vfio.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * VFIO-KVM bridge pseudo device
  4 *
  5 * Copyright (C) 2013 Red Hat, Inc.  All rights reserved.
  6 *     Author: Alex Williamson <alex.williamson@redhat.com>
  7 */
  8
  9#include <linux/errno.h>
 10#include <linux/file.h>
 11#include <linux/kvm_host.h>
 12#include <linux/list.h>
 13#include <linux/module.h>
 14#include <linux/mutex.h>
 15#include <linux/slab.h>
 16#include <linux/uaccess.h>
 17#include <linux/vfio.h>
 18#include "vfio.h"
 19
 20#ifdef CONFIG_SPAPR_TCE_IOMMU
 21#include <asm/kvm_ppc.h>
 22#endif
 23
 24struct kvm_vfio_file {
 25	struct list_head node;
 26	struct file *file;
 27#ifdef CONFIG_SPAPR_TCE_IOMMU
 28	struct iommu_group *iommu_group;
 29#endif
 30};
 31
 32struct kvm_vfio {
 33	struct list_head file_list;
 34	struct mutex lock;
 35	bool noncoherent;
 36};
 37
 38static void kvm_vfio_file_set_kvm(struct file *file, struct kvm *kvm)
 39{
 40	void (*fn)(struct file *file, struct kvm *kvm);
 41
 42	fn = symbol_get(vfio_file_set_kvm);
 43	if (!fn)
 44		return;
 45
 46	fn(file, kvm);
 47
 48	symbol_put(vfio_file_set_kvm);
 49}
 50
 51static bool kvm_vfio_file_enforced_coherent(struct file *file)
 52{
 53	bool (*fn)(struct file *file);
 54	bool ret;
 55
 56	fn = symbol_get(vfio_file_enforced_coherent);
 57	if (!fn)
 58		return false;
 59
 60	ret = fn(file);
 61
 62	symbol_put(vfio_file_enforced_coherent);
 63
 64	return ret;
 65}
 66
 67static bool kvm_vfio_file_is_valid(struct file *file)
 68{
 69	bool (*fn)(struct file *file);
 70	bool ret;
 71
 72	fn = symbol_get(vfio_file_is_valid);
 73	if (!fn)
 74		return false;
 75
 76	ret = fn(file);
 77
 78	symbol_put(vfio_file_is_valid);
 79
 80	return ret;
 81}
 82
 83#ifdef CONFIG_SPAPR_TCE_IOMMU
 84static struct iommu_group *kvm_vfio_file_iommu_group(struct file *file)
 85{
 86	struct iommu_group *(*fn)(struct file *file);
 87	struct iommu_group *ret;
 88
 89	fn = symbol_get(vfio_file_iommu_group);
 90	if (!fn)
 91		return NULL;
 92
 93	ret = fn(file);
 94
 95	symbol_put(vfio_file_iommu_group);
 96
 97	return ret;
 98}
 99
100static void kvm_spapr_tce_release_vfio_group(struct kvm *kvm,
101					     struct kvm_vfio_file *kvf)
102{
103	if (WARN_ON_ONCE(!kvf->iommu_group))
104		return;
105
106	kvm_spapr_tce_release_iommu_group(kvm, kvf->iommu_group);
107	iommu_group_put(kvf->iommu_group);
108	kvf->iommu_group = NULL;
109}
110#endif
111
112/*
113 * Groups/devices can use the same or different IOMMU domains. If the same
114 * then adding a new group/device may change the coherency of groups/devices
115 * we've previously been told about. We don't want to care about any of
116 * that so we retest each group/device and bail as soon as we find one that's
117 * noncoherent.  This means we only ever [un]register_noncoherent_dma once
118 * for the whole device.
119 */
120static void kvm_vfio_update_coherency(struct kvm_device *dev)
121{
122	struct kvm_vfio *kv = dev->private;
123	bool noncoherent = false;
124	struct kvm_vfio_file *kvf;
125
126	list_for_each_entry(kvf, &kv->file_list, node) {
127		if (!kvm_vfio_file_enforced_coherent(kvf->file)) {
128			noncoherent = true;
129			break;
130		}
131	}
132
133	if (noncoherent != kv->noncoherent) {
134		kv->noncoherent = noncoherent;
135
136		if (kv->noncoherent)
137			kvm_arch_register_noncoherent_dma(dev->kvm);
138		else
139			kvm_arch_unregister_noncoherent_dma(dev->kvm);
140	}
141}
142
143static int kvm_vfio_file_add(struct kvm_device *dev, unsigned int fd)
144{
145	struct kvm_vfio *kv = dev->private;
146	struct kvm_vfio_file *kvf;
147	struct file *filp;
148	int ret = 0;
149
150	filp = fget(fd);
151	if (!filp)
152		return -EBADF;
153
154	/* Ensure the FD is a vfio FD. */
155	if (!kvm_vfio_file_is_valid(filp)) {
156		ret = -EINVAL;
157		goto out_fput;
158	}
159
160	mutex_lock(&kv->lock);
161
162	list_for_each_entry(kvf, &kv->file_list, node) {
163		if (kvf->file == filp) {
164			ret = -EEXIST;
165			goto out_unlock;
166		}
167	}
168
169	kvf = kzalloc(sizeof(*kvf), GFP_KERNEL_ACCOUNT);
170	if (!kvf) {
171		ret = -ENOMEM;
172		goto out_unlock;
173	}
174
175	kvf->file = get_file(filp);
176	list_add_tail(&kvf->node, &kv->file_list);
177
178	kvm_vfio_file_set_kvm(kvf->file, dev->kvm);
179	kvm_vfio_update_coherency(dev);
180
181out_unlock:
182	mutex_unlock(&kv->lock);
183out_fput:
184	fput(filp);
185	return ret;
186}
187
188static int kvm_vfio_file_del(struct kvm_device *dev, unsigned int fd)
189{
190	struct kvm_vfio *kv = dev->private;
191	struct kvm_vfio_file *kvf;
192	CLASS(fd, f)(fd);
193	int ret;
194
195	if (fd_empty(f))
196		return -EBADF;
197
198	ret = -ENOENT;
199
200	mutex_lock(&kv->lock);
201
202	list_for_each_entry(kvf, &kv->file_list, node) {
203		if (kvf->file != fd_file(f))
204			continue;
205
206		list_del(&kvf->node);
207#ifdef CONFIG_SPAPR_TCE_IOMMU
208		kvm_spapr_tce_release_vfio_group(dev->kvm, kvf);
209#endif
210		kvm_vfio_file_set_kvm(kvf->file, NULL);
211		fput(kvf->file);
212		kfree(kvf);
213		ret = 0;
214		break;
215	}
216
217	kvm_vfio_update_coherency(dev);
218
219	mutex_unlock(&kv->lock);
220	return ret;
221}
222
223#ifdef CONFIG_SPAPR_TCE_IOMMU
224static int kvm_vfio_file_set_spapr_tce(struct kvm_device *dev,
225				       void __user *arg)
226{
227	struct kvm_vfio_spapr_tce param;
228	struct kvm_vfio *kv = dev->private;
229	struct kvm_vfio_file *kvf;
230	int ret;
231
232	if (copy_from_user(&param, arg, sizeof(struct kvm_vfio_spapr_tce)))
233		return -EFAULT;
234
235	CLASS(fd, f)(param.groupfd);
236	if (fd_empty(f))
237		return -EBADF;
238
239	ret = -ENOENT;
240
241	mutex_lock(&kv->lock);
242
243	list_for_each_entry(kvf, &kv->file_list, node) {
244		if (kvf->file != fd_file(f))
245			continue;
246
247		if (!kvf->iommu_group) {
248			kvf->iommu_group = kvm_vfio_file_iommu_group(kvf->file);
249			if (WARN_ON_ONCE(!kvf->iommu_group)) {
250				ret = -EIO;
251				goto err_fdput;
252			}
253		}
254
255		ret = kvm_spapr_tce_attach_iommu_group(dev->kvm, param.tablefd,
256						       kvf->iommu_group);
257		break;
258	}
259
260err_fdput:
261	mutex_unlock(&kv->lock);
262	return ret;
263}
264#endif
265
266static int kvm_vfio_set_file(struct kvm_device *dev, long attr,
267			     void __user *arg)
268{
269	int32_t __user *argp = arg;
270	int32_t fd;
271
272	switch (attr) {
273	case KVM_DEV_VFIO_FILE_ADD:
274		if (get_user(fd, argp))
275			return -EFAULT;
276		return kvm_vfio_file_add(dev, fd);
277
278	case KVM_DEV_VFIO_FILE_DEL:
279		if (get_user(fd, argp))
280			return -EFAULT;
281		return kvm_vfio_file_del(dev, fd);
282
283#ifdef CONFIG_SPAPR_TCE_IOMMU
284	case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE:
285		return kvm_vfio_file_set_spapr_tce(dev, arg);
286#endif
287	}
288
289	return -ENXIO;
290}
291
292static int kvm_vfio_set_attr(struct kvm_device *dev,
293			     struct kvm_device_attr *attr)
294{
295	switch (attr->group) {
296	case KVM_DEV_VFIO_FILE:
297		return kvm_vfio_set_file(dev, attr->attr,
298					 u64_to_user_ptr(attr->addr));
299	}
300
301	return -ENXIO;
302}
303
304static int kvm_vfio_has_attr(struct kvm_device *dev,
305			     struct kvm_device_attr *attr)
306{
307	switch (attr->group) {
308	case KVM_DEV_VFIO_FILE:
309		switch (attr->attr) {
310		case KVM_DEV_VFIO_FILE_ADD:
311		case KVM_DEV_VFIO_FILE_DEL:
312#ifdef CONFIG_SPAPR_TCE_IOMMU
313		case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE:
314#endif
315			return 0;
316		}
317
318		break;
319	}
320
321	return -ENXIO;
322}
323
324static void kvm_vfio_release(struct kvm_device *dev)
325{
326	struct kvm_vfio *kv = dev->private;
327	struct kvm_vfio_file *kvf, *tmp;
328
329	list_for_each_entry_safe(kvf, tmp, &kv->file_list, node) {
330#ifdef CONFIG_SPAPR_TCE_IOMMU
331		kvm_spapr_tce_release_vfio_group(dev->kvm, kvf);
332#endif
333		kvm_vfio_file_set_kvm(kvf->file, NULL);
334		fput(kvf->file);
335		list_del(&kvf->node);
336		kfree(kvf);
337	}
338
339	kvm_vfio_update_coherency(dev);
340
341	kfree(kv);
342	kfree(dev); /* alloc by kvm_ioctl_create_device, free by .release */
343}
344
345static int kvm_vfio_create(struct kvm_device *dev, u32 type);
346
347static const struct kvm_device_ops kvm_vfio_ops = {
348	.name = "kvm-vfio",
349	.create = kvm_vfio_create,
350	.release = kvm_vfio_release,
351	.set_attr = kvm_vfio_set_attr,
352	.has_attr = kvm_vfio_has_attr,
353};
354
355static int kvm_vfio_create(struct kvm_device *dev, u32 type)
356{
357	struct kvm_device *tmp;
358	struct kvm_vfio *kv;
359
360	lockdep_assert_held(&dev->kvm->lock);
361
362	/* Only one VFIO "device" per VM */
363	list_for_each_entry(tmp, &dev->kvm->devices, vm_node)
364		if (tmp->ops == &kvm_vfio_ops)
365			return -EBUSY;
366
367	kv = kzalloc(sizeof(*kv), GFP_KERNEL_ACCOUNT);
368	if (!kv)
369		return -ENOMEM;
370
371	INIT_LIST_HEAD(&kv->file_list);
372	mutex_init(&kv->lock);
373
374	dev->private = kv;
375
376	return 0;
377}
378
379int kvm_vfio_ops_init(void)
380{
381	return kvm_register_device_ops(&kvm_vfio_ops, KVM_DEV_TYPE_VFIO);
382}
383
384void kvm_vfio_ops_exit(void)
385{
386	kvm_unregister_device_ops(KVM_DEV_TYPE_VFIO);
387}