xref: /openbmc/linux/drivers/iommu/s390-iommu.c (revision 0edbfea5)
1 /*
2  * IOMMU API for s390 PCI devices
3  *
4  * Copyright IBM Corp. 2015
5  * Author(s): Gerald Schaefer <gerald.schaefer@de.ibm.com>
6  */
7 
8 #include <linux/pci.h>
9 #include <linux/iommu.h>
10 #include <linux/iommu-helper.h>
11 #include <linux/pci.h>
12 #include <linux/sizes.h>
13 #include <asm/pci_dma.h>
14 
15 /*
16  * Physically contiguous memory regions can be mapped with 4 KiB alignment,
17  * we allow all page sizes that are an order of 4KiB (no special large page
18  * support so far).
19  */
20 #define S390_IOMMU_PGSIZES	(~0xFFFUL)
21 
22 struct s390_domain {
23 	struct iommu_domain	domain;
24 	struct list_head	devices;
25 	unsigned long		*dma_table;
26 	spinlock_t		dma_table_lock;
27 	spinlock_t		list_lock;
28 };
29 
30 struct s390_domain_device {
31 	struct list_head	list;
32 	struct zpci_dev		*zdev;
33 };
34 
35 static struct s390_domain *to_s390_domain(struct iommu_domain *dom)
36 {
37 	return container_of(dom, struct s390_domain, domain);
38 }
39 
40 static bool s390_iommu_capable(enum iommu_cap cap)
41 {
42 	switch (cap) {
43 	case IOMMU_CAP_CACHE_COHERENCY:
44 		return true;
45 	case IOMMU_CAP_INTR_REMAP:
46 		return true;
47 	default:
48 		return false;
49 	}
50 }
51 
52 static struct iommu_domain *s390_domain_alloc(unsigned domain_type)
53 {
54 	struct s390_domain *s390_domain;
55 
56 	if (domain_type != IOMMU_DOMAIN_UNMANAGED)
57 		return NULL;
58 
59 	s390_domain = kzalloc(sizeof(*s390_domain), GFP_KERNEL);
60 	if (!s390_domain)
61 		return NULL;
62 
63 	s390_domain->dma_table = dma_alloc_cpu_table();
64 	if (!s390_domain->dma_table) {
65 		kfree(s390_domain);
66 		return NULL;
67 	}
68 
69 	spin_lock_init(&s390_domain->dma_table_lock);
70 	spin_lock_init(&s390_domain->list_lock);
71 	INIT_LIST_HEAD(&s390_domain->devices);
72 
73 	return &s390_domain->domain;
74 }
75 
76 static void s390_domain_free(struct iommu_domain *domain)
77 {
78 	struct s390_domain *s390_domain = to_s390_domain(domain);
79 
80 	dma_cleanup_tables(s390_domain->dma_table);
81 	kfree(s390_domain);
82 }
83 
84 static int s390_iommu_attach_device(struct iommu_domain *domain,
85 				    struct device *dev)
86 {
87 	struct s390_domain *s390_domain = to_s390_domain(domain);
88 	struct zpci_dev *zdev = to_pci_dev(dev)->sysdata;
89 	struct s390_domain_device *domain_device;
90 	unsigned long flags;
91 	int rc;
92 
93 	if (!zdev)
94 		return -ENODEV;
95 
96 	domain_device = kzalloc(sizeof(*domain_device), GFP_KERNEL);
97 	if (!domain_device)
98 		return -ENOMEM;
99 
100 	if (zdev->dma_table)
101 		zpci_dma_exit_device(zdev);
102 
103 	zdev->dma_table = s390_domain->dma_table;
104 	rc = zpci_register_ioat(zdev, 0, zdev->start_dma + PAGE_OFFSET,
105 				zdev->start_dma + zdev->iommu_size - 1,
106 				(u64) zdev->dma_table);
107 	if (rc)
108 		goto out_restore;
109 
110 	spin_lock_irqsave(&s390_domain->list_lock, flags);
111 	/* First device defines the DMA range limits */
112 	if (list_empty(&s390_domain->devices)) {
113 		domain->geometry.aperture_start = zdev->start_dma;
114 		domain->geometry.aperture_end = zdev->end_dma;
115 		domain->geometry.force_aperture = true;
116 	/* Allow only devices with identical DMA range limits */
117 	} else if (domain->geometry.aperture_start != zdev->start_dma ||
118 		   domain->geometry.aperture_end != zdev->end_dma) {
119 		rc = -EINVAL;
120 		spin_unlock_irqrestore(&s390_domain->list_lock, flags);
121 		goto out_restore;
122 	}
123 	domain_device->zdev = zdev;
124 	zdev->s390_domain = s390_domain;
125 	list_add(&domain_device->list, &s390_domain->devices);
126 	spin_unlock_irqrestore(&s390_domain->list_lock, flags);
127 
128 	return 0;
129 
130 out_restore:
131 	zpci_dma_init_device(zdev);
132 	kfree(domain_device);
133 
134 	return rc;
135 }
136 
137 static void s390_iommu_detach_device(struct iommu_domain *domain,
138 				     struct device *dev)
139 {
140 	struct s390_domain *s390_domain = to_s390_domain(domain);
141 	struct zpci_dev *zdev = to_pci_dev(dev)->sysdata;
142 	struct s390_domain_device *domain_device, *tmp;
143 	unsigned long flags;
144 	int found = 0;
145 
146 	if (!zdev)
147 		return;
148 
149 	spin_lock_irqsave(&s390_domain->list_lock, flags);
150 	list_for_each_entry_safe(domain_device, tmp, &s390_domain->devices,
151 				 list) {
152 		if (domain_device->zdev == zdev) {
153 			list_del(&domain_device->list);
154 			kfree(domain_device);
155 			found = 1;
156 			break;
157 		}
158 	}
159 	spin_unlock_irqrestore(&s390_domain->list_lock, flags);
160 
161 	if (found) {
162 		zdev->s390_domain = NULL;
163 		zpci_unregister_ioat(zdev, 0);
164 		zpci_dma_init_device(zdev);
165 	}
166 }
167 
168 static int s390_iommu_add_device(struct device *dev)
169 {
170 	struct iommu_group *group;
171 	int rc;
172 
173 	group = iommu_group_get(dev);
174 	if (!group) {
175 		group = iommu_group_alloc();
176 		if (IS_ERR(group))
177 			return PTR_ERR(group);
178 	}
179 
180 	rc = iommu_group_add_device(group, dev);
181 	iommu_group_put(group);
182 
183 	return rc;
184 }
185 
186 static void s390_iommu_remove_device(struct device *dev)
187 {
188 	struct zpci_dev *zdev = to_pci_dev(dev)->sysdata;
189 	struct iommu_domain *domain;
190 
191 	/*
192 	 * This is a workaround for a scenario where the IOMMU API common code
193 	 * "forgets" to call the detach_dev callback: After binding a device
194 	 * to vfio-pci and completing the VFIO_SET_IOMMU ioctl (which triggers
195 	 * the attach_dev), removing the device via
196 	 * "echo 1 > /sys/bus/pci/devices/.../remove" won't trigger detach_dev,
197 	 * only remove_device will be called via the BUS_NOTIFY_REMOVED_DEVICE
198 	 * notifier.
199 	 *
200 	 * So let's call detach_dev from here if it hasn't been called before.
201 	 */
202 	if (zdev && zdev->s390_domain) {
203 		domain = iommu_get_domain_for_dev(dev);
204 		if (domain)
205 			s390_iommu_detach_device(domain, dev);
206 	}
207 
208 	iommu_group_remove_device(dev);
209 }
210 
211 static int s390_iommu_update_trans(struct s390_domain *s390_domain,
212 				   unsigned long pa, dma_addr_t dma_addr,
213 				   size_t size, int flags)
214 {
215 	struct s390_domain_device *domain_device;
216 	u8 *page_addr = (u8 *) (pa & PAGE_MASK);
217 	dma_addr_t start_dma_addr = dma_addr;
218 	unsigned long irq_flags, nr_pages, i;
219 	unsigned long *entry;
220 	int rc = 0;
221 
222 	if (dma_addr < s390_domain->domain.geometry.aperture_start ||
223 	    dma_addr + size > s390_domain->domain.geometry.aperture_end)
224 		return -EINVAL;
225 
226 	nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
227 	if (!nr_pages)
228 		return 0;
229 
230 	spin_lock_irqsave(&s390_domain->dma_table_lock, irq_flags);
231 	for (i = 0; i < nr_pages; i++) {
232 		entry = dma_walk_cpu_trans(s390_domain->dma_table, dma_addr);
233 		if (!entry) {
234 			rc = -ENOMEM;
235 			goto undo_cpu_trans;
236 		}
237 		dma_update_cpu_trans(entry, page_addr, flags);
238 		page_addr += PAGE_SIZE;
239 		dma_addr += PAGE_SIZE;
240 	}
241 
242 	spin_lock(&s390_domain->list_lock);
243 	list_for_each_entry(domain_device, &s390_domain->devices, list) {
244 		rc = zpci_refresh_trans((u64) domain_device->zdev->fh << 32,
245 					start_dma_addr, nr_pages * PAGE_SIZE);
246 		if (rc)
247 			break;
248 	}
249 	spin_unlock(&s390_domain->list_lock);
250 
251 undo_cpu_trans:
252 	if (rc && ((flags & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID)) {
253 		flags = ZPCI_PTE_INVALID;
254 		while (i-- > 0) {
255 			page_addr -= PAGE_SIZE;
256 			dma_addr -= PAGE_SIZE;
257 			entry = dma_walk_cpu_trans(s390_domain->dma_table,
258 						   dma_addr);
259 			if (!entry)
260 				break;
261 			dma_update_cpu_trans(entry, page_addr, flags);
262 		}
263 	}
264 	spin_unlock_irqrestore(&s390_domain->dma_table_lock, irq_flags);
265 
266 	return rc;
267 }
268 
269 static int s390_iommu_map(struct iommu_domain *domain, unsigned long iova,
270 			  phys_addr_t paddr, size_t size, int prot)
271 {
272 	struct s390_domain *s390_domain = to_s390_domain(domain);
273 	int flags = ZPCI_PTE_VALID, rc = 0;
274 
275 	if (!(prot & IOMMU_READ))
276 		return -EINVAL;
277 
278 	if (!(prot & IOMMU_WRITE))
279 		flags |= ZPCI_TABLE_PROTECTED;
280 
281 	rc = s390_iommu_update_trans(s390_domain, (unsigned long) paddr, iova,
282 				     size, flags);
283 
284 	return rc;
285 }
286 
287 static phys_addr_t s390_iommu_iova_to_phys(struct iommu_domain *domain,
288 					   dma_addr_t iova)
289 {
290 	struct s390_domain *s390_domain = to_s390_domain(domain);
291 	unsigned long *sto, *pto, *rto, flags;
292 	unsigned int rtx, sx, px;
293 	phys_addr_t phys = 0;
294 
295 	if (iova < domain->geometry.aperture_start ||
296 	    iova > domain->geometry.aperture_end)
297 		return 0;
298 
299 	rtx = calc_rtx(iova);
300 	sx = calc_sx(iova);
301 	px = calc_px(iova);
302 	rto = s390_domain->dma_table;
303 
304 	spin_lock_irqsave(&s390_domain->dma_table_lock, flags);
305 	if (rto && reg_entry_isvalid(rto[rtx])) {
306 		sto = get_rt_sto(rto[rtx]);
307 		if (sto && reg_entry_isvalid(sto[sx])) {
308 			pto = get_st_pto(sto[sx]);
309 			if (pto && pt_entry_isvalid(pto[px]))
310 				phys = pto[px] & ZPCI_PTE_ADDR_MASK;
311 		}
312 	}
313 	spin_unlock_irqrestore(&s390_domain->dma_table_lock, flags);
314 
315 	return phys;
316 }
317 
318 static size_t s390_iommu_unmap(struct iommu_domain *domain,
319 			       unsigned long iova, size_t size)
320 {
321 	struct s390_domain *s390_domain = to_s390_domain(domain);
322 	int flags = ZPCI_PTE_INVALID;
323 	phys_addr_t paddr;
324 	int rc;
325 
326 	paddr = s390_iommu_iova_to_phys(domain, iova);
327 	if (!paddr)
328 		return 0;
329 
330 	rc = s390_iommu_update_trans(s390_domain, (unsigned long) paddr, iova,
331 				     size, flags);
332 	if (rc)
333 		return 0;
334 
335 	return size;
336 }
337 
338 static struct iommu_ops s390_iommu_ops = {
339 	.capable = s390_iommu_capable,
340 	.domain_alloc = s390_domain_alloc,
341 	.domain_free = s390_domain_free,
342 	.attach_dev = s390_iommu_attach_device,
343 	.detach_dev = s390_iommu_detach_device,
344 	.map = s390_iommu_map,
345 	.unmap = s390_iommu_unmap,
346 	.iova_to_phys = s390_iommu_iova_to_phys,
347 	.add_device = s390_iommu_add_device,
348 	.remove_device = s390_iommu_remove_device,
349 	.pgsize_bitmap = S390_IOMMU_PGSIZES,
350 };
351 
352 static int __init s390_iommu_init(void)
353 {
354 	return bus_set_iommu(&pci_bus_type, &s390_iommu_ops);
355 }
356 subsys_initcall(s390_iommu_init);
357