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 int coalesced_mmio_in_range(struct kvm_io_device *this,
  18                                   gpa_t addr, int len, int is_write)
  19{
  20        struct kvm_coalesced_mmio_dev *dev =
  21                                (struct kvm_coalesced_mmio_dev*)this->private;
  22        struct kvm_coalesced_mmio_zone *zone;
  23        int next;
  24        int i;
  25
  26        if (!is_write)
  27                return 0;
  28
  29        /* kvm->lock is taken by the caller and must be not released before
  30         * dev.read/write
  31         */
  32
  33        /* Are we able to batch it ? */
  34
  35        /* last is the first free entry
  36         * check if we don't meet the first used entry
  37         * there is always one unused entry in the buffer
  38         */
  39
  40        next = (dev->kvm->coalesced_mmio_ring->last + 1) %
  41                                                        KVM_COALESCED_MMIO_MAX;
  42        if (next == dev->kvm->coalesced_mmio_ring->first) {
  43                /* full */
  44                return 0;
  45        }
  46
  47        /* is it in a batchable area ? */
  48
  49        for (i = 0; i < dev->nb_zones; i++) {
  50                zone = &dev->zone[i];
  51
  52                /* (addr,len) is fully included in
  53                 * (zone->addr, zone->size)
  54                 */
  55
  56                if (zone->addr <= addr &&
  57                    addr + len <= zone->addr + zone->size)
  58                        return 1;
  59        }
  60        return 0;
  61}
  62
  63static void coalesced_mmio_write(struct kvm_io_device *this,
  64                                 gpa_t addr, int len, const void *val)
  65{
  66        struct kvm_coalesced_mmio_dev *dev =
  67                                (struct kvm_coalesced_mmio_dev*)this->private;
  68        struct kvm_coalesced_mmio_ring *ring = dev->kvm->coalesced_mmio_ring;
  69
  70        /* kvm->lock must be taken by caller before call to in_range()*/
  71
  72        /* copy data in first free entry of the ring */
  73
  74        ring->coalesced_mmio[ring->last].phys_addr = addr;
  75        ring->coalesced_mmio[ring->last].len = len;
  76        memcpy(ring->coalesced_mmio[ring->last].data, val, len);
  77        smp_wmb();
  78        ring->last = (ring->last + 1) % KVM_COALESCED_MMIO_MAX;
  79}
  80
  81static void coalesced_mmio_destructor(struct kvm_io_device *this)
  82{
  83        kfree(this);
  84}
  85
  86int kvm_coalesced_mmio_init(struct kvm *kvm)
  87{
  88        struct kvm_coalesced_mmio_dev *dev;
  89
  90        dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), GFP_KERNEL);
  91        if (!dev)
  92                return -ENOMEM;
  93        dev->dev.write  = coalesced_mmio_write;
  94        dev->dev.in_range  = coalesced_mmio_in_range;
  95        dev->dev.destructor  = coalesced_mmio_destructor;
  96        dev->dev.private  = dev;
  97        dev->kvm = kvm;
  98        kvm->coalesced_mmio_dev = dev;
  99        kvm_io_bus_register_dev(&kvm->mmio_bus, &dev->dev);
 100
 101        return 0;
 102}
 103
 104int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,
 105                                         struct kvm_coalesced_mmio_zone *zone)
 106{
 107        struct kvm_coalesced_mmio_dev *dev = kvm->coalesced_mmio_dev;
 108
 109        if (dev == NULL)
 110                return -EINVAL;
 111
 112        mutex_lock(&kvm->lock);
 113        if (dev->nb_zones >= KVM_COALESCED_MMIO_ZONE_MAX) {
 114                mutex_unlock(&kvm->lock);
 115                return -ENOBUFS;
 116        }
 117
 118        dev->zone[dev->nb_zones] = *zone;
 119        dev->nb_zones++;
 120
 121        mutex_unlock(&kvm->lock);
 122        return 0;
 123}
 124
 125int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
 126                                           struct kvm_coalesced_mmio_zone *zone)
 127{
 128        int i;
 129        struct kvm_coalesced_mmio_dev *dev = kvm->coalesced_mmio_dev;
 130        struct kvm_coalesced_mmio_zone *z;
 131
 132        if (dev == NULL)
 133                return -EINVAL;
 134
 135        mutex_lock(&kvm->lock);
 136
 137        i = dev->nb_zones;
 138        while(i) {
 139                z = &dev->zone[i - 1];
 140
 141                /* unregister all zones
 142                 * included in (zone->addr, zone->size)
 143                 */
 144
 145                if (zone->addr <= z->addr &&
 146                    z->addr + z->size <= zone->addr + zone->size) {
 147                        dev->nb_zones--;
 148                        *z = dev->zone[dev->nb_zones];
 149                }
 150                i--;
 151        }
 152
 153        mutex_unlock(&kvm->lock);
 154
 155        return 0;
 156}
 157