1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * KVM coalesced MMIO 4 * 5 * Copyright (c) 2008 Bull S.A.S. 6 * Copyright 2009 Red Hat, Inc. and/or its affiliates. 7 * 8 * Author: Laurent Vivier <Laurent.Vivier@bull.net> 9 * 10 */ 11 12 #include <kvm/iodev.h> 13 14 #include <linux/kvm_host.h> 15 #include <linux/slab.h> 16 #include <linux/kvm.h> 17 18 #include "coalesced_mmio.h" 19 20 static inline struct kvm_coalesced_mmio_dev *to_mmio(struct kvm_io_device *dev) 21 { 22 return container_of(dev, struct kvm_coalesced_mmio_dev, dev); 23 } 24 25 static int coalesced_mmio_in_range(struct kvm_coalesced_mmio_dev *dev, 26 gpa_t addr, int len) 27 { 28 /* is it in a batchable area ? 29 * (addr,len) is fully included in 30 * (zone->addr, zone->size) 31 */ 32 if (len < 0) 33 return 0; 34 if (addr + len < addr) 35 return 0; 36 if (addr < dev->zone.addr) 37 return 0; 38 if (addr + len > dev->zone.addr + dev->zone.size) 39 return 0; 40 return 1; 41 } 42 43 static int coalesced_mmio_has_room(struct kvm_coalesced_mmio_dev *dev) 44 { 45 struct kvm_coalesced_mmio_ring *ring; 46 unsigned avail; 47 48 /* Are we able to batch it ? */ 49 50 /* last is the first free entry 51 * check if we don't meet the first used entry 52 * there is always one unused entry in the buffer 53 */ 54 ring = dev->kvm->coalesced_mmio_ring; 55 avail = (ring->first - ring->last - 1) % KVM_COALESCED_MMIO_MAX; 56 if (avail == 0) { 57 /* full */ 58 return 0; 59 } 60 61 return 1; 62 } 63 64 static int coalesced_mmio_write(struct kvm_vcpu *vcpu, 65 struct kvm_io_device *this, gpa_t addr, 66 int len, const void *val) 67 { 68 struct kvm_coalesced_mmio_dev *dev = to_mmio(this); 69 struct kvm_coalesced_mmio_ring *ring = dev->kvm->coalesced_mmio_ring; 70 71 if (!coalesced_mmio_in_range(dev, addr, len)) 72 return -EOPNOTSUPP; 73 74 spin_lock(&dev->kvm->ring_lock); 75 76 if (!coalesced_mmio_has_room(dev)) { 77 spin_unlock(&dev->kvm->ring_lock); 78 return -EOPNOTSUPP; 79 } 80 81 /* copy data in first free entry of the ring */ 82 83 ring->coalesced_mmio[ring->last].phys_addr = addr; 84 ring->coalesced_mmio[ring->last].len = len; 85 memcpy(ring->coalesced_mmio[ring->last].data, val, len); 86 ring->coalesced_mmio[ring->last].pio = dev->zone.pio; 87 smp_wmb(); 88 ring->last = (ring->last + 1) % KVM_COALESCED_MMIO_MAX; 89 spin_unlock(&dev->kvm->ring_lock); 90 return 0; 91 } 92 93 static void coalesced_mmio_destructor(struct kvm_io_device *this) 94 { 95 struct kvm_coalesced_mmio_dev *dev = to_mmio(this); 96 97 list_del(&dev->list); 98 99 kfree(dev); 100 } 101 102 static const struct kvm_io_device_ops coalesced_mmio_ops = { 103 .write = coalesced_mmio_write, 104 .destructor = coalesced_mmio_destructor, 105 }; 106 107 int kvm_coalesced_mmio_init(struct kvm *kvm) 108 { 109 struct page *page; 110 int ret; 111 112 ret = -ENOMEM; 113 page = alloc_page(GFP_KERNEL | __GFP_ZERO); 114 if (!page) 115 goto out_err; 116 117 ret = 0; 118 kvm->coalesced_mmio_ring = page_address(page); 119 120 /* 121 * We're using this spinlock to sync access to the coalesced ring. 122 * The list doesn't need it's own lock since device registration and 123 * unregistration should only happen when kvm->slots_lock is held. 124 */ 125 spin_lock_init(&kvm->ring_lock); 126 INIT_LIST_HEAD(&kvm->coalesced_zones); 127 128 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 int ret; 142 struct kvm_coalesced_mmio_dev *dev; 143 144 if (zone->pio != 1 && zone->pio != 0) 145 return -EINVAL; 146 147 dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), 148 GFP_KERNEL_ACCOUNT); 149 if (!dev) 150 return -ENOMEM; 151 152 kvm_iodevice_init(&dev->dev, &coalesced_mmio_ops); 153 dev->kvm = kvm; 154 dev->zone = *zone; 155 156 mutex_lock(&kvm->slots_lock); 157 ret = kvm_io_bus_register_dev(kvm, 158 zone->pio ? KVM_PIO_BUS : KVM_MMIO_BUS, 159 zone->addr, zone->size, &dev->dev); 160 if (ret < 0) 161 goto out_free_dev; 162 list_add_tail(&dev->list, &kvm->coalesced_zones); 163 mutex_unlock(&kvm->slots_lock); 164 165 return 0; 166 167 out_free_dev: 168 mutex_unlock(&kvm->slots_lock); 169 kfree(dev); 170 171 return ret; 172 } 173 174 int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm, 175 struct kvm_coalesced_mmio_zone *zone) 176 { 177 struct kvm_coalesced_mmio_dev *dev, *tmp; 178 179 if (zone->pio != 1 && zone->pio != 0) 180 return -EINVAL; 181 182 mutex_lock(&kvm->slots_lock); 183 184 list_for_each_entry_safe(dev, tmp, &kvm->coalesced_zones, list) 185 if (zone->pio == dev->zone.pio && 186 coalesced_mmio_in_range(dev, zone->addr, zone->size)) { 187 kvm_io_bus_unregister_dev(kvm, 188 zone->pio ? KVM_PIO_BUS : KVM_MMIO_BUS, &dev->dev); 189 kvm_iodevice_destructor(&dev->dev); 190 } 191 192 mutex_unlock(&kvm->slots_lock); 193 194 return 0; 195 } 196