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