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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Virtual I/O topology
4 *
5 * The Virtual I/O Translation Table (VIOT) describes the topology of
6 * para-virtual IOMMUs and the endpoints they manage. The OS uses it to
7 * initialize devices in the right order, preventing endpoints from issuing DMA
8 * before their IOMMU is ready.
9 *
10 * When binding a driver to a device, before calling the device driver's probe()
11 * method, the driver infrastructure calls dma_configure(). At that point the
12 * VIOT driver looks for an IOMMU associated to the device in the VIOT table.
13 * If an IOMMU exists and has been initialized, the VIOT driver initializes the
14 * device's IOMMU fwspec, allowing the DMA infrastructure to invoke the IOMMU
15 * ops when the device driver configures DMA mappings. If an IOMMU exists and
16 * hasn't yet been initialized, VIOT returns -EPROBE_DEFER to postpone probing
17 * the device until the IOMMU is available.
18 */
19#define pr_fmt(fmt) "ACPI: VIOT: " fmt
20
21#include <linux/acpi_viot.h>
22#include <linux/dma-iommu.h>
23#include <linux/fwnode.h>
24#include <linux/iommu.h>
25#include <linux/list.h>
26#include <linux/pci.h>
27#include <linux/platform_device.h>
28
29struct viot_iommu {
30 /* Node offset within the table */
31 unsigned int offset;
32 struct fwnode_handle *fwnode;
33 struct list_head list;
34};
35
36struct viot_endpoint {
37 union {
38 /* PCI range */
39 struct {
40 u16 segment_start;
41 u16 segment_end;
42 u16 bdf_start;
43 u16 bdf_end;
44 };
45 /* MMIO */
46 u64 address;
47 };
48 u32 endpoint_id;
49 struct viot_iommu *viommu;
50 struct list_head list;
51};
52
53static struct acpi_table_viot *viot;
54static LIST_HEAD(viot_iommus);
55static LIST_HEAD(viot_pci_ranges);
56static LIST_HEAD(viot_mmio_endpoints);
57
58static int __init viot_check_bounds(const struct acpi_viot_header *hdr)
59{
60 struct acpi_viot_header *start, *end, *hdr_end;
61
62 start = ACPI_ADD_PTR(struct acpi_viot_header, viot,
63 max_t(size_t, sizeof(*viot), viot->node_offset));
64 end = ACPI_ADD_PTR(struct acpi_viot_header, viot, viot->header.length);
65 hdr_end = ACPI_ADD_PTR(struct acpi_viot_header, hdr, sizeof(*hdr));
66
67 if (hdr < start || hdr_end > end) {
68 pr_err(FW_BUG "Node pointer overflows\n");
69 return -EOVERFLOW;
70 }
71 if (hdr->length < sizeof(*hdr)) {
72 pr_err(FW_BUG "Empty node\n");
73 return -EINVAL;
74 }
75 return 0;
76}
77
78static int __init viot_get_pci_iommu_fwnode(struct viot_iommu *viommu,
79 u16 segment, u16 bdf)
80{
81 struct pci_dev *pdev;
82 struct fwnode_handle *fwnode;
83
84 pdev = pci_get_domain_bus_and_slot(segment, PCI_BUS_NUM(bdf),
85 bdf & 0xff);
86 if (!pdev) {
87 pr_err("Could not find PCI IOMMU\n");
88 return -ENODEV;
89 }
90
91 fwnode = pdev->dev.fwnode;
92 if (!fwnode) {
93 /*
94 * PCI devices aren't necessarily described by ACPI. Create a
95 * fwnode so the IOMMU subsystem can identify this device.
96 */
97 fwnode = acpi_alloc_fwnode_static();
98 if (!fwnode) {
99 pci_dev_put(pdev);
100 return -ENOMEM;
101 }
102 set_primary_fwnode(&pdev->dev, fwnode);
103 }
104 viommu->fwnode = pdev->dev.fwnode;
105 pci_dev_put(pdev);
106 return 0;
107}
108
109static int __init viot_get_mmio_iommu_fwnode(struct viot_iommu *viommu,
110 u64 address)
111{
112 struct acpi_device *adev;
113 struct resource res = {
114 .start = address,
115 .end = address,
116 .flags = IORESOURCE_MEM,
117 };
118
119 adev = acpi_resource_consumer(&res);
120 if (!adev) {
121 pr_err("Could not find MMIO IOMMU\n");
122 return -EINVAL;
123 }
124 viommu->fwnode = &adev->fwnode;
125 return 0;
126}
127
128static struct viot_iommu * __init viot_get_iommu(unsigned int offset)
129{
130 int ret;
131 struct viot_iommu *viommu;
132 struct acpi_viot_header *hdr = ACPI_ADD_PTR(struct acpi_viot_header,
133 viot, offset);
134 union {
135 struct acpi_viot_virtio_iommu_pci pci;
136 struct acpi_viot_virtio_iommu_mmio mmio;
137 } *node = (void *)hdr;
138
139 list_for_each_entry(viommu, &viot_iommus, list)
140 if (viommu->offset == offset)
141 return viommu;
142
143 if (viot_check_bounds(hdr))
144 return NULL;
145
146 viommu = kzalloc(sizeof(*viommu), GFP_KERNEL);
147 if (!viommu)
148 return NULL;
149
150 viommu->offset = offset;
151 switch (hdr->type) {
152 case ACPI_VIOT_NODE_VIRTIO_IOMMU_PCI:
153 if (hdr->length < sizeof(node->pci))
154 goto err_free;
155
156 ret = viot_get_pci_iommu_fwnode(viommu, node->pci.segment,
157 node->pci.bdf);
158 break;
159 case ACPI_VIOT_NODE_VIRTIO_IOMMU_MMIO:
160 if (hdr->length < sizeof(node->mmio))
161 goto err_free;
162
163 ret = viot_get_mmio_iommu_fwnode(viommu,
164 node->mmio.base_address);
165 break;
166 default:
167 ret = -EINVAL;
168 }
169 if (ret)
170 goto err_free;
171
172 list_add(&viommu->list, &viot_iommus);
173 return viommu;
174
175err_free:
176 kfree(viommu);
177 return NULL;
178}
179
180static int __init viot_parse_node(const struct acpi_viot_header *hdr)
181{
182 int ret = -EINVAL;
183 struct list_head *list;
184 struct viot_endpoint *ep;
185 union {
186 struct acpi_viot_mmio mmio;
187 struct acpi_viot_pci_range pci;
188 } *node = (void *)hdr;
189
190 if (viot_check_bounds(hdr))
191 return -EINVAL;
192
193 if (hdr->type == ACPI_VIOT_NODE_VIRTIO_IOMMU_PCI ||
194 hdr->type == ACPI_VIOT_NODE_VIRTIO_IOMMU_MMIO)
195 return 0;
196
197 ep = kzalloc(sizeof(*ep), GFP_KERNEL);
198 if (!ep)
199 return -ENOMEM;
200
201 switch (hdr->type) {
202 case ACPI_VIOT_NODE_PCI_RANGE:
203 if (hdr->length < sizeof(node->pci)) {
204 pr_err(FW_BUG "Invalid PCI node size\n");
205 goto err_free;
206 }
207
208 ep->segment_start = node->pci.segment_start;
209 ep->segment_end = node->pci.segment_end;
210 ep->bdf_start = node->pci.bdf_start;
211 ep->bdf_end = node->pci.bdf_end;
212 ep->endpoint_id = node->pci.endpoint_start;
213 ep->viommu = viot_get_iommu(node->pci.output_node);
214 list = &viot_pci_ranges;
215 break;
216 case ACPI_VIOT_NODE_MMIO:
217 if (hdr->length < sizeof(node->mmio)) {
218 pr_err(FW_BUG "Invalid MMIO node size\n");
219 goto err_free;
220 }
221
222 ep->address = node->mmio.base_address;
223 ep->endpoint_id = node->mmio.endpoint;
224 ep->viommu = viot_get_iommu(node->mmio.output_node);
225 list = &viot_mmio_endpoints;
226 break;
227 default:
228 pr_warn("Unsupported node %x\n", hdr->type);
229 ret = 0;
230 goto err_free;
231 }
232
233 if (!ep->viommu) {
234 pr_warn("No IOMMU node found\n");
235 /*
236 * A future version of the table may use the node for other
237 * purposes. Keep parsing.
238 */
239 ret = 0;
240 goto err_free;
241 }
242
243 list_add(&ep->list, list);
244 return 0;
245
246err_free:
247 kfree(ep);
248 return ret;
249}
250
251/**
252 * acpi_viot_init - Parse the VIOT table
253 *
254 * Parse the VIOT table, prepare the list of endpoints to be used during DMA
255 * setup of devices.
256 */
257void __init acpi_viot_init(void)
258{
259 int i;
260 acpi_status status;
261 struct acpi_table_header *hdr;
262 struct acpi_viot_header *node;
263
264 status = acpi_get_table(ACPI_SIG_VIOT, 0, &hdr);
265 if (ACPI_FAILURE(status)) {
266 if (status != AE_NOT_FOUND) {
267 const char *msg = acpi_format_exception(status);
268
269 pr_err("Failed to get table, %s\n", msg);
270 }
271 return;
272 }
273
274 viot = (void *)hdr;
275
276 node = ACPI_ADD_PTR(struct acpi_viot_header, viot, viot->node_offset);
277 for (i = 0; i < viot->node_count; i++) {
278 if (viot_parse_node(node))
279 return;
280
281 node = ACPI_ADD_PTR(struct acpi_viot_header, node,
282 node->length);
283 }
284
285 acpi_put_table(hdr);
286}
287
288static int viot_dev_iommu_init(struct device *dev, struct viot_iommu *viommu,
289 u32 epid)
290{
291 const struct iommu_ops *ops;
292
293 if (!viommu)
294 return -ENODEV;
295
296 /* We're not translating ourself */
297 if (viommu->fwnode == dev->fwnode)
298 return -EINVAL;
299
300 ops = iommu_ops_from_fwnode(viommu->fwnode);
301 if (!ops)
302 return IS_ENABLED(CONFIG_VIRTIO_IOMMU) ?
303 -EPROBE_DEFER : -ENODEV;
304
305 return acpi_iommu_fwspec_init(dev, epid, viommu->fwnode, ops);
306}
307
308static int viot_pci_dev_iommu_init(struct pci_dev *pdev, u16 dev_id, void *data)
309{
310 u32 epid;
311 struct viot_endpoint *ep;
312 u32 domain_nr = pci_domain_nr(pdev->bus);
313
314 list_for_each_entry(ep, &viot_pci_ranges, list) {
315 if (domain_nr >= ep->segment_start &&
316 domain_nr <= ep->segment_end &&
317 dev_id >= ep->bdf_start &&
318 dev_id <= ep->bdf_end) {
319 epid = ((domain_nr - ep->segment_start) << 16) +
320 dev_id - ep->bdf_start + ep->endpoint_id;
321
322 /*
323 * If we found a PCI range managed by the viommu, we're
324 * the one that has to request ACS.
325 */
326 pci_request_acs();
327
328 return viot_dev_iommu_init(&pdev->dev, ep->viommu,
329 epid);
330 }
331 }
332 return -ENODEV;
333}
334
335static int viot_mmio_dev_iommu_init(struct platform_device *pdev)
336{
337 struct resource *mem;
338 struct viot_endpoint *ep;
339
340 mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
341 if (!mem)
342 return -ENODEV;
343
344 list_for_each_entry(ep, &viot_mmio_endpoints, list) {
345 if (ep->address == mem->start)
346 return viot_dev_iommu_init(&pdev->dev, ep->viommu,
347 ep->endpoint_id);
348 }
349 return -ENODEV;
350}
351
352/**
353 * viot_iommu_configure - Setup IOMMU ops for an endpoint described by VIOT
354 * @dev: the endpoint
355 *
356 * Return: 0 on success, <0 on failure
357 */
358int viot_iommu_configure(struct device *dev)
359{
360 if (dev_is_pci(dev))
361 return pci_for_each_dma_alias(to_pci_dev(dev),
362 viot_pci_dev_iommu_init, NULL);
363 else if (dev_is_platform(dev))
364 return viot_mmio_dev_iommu_init(to_platform_device(dev));
365 return -ENODEV;
366}