqueue *vq) | |
161 | { | |
162 | struct kvm_vqconfig *config = vq->priv; | |
163 | ||
164 | kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, config->address); | |
165 | } | |
166 | ||
167 | /* | |
168 | * This routine finds the first virtqueue described in the configuration of | |
169 | * this device and sets it up. | |
170 | */ | |
171 | static struct virtqueue *kvm_find_vq(struct virtio_device *vdev, | |
172 | unsigned index, | |
173 | void (*callback)(struct virtqueue *vq)) | |
174 | { | |
175 | struct kvm_device *kdev = to_kvmdev(vdev); | |
176 | struct kvm_vqconfig *config; | |
177 | struct virtqueue *vq; | |
178 | int err; | |
179 | ||
180 | if (index >= kdev->desc->num_vq) | |
181 | return ERR_PTR(-ENOENT); | |
182 | ||
183 | config = kvm_vq_config(kdev->desc)+index; | |
184 | ||
17f34580 HC |
185 | err = vmem_add_mapping(config->address, |
186 | vring_size(config->num, PAGE_SIZE)); | |
187 | if (err) | |
e976a2b9 | 188 | goto out; |
e976a2b9 CB |
189 | |
190 | vq = vring_new_virtqueue(config->num, vdev, (void *) config->address, | |
191 | kvm_notify, callback); | |
192 | if (!vq) { | |
193 | err = -ENOMEM; | |
194 | goto unmap; | |
195 | } | |
196 | ||
197 | /* | |
198 | * register a callback token | |
199 | * The host will sent this via the external interrupt parameter | |
200 | */ | |
201 | config->token = (u64) vq; | |
202 | ||
203 | vq->priv = config; | |
204 | return vq; | |
205 | unmap: | |
17f34580 HC |
206 | vmem_remove_mapping(config->address, |
207 | vring_size(config->num, PAGE_SIZE)); | |
e976a2b9 CB |
208 | out: |
209 | return ERR_PTR(err); | |
210 | } | |
211 | ||
212 | static void kvm_del_vq(struct virtqueue *vq) | |
213 | { | |
214 | struct kvm_vqconfig *config = vq->priv; | |
215 | ||
216 | vring_del_virtqueue(vq); | |
17f34580 HC |
217 | vmem_remove_mapping(config->address, |
218 | vring_size(config->num, PAGE_SIZE)); | |
e976a2b9 CB |
219 | } |
220 | ||
221 | /* | |
222 | * The config ops structure as defined by virtio config | |
223 | */ | |
224 | static struct virtio_config_ops kvm_vq_configspace_ops = { | |
5ca9fd54 HC |
225 | .get_features = kvm_get_features, |
226 | .set_features = kvm_set_features, | |
e976a2b9 CB |
227 | .get = kvm_get, |
228 | .set = kvm_set, | |
229 | .get_status = kvm_get_status, | |
230 | .set_status = kvm_set_status, | |
231 | .reset = kvm_reset, | |
232 | .find_vq = kvm_find_vq, | |
233 | .del_vq = kvm_del_vq, | |
234 | }; | |
235 | ||
236 | /* | |
237 | * The root device for the kvm virtio devices. | |
238 | * This makes them appear as /sys/devices/kvm_s390/0,1,2 not /sys/devices/0,1,2. | |
239 | */ | |
240 | static struct device kvm_root = { | |
241 | .parent = NULL, | |
242 | .bus_id = "kvm_s390", | |
243 | }; | |
244 | ||
245 | /* | |
246 | * adds a new device and register it with virtio | |
247 | * appropriate drivers are loaded by the device model | |
248 | */ | |
b769f579 | 249 | static void add_kvm_device(struct kvm_device_desc *d, unsigned int offset) |
e976a2b9 CB |
250 | { |
251 | struct kvm_device *kdev; | |
252 | ||
253 | kdev = kzalloc(sizeof(*kdev), GFP_KERNEL); | |
254 | if (!kdev) { | |
b769f579 RR |
255 | printk(KERN_EMERG "Cannot allocate kvm dev %u type %u\n", |
256 | offset, d->type); | |
e976a2b9 CB |
257 | return; |
258 | } | |
259 | ||
260 | kdev->vdev.dev.parent = &kvm_root; | |
e976a2b9 CB |
261 | kdev->vdev.id.device = d->type; |
262 | kdev->vdev.config = &kvm_vq_configspace_ops; | |
263 | kdev->desc = d; | |
264 | ||
265 | if (register_virtio_device(&kdev->vdev) != 0) { | |
b769f579 RR |
266 | printk(KERN_ERR "Failed to register kvm device %u type %u\n", |
267 | offset, d->type); | |
e976a2b9 CB |
268 | kfree(kdev); |
269 | } | |
270 | } | |
271 | ||
272 | /* | |
273 | * scan_devices() simply iterates through the device page. | |
274 | * The type 0 is reserved to mean "end of devices". | |
275 | */ | |
276 | static void scan_devices(void) | |
277 | { | |
278 | unsigned int i; | |
279 | struct kvm_device_desc *d; | |
280 | ||
281 | for (i = 0; i < PAGE_SIZE; i += desc_size(d)) { | |
282 | d = kvm_devices + i; | |
283 | ||
284 | if (d->type == 0) | |
285 | break; | |
286 | ||
b769f579 | 287 | add_kvm_device(d, i); |
e976a2b9 CB |
288 | } |
289 | } | |
290 | ||
291 | /* | |
292 | * we emulate the request_irq behaviour on top of s390 extints | |
293 | */ | |
294 | static void kvm_extint_handler(u16 code) | |
295 | { | |
296 | void *data = (void *) *(long *) __LC_PFAULT_INTPARM; | |
297 | u16 subcode = S390_lowcore.cpu_addr; | |
298 | ||
299 | if ((subcode & 0xff00) != VIRTIO_SUBCODE_64) | |
300 | return; | |
301 | ||
302 | vring_interrupt(0, data); | |
303 | } | |
304 | ||
305 | /* | |
306 | * Init function for virtio | |
307 | * devices are in a single page above top of "normal" mem | |
308 | */ | |
309 | static int __init kvm_devices_init(void) | |
310 | { | |
311 | int rc; | |
312 | ||
313 | if (!MACHINE_IS_KVM) | |
314 | return -ENODEV; | |
315 | ||
316 | rc = device_register(&kvm_root); | |
317 | if (rc) { | |
318 | printk(KERN_ERR "Could not register kvm_s390 root device"); | |
319 | return rc; | |
320 | } | |
321 | ||
17f34580 HC |
322 | rc = vmem_add_mapping(PFN_PHYS(max_pfn), PAGE_SIZE); |
323 | if (rc) { | |
e976a2b9 | 324 | device_unregister(&kvm_root); |
17f34580 | 325 | return rc; |
e976a2b9 CB |
326 | } |
327 | ||
17f34580 | 328 | kvm_devices = (void *) PFN_PHYS(max_pfn); |
e976a2b9 CB |
329 | |
330 | ctl_set_bit(0, 9); | |
331 | register_external_interrupt(0x2603, kvm_extint_handler); | |
332 | ||
333 | scan_devices(); | |
334 | return 0; | |
335 | } | |
336 | ||
faeba830 CB |
337 | /* code for early console output with virtio_console */ |
338 | static __init int early_put_chars(u32 vtermno, const char *buf, int count) | |
339 | { | |
340 | char scratch[17]; | |
341 | unsigned int len = count; | |
342 | ||
343 | if (len > sizeof(scratch) - 1) | |
344 | len = sizeof(scratch) - 1; | |
345 | scratch[len] = '\0'; | |
346 | memcpy(scratch, buf, len); | |
347 | kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, __pa(scratch)); | |
348 | return len; | |
349 | } | |
350 | ||
351 | void s390_virtio_console_init(void) | |
352 | { | |
353 | virtio_cons_early_init(early_put_chars); | |
354 | } | |
355 | ||
e976a2b9 CB |
356 | /* |
357 | * We do this after core stuff, but before the drivers. | |
358 | */ | |
359 | postcore_initcall(kvm_devices_init); |