tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
20static 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
25static 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
43static 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
64static 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
93static 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
102static const struct kvm_io_device_ops coalesced_mmio_ops = {
103 .write = coalesced_mmio_write,
104 .destructor = coalesced_mmio_destructor,
105};
106
107int 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
128out_err:
129 return ret;
130}
131
132void 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
138int 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), GFP_KERNEL);
148 if (!dev)
149 return -ENOMEM;
150
151 kvm_iodevice_init(&dev->dev, &coalesced_mmio_ops);
152 dev->kvm = kvm;
153 dev->zone = *zone;
154
155 mutex_lock(&kvm->slots_lock);
156 ret = kvm_io_bus_register_dev(kvm,
157 zone->pio ? KVM_PIO_BUS : KVM_MMIO_BUS,
158 zone->addr, zone->size, &dev->dev);
159 if (ret < 0)
160 goto out_free_dev;
161 list_add_tail(&dev->list, &kvm->coalesced_zones);
162 mutex_unlock(&kvm->slots_lock);
163
164 return 0;
165
166out_free_dev:
167 mutex_unlock(&kvm->slots_lock);
168 kfree(dev);
169
170 return ret;
171}
172
173int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
174 struct kvm_coalesced_mmio_zone *zone)
175{
176 struct kvm_coalesced_mmio_dev *dev, *tmp;
177
178 if (zone->pio != 1 && zone->pio != 0)
179 return -EINVAL;
180
181 mutex_lock(&kvm->slots_lock);
182
183 list_for_each_entry_safe(dev, tmp, &kvm->coalesced_zones, list)
184 if (zone->pio == dev->zone.pio &&
185 coalesced_mmio_in_range(dev, zone->addr, zone->size)) {
186 kvm_io_bus_unregister_dev(kvm,
187 zone->pio ? KVM_PIO_BUS : KVM_MMIO_BUS, &dev->dev);
188 kvm_iodevice_destructor(&dev->dev);
189 }
190
191 mutex_unlock(&kvm->slots_lock);
192
193 return 0;
194}