diff options
Diffstat (limited to 'drivers/s390/kvm')
| -rw-r--r-- | drivers/s390/kvm/Makefile | 9 | ||||
| -rw-r--r-- | drivers/s390/kvm/kvm_virtio.c | 338 |
2 files changed, 347 insertions, 0 deletions
diff --git a/drivers/s390/kvm/Makefile b/drivers/s390/kvm/Makefile new file mode 100644 index 00000000000..4a5ec39f9ca --- /dev/null +++ b/drivers/s390/kvm/Makefile @@ -0,0 +1,9 @@ +# Makefile for kvm guest drivers 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. + +obj-$(CONFIG_VIRTIO) += kvm_virtio.o diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c new file mode 100644 index 00000000000..bbef3764fbf --- /dev/null +++ b/drivers/s390/kvm/kvm_virtio.c @@ -0,0 +1,338 @@ +/* + * 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/interrupt.h> +#include <linux/virtio_ring.h> +#include <asm/io.h> +#include <asm/kvm_para.h> +#include <asm/kvm_virtio.h> +#include <asm/setup.h> +#include <asm/s390_ext.h> + +#define VIRTIO_SUBCODE_64 0x0D00 + +/* + * The pointer to our (page) of device descriptions. + */ +static void *kvm_devices; + +/* + * Unique numbering for kvm devices. + */ +static unsigned int dev_index; + +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 tests (and acknowleges) a feature bit. + */ +static bool kvm_feature(struct virtio_device *vdev, unsigned fbit) +{ + struct kvm_device_desc *desc = to_kvmdev(vdev)->desc; + u8 *features; + + if (fbit / 8 > desc->feature_len) + return false; + + features = kvm_vq_features(desc); + if (!(features[fbit / 8] & (1 << (fbit % 8)))) + return false; + + /* + * We set the matching bit in the other half of the bitmap to tell the + * Host we want to use this feature. + */ + features[desc->feature_len + fbit / 8] |= (1 << (fbit % 8)); + return true; +} + +/* + * 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; + + if (add_shared_memory(config->address, + vring_size(config->num, PAGE_SIZE))) { + err = -ENOMEM; + 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: + remove_shared_memory(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); + remove_shared_memory(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 = { + .feature = kvm_feature, + .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 = { + .parent = NULL, + .bus_id = "kvm_s390", +}; + +/* + * 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) +{ + struct kvm_device *kdev; + + kdev = kzalloc(sizeof(*kdev), GFP_KERNEL); + if (!kdev) { + printk(KERN_EMERG "Cannot allocate kvm dev %u\n", + dev_index++); + return; + } + + kdev->vdev.dev.parent = &kvm_root; + kdev->vdev.index = dev_index++; + 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\n", + kdev->vdev.index); + 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); + } +} + +/* + * 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; + + rc = device_register(&kvm_root); + if (rc) { + printk(KERN_ERR "Could not register kvm_s390 root device"); + return rc; + } + + if (add_shared_memory((max_pfn) << PAGE_SHIFT, PAGE_SIZE)) { + device_unregister(&kvm_root); + return -ENOMEM; + } + + kvm_devices = (void *) (max_pfn << PAGE_SHIFT); + + ctl_set_bit(0, 9); + register_external_interrupt(0x2603, kvm_extint_handler); + + scan_devices(); + return 0; +} + +/* + * We do this after core stuff, but before the drivers. + */ +postcore_initcall(kvm_devices_init); |