xref: /openbmc/linux/drivers/misc/cxl/context.c (revision 6774def6)
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 = NULL; /* Set in start work ioctl */
45 
46 	/*
47 	 * Allocate the segment table before we put it in the IDR so that we
48 	 * can always access it when dereferenced from IDR. For the same
49 	 * reason, the segment table is only destroyed after the context is
50 	 * removed from the IDR.  Access to this in the IOCTL is protected by
51 	 * Linux filesytem symantics (can't IOCTL until open is complete).
52 	 */
53 	i = cxl_alloc_sst(ctx);
54 	if (i)
55 		return i;
56 
57 	INIT_WORK(&ctx->fault_work, cxl_handle_fault);
58 
59 	init_waitqueue_head(&ctx->wq);
60 	spin_lock_init(&ctx->lock);
61 
62 	ctx->irq_bitmap = NULL;
63 	ctx->pending_irq = false;
64 	ctx->pending_fault = false;
65 	ctx->pending_afu_err = false;
66 
67 	/*
68 	 * When we have to destroy all contexts in cxl_context_detach_all() we
69 	 * end up with afu_release_irqs() called from inside a
70 	 * idr_for_each_entry(). Hence we need to make sure that anything
71 	 * dereferenced from this IDR is ok before we allocate the IDR here.
72 	 * This clears out the IRQ ranges to ensure this.
73 	 */
74 	for (i = 0; i < CXL_IRQ_RANGES; i++)
75 		ctx->irqs.range[i] = 0;
76 
77 	mutex_init(&ctx->status_mutex);
78 
79 	ctx->status = OPENED;
80 
81 	/*
82 	 * Allocating IDR! We better make sure everything's setup that
83 	 * dereferences from it.
84 	 */
85 	idr_preload(GFP_KERNEL);
86 	spin_lock(&afu->contexts_lock);
87 	i = idr_alloc(&ctx->afu->contexts_idr, ctx, 0,
88 		      ctx->afu->num_procs, GFP_NOWAIT);
89 	spin_unlock(&afu->contexts_lock);
90 	idr_preload_end();
91 	if (i < 0)
92 		return i;
93 
94 	ctx->pe = i;
95 	ctx->elem = &ctx->afu->spa[i];
96 	ctx->pe_inserted = false;
97 	return 0;
98 }
99 
100 /*
101  * Map a per-context mmio space into the given vma.
102  */
103 int cxl_context_iomap(struct cxl_context *ctx, struct vm_area_struct *vma)
104 {
105 	u64 len = vma->vm_end - vma->vm_start;
106 	len = min(len, ctx->psn_size);
107 
108 	if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
109 		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
110 		return vm_iomap_memory(vma, ctx->afu->psn_phys, ctx->afu->adapter->ps_size);
111 	}
112 
113 	/* make sure there is a valid per process space for this AFU */
114 	if ((ctx->master && !ctx->afu->psa) || (!ctx->afu->pp_psa)) {
115 		pr_devel("AFU doesn't support mmio space\n");
116 		return -EINVAL;
117 	}
118 
119 	/* Can't mmap until the AFU is enabled */
120 	if (!ctx->afu->enabled)
121 		return -EBUSY;
122 
123 	pr_devel("%s: mmio physical: %llx pe: %i master:%i\n", __func__,
124 		 ctx->psn_phys, ctx->pe , ctx->master);
125 
126 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
127 	return vm_iomap_memory(vma, ctx->psn_phys, len);
128 }
129 
130 /*
131  * Detach a context from the hardware. This disables interrupts and doesn't
132  * return until all outstanding interrupts for this context have completed. The
133  * hardware should no longer access *ctx after this has returned.
134  */
135 static void __detach_context(struct cxl_context *ctx)
136 {
137 	enum cxl_context_status status;
138 
139 	mutex_lock(&ctx->status_mutex);
140 	status = ctx->status;
141 	ctx->status = CLOSED;
142 	mutex_unlock(&ctx->status_mutex);
143 	if (status != STARTED)
144 		return;
145 
146 	WARN_ON(cxl_detach_process(ctx));
147 	afu_release_irqs(ctx);
148 	flush_work(&ctx->fault_work); /* Only needed for dedicated process */
149 	wake_up_all(&ctx->wq);
150 }
151 
152 /*
153  * Detach the given context from the AFU. This doesn't actually
154  * free the context but it should stop the context running in hardware
155  * (ie. prevent this context from generating any further interrupts
156  * so that it can be freed).
157  */
158 void cxl_context_detach(struct cxl_context *ctx)
159 {
160 	__detach_context(ctx);
161 }
162 
163 /*
164  * Detach all contexts on the given AFU.
165  */
166 void cxl_context_detach_all(struct cxl_afu *afu)
167 {
168 	struct cxl_context *ctx;
169 	int tmp;
170 
171 	rcu_read_lock();
172 	idr_for_each_entry(&afu->contexts_idr, ctx, tmp)
173 		/*
174 		 * Anything done in here needs to be setup before the IDR is
175 		 * created and torn down after the IDR removed
176 		 */
177 		__detach_context(ctx);
178 	rcu_read_unlock();
179 }
180 
181 void cxl_context_free(struct cxl_context *ctx)
182 {
183 	spin_lock(&ctx->afu->contexts_lock);
184 	idr_remove(&ctx->afu->contexts_idr, ctx->pe);
185 	spin_unlock(&ctx->afu->contexts_lock);
186 	synchronize_rcu();
187 
188 	free_page((u64)ctx->sstp);
189 	ctx->sstp = NULL;
190 
191 	put_pid(ctx->pid);
192 	kfree(ctx);
193 }
194