/* * 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 u64 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 int 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); /* Make sure we don't have any features > 32 bits! */ BUG_ON((u32)vdev->features != vdev->features); 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 (__virtio_test_bit(vdev, i)) out_features[i / 8] |= (1 << (i % 8)); } return 0; } /* * 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 * const 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: virtio_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.rzm * sclp.rnmax; if (!MACHINE_IS_KVM) return -ENODEV; if (test_devices_support(total_memory_size) < 0) return -ENODEV; pr_warn("The s390-virtio transport is deprecated. Please switch to a modern host providing virtio-ccw.\n"); 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_irq(EXT_IRQ_CP_SERVICE, kvm_extint_handler); scan_devices(); return 0; } /* code for early console output with virtio_console */ static 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);