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