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_arch_start_assignment(dev->kvm);
179	kvm_vfio_file_set_kvm(kvf->file, dev->kvm);
180	kvm_vfio_update_coherency(dev);
181
182out_unlock:
183	mutex_unlock(&kv->lock);
184out_fput:
185	fput(filp);
186	return ret;
187}
188
189static int kvm_vfio_file_del(struct kvm_device *dev, unsigned int fd)
190{
191	struct kvm_vfio *kv = dev->private;
192	struct kvm_vfio_file *kvf;
193	CLASS(fd, f)(fd);
194	int ret;
195
196	if (fd_empty(f))
197		return -EBADF;
198
199	ret = -ENOENT;
200
201	mutex_lock(&kv->lock);
202
203	list_for_each_entry(kvf, &kv->file_list, node) {
204		if (kvf->file != fd_file(f))
205			continue;
206
207		list_del(&kvf->node);
208		kvm_arch_end_assignment(dev->kvm);
209#ifdef CONFIG_SPAPR_TCE_IOMMU
210		kvm_spapr_tce_release_vfio_group(dev->kvm, kvf);
211#endif
212		kvm_vfio_file_set_kvm(kvf->file, NULL);
213		fput(kvf->file);
214		kfree(kvf);
215		ret = 0;
216		break;
217	}
218
219	kvm_vfio_update_coherency(dev);
220
221	mutex_unlock(&kv->lock);
222	return ret;
223}
224
225#ifdef CONFIG_SPAPR_TCE_IOMMU
226static int kvm_vfio_file_set_spapr_tce(struct kvm_device *dev,
227				       void __user *arg)
228{
229	struct kvm_vfio_spapr_tce param;
230	struct kvm_vfio *kv = dev->private;
231	struct kvm_vfio_file *kvf;
232	int ret;
233
234	if (copy_from_user(&param, arg, sizeof(struct kvm_vfio_spapr_tce)))
235		return -EFAULT;
236
237	CLASS(fd, f)(param.groupfd);
238	if (fd_empty(f))
239		return -EBADF;
240
241	ret = -ENOENT;
242
243	mutex_lock(&kv->lock);
244
245	list_for_each_entry(kvf, &kv->file_list, node) {
246		if (kvf->file != fd_file(f))
247			continue;
248
249		if (!kvf->iommu_group) {
250			kvf->iommu_group = kvm_vfio_file_iommu_group(kvf->file);
251			if (WARN_ON_ONCE(!kvf->iommu_group)) {
252				ret = -EIO;
253				goto err_fdput;
254			}
255		}
256
257		ret = kvm_spapr_tce_attach_iommu_group(dev->kvm, param.tablefd,
258						       kvf->iommu_group);
259		break;
260	}
261
262err_fdput:
263	mutex_unlock(&kv->lock);
264	return ret;
265}
266#endif
267
268static int kvm_vfio_set_file(struct kvm_device *dev, long attr,
269			     void __user *arg)
270{
271	int32_t __user *argp = arg;
272	int32_t fd;
273
274	switch (attr) {
275	case KVM_DEV_VFIO_FILE_ADD:
276		if (get_user(fd, argp))
277			return -EFAULT;
278		return kvm_vfio_file_add(dev, fd);
279
280	case KVM_DEV_VFIO_FILE_DEL:
281		if (get_user(fd, argp))
282			return -EFAULT;
283		return kvm_vfio_file_del(dev, fd);
284
285#ifdef CONFIG_SPAPR_TCE_IOMMU
286	case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE:
287		return kvm_vfio_file_set_spapr_tce(dev, arg);
288#endif
289	}
290
291	return -ENXIO;
292}
293
294static int kvm_vfio_set_attr(struct kvm_device *dev,
295			     struct kvm_device_attr *attr)
296{
297	switch (attr->group) {
298	case KVM_DEV_VFIO_FILE:
299		return kvm_vfio_set_file(dev, attr->attr,
300					 u64_to_user_ptr(attr->addr));
301	}
302
303	return -ENXIO;
304}
305
306static int kvm_vfio_has_attr(struct kvm_device *dev,
307			     struct kvm_device_attr *attr)
308{
309	switch (attr->group) {
310	case KVM_DEV_VFIO_FILE:
311		switch (attr->attr) {
312		case KVM_DEV_VFIO_FILE_ADD:
313		case KVM_DEV_VFIO_FILE_DEL:
314#ifdef CONFIG_SPAPR_TCE_IOMMU
315		case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE:
316#endif
317			return 0;
318		}
319
320		break;
321	}
322
323	return -ENXIO;
324}
325
326static void kvm_vfio_release(struct kvm_device *dev)
327{
328	struct kvm_vfio *kv = dev->private;
329	struct kvm_vfio_file *kvf, *tmp;
330
331	list_for_each_entry_safe(kvf, tmp, &kv->file_list, node) {
332#ifdef CONFIG_SPAPR_TCE_IOMMU
333		kvm_spapr_tce_release_vfio_group(dev->kvm, kvf);
334#endif
335		kvm_vfio_file_set_kvm(kvf->file, NULL);
336		fput(kvf->file);
337		list_del(&kvf->node);
338		kfree(kvf);
339		kvm_arch_end_assignment(dev->kvm);
340	}
341
342	kvm_vfio_update_coherency(dev);
343
344	kfree(kv);
345	kfree(dev); /* alloc by kvm_ioctl_create_device, free by .release */
346}
347
348static int kvm_vfio_create(struct kvm_device *dev, u32 type);
349
350static const struct kvm_device_ops kvm_vfio_ops = {
351	.name = "kvm-vfio",
352	.create = kvm_vfio_create,
353	.release = kvm_vfio_release,
354	.set_attr = kvm_vfio_set_attr,
355	.has_attr = kvm_vfio_has_attr,
356};
357
358static int kvm_vfio_create(struct kvm_device *dev, u32 type)
359{
360	struct kvm_device *tmp;
361	struct kvm_vfio *kv;
362
363	lockdep_assert_held(&dev->kvm->lock);
364
365	/* Only one VFIO "device" per VM */
366	list_for_each_entry(tmp, &dev->kvm->devices, vm_node)
367		if (tmp->ops == &kvm_vfio_ops)
368			return -EBUSY;
369
370	kv = kzalloc(sizeof(*kv), GFP_KERNEL_ACCOUNT);
371	if (!kv)
372		return -ENOMEM;
373
374	INIT_LIST_HEAD(&kv->file_list);
375	mutex_init(&kv->lock);
376
377	dev->private = kv;
378
379	return 0;
380}
381
382int kvm_vfio_ops_init(void)
383{
384	return kvm_register_device_ops(&kvm_vfio_ops, KVM_DEV_TYPE_VFIO);
385}
386
387void kvm_vfio_ops_exit(void)
388{
389	kvm_unregister_device_ops(KVM_DEV_TYPE_VFIO);
390}