2 * kvm_virtio.c - virtio for kvm on s390
4 * Copyright IBM Corp. 2008
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.
10 * Author(s): Christian Borntraeger <borntraeger@de.ibm.com>
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>
18 #include <linux/virtio_console.h>
19 #include <linux/interrupt.h>
20 #include <linux/virtio_ring.h>
21 #include <linux/pfn.h>
23 #include <asm/kvm_para.h>
24 #include <asm/kvm_virtio.h>
25 #include <asm/setup.h>
26 #include <asm/s390_ext.h>
28 #define VIRTIO_SUBCODE_64 0x0D00
31 * The pointer to our (page) of device descriptions.
33 static void *kvm_devices;
36 struct virtio_device vdev;
37 struct kvm_device_desc *desc;
40 #define to_kvmdev(vd) container_of(vd, struct kvm_device, vdev)
44 * - kvm_device_descriptor
45 * struct kvm_device_desc
51 static struct kvm_vqconfig *kvm_vq_config(const struct kvm_device_desc *desc)
53 return (struct kvm_vqconfig *)(desc + 1);
56 static u8 *kvm_vq_features(const struct kvm_device_desc *desc)
58 return (u8 *)(kvm_vq_config(desc) + desc->num_vq);
61 static u8 *kvm_vq_configspace(const struct kvm_device_desc *desc)
63 return kvm_vq_features(desc) + desc->feature_len * 2;
67 * The total size of the config page used by this device (incl. desc)
69 static unsigned desc_size(const struct kvm_device_desc *desc)
72 + desc->num_vq * sizeof(struct kvm_vqconfig)
73 + desc->feature_len * 2
77 /* This gets the device's feature bits. */
78 static u32 kvm_get_features(struct virtio_device *vdev)
82 struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
83 u8 *in_features = kvm_vq_features(desc);
85 for (i = 0; i < min(desc->feature_len * 8, 32); i++)
86 if (in_features[i / 8] & (1 << (i % 8)))
91 static void kvm_set_features(struct virtio_device *vdev, u32 features)
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;
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));
106 * Reading and writing elements in config space
108 static void kvm_get(struct virtio_device *vdev, unsigned int offset,
109 void *buf, unsigned len)
111 struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
113 BUG_ON(offset + len > desc->config_len);
114 memcpy(buf, kvm_vq_configspace(desc) + offset, len);
117 static void kvm_set(struct virtio_device *vdev, unsigned int offset,
118 const void *buf, unsigned len)
120 struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
122 BUG_ON(offset + len > desc->config_len);
123 memcpy(kvm_vq_configspace(desc) + offset, buf, len);
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
131 static u8 kvm_get_status(struct virtio_device *vdev)
133 return to_kvmdev(vdev)->desc->status;
136 static void kvm_set_status(struct virtio_device *vdev, u8 status)
139 to_kvmdev(vdev)->desc->status = status;
140 kvm_hypercall1(KVM_S390_VIRTIO_SET_STATUS,
141 (unsigned long) to_kvmdev(vdev)->desc);
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
149 static void kvm_reset(struct virtio_device *vdev)
151 kvm_hypercall1(KVM_S390_VIRTIO_RESET,
152 (unsigned long) to_kvmdev(vdev)->desc);
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.
160 static void kvm_notify(struct virtqueue *vq)
162 struct kvm_vqconfig *config = vq->priv;
164 kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, config->address);
168 * This routine finds the first virtqueue described in the configuration of
169 * this device and sets it up.
171 static struct virtqueue *kvm_find_vq(struct virtio_device *vdev,
173 void (*callback)(struct virtqueue *vq))
175 struct kvm_device *kdev = to_kvmdev(vdev);
176 struct kvm_vqconfig *config;
177 struct virtqueue *vq;
180 if (index >= kdev->desc->num_vq)
181 return ERR_PTR(-ENOENT);
183 config = kvm_vq_config(kdev->desc)+index;
185 err = vmem_add_mapping(config->address,
186 vring_size(config->num, PAGE_SIZE));
190 vq = vring_new_virtqueue(config->num, vdev, (void *) config->address,
191 kvm_notify, callback);
198 * register a callback token
199 * The host will sent this via the external interrupt parameter
201 config->token = (u64) vq;
206 vmem_remove_mapping(config->address,
207 vring_size(config->num, PAGE_SIZE));
212 static void kvm_del_vq(struct virtqueue *vq)
214 struct kvm_vqconfig *config = vq->priv;
216 vring_del_virtqueue(vq);
217 vmem_remove_mapping(config->address,
218 vring_size(config->num, PAGE_SIZE));
222 * The config ops structure as defined by virtio config
224 static struct virtio_config_ops kvm_vq_configspace_ops = {
225 .get_features = kvm_get_features,
226 .set_features = kvm_set_features,
229 .get_status = kvm_get_status,
230 .set_status = kvm_set_status,
232 .find_vq = kvm_find_vq,
233 .del_vq = kvm_del_vq,
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.
240 static struct device kvm_root = {
242 .bus_id = "kvm_s390",
246 * adds a new device and register it with virtio
247 * appropriate drivers are loaded by the device model
249 static void add_kvm_device(struct kvm_device_desc *d, unsigned int offset)
251 struct kvm_device *kdev;
253 kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
255 printk(KERN_EMERG "Cannot allocate kvm dev %u type %u\n",
260 kdev->vdev.dev.parent = &kvm_root;
261 kdev->vdev.id.device = d->type;
262 kdev->vdev.config = &kvm_vq_configspace_ops;
265 if (register_virtio_device(&kdev->vdev) != 0) {
266 printk(KERN_ERR "Failed to register kvm device %u type %u\n",
273 * scan_devices() simply iterates through the device page.
274 * The type 0 is reserved to mean "end of devices".
276 static void scan_devices(void)
279 struct kvm_device_desc *d;
281 for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
287 add_kvm_device(d, i);
292 * we emulate the request_irq behaviour on top of s390 extints
294 static void kvm_extint_handler(u16 code)
296 void *data = (void *) *(long *) __LC_PFAULT_INTPARM;
297 u16 subcode = S390_lowcore.cpu_addr;
299 if ((subcode & 0xff00) != VIRTIO_SUBCODE_64)
302 vring_interrupt(0, data);
306 * Init function for virtio
307 * devices are in a single page above top of "normal" mem
309 static int __init kvm_devices_init(void)
316 rc = device_register(&kvm_root);
318 printk(KERN_ERR "Could not register kvm_s390 root device");
322 rc = vmem_add_mapping(PFN_PHYS(max_pfn), PAGE_SIZE);
324 device_unregister(&kvm_root);
328 kvm_devices = (void *) PFN_PHYS(max_pfn);
331 register_external_interrupt(0x2603, kvm_extint_handler);
337 /* code for early console output with virtio_console */
338 static __init int early_put_chars(u32 vtermno, const char *buf, int count)
341 unsigned int len = count;
343 if (len > sizeof(scratch) - 1)
344 len = sizeof(scratch) - 1;
346 memcpy(scratch, buf, len);
347 kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, __pa(scratch));
351 void s390_virtio_console_init(void)
353 virtio_cons_early_init(early_put_chars);
357 * We do this after core stuff, but before the drivers.
359 postcore_initcall(kvm_devices_init);