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 smp_wmb(); 87 ring->last = (ring->last + 1) % KVM_COALESCED_MMIO_MAX; 88 spin_unlock(&dev->kvm->ring_lock); 89 return 0; 90 } 91 92 static void coalesced_mmio_destructor(struct kvm_io_device *this) 93 { 94 struct kvm_coalesced_mmio_dev *dev = to_mmio(this); 95 96 list_del(&dev->list); 97 98 kfree(dev); 99 } 100 101 static const struct kvm_io_device_ops coalesced_mmio_ops = { 102 .write = coalesced_mmio_write, 103 .destructor = coalesced_mmio_destructor, 104 }; 105 106 int kvm_coalesced_mmio_init(struct kvm *kvm) 107 { 108 struct page *page; 109 int ret; 110 111 ret = -ENOMEM; 112 page = alloc_page(GFP_KERNEL | __GFP_ZERO); 113 if (!page) 114 goto out_err; 115 116 ret = 0; 117 kvm->coalesced_mmio_ring = page_address(page); 118 119 /* 120 * We're using this spinlock to sync access to the coalesced ring. 121 * The list doesn't need it's own lock since device registration and 122 * unregistration should only happen when kvm->slots_lock is held. 123 */ 124 spin_lock_init(&kvm->ring_lock); 125 INIT_LIST_HEAD(&kvm->coalesced_zones); 126 127 out_err: 128 return ret; 129 } 130 131 void kvm_coalesced_mmio_free(struct kvm *kvm) 132 { 133 if (kvm->coalesced_mmio_ring) 134 free_page((unsigned long)kvm->coalesced_mmio_ring); 135 } 136 137 int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm, 138 struct kvm_coalesced_mmio_zone *zone) 139 { 140 int ret; 141 struct kvm_coalesced_mmio_dev *dev; 142 143 dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), GFP_KERNEL); 144 if (!dev) 145 return -ENOMEM; 146 147 kvm_iodevice_init(&dev->dev, &coalesced_mmio_ops); 148 dev->kvm = kvm; 149 dev->zone = *zone; 150 151 mutex_lock(&kvm->slots_lock); 152 ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, zone->addr, 153 zone->size, &dev->dev); 154 if (ret < 0) 155 goto out_free_dev; 156 list_add_tail(&dev->list, &kvm->coalesced_zones); 157 mutex_unlock(&kvm->slots_lock); 158 159 return 0; 160 161 out_free_dev: 162 mutex_unlock(&kvm->slots_lock); 163 kfree(dev); 164 165 return ret; 166 } 167 168 int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm, 169 struct kvm_coalesced_mmio_zone *zone) 170 { 171 struct kvm_coalesced_mmio_dev *dev, *tmp; 172 173 mutex_lock(&kvm->slots_lock); 174 175 list_for_each_entry_safe(dev, tmp, &kvm->coalesced_zones, list) 176 if (coalesced_mmio_in_range(dev, zone->addr, zone->size)) { 177 kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS, &dev->dev); 178 kvm_iodevice_destructor(&dev->dev); 179 } 180 181 mutex_unlock(&kvm->slots_lock); 182 183 return 0; 184 } 185