LXR linux/virt/kvm/coalesced

   1/*
   2 * KVM coalesced MMIO
   3 *
   4 * Copyright (c) 2008 Bull S.A.S.
   5 * Copyright 2009 Red Hat, Inc. and/or its affiliates.
   6 *
   7 *  Author: Laurent Vivier <Laurent.Vivier@bull.net>
   8 *
   9 */
  10
  11#include <kvm/iodev.h>
  12
  13#include <linux/kvm_host.h>
  14#include <linux/slab.h>
  15#include <linux/kvm.h>
  16
  17#include "coalesced_mmio.h"
  18
  19static inline struct kvm_coalesced_mmio_dev *to_mmio(struct kvm_io_device *dev)
  20{
  21        return container_of(dev, struct kvm_coalesced_mmio_dev, dev);
  22}
  23
  24static int coalesced_mmio_in_range(struct kvm_coalesced_mmio_dev *dev,
  25                                   gpa_t addr, int len)
  26{
  27        /* is it in a batchable area ?
  28         * (addr,len) is fully included in
  29         * (zone->addr, zone->size)
  30         */
  31        if (len < 0)
  32                return 0;
  33        if (addr + len < addr)
  34                return 0;
  35        if (addr < dev->zone.addr)
  36                return 0;
  37        if (addr + len > dev->zone.addr + dev->zone.size)
  38                return 0;
  39        return 1;
  40}
  41
  42static int coalesced_mmio_has_room(struct kvm_coalesced_mmio_dev *dev)
  43{
  44        struct kvm_coalesced_mmio_ring *ring;
  45        unsigned avail;
  46
  47        /* Are we able to batch it ? */
  48
  49        /* last is the first free entry
  50         * check if we don't meet the first used entry
  51         * there is always one unused entry in the buffer
  52         */
  53        ring = dev->kvm->coalesced_mmio_ring;
  54        avail = (ring->first - ring->last - 1) % KVM_COALESCED_MMIO_MAX;
  55        if (avail == 0) {
  56                /* full */
  57                return 0;
  58        }
  59
  60        return 1;
  61}
  62
  63static int coalesced_mmio_write(struct kvm_vcpu *vcpu,
  64                                struct kvm_io_device *this, gpa_t addr,
  65                                int len, const void *val)
  66{
  67        struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
  68        struct kvm_coalesced_mmio_ring *ring = dev->kvm->coalesced_mmio_ring;
  69
  70        if (!coalesced_mmio_in_range(dev, addr, len))
  71                return -EOPNOTSUPP;
  72
  73        spin_lock(&dev->kvm->ring_lock);
  74
  75        if (!coalesced_mmio_has_room(dev)) {
  76                spin_unlock(&dev->kvm->ring_lock);
  77                return -EOPNOTSUPP;
  78        }
  79
  80        /* copy data in first free entry of the ring */
  81
  82        ring->coalesced_mmio[ring->last].phys_addr = addr;
  83        ring->coalesced_mmio[ring->last].len = len;
  84        memcpy(ring->coalesced_mmio[ring->last].data, val, len);
  85        smp_wmb();
  86        ring->last = (ring->last + 1) % KVM_COALESCED_MMIO_MAX;
  87        spin_unlock(&dev->kvm->ring_lock);
  88        return 0;
  89}
  90
  91static void coalesced_mmio_destructor(struct kvm_io_device *this)
  92{
  93        struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
  94
  95        list_del(&dev->list);
  96
  97        kfree(dev);
  98}
  99
 100static const struct kvm_io_device_ops coalesced_mmio_ops = {
 101        .write      = coalesced_mmio_write,
 102        .destructor = coalesced_mmio_destructor,
 103};
 104
 105int kvm_coalesced_mmio_init(struct kvm *kvm)
 106{
 107        struct page *page;
 108        int ret;
 109
 110        ret = -ENOMEM;
 111        page = alloc_page(GFP_KERNEL | __GFP_ZERO);
 112        if (!page)
 113                goto out_err;
 114
 115        ret = 0;
 116        kvm->coalesced_mmio_ring = page_address(page);
 117
 118        /*
 119         * We're using this spinlock to sync access to the coalesced ring.
 120         * The list doesn't need it's own lock since device registration and
 121         * unregistration should only happen when kvm->slots_lock is held.
 122         */
 123        spin_lock_init(&kvm->ring_lock);
 124        INIT_LIST_HEAD(&kvm->coalesced_zones);
 125
 126out_err:
 127        return ret;
 128}
 129
 130void kvm_coalesced_mmio_free(struct kvm *kvm)
 131{
 132        if (kvm->coalesced_mmio_ring)
 133                free_page((unsigned long)kvm->coalesced_mmio_ring);
 134}
 135
 136int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,
 137                                         struct kvm_coalesced_mmio_zone *zone)
 138{
 139        int ret;
 140        struct kvm_coalesced_mmio_dev *dev;
 141
 142        dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), GFP_KERNEL);
 143        if (!dev)
 144                return -ENOMEM;
 145
 146        kvm_iodevice_init(&dev->dev, &coalesced_mmio_ops);
 147        dev->kvm = kvm;
 148        dev->zone = *zone;
 149
 150        mutex_lock(&kvm->slots_lock);
 151        ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, zone->addr,
 152                                      zone->size, &dev->dev);
 153        if (ret < 0)
 154                goto out_free_dev;
 155        list_add_tail(&dev->list, &kvm->coalesced_zones);
 156        mutex_unlock(&kvm->slots_lock);
 157
 158        return 0;
 159
 160out_free_dev:
 161        mutex_unlock(&kvm->slots_lock);
 162        kfree(dev);
 163
 164        return ret;
 165}
 166
 167int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
 168                                           struct kvm_coalesced_mmio_zone *zone)
 169{
 170        struct kvm_coalesced_mmio_dev *dev, *tmp;
 171
 172        mutex_lock(&kvm->slots_lock);
 173
 174        list_for_each_entry_safe(dev, tmp, &kvm->coalesced_zones, list)
 175                if (coalesced_mmio_in_range(dev, zone->addr, zone->size)) {
 176                        kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS, &dev->dev);
 177                        kvm_iodevice_destructor(&dev->dev);
 178                }
 179
 180        mutex_unlock(&kvm->slots_lock);
 181
 182        return 0;
 183}
 184