virt/kvm/coalesced_mmio.c

   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
  17 static 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
  22 static 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
  59 static 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
  80 static 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
  87 static const struct kvm_io_device_ops coalesced_mmio_ops = {
  88         .write      = coalesced_mmio_write,
  89         .destructor = coalesced_mmio_destructor,
  90 };
  91
  92 int 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
 112 int 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
 133 int 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 }