virt/kvm/coalesced_mmio.c

   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 "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
  19 static 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
  24 static int coalesced_mmio_in_range(struct kvm_coalesced_mmio_dev *dev,
  25                                    gpa_t addr, int len)
  26 {
  27         struct kvm_coalesced_mmio_zone *zone;
  28         struct kvm_coalesced_mmio_ring *ring;
  29         unsigned avail;
  30         int i;
  31
  32         /* Are we able to batch it ? */
  33
  34         /* last is the first free entry
  35          * check if we don't meet the first used entry
  36          * there is always one unused entry in the buffer
  37          */
  38         ring = dev->kvm->coalesced_mmio_ring;
  39         avail = (ring->first - ring->last - 1) % KVM_COALESCED_MMIO_MAX;
  40         if (avail < KVM_MAX_VCPUS) {
  41                 /* full */
  42                 return 0;
  43         }
  44
  45         /* is it in a batchable area ? */
  46
  47         for (i = 0; i < dev->nb_zones; i++) {
  48                 zone = &dev->zone[i];
  49
  50                 /* (addr,len) is fully included in
  51                  * (zone->addr, zone->size)
  52                  */
  53
  54                 if (zone->addr <= addr &&
  55                     addr + len <= zone->addr + zone->size)
  56                         return 1;
  57         }
  58         return 0;
  59 }
  60
  61 static int coalesced_mmio_write(struct kvm_io_device *this,
  62                                 gpa_t addr, int len, const void *val)
  63 {
  64         struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
  65         struct kvm_coalesced_mmio_ring *ring = dev->kvm->coalesced_mmio_ring;
  66         if (!coalesced_mmio_in_range(dev, addr, len))
  67                 return -EOPNOTSUPP;
  68
  69         spin_lock(&dev->lock);
  70
  71         /* copy data in first free entry of the ring */
  72
  73         ring->coalesced_mmio[ring->last].phys_addr = addr;
  74         ring->coalesced_mmio[ring->last].len = len;
  75         memcpy(ring->coalesced_mmio[ring->last].data, val, len);
  76         smp_wmb();
  77         ring->last = (ring->last + 1) % KVM_COALESCED_MMIO_MAX;
  78         spin_unlock(&dev->lock);
  79         return 0;
  80 }
  81
  82 static void coalesced_mmio_destructor(struct kvm_io_device *this)
  83 {
  84         struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
  85
  86         kfree(dev);
  87 }
  88
  89 static const struct kvm_io_device_ops coalesced_mmio_ops = {
  90         .write      = coalesced_mmio_write,
  91         .destructor = coalesced_mmio_destructor,
  92 };
  93
  94 int kvm_coalesced_mmio_init(struct kvm *kvm)
  95 {
  96         struct kvm_coalesced_mmio_dev *dev;
  97         struct page *page;
  98         int ret;
  99
 100         ret = -ENOMEM;
 101         page = alloc_page(GFP_KERNEL | __GFP_ZERO);
 102         if (!page)
 103                 goto out_err;
 104         kvm->coalesced_mmio_ring = page_address(page);
 105
 106         ret = -ENOMEM;
 107         dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), GFP_KERNEL);
 108         if (!dev)
 109                 goto out_free_page;
 110         spin_lock_init(&dev->lock);
 111         kvm_iodevice_init(&dev->dev, &coalesced_mmio_ops);
 112         dev->kvm = kvm;
 113         kvm->coalesced_mmio_dev = dev;
 114
 115         mutex_lock(&kvm->slots_lock);
 116         ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, &dev->dev);
 117         mutex_unlock(&kvm->slots_lock);
 118         if (ret < 0)
 119                 goto out_free_dev;
 120
 121         return ret;
 122
 123 out_free_dev:
 124         kvm->coalesced_mmio_dev = NULL;
 125         kfree(dev);
 126 out_free_page:
 127         kvm->coalesced_mmio_ring = NULL;
 128         __free_page(page);
 129 out_err:
 130         return ret;
 131 }
 132
 133 void kvm_coalesced_mmio_free(struct kvm *kvm)
 134 {
 135         if (kvm->coalesced_mmio_ring)
 136                 free_page((unsigned long)kvm->coalesced_mmio_ring);
 137 }
 138
 139 int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,
 140                                          struct kvm_coalesced_mmio_zone *zone)
 141 {
 142         struct kvm_coalesced_mmio_dev *dev = kvm->coalesced_mmio_dev;
 143
 144         if (dev == NULL)
 145                 return -ENXIO;
 146
 147         mutex_lock(&kvm->slots_lock);
 148         if (dev->nb_zones >= KVM_COALESCED_MMIO_ZONE_MAX) {
 149                 mutex_unlock(&kvm->slots_lock);
 150                 return -ENOBUFS;
 151         }
 152
 153         dev->zone[dev->nb_zones] = *zone;
 154         dev->nb_zones++;
 155
 156         mutex_unlock(&kvm->slots_lock);
 157         return 0;
 158 }
 159
 160 int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
 161                                            struct kvm_coalesced_mmio_zone *zone)
 162 {
 163         int i;
 164         struct kvm_coalesced_mmio_dev *dev = kvm->coalesced_mmio_dev;
 165         struct kvm_coalesced_mmio_zone *z;
 166
 167         if (dev == NULL)
 168                 return -ENXIO;
 169
 170         mutex_lock(&kvm->slots_lock);
 171
 172         i = dev->nb_zones;
 173         while (i) {
 174                 z = &dev->zone[i - 1];
 175
 176                 /* unregister all zones
 177                  * included in (zone->addr, zone->size)
 178                  */
 179
 180                 if (zone->addr <= z->addr &&
 181                     z->addr + z->size <= zone->addr + zone->size) {
 182                         dev->nb_zones--;
 183                         *z = dev->zone[dev->nb_zones];
 184                 }
 185                 i--;
 186         }
 187
 188         mutex_unlock(&kvm->slots_lock);
 189
 190         return 0;
 191 }