LXR linux/virt/kvm/coalesced

   1/*
   2 * KVM coalesced MMIO
   3 *
   4 * Copyright (c) 2008 Bull S.A.S.
   5 *
   6 *  Author: Laurent Vivier <Laurent.Vivier@bull.net>
   7 *
   8 */
   9
  10#include "iodev.h"
  11
  12#include <linux/kvm_host.h>
  13#include <linux/kvm.h>
  14
  15#include "coalesced_mmio.h"
  16
  17static inline struct kvm_coalesced_mmio_dev *to_mmio(struct kvm_io_device *dev)
  18{
  19        return container_of(dev, struct kvm_coalesced_mmio_dev, dev);
  20}
  21
  22static int coalesced_mmio_in_range(struct kvm_coalesced_mmio_dev *dev,
  23                                   gpa_t addr, int len)
  24{
  25        struct kvm_coalesced_mmio_zone *zone;
  26        struct kvm_coalesced_mmio_ring *ring;
  27        unsigned avail;
  28        int i;
  29
  30        /* Are we able to batch it ? */
  31
  32        /* last is the first free entry
  33         * check if we don't meet the first used entry
  34         * there is always one unused entry in the buffer
  35         */
  36        ring = dev->kvm->coalesced_mmio_ring;
  37        avail = (ring->first - ring->last - 1) % KVM_COALESCED_MMIO_MAX;
  38        if (avail < KVM_MAX_VCPUS) {
  39                /* full */
  40                return 0;
  41        }
  42
  43        /* is it in a batchable area ? */
  44
  45        for (i = 0; i < dev->nb_zones; i++) {
  46                zone = &dev->zone[i];
  47
  48                /* (addr,len) is fully included in
  49                 * (zone->addr, zone->size)
  50                 */
  51
  52                if (zone->addr <= addr &&
  53                    addr + len <= zone->addr + zone->size)
  54                        return 1;
  55        }
  56        return 0;
  57}
  58
  59static int coalesced_mmio_write(struct kvm_io_device *this,
  60                                gpa_t addr, int len, const void *val)
  61{
  62        struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
  63        struct kvm_coalesced_mmio_ring *ring = dev->kvm->coalesced_mmio_ring;
  64        if (!coalesced_mmio_in_range(dev, addr, len))
  65                return -EOPNOTSUPP;
  66
  67        spin_lock(&dev->lock);
  68
  69        /* copy data in first free entry of the ring */
  70
  71        ring->coalesced_mmio[ring->last].phys_addr = addr;
  72        ring->coalesced_mmio[ring->last].len = len;
  73        memcpy(ring->coalesced_mmio[ring->last].data, val, len);
  74        smp_wmb();
  75        ring->last = (ring->last + 1) % KVM_COALESCED_MMIO_MAX;
  76        spin_unlock(&dev->lock);
  77        return 0;
  78}
  79
  80static void coalesced_mmio_destructor(struct kvm_io_device *this)
  81{
  82        struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
  83
  84        kfree(dev);
  85}
  86
  87static const struct kvm_io_device_ops coalesced_mmio_ops = {
  88        .write      = coalesced_mmio_write,
  89        .destructor = coalesced_mmio_destructor,
  90};
  91
  92int kvm_coalesced_mmio_init(struct kvm *kvm)
  93{
  94        struct kvm_coalesced_mmio_dev *dev;
  95        int ret;
  96
  97        dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), GFP_KERNEL);
  98        if (!dev)
  99                return -ENOMEM;
 100        spin_lock_init(&dev->lock);
 101        kvm_iodevice_init(&dev->dev, &coalesced_mmio_ops);
 102        dev->kvm = kvm;
 103        kvm->coalesced_mmio_dev = dev;
 104
 105        ret = kvm_io_bus_register_dev(kvm, &kvm->mmio_bus, &dev->dev);
 106        if (ret < 0)
 107                kfree(dev);
 108
 109        return ret;
 110}
 111
 112int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,
 113                                         struct kvm_coalesced_mmio_zone *zone)
 114{
 115        struct kvm_coalesced_mmio_dev *dev = kvm->coalesced_mmio_dev;
 116
 117        if (dev == NULL)
 118                return -EINVAL;
 119
 120        down_write(&kvm->slots_lock);
 121        if (dev->nb_zones >= KVM_COALESCED_MMIO_ZONE_MAX) {
 122                up_write(&kvm->slots_lock);
 123                return -ENOBUFS;
 124        }
 125
 126        dev->zone[dev->nb_zones] = *zone;
 127        dev->nb_zones++;
 128
 129        up_write(&kvm->slots_lock);
 130        return 0;
 131}
 132
 133int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
 134                                           struct kvm_coalesced_mmio_zone *zone)
 135{
 136        int i;
 137        struct kvm_coalesced_mmio_dev *dev = kvm->coalesced_mmio_dev;
 138        struct kvm_coalesced_mmio_zone *z;
 139
 140        if (dev == NULL)
 141                return -EINVAL;
 142
 143        down_write(&kvm->slots_lock);
 144
 145        i = dev->nb_zones;
 146        while(i) {
 147                z = &dev->zone[i - 1];
 148
 149                /* unregister all zones
 150                 * included in (zone->addr, zone->size)
 151                 */
 152
 153                if (zone->addr <= z->addr &&
 154                    z->addr + z->size <= zone->addr + zone->size) {
 155                        dev->nb_zones--;
 156                        *z = dev->zone[dev->nb_zones];
 157                }
 158                i--;
 159        }
 160
 161        up_write(&kvm->slots_lock);
 162
 163        return 0;
 164}
 165