/*
* kvm_virtio.c - virtio for kvm on s390
*
* Copyright IBM Corp. 2008
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License (version 2 only)
* as published by the Free Software Foundation.
*
* Author(s): Christian Borntraeger <borntraeger@de.ibm.com>
*/
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/err.h>
#include <linux/virtio.h>
#include <linux/virtio_config.h>
#include <linux/virtio_console.h>
#include <linux/interrupt.h>
#include <linux/virtio_ring.h>
#include <linux/pfn.h>
#include <asm/io.h>
#include <asm/kvm_para.h>
#include <asm/kvm_virtio.h>
#include <asm/setup.h>
#include <asm/s390_ext.h>
#include <asm/s390_rdev.h>
#define VIRTIO_SUBCODE_64 0x0D00
/*
* The pointer to our (page) of device descriptions.
*/
static void *kvm_devices;
struct kvm_device {
struct virtio_device vdev;
struct kvm_device_desc *desc;
};
#define to_kvmdev(vd) container_of(vd, struct kvm_device, vdev)
/*
* memory layout:
* - kvm_device_descriptor
* struct kvm_device_desc
* - configuration
* struct kvm_vqconfig
* - feature bits
* - config space
*/
static struct kvm_vqconfig *kvm_vq_config(const struct kvm_device_desc *desc)
{
return (struct kvm_vqconfig *)(desc + 1);
}
static u8 *kvm_vq_features(const struct kvm_device_desc *desc)
{
return (u8 *)(kvm_vq_config(desc) + desc->num_vq);
}
static u8 *kvm_vq_configspace(const struct kvm_device_desc *desc)
{
return kvm_vq_features(desc) + desc->feature_len * 2;
}
/*
* The total size of the config page used by this device (incl. desc)
*/
static unsigned desc_size(const struct kvm_device_desc *desc)
{
return sizeof(*desc)
+ desc->num_vq * sizeof(struct kvm_vqconfig)
+ desc->feature_len * 2
+ desc->config_len;
}
/* This gets the device's feature bits. */
static u32 kvm_get_features(struct virtio_device *vdev)
{
unsigned int i;
u32 features = 0;
struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
u8 *in_features = kvm_vq_features(desc);
for (i = 0; i < min(desc->feature_len * 8, 32); i++)
if (in_features[i / 8] & (1 << (i % 8)))
features |= (1 << i);
return features;
}
static void kvm_finalize_features(struct virtio_device *vdev)
{
unsigned int i, bits;
struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
/* Second half of bitmap is features we accept. */
u8 *out_features = kvm_vq_features(desc) + desc->feature_len;
/* Give virtio_ring a chance to accept features. */
vring_transport_features(vdev);
memset(out_features, 0, desc->feature_len);
bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
for (i = 0; i < bits; i++) {
if (test_bit(i, vdev->features))
out_features[i / 8] |= (1 << (i % 8));
}
}
/*
* Reading and writing elements in config space
*/
static void kvm_get(struct virtio_device *vdev, unsigned int offset,
void *buf, unsigned len)
{
struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
BUG_ON(offset + len > desc->config_len);
memcpy(buf, kvm_vq_configspace(desc) + offset, len);
}
static void kvm_set(struct virtio_device *vdev, unsigned int offset,
const void *buf, unsigned len)
{
struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
BUG_ON(offset + len > desc->config_len);
memcpy(kvm_vq_configspace(desc) + offset, buf, len);
}
/*
* The operations to get and set the status word just access
* the status field of the device descriptor. set_status will also
* make a hypercall to the host, to tell about status changes
*/
static u8 kvm_get_status(struct virtio_device *vdev)
{
return to_kvmdev(vdev)->desc->status;
}
static void kvm_set_status(struct virtio_device *vdev, u8 status)
{
BUG_ON(!status);
to_kvmdev(vdev)->desc->status = status;
kvm_hypercall1(KVM_S390_VIRTIO_SET_STATUS,
(unsigned long) to_kvmdev(vdev)->desc);
}
/*
* To reset the device, we use the KVM_VIRTIO_RESET hypercall, using the
* descriptor address. The Host will zero the status and all the
* features.
*/
static void kvm_reset(struct virtio_device *vdev)
{
kvm_hypercall1(KVM_S390_VIRTIO_RESET,
(unsigned long) to_kvmdev(vdev)->desc);
}
/*
* When the virtio_ring code wants to notify the Host, it calls us here and we
* make a hypercall. We hand the address of the virtqueue so the Host
* knows which virtqueue we're talking about.
*/
static void kvm_notify(struct virtqueue *vq)
{
struct kvm_vqconfig *config = vq->priv;
kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, config->address);
}
/*
* This routine finds the first virtqueue described in the configuration of
* this device and sets it up.
*/
static struct virtqueue *kvm_find_vq(struct virtio_device *vdev,
unsigned index,
void (*callback)(struct virtqueue *vq))
{
struct kvm_device *kdev = to_kvmdev(vdev);
struct kvm_vqconfig *config;
struct virtqueue *vq;
int err;
if (index >= kdev->desc->num_vq)
return ERR_PTR(-ENOENT);
config = kvm_vq_config(kdev->desc)+index;
err = vmem_add_mapping(config->address,
vring_size(config->num, PAGE_SIZE));
if (err)
goto out;
vq = vring_new_virtqueue(config->num, vdev, (void *) config->address,
kvm_notify, callback);
if (!vq) {
err = -ENOMEM;
goto unmap;
}
/*
* register a callback token
* The host will sent this via the external interrupt parameter
*/
config->token = (u64) vq;
vq->priv = config;
return vq;
unmap:
vmem_remove_mapping(config->address,
vring_size(config->num, PAGE_SIZE));
out:
return ERR_PTR(err);
}
static void kvm_del_vq(struct virtqueue *vq)
{
struct kvm_vqconfig *config = vq->priv;
vring_del_virtqueue(vq);
vmem_remove_mapping(config->address,
vring_size(config->num, PAGE_SIZE));
}
/*
* The config ops structure as defined by virtio config
*/
static struct virtio_config_ops kvm_vq_configspace_ops = {
.get_features = kvm_get_features,
.finalize_features = kvm_finalize_features,
.get = kvm_get,
.set = kvm_set,
.get_status = kvm_get_status,
.set_status = kvm_set_status,
.reset = kvm_reset,
.find_vq = kvm_find_vq,
.del_vq = kvm_del_vq,
};
/*
* The root device for the kvm virtio devices.
* This makes them appear as /sys/devices/kvm_s390/0,1,2 not /sys/devices/0,1,2.
*/
static struct device *kvm_root;
/*
* adds a new device and register it with virtio
* appropriate drivers are loaded by the device model
*/
static void add_kvm_device(struct kvm_device_desc *d, unsigned int offset)
{
struct kvm_device *kdev;
kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
if (!kdev) {
printk(KERN_EMERG "Cannot allocate kvm dev %u type %u\n",
offset, d->type);
return;
}
kdev->vdev.dev.parent = kvm_root;
kdev->vdev.id.device = d->type;
kdev->vdev.config = &kvm_vq_configspace_ops;
kdev->desc = d;
if (register_virtio_device(&kdev->vdev) != 0) {
printk(KERN_ERR "Failed to register kvm device %u type %u\n",
offset, d->type);
kfree(kdev);
}
}
/*
* scan_devices() simply iterates through the device page.
* The type 0 is reserved to mean "end of devices".
*/
static void scan_devices(void)
{
unsigned int i;
struct kvm_device_desc *d;
for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
d = kvm_devices + i;
if (d->type == 0)
break;
add_kvm_device(d, i);
}
}
/*
* we emulate the request_irq behaviour on top of s390 extints
*/
static void kvm_extint_handler(u16 code)
{
void *data = (void *) *(long *) __LC_PFAULT_INTPARM;
u16 subcode = S390_lowcore.cpu_addr;
if ((subcode & 0xff00) != VIRTIO_SUBCODE_64)
return;
vring_interrupt(0, data);
}
/*
* Init function for virtio
* devices are in a single page above top of "normal" mem
*/
static int __init kvm_devices_init(void)
{
int rc;
if (!MACHINE_IS_KVM)
return -ENODEV;
kvm_root = s390_root_dev_register("kvm_s390");
if (IS_ERR(kvm_root)) {
rc = PTR_ERR(kvm_root);
printk(KERN_ERR "Could not register kvm_s390 root device");
return rc;
}
rc = vmem_add_mapping(PFN_PHYS(max_pfn), PAGE_SIZE);
if (rc) {
s390_root_dev_unregister(kvm_root);
return rc;
}
kvm_devices = (void *) PFN_PHYS(max_pfn);
ctl_set_bit(0, 9);
register_external_interrupt(0x2603, kvm_extint_handler);
scan_devices();
return 0;
}
/* code for early console output with virtio_console */
static __init int early_put_chars(u32 vtermno, const char *buf, int count)
{
char scratch[17];
unsigned int len = count;
if (len > sizeof(scratch) - 1)
len = sizeof(scratch) - 1;
scratch[len] = '\0';
memcpy(scratch, buf, len);
kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, __pa(scratch));
return len;
}
void __init s390_virtio_console_init(void)
{
virtio_cons_early_init(early_put_chars);
}
/*
* We do this after core stuff, but before the drivers.
*/
postcore_initcall(kvm_devices_init);
