LXR linux/virt/kvm/coalesced

   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
  19static 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
  24static 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
  61static 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
  82static 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
  89static const struct kvm_io_device_ops coalesced_mmio_ops = {
  90        .write      = coalesced_mmio_write,
  91        .destructor = coalesced_mmio_destructor,
  92};
  93
  94int 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
 123out_free_dev:
 124        kvm->coalesced_mmio_dev = NULL;
 125        kfree(dev);
 126out_free_page:
 127        kvm->coalesced_mmio_ring = NULL;
 128        __free_page(page);
 129out_err:
 130        return ret;
 131}
 132
 133void 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
 139int 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
 160int 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}
 192