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{
 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
116void 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
124static 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
171static 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 */
178int 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 */
217int __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 */
259void 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 */
274void 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
301static 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
318void 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}