xref: /openbmc/linux/drivers/misc/cxl/context.c (revision ae3473231e77a3f1909d48cd144cebe5e1d049b3)
1 /*
2  * Copyright 2014 IBM Corp.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public License
6  * as published by the Free Software Foundation; either version
7  * 2 of the License, or (at your option) any later version.
8  */
9 
10 #include <linux/module.h>
11 #include <linux/kernel.h>
12 #include <linux/bitmap.h>
13 #include <linux/sched.h>
14 #include <linux/pid.h>
15 #include <linux/fs.h>
16 #include <linux/mm.h>
17 #include <linux/debugfs.h>
18 #include <linux/slab.h>
19 #include <linux/idr.h>
20 #include <asm/cputable.h>
21 #include <asm/current.h>
22 #include <asm/copro.h>
23 
24 #include "cxl.h"
25 
26 /*
27  * Allocates space for a CXL context.
28  */
29 struct cxl_context *cxl_context_alloc(void)
30 {
31 	return kzalloc(sizeof(struct cxl_context), GFP_KERNEL);
32 }
33 
34 /*
35  * Initialises a CXL context.
36  */
37 int cxl_context_init(struct cxl_context *ctx, struct cxl_afu *afu, bool master)
38 {
39 	int i;
40 
41 	spin_lock_init(&ctx->sste_lock);
42 	ctx->afu = afu;
43 	ctx->master = master;
44 	ctx->pid = ctx->glpid = NULL; /* Set in start work ioctl */
45 	mutex_init(&ctx->mapping_lock);
46 	ctx->mapping = NULL;
47 
48 	/*
49 	 * Allocate the segment table before we put it in the IDR so that we
50 	 * can always access it when dereferenced from IDR. For the same
51 	 * reason, the segment table is only destroyed after the context is
52 	 * removed from the IDR.  Access to this in the IOCTL is protected by
53 	 * Linux filesytem symantics (can't IOCTL until open is complete).
54 	 */
55 	i = cxl_alloc_sst(ctx);
56 	if (i)
57 		return i;
58 
59 	INIT_WORK(&ctx->fault_work, cxl_handle_fault);
60 
61 	init_waitqueue_head(&ctx->wq);
62 	spin_lock_init(&ctx->lock);
63 
64 	ctx->irq_bitmap = NULL;
65 	ctx->pending_irq = false;
66 	ctx->pending_fault = false;
67 	ctx->pending_afu_err = false;
68 
69 	INIT_LIST_HEAD(&ctx->irq_names);
70 	INIT_LIST_HEAD(&ctx->extra_irq_contexts);
71 
72 	/*
73 	 * When we have to destroy all contexts in cxl_context_detach_all() we
74 	 * end up with afu_release_irqs() called from inside a
75 	 * idr_for_each_entry(). Hence we need to make sure that anything
76 	 * dereferenced from this IDR is ok before we allocate the IDR here.
77 	 * This clears out the IRQ ranges to ensure this.
78 	 */
79 	for (i = 0; i < CXL_IRQ_RANGES; i++)
80 		ctx->irqs.range[i] = 0;
81 
82 	mutex_init(&ctx->status_mutex);
83 
84 	ctx->status = OPENED;
85 
86 	/*
87 	 * Allocating IDR! We better make sure everything's setup that
88 	 * dereferences from it.
89 	 */
90 	mutex_lock(&afu->contexts_lock);
91 	idr_preload(GFP_KERNEL);
92 	i = idr_alloc(&ctx->afu->contexts_idr, ctx, ctx->afu->adapter->min_pe,
93 		      ctx->afu->num_procs, GFP_NOWAIT);
94 	idr_preload_end();
95 	mutex_unlock(&afu->contexts_lock);
96 	if (i < 0)
97 		return i;
98 
99 	ctx->pe = i;
100 	if (cpu_has_feature(CPU_FTR_HVMODE)) {
101 		ctx->elem = &ctx->afu->native->spa[i];
102 		ctx->external_pe = ctx->pe;
103 	} else {
104 		ctx->external_pe = -1; /* assigned when attaching */
105 	}
106 	ctx->pe_inserted = false;
107 
108 	/*
109 	 * take a ref on the afu so that it stays alive at-least till
110 	 * this context is reclaimed inside reclaim_ctx.
111 	 */
112 	cxl_afu_get(afu);
113 	return 0;
114 }
115 
116 void cxl_context_set_mapping(struct cxl_context *ctx,
117 			struct address_space *mapping)
118 {
119 	mutex_lock(&ctx->mapping_lock);
120 	ctx->mapping = mapping;
121 	mutex_unlock(&ctx->mapping_lock);
122 }
123 
124 static int cxl_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
125 {
126 	struct cxl_context *ctx = vma->vm_file->private_data;
127 	u64 area, offset;
128 
129 	offset = vmf->pgoff << PAGE_SHIFT;
130 
131 	pr_devel("%s: pe: %i address: 0x%lx offset: 0x%llx\n",
132 			__func__, ctx->pe, vmf->address, offset);
133 
134 	if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
135 		area = ctx->afu->psn_phys;
136 		if (offset >= ctx->afu->adapter->ps_size)
137 			return VM_FAULT_SIGBUS;
138 	} else {
139 		area = ctx->psn_phys;
140 		if (offset >= ctx->psn_size)
141 			return VM_FAULT_SIGBUS;
142 	}
143 
144 	mutex_lock(&ctx->status_mutex);
145 
146 	if (ctx->status != STARTED) {
147 		mutex_unlock(&ctx->status_mutex);
148 		pr_devel("%s: Context not started, failing problem state access\n", __func__);
149 		if (ctx->mmio_err_ff) {
150 			if (!ctx->ff_page) {
151 				ctx->ff_page = alloc_page(GFP_USER);
152 				if (!ctx->ff_page)
153 					return VM_FAULT_OOM;
154 				memset(page_address(ctx->ff_page), 0xff, PAGE_SIZE);
155 			}
156 			get_page(ctx->ff_page);
157 			vmf->page = ctx->ff_page;
158 			vma->vm_page_prot = pgprot_cached(vma->vm_page_prot);
159 			return 0;
160 		}
161 		return VM_FAULT_SIGBUS;
162 	}
163 
164 	vm_insert_pfn(vma, vmf->address, (area + offset) >> PAGE_SHIFT);
165 
166 	mutex_unlock(&ctx->status_mutex);
167 
168 	return VM_FAULT_NOPAGE;
169 }
170 
171 static const struct vm_operations_struct cxl_mmap_vmops = {
172 	.fault = cxl_mmap_fault,
173 };
174 
175 /*
176  * Map a per-context mmio space into the given vma.
177  */
178 int cxl_context_iomap(struct cxl_context *ctx, struct vm_area_struct *vma)
179 {
180 	u64 start = vma->vm_pgoff << PAGE_SHIFT;
181 	u64 len = vma->vm_end - vma->vm_start;
182 
183 	if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
184 		if (start + len > ctx->afu->adapter->ps_size)
185 			return -EINVAL;
186 	} else {
187 		if (start + len > ctx->psn_size)
188 			return -EINVAL;
189 	}
190 
191 	if (ctx->afu->current_mode != CXL_MODE_DEDICATED) {
192 		/* make sure there is a valid per process space for this AFU */
193 		if ((ctx->master && !ctx->afu->psa) || (!ctx->afu->pp_psa)) {
194 			pr_devel("AFU doesn't support mmio space\n");
195 			return -EINVAL;
196 		}
197 
198 		/* Can't mmap until the AFU is enabled */
199 		if (!ctx->afu->enabled)
200 			return -EBUSY;
201 	}
202 
203 	pr_devel("%s: mmio physical: %llx pe: %i master:%i\n", __func__,
204 		 ctx->psn_phys, ctx->pe , ctx->master);
205 
206 	vma->vm_flags |= VM_IO | VM_PFNMAP;
207 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
208 	vma->vm_ops = &cxl_mmap_vmops;
209 	return 0;
210 }
211 
212 /*
213  * Detach a context from the hardware. This disables interrupts and doesn't
214  * return until all outstanding interrupts for this context have completed. The
215  * hardware should no longer access *ctx after this has returned.
216  */
217 int __detach_context(struct cxl_context *ctx)
218 {
219 	enum cxl_context_status status;
220 
221 	mutex_lock(&ctx->status_mutex);
222 	status = ctx->status;
223 	ctx->status = CLOSED;
224 	mutex_unlock(&ctx->status_mutex);
225 	if (status != STARTED)
226 		return -EBUSY;
227 
228 	/* Only warn if we detached while the link was OK.
229 	 * If detach fails when hw is down, we don't care.
230 	 */
231 	WARN_ON(cxl_ops->detach_process(ctx) &&
232 		cxl_ops->link_ok(ctx->afu->adapter, ctx->afu));
233 	flush_work(&ctx->fault_work); /* Only needed for dedicated process */
234 
235 	/*
236 	 * Wait until no further interrupts are presented by the PSL
237 	 * for this context.
238 	 */
239 	if (cxl_ops->irq_wait)
240 		cxl_ops->irq_wait(ctx);
241 
242 	/* release the reference to the group leader and mm handling pid */
243 	put_pid(ctx->pid);
244 	put_pid(ctx->glpid);
245 
246 	cxl_ctx_put();
247 
248 	/* Decrease the attached context count on the adapter */
249 	cxl_adapter_context_put(ctx->afu->adapter);
250 	return 0;
251 }
252 
253 /*
254  * Detach the given context from the AFU. This doesn't actually
255  * free the context but it should stop the context running in hardware
256  * (ie. prevent this context from generating any further interrupts
257  * so that it can be freed).
258  */
259 void cxl_context_detach(struct cxl_context *ctx)
260 {
261 	int rc;
262 
263 	rc = __detach_context(ctx);
264 	if (rc)
265 		return;
266 
267 	afu_release_irqs(ctx, ctx);
268 	wake_up_all(&ctx->wq);
269 }
270 
271 /*
272  * Detach all contexts on the given AFU.
273  */
274 void cxl_context_detach_all(struct cxl_afu *afu)
275 {
276 	struct cxl_context *ctx;
277 	int tmp;
278 
279 	mutex_lock(&afu->contexts_lock);
280 	idr_for_each_entry(&afu->contexts_idr, ctx, tmp) {
281 		/*
282 		 * Anything done in here needs to be setup before the IDR is
283 		 * created and torn down after the IDR removed
284 		 */
285 		cxl_context_detach(ctx);
286 
287 		/*
288 		 * We are force detaching - remove any active PSA mappings so
289 		 * userspace cannot interfere with the card if it comes back.
290 		 * Easiest way to exercise this is to unbind and rebind the
291 		 * driver via sysfs while it is in use.
292 		 */
293 		mutex_lock(&ctx->mapping_lock);
294 		if (ctx->mapping)
295 			unmap_mapping_range(ctx->mapping, 0, 0, 1);
296 		mutex_unlock(&ctx->mapping_lock);
297 	}
298 	mutex_unlock(&afu->contexts_lock);
299 }
300 
301 static void reclaim_ctx(struct rcu_head *rcu)
302 {
303 	struct cxl_context *ctx = container_of(rcu, struct cxl_context, rcu);
304 
305 	free_page((u64)ctx->sstp);
306 	if (ctx->ff_page)
307 		__free_page(ctx->ff_page);
308 	ctx->sstp = NULL;
309 
310 	kfree(ctx->irq_bitmap);
311 
312 	/* Drop ref to the afu device taken during cxl_context_init */
313 	cxl_afu_put(ctx->afu);
314 
315 	kfree(ctx);
316 }
317 
318 void cxl_context_free(struct cxl_context *ctx)
319 {
320 	if (ctx->kernelapi && ctx->mapping)
321 		cxl_release_mapping(ctx);
322 	mutex_lock(&ctx->afu->contexts_lock);
323 	idr_remove(&ctx->afu->contexts_idr, ctx->pe);
324 	mutex_unlock(&ctx->afu->contexts_lock);
325 	call_rcu(&ctx->rcu, reclaim_ctx);
326 }
327