xref: /openbmc/linux/drivers/misc/cxl/context.c (revision a2cce7a9)
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 		     struct address_space *mapping)
39 {
40 	int i;
41 
42 	spin_lock_init(&ctx->sste_lock);
43 	ctx->afu = afu;
44 	ctx->master = master;
45 	ctx->pid = NULL; /* Set in start work ioctl */
46 	mutex_init(&ctx->mapping_lock);
47 	ctx->mapping = mapping;
48 
49 	/*
50 	 * Allocate the segment table before we put it in the IDR so that we
51 	 * can always access it when dereferenced from IDR. For the same
52 	 * reason, the segment table is only destroyed after the context is
53 	 * removed from the IDR.  Access to this in the IOCTL is protected by
54 	 * Linux filesytem symantics (can't IOCTL until open is complete).
55 	 */
56 	i = cxl_alloc_sst(ctx);
57 	if (i)
58 		return i;
59 
60 	INIT_WORK(&ctx->fault_work, cxl_handle_fault);
61 
62 	init_waitqueue_head(&ctx->wq);
63 	spin_lock_init(&ctx->lock);
64 
65 	ctx->irq_bitmap = NULL;
66 	ctx->pending_irq = false;
67 	ctx->pending_fault = false;
68 	ctx->pending_afu_err = false;
69 
70 	/*
71 	 * When we have to destroy all contexts in cxl_context_detach_all() we
72 	 * end up with afu_release_irqs() called from inside a
73 	 * idr_for_each_entry(). Hence we need to make sure that anything
74 	 * dereferenced from this IDR is ok before we allocate the IDR here.
75 	 * This clears out the IRQ ranges to ensure this.
76 	 */
77 	for (i = 0; i < CXL_IRQ_RANGES; i++)
78 		ctx->irqs.range[i] = 0;
79 
80 	mutex_init(&ctx->status_mutex);
81 
82 	ctx->status = OPENED;
83 
84 	/*
85 	 * Allocating IDR! We better make sure everything's setup that
86 	 * dereferences from it.
87 	 */
88 	mutex_lock(&afu->contexts_lock);
89 	idr_preload(GFP_KERNEL);
90 	i = idr_alloc(&ctx->afu->contexts_idr, ctx, 0,
91 		      ctx->afu->num_procs, GFP_NOWAIT);
92 	idr_preload_end();
93 	mutex_unlock(&afu->contexts_lock);
94 	if (i < 0)
95 		return i;
96 
97 	ctx->pe = i;
98 	ctx->elem = &ctx->afu->spa[i];
99 	ctx->pe_inserted = false;
100 	return 0;
101 }
102 
103 static int cxl_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
104 {
105 	struct cxl_context *ctx = vma->vm_file->private_data;
106 	unsigned long address = (unsigned long)vmf->virtual_address;
107 	u64 area, offset;
108 
109 	offset = vmf->pgoff << PAGE_SHIFT;
110 
111 	pr_devel("%s: pe: %i address: 0x%lx offset: 0x%llx\n",
112 			__func__, ctx->pe, address, offset);
113 
114 	if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
115 		area = ctx->afu->psn_phys;
116 		if (offset >= ctx->afu->adapter->ps_size)
117 			return VM_FAULT_SIGBUS;
118 	} else {
119 		area = ctx->psn_phys;
120 		if (offset >= ctx->psn_size)
121 			return VM_FAULT_SIGBUS;
122 	}
123 
124 	mutex_lock(&ctx->status_mutex);
125 
126 	if (ctx->status != STARTED) {
127 		mutex_unlock(&ctx->status_mutex);
128 		pr_devel("%s: Context not started, failing problem state access\n", __func__);
129 		if (ctx->mmio_err_ff) {
130 			if (!ctx->ff_page) {
131 				ctx->ff_page = alloc_page(GFP_USER);
132 				if (!ctx->ff_page)
133 					return VM_FAULT_OOM;
134 				memset(page_address(ctx->ff_page), 0xff, PAGE_SIZE);
135 			}
136 			get_page(ctx->ff_page);
137 			vmf->page = ctx->ff_page;
138 			vma->vm_page_prot = pgprot_cached(vma->vm_page_prot);
139 			return 0;
140 		}
141 		return VM_FAULT_SIGBUS;
142 	}
143 
144 	vm_insert_pfn(vma, address, (area + offset) >> PAGE_SHIFT);
145 
146 	mutex_unlock(&ctx->status_mutex);
147 
148 	return VM_FAULT_NOPAGE;
149 }
150 
151 static const struct vm_operations_struct cxl_mmap_vmops = {
152 	.fault = cxl_mmap_fault,
153 };
154 
155 /*
156  * Map a per-context mmio space into the given vma.
157  */
158 int cxl_context_iomap(struct cxl_context *ctx, struct vm_area_struct *vma)
159 {
160 	u64 start = vma->vm_pgoff << PAGE_SHIFT;
161 	u64 len = vma->vm_end - vma->vm_start;
162 
163 	if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
164 		if (start + len > ctx->afu->adapter->ps_size)
165 			return -EINVAL;
166 	} else {
167 		if (start + len > ctx->psn_size)
168 			return -EINVAL;
169 	}
170 
171 	if (ctx->afu->current_mode != CXL_MODE_DEDICATED) {
172 		/* make sure there is a valid per process space for this AFU */
173 		if ((ctx->master && !ctx->afu->psa) || (!ctx->afu->pp_psa)) {
174 			pr_devel("AFU doesn't support mmio space\n");
175 			return -EINVAL;
176 		}
177 
178 		/* Can't mmap until the AFU is enabled */
179 		if (!ctx->afu->enabled)
180 			return -EBUSY;
181 	}
182 
183 	pr_devel("%s: mmio physical: %llx pe: %i master:%i\n", __func__,
184 		 ctx->psn_phys, ctx->pe , ctx->master);
185 
186 	vma->vm_flags |= VM_IO | VM_PFNMAP;
187 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
188 	vma->vm_ops = &cxl_mmap_vmops;
189 	return 0;
190 }
191 
192 /*
193  * Detach a context from the hardware. This disables interrupts and doesn't
194  * return until all outstanding interrupts for this context have completed. The
195  * hardware should no longer access *ctx after this has returned.
196  */
197 int __detach_context(struct cxl_context *ctx)
198 {
199 	enum cxl_context_status status;
200 
201 	mutex_lock(&ctx->status_mutex);
202 	status = ctx->status;
203 	ctx->status = CLOSED;
204 	mutex_unlock(&ctx->status_mutex);
205 	if (status != STARTED)
206 		return -EBUSY;
207 
208 	/* Only warn if we detached while the link was OK.
209 	 * If detach fails when hw is down, we don't care.
210 	 */
211 	WARN_ON(cxl_detach_process(ctx) &&
212 		cxl_adapter_link_ok(ctx->afu->adapter));
213 	flush_work(&ctx->fault_work); /* Only needed for dedicated process */
214 	put_pid(ctx->pid);
215 	cxl_ctx_put();
216 	return 0;
217 }
218 
219 /*
220  * Detach the given context from the AFU. This doesn't actually
221  * free the context but it should stop the context running in hardware
222  * (ie. prevent this context from generating any further interrupts
223  * so that it can be freed).
224  */
225 void cxl_context_detach(struct cxl_context *ctx)
226 {
227 	int rc;
228 
229 	rc = __detach_context(ctx);
230 	if (rc)
231 		return;
232 
233 	afu_release_irqs(ctx, ctx);
234 	wake_up_all(&ctx->wq);
235 }
236 
237 /*
238  * Detach all contexts on the given AFU.
239  */
240 void cxl_context_detach_all(struct cxl_afu *afu)
241 {
242 	struct cxl_context *ctx;
243 	int tmp;
244 
245 	mutex_lock(&afu->contexts_lock);
246 	idr_for_each_entry(&afu->contexts_idr, ctx, tmp) {
247 		/*
248 		 * Anything done in here needs to be setup before the IDR is
249 		 * created and torn down after the IDR removed
250 		 */
251 		cxl_context_detach(ctx);
252 
253 		/*
254 		 * We are force detaching - remove any active PSA mappings so
255 		 * userspace cannot interfere with the card if it comes back.
256 		 * Easiest way to exercise this is to unbind and rebind the
257 		 * driver via sysfs while it is in use.
258 		 */
259 		mutex_lock(&ctx->mapping_lock);
260 		if (ctx->mapping)
261 			unmap_mapping_range(ctx->mapping, 0, 0, 1);
262 		mutex_unlock(&ctx->mapping_lock);
263 	}
264 	mutex_unlock(&afu->contexts_lock);
265 }
266 
267 static void reclaim_ctx(struct rcu_head *rcu)
268 {
269 	struct cxl_context *ctx = container_of(rcu, struct cxl_context, rcu);
270 
271 	free_page((u64)ctx->sstp);
272 	if (ctx->ff_page)
273 		__free_page(ctx->ff_page);
274 	ctx->sstp = NULL;
275 	if (ctx->kernelapi)
276 		kfree(ctx->mapping);
277 
278 	kfree(ctx);
279 }
280 
281 void cxl_context_free(struct cxl_context *ctx)
282 {
283 	mutex_lock(&ctx->afu->contexts_lock);
284 	idr_remove(&ctx->afu->contexts_idr, ctx->pe);
285 	mutex_unlock(&ctx->afu->contexts_lock);
286 	call_rcu(&ctx->rcu, reclaim_ctx);
287 }
288