1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright 2014 IBM Corp.
4 */
5
6#include <linux/module.h>
7#include <linux/kernel.h>
8#include <linux/bitmap.h>
9#include <linux/sched.h>
10#include <linux/pid.h>
11#include <linux/fs.h>
12#include <linux/mm.h>
13#include <linux/debugfs.h>
14#include <linux/slab.h>
15#include <linux/idr.h>
16#include <linux/sched/mm.h>
17#include <linux/mmu_context.h>
18#include <asm/cputable.h>
19#include <asm/current.h>
20#include <asm/copro.h>
21
22#include "cxl.h"
23
24/*
25 * Allocates space for a CXL context.
26 */
27struct cxl_context *cxl_context_alloc(void)
28{
29	return kzalloc(sizeof(struct cxl_context), GFP_KERNEL);
30}
31
32/*
33 * Initialises a CXL context.
34 */
35int cxl_context_init(struct cxl_context *ctx, struct cxl_afu *afu, bool master)
36{
37	int i;
38
39	ctx->afu = afu;
40	ctx->master = master;
41	ctx->pid = NULL; /* Set in start work ioctl */
42	mutex_init(&ctx->mapping_lock);
43	ctx->mapping = NULL;
44	ctx->tidr = 0;
45	ctx->assign_tidr = false;
46
47	if (cxl_is_power8()) {
48		spin_lock_init(&ctx->sste_lock);
49
50		/*
51		 * Allocate the segment table before we put it in the IDR so that we
52		 * can always access it when dereferenced from IDR. For the same
53		 * reason, the segment table is only destroyed after the context is
54		 * removed from the IDR.  Access to this in the IOCTL is protected by
55		 * Linux filesystem semantics (can't IOCTL until open is complete).
56		 */
57		i = cxl_alloc_sst(ctx);
58		if (i)
59			return i;
60	}
61
62	INIT_WORK(&ctx->fault_work, cxl_handle_fault);
63
64	init_waitqueue_head(&ctx->wq);
65	spin_lock_init(&ctx->lock);
66
67	ctx->irq_bitmap = NULL;
68	ctx->pending_irq = false;
69	ctx->pending_fault = false;
70	ctx->pending_afu_err = false;
71
72	INIT_LIST_HEAD(&ctx->irq_names);
73
74	/*
75	 * When we have to destroy all contexts in cxl_context_detach_all() we
76	 * end up with afu_release_irqs() called from inside a
77	 * idr_for_each_entry(). Hence we need to make sure that anything
78	 * dereferenced from this IDR is ok before we allocate the IDR here.
79	 * This clears out the IRQ ranges to ensure this.
80	 */
81	for (i = 0; i < CXL_IRQ_RANGES; i++)
82		ctx->irqs.range[i] = 0;
83
84	mutex_init(&ctx->status_mutex);
85
86	ctx->status = OPENED;
87
88	/*
89	 * Allocating IDR! We better make sure everything's setup that
90	 * dereferences from it.
91	 */
92	mutex_lock(&afu->contexts_lock);
93	idr_preload(GFP_KERNEL);
94	i = idr_alloc(&ctx->afu->contexts_idr, ctx, 0,
95		      ctx->afu->num_procs, GFP_NOWAIT);
96	idr_preload_end();
97	mutex_unlock(&afu->contexts_lock);
98	if (i < 0)
99		return i;
100
101	ctx->pe = i;
102	if (cpu_has_feature(CPU_FTR_HVMODE)) {
103		ctx->elem = &ctx->afu->native->spa[i];
104		ctx->external_pe = ctx->pe;
105	} else {
106		ctx->external_pe = -1; /* assigned when attaching */
107	}
108	ctx->pe_inserted = false;
109
110	/*
111	 * take a ref on the afu so that it stays alive at-least till
112	 * this context is reclaimed inside reclaim_ctx.
113	 */
114	cxl_afu_get(afu);
115	return 0;
116}
117
118void cxl_context_set_mapping(struct cxl_context *ctx,
119			struct address_space *mapping)
120{
121	mutex_lock(&ctx->mapping_lock);
122	ctx->mapping = mapping;
123	mutex_unlock(&ctx->mapping_lock);
124}
125
126static vm_fault_t cxl_mmap_fault(struct vm_fault *vmf)
127{
128	struct vm_area_struct *vma = vmf->vma;
129	struct cxl_context *ctx = vma->vm_file->private_data;
130	u64 area, offset;
131	vm_fault_t ret;
132
133	offset = vmf->pgoff << PAGE_SHIFT;
134
135	pr_devel("%s: pe: %i address: 0x%lx offset: 0x%llx\n",
136			__func__, ctx->pe, vmf->address, offset);
137
138	if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
139		area = ctx->afu->psn_phys;
140		if (offset >= ctx->afu->adapter->ps_size)
141			return VM_FAULT_SIGBUS;
142	} else {
143		area = ctx->psn_phys;
144		if (offset >= ctx->psn_size)
145			return VM_FAULT_SIGBUS;
146	}
147
148	mutex_lock(&ctx->status_mutex);
149
150	if (ctx->status != STARTED) {
151		mutex_unlock(&ctx->status_mutex);
152		pr_devel("%s: Context not started, failing problem state access\n", __func__);
153		if (ctx->mmio_err_ff) {
154			if (!ctx->ff_page) {
155				ctx->ff_page = alloc_page(GFP_USER);
156				if (!ctx->ff_page)
157					return VM_FAULT_OOM;
158				memset(page_address(ctx->ff_page), 0xff, PAGE_SIZE);
159			}
160			get_page(ctx->ff_page);
161			vmf->page = ctx->ff_page;
162			vma->vm_page_prot = pgprot_cached(vma->vm_page_prot);
163			return 0;
164		}
165		return VM_FAULT_SIGBUS;
166	}
167
168	ret = vmf_insert_pfn(vma, vmf->address, (area + offset) >> PAGE_SHIFT);
169
170	mutex_unlock(&ctx->status_mutex);
171
172	return ret;
173}
174
175static const struct vm_operations_struct cxl_mmap_vmops = {
176	.fault = cxl_mmap_fault,
177};
178
179/*
180 * Map a per-context mmio space into the given vma.
181 */
182int cxl_context_iomap(struct cxl_context *ctx, struct vm_area_struct *vma)
183{
184	u64 start = vma->vm_pgoff << PAGE_SHIFT;
185	u64 len = vma->vm_end - vma->vm_start;
186
187	if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
188		if (start + len > ctx->afu->adapter->ps_size)
189			return -EINVAL;
190
191		if (cxl_is_power9()) {
192			/*
193			 * Make sure there is a valid problem state
194			 * area space for this AFU.
195			 */
196			if (ctx->master && !ctx->afu->psa) {
197				pr_devel("AFU doesn't support mmio space\n");
198				return -EINVAL;
199			}
200
201			/* Can't mmap until the AFU is enabled */
202			if (!ctx->afu->enabled)
203				return -EBUSY;
204		}
205	} else {
206		if (start + len > ctx->psn_size)
207			return -EINVAL;
208
209		/* Make sure there is a valid per process space for this AFU */
210		if ((ctx->master && !ctx->afu->psa) || (!ctx->afu->pp_psa)) {
211			pr_devel("AFU doesn't support mmio space\n");
212			return -EINVAL;
213		}
214
215		/* Can't mmap until the AFU is enabled */
216		if (!ctx->afu->enabled)
217			return -EBUSY;
218	}
219
220	pr_devel("%s: mmio physical: %llx pe: %i master:%i\n", __func__,
221		 ctx->psn_phys, ctx->pe , ctx->master);
222
223	vm_flags_set(vma, VM_IO | VM_PFNMAP);
224	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
225	vma->vm_ops = &cxl_mmap_vmops;
226	return 0;
227}
228
229/*
230 * Detach a context from the hardware. This disables interrupts and doesn't
231 * return until all outstanding interrupts for this context have completed. The
232 * hardware should no longer access *ctx after this has returned.
233 */
234int __detach_context(struct cxl_context *ctx)
235{
236	enum cxl_context_status status;
237
238	mutex_lock(&ctx->status_mutex);
239	status = ctx->status;
240	ctx->status = CLOSED;
241	mutex_unlock(&ctx->status_mutex);
242	if (status != STARTED)
243		return -EBUSY;
244
245	/* Only warn if we detached while the link was OK.
246	 * If detach fails when hw is down, we don't care.
247	 */
248	WARN_ON(cxl_ops->detach_process(ctx) &&
249		cxl_ops->link_ok(ctx->afu->adapter, ctx->afu));
250	flush_work(&ctx->fault_work); /* Only needed for dedicated process */
251
252	/*
253	 * Wait until no further interrupts are presented by the PSL
254	 * for this context.
255	 */
256	if (cxl_ops->irq_wait)
257		cxl_ops->irq_wait(ctx);
258
259	/* release the reference to the group leader and mm handling pid */
260	put_pid(ctx->pid);
261
262	cxl_ctx_put();
263
264	/* Decrease the attached context count on the adapter */
265	cxl_adapter_context_put(ctx->afu->adapter);
266
267	/* Decrease the mm count on the context */
268	cxl_context_mm_count_put(ctx);
269	if (ctx->mm)
270		mm_context_remove_copro(ctx->mm);
271	ctx->mm = NULL;
272
273	return 0;
274}
275
276/*
277 * Detach the given context from the AFU. This doesn't actually
278 * free the context but it should stop the context running in hardware
279 * (ie. prevent this context from generating any further interrupts
280 * so that it can be freed).
281 */
282void cxl_context_detach(struct cxl_context *ctx)
283{
284	int rc;
285
286	rc = __detach_context(ctx);
287	if (rc)
288		return;
289
290	afu_release_irqs(ctx, ctx);
291	wake_up_all(&ctx->wq);
292}
293
294/*
295 * Detach all contexts on the given AFU.
296 */
297void cxl_context_detach_all(struct cxl_afu *afu)
298{
299	struct cxl_context *ctx;
300	int tmp;
301
302	mutex_lock(&afu->contexts_lock);
303	idr_for_each_entry(&afu->contexts_idr, ctx, tmp) {
304		/*
305		 * Anything done in here needs to be setup before the IDR is
306		 * created and torn down after the IDR removed
307		 */
308		cxl_context_detach(ctx);
309
310		/*
311		 * We are force detaching - remove any active PSA mappings so
312		 * userspace cannot interfere with the card if it comes back.
313		 * Easiest way to exercise this is to unbind and rebind the
314		 * driver via sysfs while it is in use.
315		 */
316		mutex_lock(&ctx->mapping_lock);
317		if (ctx->mapping)
318			unmap_mapping_range(ctx->mapping, 0, 0, 1);
319		mutex_unlock(&ctx->mapping_lock);
320	}
321	mutex_unlock(&afu->contexts_lock);
322}
323
324static void reclaim_ctx(struct rcu_head *rcu)
325{
326	struct cxl_context *ctx = container_of(rcu, struct cxl_context, rcu);
327
328	if (cxl_is_power8())
329		free_page((u64)ctx->sstp);
330	if (ctx->ff_page)
331		__free_page(ctx->ff_page);
332	ctx->sstp = NULL;
333
334	bitmap_free(ctx->irq_bitmap);
335
336	/* Drop ref to the afu device taken during cxl_context_init */
337	cxl_afu_put(ctx->afu);
338
339	kfree(ctx);
340}
341
342void cxl_context_free(struct cxl_context *ctx)
343{
344	if (ctx->kernelapi && ctx->mapping)
345		cxl_release_mapping(ctx);
346	mutex_lock(&ctx->afu->contexts_lock);
347	idr_remove(&ctx->afu->contexts_idr, ctx->pe);
348	mutex_unlock(&ctx->afu->contexts_lock);
349	call_rcu(&ctx->rcu, reclaim_ctx);
350}
351
352void cxl_context_mm_count_get(struct cxl_context *ctx)
353{
354	if (ctx->mm)
355		mmgrab(ctx->mm);
356}
357
358void cxl_context_mm_count_put(struct cxl_context *ctx)
359{
360	if (ctx->mm)
361		mmdrop(ctx->mm);
362}
363