linux/drivers/s390/kvm/kvm_virtio.c
Heinz Graalfs 46f9c2b925 virtio_ring: change host notification API
Currently a host kick error is silently ignored and not reflected in
the virtqueue of a particular virtio device.

Changing the notify API for guest->host notification seems to be one
prerequisite in order to be able to handle such errors in the context
where the kick is triggered.

This patch changes the notify API. The notify function must return a
bool return value. It returns false if the host notification failed.

Signed-off-by: Heinz Graalfs <graalfs@linux.vnet.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2013-10-29 11:28:11 +10:30

513 lines
12 KiB
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/kernel_stat.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/err.h>
#include <linux/virtio.h>
#include <linux/virtio_config.h>
#include <linux/slab.h>
#include <linux/virtio_console.h>
#include <linux/interrupt.h>
#include <linux/virtio_ring.h>
#include <linux/export.h>
#include <linux/pfn.h>
#include <asm/io.h>
#include <asm/kvm_para.h>
#include <asm/kvm_virtio.h>
#include <asm/sclp.h>
#include <asm/setup.h>
#include <asm/irq.h>
#define VIRTIO_SUBCODE_64 0x0D00
/*
* The pointer to our (page) of device descriptions.
*/
static void *kvm_devices;
static struct work_struct hotplug_work;
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 bool kvm_notify(struct virtqueue *vq)
{
long rc;
struct kvm_vqconfig *config = vq->priv;
rc = kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, config->address);
if (rc < 0)
return false;
return true;
}
/*
* 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),
const char *name)
{
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);
if (!name)
return NULL;
config = kvm_vq_config(kdev->desc)+index;
err = vmem_add_mapping(config->address,
vring_size(config->num,
KVM_S390_VIRTIO_RING_ALIGN));
if (err)
goto out;
vq = vring_new_virtqueue(index, config->num, KVM_S390_VIRTIO_RING_ALIGN,
vdev, true, (void *) config->address,
kvm_notify, callback, name);
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,
KVM_S390_VIRTIO_RING_ALIGN));
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,
KVM_S390_VIRTIO_RING_ALIGN));
}
static void kvm_del_vqs(struct virtio_device *vdev)
{
struct virtqueue *vq, *n;
list_for_each_entry_safe(vq, n, &vdev->vqs, list)
kvm_del_vq(vq);
}
static int kvm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
struct virtqueue *vqs[],
vq_callback_t *callbacks[],
const char *names[])
{
struct kvm_device *kdev = to_kvmdev(vdev);
int i;
/* We must have this many virtqueues. */
if (nvqs > kdev->desc->num_vq)
return -ENOENT;
for (i = 0; i < nvqs; ++i) {
vqs[i] = kvm_find_vq(vdev, i, callbacks[i], names[i]);
if (IS_ERR(vqs[i]))
goto error;
}
return 0;
error:
kvm_del_vqs(vdev);
return PTR_ERR(vqs[i]);
}
static const char *kvm_bus_name(struct virtio_device *vdev)
{
return "";
}
/*
* The config ops structure as defined by virtio config
*/
static const 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_vqs = kvm_find_vqs,
.del_vqs = kvm_del_vqs,
.bus_name = kvm_bus_name,
};
/*
* 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);
}
}
/*
* match for a kvm device with a specific desc pointer
*/
static int match_desc(struct device *dev, void *data)
{
struct virtio_device *vdev = dev_to_virtio(dev);
struct kvm_device *kdev = to_kvmdev(vdev);
return kdev->desc == data;
}
/*
* hotplug_device tries to find changes in the device page.
*/
static void hotplug_devices(struct work_struct *dummy)
{
unsigned int i;
struct kvm_device_desc *d;
struct device *dev;
for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
d = kvm_devices + i;
/* end of list */
if (d->type == 0)
break;
/* device already exists */
dev = device_find_child(kvm_root, d, match_desc);
if (dev) {
/* XXX check for hotplug remove */
put_device(dev);
continue;
}
/* new device */
printk(KERN_INFO "Adding new virtio device %p\n", d);
add_kvm_device(d, i);
}
}
/*
* we emulate the request_irq behaviour on top of s390 extints
*/
static void kvm_extint_handler(struct ext_code ext_code,
unsigned int param32, unsigned long param64)
{
struct virtqueue *vq;
u32 param;
if ((ext_code.subcode & 0xff00) != VIRTIO_SUBCODE_64)
return;
inc_irq_stat(IRQEXT_VRT);
/* The LSB might be overloaded, we have to mask it */
vq = (struct virtqueue *)(param64 & ~1UL);
/* We use ext_params to decide what this interrupt means */
param = param32 & VIRTIO_PARAM_MASK;
switch (param) {
case VIRTIO_PARAM_CONFIG_CHANGED:
{
struct virtio_driver *drv;
drv = container_of(vq->vdev->dev.driver,
struct virtio_driver, driver);
if (drv->config_changed)
drv->config_changed(vq->vdev);
break;
}
case VIRTIO_PARAM_DEV_ADD:
schedule_work(&hotplug_work);
break;
case VIRTIO_PARAM_VRING_INTERRUPT:
default:
vring_interrupt(0, vq);
break;
}
}
/*
* For s390-virtio, we expect a page above main storage containing
* the virtio configuration. Try to actually load from this area
* in order to figure out if the host provides this page.
*/
static int __init test_devices_support(unsigned long addr)
{
int ret = -EIO;
asm volatile(
"0: lura 0,%1\n"
"1: xgr %0,%0\n"
"2:\n"
EX_TABLE(0b,2b)
EX_TABLE(1b,2b)
: "+d" (ret)
: "a" (addr)
: "0", "cc");
return ret;
}
/*
* Init function for virtio
* devices are in a single page above top of "normal" + standby mem
*/
static int __init kvm_devices_init(void)
{
int rc;
unsigned long total_memory_size = sclp_get_rzm() * sclp_get_rnmax();
if (!MACHINE_IS_KVM)
return -ENODEV;
if (test_devices_support(total_memory_size) < 0)
return -ENODEV;
rc = vmem_add_mapping(total_memory_size, PAGE_SIZE);
if (rc)
return rc;
kvm_devices = (void *) total_memory_size;
kvm_root = root_device_register("kvm_s390");
if (IS_ERR(kvm_root)) {
rc = PTR_ERR(kvm_root);
printk(KERN_ERR "Could not register kvm_s390 root device");
vmem_remove_mapping(total_memory_size, PAGE_SIZE);
return rc;
}
INIT_WORK(&hotplug_work, hotplug_devices);
irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
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;
}
static int __init s390_virtio_console_init(void)
{
if (sclp_has_vt220() || sclp_has_linemode())
return -ENODEV;
return virtio_cons_early_init(early_put_chars);
}
console_initcall(s390_virtio_console_init);
/*
* We do this after core stuff, but before the drivers.
*/
postcore_initcall(kvm_devices_init);