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/slab.h>
  14 #include <linux/kvm.h>
  15
  16 #include "coalesced_mmio.h"
  17
  18 static inline struct kvm_coalesced_mmio_dev *to_mmio(struct kvm_io_device *dev)
  19 {
  20         return container_of(dev, struct kvm_coalesced_mmio_dev, dev);
  21 }
  22
  23 static int coalesced_mmio_in_range(struct kvm_coalesced_mmio_dev *dev,
  24                                    gpa_t addr, int len)
  25 {
  26         struct kvm_coalesced_mmio_zone *zone;
  27         struct kvm_coalesced_mmio_ring *ring;
  28         unsigned avail;
  29         int i;
  30
  31         /* Are we able to batch it ? */
  32
  33         /* last is the first free entry
  34          * check if we don't meet the first used entry
  35          * there is always one unused entry in the buffer
  36          */
  37         ring = dev->kvm->coalesced_mmio_ring;
  38         avail = (ring->first - ring->last - 1) % KVM_COALESCED_MMIO_MAX;
  39         if (avail < KVM_MAX_VCPUS) {
  40                 /* full */
  41                 return 0;
  42         }
  43
  44         /* is it in a batchable area ? */
  45
  46         for (i = 0; i < dev->nb_zones; i++) {
  47                 zone = &dev->zone[i];
  48
  49                 /* (addr,len) is fully included in
  50                  * (zone->addr, zone->size)
  51                  */
  52
  53                 if (zone->addr <= addr &&
  54                     addr + len <= zone->addr + zone->size)
  55                         return 1;
  56         }
  57         return 0;
  58 }
  59
  60 static int coalesced_mmio_write(struct kvm_io_device *this,
  61                                 gpa_t addr, int len, const void *val)
  62 {
  63         struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
  64         struct kvm_coalesced_mmio_ring *ring = dev->kvm->coalesced_mmio_ring;
  65         if (!coalesced_mmio_in_range(dev, addr, len))
  66                 return -EOPNOTSUPP;
  67
  68         spin_lock(&dev->lock);
  69
  70         /* copy data in first free entry of the ring */
  71
  72         ring->coalesced_mmio[ring->last].phys_addr = addr;
  73         ring->coalesced_mmio[ring->last].len = len;
  74         memcpy(ring->coalesced_mmio[ring->last].data, val, len);
  75         smp_wmb();
  76         ring->last = (ring->last + 1) % KVM_COALESCED_MMIO_MAX;
  77         spin_unlock(&dev->lock);
  78         return 0;
  79 }
  80
  81 static void coalesced_mmio_destructor(struct kvm_io_device *this)
  82 {
  83         struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
  84
  85         kfree(dev);
  86 }
  87
  88 static const struct kvm_io_device_ops coalesced_mmio_ops = {
  89         .write      = coalesced_mmio_write,
  90         .destructor = coalesced_mmio_destructor,
  91 };
  92
  93 int kvm_coalesced_mmio_init(struct kvm *kvm)
  94 {
  95         struct kvm_coalesced_mmio_dev *dev;
  96         struct page *page;
  97         int ret;
  98
  99         ret = -ENOMEM;
 100         page = alloc_page(GFP_KERNEL | __GFP_ZERO);
 101         if (!page)
 102                 goto out_err;
 103         kvm->coalesced_mmio_ring = page_address(page);
 104
 105         ret = -ENOMEM;
 106         dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), GFP_KERNEL);
 107         if (!dev)
 108                 goto out_free_page;
 109         spin_lock_init(&dev->lock);
 110         kvm_iodevice_init(&dev->dev, &coalesced_mmio_ops);
 111         dev->kvm = kvm;
 112         kvm->coalesced_mmio_dev = dev;
 113
 114         mutex_lock(&kvm->slots_lock);
 115         ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, &dev->dev);
 116         mutex_unlock(&kvm->slots_lock);
 117         if (ret < 0)
 118                 goto out_free_dev;
 119
 120         return ret;
 121
 122 out_free_dev:
 123         kvm->coalesced_mmio_dev = NULL;
 124         kfree(dev);
 125 out_free_page:
 126         kvm->coalesced_mmio_ring = NULL;
 127         __free_page(page);
 128 out_err:
 129         return ret;
 130 }
 131
 132 void kvm_coalesced_mmio_free(struct kvm *kvm)
 133 {
 134         if (kvm->coalesced_mmio_ring)
 135                 free_page((unsigned long)kvm->coalesced_mmio_ring);
 136 }
 137
 138 int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,
 139                                          struct kvm_coalesced_mmio_zone *zone)
 140 {
 141         struct kvm_coalesced_mmio_dev *dev = kvm->coalesced_mmio_dev;
 142
 143         if (dev == NULL)
 144                 return -ENXIO;
 145
 146         mutex_lock(&kvm->slots_lock);
 147         if (dev->nb_zones >= KVM_COALESCED_MMIO_ZONE_MAX) {
 148                 mutex_unlock(&kvm->slots_lock);
 149                 return -ENOBUFS;
 150         }
 151
 152         dev->zone[dev->nb_zones] = *zone;
 153         dev->nb_zones++;
 154
 155         mutex_unlock(&kvm->slots_lock);
 156         return 0;
 157 }
 158
 159 int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
 160                                            struct kvm_coalesced_mmio_zone *zone)
 161 {
 162         int i;
 163         struct kvm_coalesced_mmio_dev *dev = kvm->coalesced_mmio_dev;
 164         struct kvm_coalesced_mmio_zone *z;
 165
 166         if (dev == NULL)
 167                 return -ENXIO;
 168
 169         mutex_lock(&kvm->slots_lock);
 170
 171         i = dev->nb_zones;
 172         while (i) {
 173                 z = &dev->zone[i - 1];
 174
 175                 /* unregister all zones
 176                  * included in (zone->addr, zone->size)
 177                  */
 178
 179                 if (zone->addr <= z->addr &&
 180                     z->addr + z->size <= zone->addr + zone->size) {
 181                         dev->nb_zones--;
 182                         *z = dev->zone[dev->nb_zones];
 183                 }
 184                 i--;
 185         }
 186
 187         mutex_unlock(&kvm->slots_lock);
 188
 189         return 0;
 190 }