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 */
29struct 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 */
37int 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
103static 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		return VM_FAULT_SIGBUS;
130	}
131
132	vm_insert_pfn(vma, address, (area + offset) >> PAGE_SHIFT);
133
134	mutex_unlock(&ctx->status_mutex);
135
136	return VM_FAULT_NOPAGE;
137}
138
139static const struct vm_operations_struct cxl_mmap_vmops = {
140	.fault = cxl_mmap_fault,
141};
142
143/*
144 * Map a per-context mmio space into the given vma.
145 */
146int cxl_context_iomap(struct cxl_context *ctx, struct vm_area_struct *vma)
147{
148	u64 len = vma->vm_end - vma->vm_start;
149	len = min(len, ctx->psn_size);
150
151	if (ctx->afu->current_mode != CXL_MODE_DEDICATED) {
152		/* make sure there is a valid per process space for this AFU */
153		if ((ctx->master && !ctx->afu->psa) || (!ctx->afu->pp_psa)) {
154			pr_devel("AFU doesn't support mmio space\n");
155			return -EINVAL;
156		}
157
158		/* Can't mmap until the AFU is enabled */
159		if (!ctx->afu->enabled)
160			return -EBUSY;
161	}
162
163	pr_devel("%s: mmio physical: %llx pe: %i master:%i\n", __func__,
164		 ctx->psn_phys, ctx->pe , ctx->master);
165
166	vma->vm_flags |= VM_IO | VM_PFNMAP;
167	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
168	vma->vm_ops = &cxl_mmap_vmops;
169	return 0;
170}
171
172/*
173 * Detach a context from the hardware. This disables interrupts and doesn't
174 * return until all outstanding interrupts for this context have completed. The
175 * hardware should no longer access *ctx after this has returned.
176 */
177static void __detach_context(struct cxl_context *ctx)
178{
179	enum cxl_context_status status;
180
181	mutex_lock(&ctx->status_mutex);
182	status = ctx->status;
183	ctx->status = CLOSED;
184	mutex_unlock(&ctx->status_mutex);
185	if (status != STARTED)
186		return;
187
188	WARN_ON(cxl_detach_process(ctx));
189	afu_release_irqs(ctx);
190	flush_work(&ctx->fault_work); /* Only needed for dedicated process */
191	wake_up_all(&ctx->wq);
192}
193
194/*
195 * Detach the given context from the AFU. This doesn't actually
196 * free the context but it should stop the context running in hardware
197 * (ie. prevent this context from generating any further interrupts
198 * so that it can be freed).
199 */
200void cxl_context_detach(struct cxl_context *ctx)
201{
202	__detach_context(ctx);
203}
204
205/*
206 * Detach all contexts on the given AFU.
207 */
208void cxl_context_detach_all(struct cxl_afu *afu)
209{
210	struct cxl_context *ctx;
211	int tmp;
212
213	mutex_lock(&afu->contexts_lock);
214	idr_for_each_entry(&afu->contexts_idr, ctx, tmp) {
215		/*
216		 * Anything done in here needs to be setup before the IDR is
217		 * created and torn down after the IDR removed
218		 */
219		__detach_context(ctx);
220
221		/*
222		 * We are force detaching - remove any active PSA mappings so
223		 * userspace cannot interfere with the card if it comes back.
224		 * Easiest way to exercise this is to unbind and rebind the
225		 * driver via sysfs while it is in use.
226		 */
227		mutex_lock(&ctx->mapping_lock);
228		if (ctx->mapping)
229			unmap_mapping_range(ctx->mapping, 0, 0, 1);
230		mutex_unlock(&ctx->mapping_lock);
231	}
232	mutex_unlock(&afu->contexts_lock);
233}
234
235void cxl_context_free(struct cxl_context *ctx)
236{
237	mutex_lock(&ctx->afu->contexts_lock);
238	idr_remove(&ctx->afu->contexts_idr, ctx->pe);
239	mutex_unlock(&ctx->afu->contexts_lock);
240	synchronize_rcu();
241
242	free_page((u64)ctx->sstp);
243	ctx->sstp = NULL;
244
245	put_pid(ctx->pid);
246	kfree(ctx);
247}
248