1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Helpers for IOMMU drivers implementing SVA
4 */
5 #include <linux/mmu_context.h>
6 #include <linux/mutex.h>
7 #include <linux/sched/mm.h>
8 #include <linux/iommu.h>
9
10 #include "iommu-priv.h"
11
12 static DEFINE_MUTEX(iommu_sva_lock);
13 static struct iommu_domain *iommu_sva_domain_alloc(struct device *dev,
14 struct mm_struct *mm);
15
16 /* Allocate a PASID for the mm within range (inclusive) */
iommu_alloc_mm_data(struct mm_struct * mm,struct device * dev)17 static struct iommu_mm_data *iommu_alloc_mm_data(struct mm_struct *mm, struct device *dev)
18 {
19 struct iommu_mm_data *iommu_mm;
20 ioasid_t pasid;
21
22 lockdep_assert_held(&iommu_sva_lock);
23
24 if (!arch_pgtable_dma_compat(mm))
25 return ERR_PTR(-EBUSY);
26
27 iommu_mm = mm->iommu_mm;
28 /* Is a PASID already associated with this mm? */
29 if (iommu_mm) {
30 if (iommu_mm->pasid >= dev->iommu->max_pasids)
31 return ERR_PTR(-EOVERFLOW);
32 return iommu_mm;
33 }
34
35 iommu_mm = kzalloc(sizeof(struct iommu_mm_data), GFP_KERNEL);
36 if (!iommu_mm)
37 return ERR_PTR(-ENOMEM);
38
39 pasid = iommu_alloc_global_pasid(dev);
40 if (pasid == IOMMU_PASID_INVALID) {
41 kfree(iommu_mm);
42 return ERR_PTR(-ENOSPC);
43 }
44 iommu_mm->pasid = pasid;
45 INIT_LIST_HEAD(&iommu_mm->sva_domains);
46 /*
47 * Make sure the write to mm->iommu_mm is not reordered in front of
48 * initialization to iommu_mm fields. If it does, readers may see a
49 * valid iommu_mm with uninitialized values.
50 */
51 smp_store_release(&mm->iommu_mm, iommu_mm);
52 return iommu_mm;
53 }
54
55 /**
56 * iommu_sva_bind_device() - Bind a process address space to a device
57 * @dev: the device
58 * @mm: the mm to bind, caller must hold a reference to mm_users
59 *
60 * Create a bond between device and address space, allowing the device to
61 * access the mm using the PASID returned by iommu_sva_get_pasid(). If a
62 * bond already exists between @device and @mm, an additional internal
63 * reference is taken. Caller must call iommu_sva_unbind_device()
64 * to release each reference.
65 *
66 * iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA) must be called first, to
67 * initialize the required SVA features.
68 *
69 * On error, returns an ERR_PTR value.
70 */
iommu_sva_bind_device(struct device * dev,struct mm_struct * mm)71 struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm)
72 {
73 struct iommu_group *group = dev->iommu_group;
74 struct iommu_attach_handle *attach_handle;
75 struct iommu_mm_data *iommu_mm;
76 struct iommu_domain *domain;
77 struct iommu_sva *handle;
78 int ret;
79
80 if (!group)
81 return ERR_PTR(-ENODEV);
82
83 mutex_lock(&iommu_sva_lock);
84
85 /* Allocate mm->pasid if necessary. */
86 iommu_mm = iommu_alloc_mm_data(mm, dev);
87 if (IS_ERR(iommu_mm)) {
88 ret = PTR_ERR(iommu_mm);
89 goto out_unlock;
90 }
91
92 /* A bond already exists, just take a reference`. */
93 attach_handle = iommu_attach_handle_get(group, iommu_mm->pasid, IOMMU_DOMAIN_SVA);
94 if (!IS_ERR(attach_handle)) {
95 handle = container_of(attach_handle, struct iommu_sva, handle);
96 if (attach_handle->domain->mm != mm) {
97 ret = -EBUSY;
98 goto out_unlock;
99 }
100 refcount_inc(&handle->users);
101 mutex_unlock(&iommu_sva_lock);
102 return handle;
103 }
104
105 if (PTR_ERR(attach_handle) != -ENOENT) {
106 ret = PTR_ERR(attach_handle);
107 goto out_unlock;
108 }
109
110 handle = kzalloc(sizeof(*handle), GFP_KERNEL);
111 if (!handle) {
112 ret = -ENOMEM;
113 goto out_unlock;
114 }
115
116 /* Search for an existing domain. */
117 list_for_each_entry(domain, &mm->iommu_mm->sva_domains, next) {
118 ret = iommu_attach_device_pasid(domain, dev, iommu_mm->pasid,
119 &handle->handle);
120 if (!ret) {
121 domain->users++;
122 goto out;
123 }
124 }
125
126 /* Allocate a new domain and set it on device pasid. */
127 domain = iommu_sva_domain_alloc(dev, mm);
128 if (IS_ERR(domain)) {
129 ret = PTR_ERR(domain);
130 goto out_free_handle;
131 }
132
133 ret = iommu_attach_device_pasid(domain, dev, iommu_mm->pasid,
134 &handle->handle);
135 if (ret)
136 goto out_free_domain;
137 domain->users = 1;
138 list_add(&domain->next, &mm->iommu_mm->sva_domains);
139
140 out:
141 refcount_set(&handle->users, 1);
142 mutex_unlock(&iommu_sva_lock);
143 handle->dev = dev;
144 return handle;
145
146 out_free_domain:
147 iommu_domain_free(domain);
148 out_free_handle:
149 kfree(handle);
150 out_unlock:
151 mutex_unlock(&iommu_sva_lock);
152 return ERR_PTR(ret);
153 }
154 EXPORT_SYMBOL_GPL(iommu_sva_bind_device);
155
156 /**
157 * iommu_sva_unbind_device() - Remove a bond created with iommu_sva_bind_device
158 * @handle: the handle returned by iommu_sva_bind_device()
159 *
160 * Put reference to a bond between device and address space. The device should
161 * not be issuing any more transaction for this PASID. All outstanding page
162 * requests for this PASID must have been flushed to the IOMMU.
163 */
iommu_sva_unbind_device(struct iommu_sva * handle)164 void iommu_sva_unbind_device(struct iommu_sva *handle)
165 {
166 struct iommu_domain *domain = handle->handle.domain;
167 struct iommu_mm_data *iommu_mm = domain->mm->iommu_mm;
168 struct device *dev = handle->dev;
169
170 mutex_lock(&iommu_sva_lock);
171 if (!refcount_dec_and_test(&handle->users)) {
172 mutex_unlock(&iommu_sva_lock);
173 return;
174 }
175
176 iommu_detach_device_pasid(domain, dev, iommu_mm->pasid);
177 if (--domain->users == 0) {
178 list_del(&domain->next);
179 iommu_domain_free(domain);
180 }
181 mutex_unlock(&iommu_sva_lock);
182 kfree(handle);
183 }
184 EXPORT_SYMBOL_GPL(iommu_sva_unbind_device);
185
iommu_sva_get_pasid(struct iommu_sva * handle)186 u32 iommu_sva_get_pasid(struct iommu_sva *handle)
187 {
188 struct iommu_domain *domain = handle->handle.domain;
189
190 return mm_get_enqcmd_pasid(domain->mm);
191 }
192 EXPORT_SYMBOL_GPL(iommu_sva_get_pasid);
193
mm_pasid_drop(struct mm_struct * mm)194 void mm_pasid_drop(struct mm_struct *mm)
195 {
196 struct iommu_mm_data *iommu_mm = mm->iommu_mm;
197
198 if (!iommu_mm)
199 return;
200
201 iommu_free_global_pasid(iommu_mm->pasid);
202 kfree(iommu_mm);
203 }
204
205 /*
206 * I/O page fault handler for SVA
207 */
208 static enum iommu_page_response_code
iommu_sva_handle_mm(struct iommu_fault * fault,struct mm_struct * mm)209 iommu_sva_handle_mm(struct iommu_fault *fault, struct mm_struct *mm)
210 {
211 vm_fault_t ret;
212 struct vm_area_struct *vma;
213 unsigned int access_flags = 0;
214 unsigned int fault_flags = FAULT_FLAG_REMOTE;
215 struct iommu_fault_page_request *prm = &fault->prm;
216 enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID;
217
218 if (!(prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID))
219 return status;
220
221 if (!mmget_not_zero(mm))
222 return status;
223
224 mmap_read_lock(mm);
225
226 vma = vma_lookup(mm, prm->addr);
227 if (!vma)
228 /* Unmapped area */
229 goto out_put_mm;
230
231 if (prm->perm & IOMMU_FAULT_PERM_READ)
232 access_flags |= VM_READ;
233
234 if (prm->perm & IOMMU_FAULT_PERM_WRITE) {
235 access_flags |= VM_WRITE;
236 fault_flags |= FAULT_FLAG_WRITE;
237 }
238
239 if (prm->perm & IOMMU_FAULT_PERM_EXEC) {
240 access_flags |= VM_EXEC;
241 fault_flags |= FAULT_FLAG_INSTRUCTION;
242 }
243
244 if (!(prm->perm & IOMMU_FAULT_PERM_PRIV))
245 fault_flags |= FAULT_FLAG_USER;
246
247 if (access_flags & ~vma->vm_flags)
248 /* Access fault */
249 goto out_put_mm;
250
251 ret = handle_mm_fault(vma, prm->addr, fault_flags, NULL);
252 status = ret & VM_FAULT_ERROR ? IOMMU_PAGE_RESP_INVALID :
253 IOMMU_PAGE_RESP_SUCCESS;
254
255 out_put_mm:
256 mmap_read_unlock(mm);
257 mmput(mm);
258
259 return status;
260 }
261
iommu_sva_handle_iopf(struct work_struct * work)262 static void iommu_sva_handle_iopf(struct work_struct *work)
263 {
264 struct iopf_fault *iopf;
265 struct iopf_group *group;
266 enum iommu_page_response_code status = IOMMU_PAGE_RESP_SUCCESS;
267
268 group = container_of(work, struct iopf_group, work);
269 list_for_each_entry(iopf, &group->faults, list) {
270 /*
271 * For the moment, errors are sticky: don't handle subsequent
272 * faults in the group if there is an error.
273 */
274 if (status != IOMMU_PAGE_RESP_SUCCESS)
275 break;
276
277 status = iommu_sva_handle_mm(&iopf->fault,
278 group->attach_handle->domain->mm);
279 }
280
281 iopf_group_response(group, status);
282 iopf_free_group(group);
283 }
284
iommu_sva_iopf_handler(struct iopf_group * group)285 static int iommu_sva_iopf_handler(struct iopf_group *group)
286 {
287 struct iommu_fault_param *fault_param = group->fault_param;
288
289 INIT_WORK(&group->work, iommu_sva_handle_iopf);
290 if (!queue_work(fault_param->queue->wq, &group->work))
291 return -EBUSY;
292
293 return 0;
294 }
295
iommu_sva_domain_alloc(struct device * dev,struct mm_struct * mm)296 static struct iommu_domain *iommu_sva_domain_alloc(struct device *dev,
297 struct mm_struct *mm)
298 {
299 const struct iommu_ops *ops = dev_iommu_ops(dev);
300 struct iommu_domain *domain;
301
302 if (ops->domain_alloc_sva) {
303 domain = ops->domain_alloc_sva(dev, mm);
304 if (IS_ERR(domain))
305 return domain;
306 } else {
307 domain = ops->domain_alloc(IOMMU_DOMAIN_SVA);
308 if (!domain)
309 return ERR_PTR(-ENOMEM);
310 }
311
312 domain->type = IOMMU_DOMAIN_SVA;
313 mmgrab(mm);
314 domain->mm = mm;
315 domain->owner = ops;
316 domain->iopf_handler = iommu_sva_iopf_handler;
317
318 return domain;
319 }
320