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