drivers/misc/cxl/context.c

   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 <linux/sched/mm.h>
  21 #include <asm/cputable.h>
  22 #include <asm/current.h>
  23 #include <asm/copro.h>
  24
  25 #include "cxl.h"
  26
  27 /*
  28  * Allocates space for a CXL context.
  29  */
  30 struct cxl_context *cxl_context_alloc(void)
  31 {
  32         return kzalloc(sizeof(struct cxl_context), GFP_KERNEL);
  33 }
  34
  35 /*
  36  * Initialises a CXL context.
  37  */
  38 int cxl_context_init(struct cxl_context *ctx, struct cxl_afu *afu, bool master)
  39 {
  40         int i;
  41
  42         ctx->afu = afu;
  43         ctx->master = master;
  44         ctx->pid = NULL; /* Set in start work ioctl */
  45         mutex_init(&ctx->mapping_lock);
  46         ctx->mapping = NULL;
  47
  48         if (cxl_is_psl8(afu)) {
  49                 spin_lock_init(&ctx->sste_lock);
  50
  51                 /*
  52                  * Allocate the segment table before we put it in the IDR so that we
  53                  * can always access it when dereferenced from IDR. For the same
  54                  * reason, the segment table is only destroyed after the context is
  55                  * removed from the IDR.  Access to this in the IOCTL is protected by
  56                  * Linux filesytem symantics (can't IOCTL until open is complete).
  57                  */
  58                 i = cxl_alloc_sst(ctx);
  59                 if (i)
  60                         return i;
  61         }
  62
  63         INIT_WORK(&ctx->fault_work, cxl_handle_fault);
  64
  65         init_waitqueue_head(&ctx->wq);
  66         spin_lock_init(&ctx->lock);
  67
  68         ctx->irq_bitmap = NULL;
  69         ctx->pending_irq = false;
  70         ctx->pending_fault = false;
  71         ctx->pending_afu_err = false;
  72
  73         INIT_LIST_HEAD(&ctx->irq_names);
  74         INIT_LIST_HEAD(&ctx->extra_irq_contexts);
  75
  76         /*
  77          * When we have to destroy all contexts in cxl_context_detach_all() we
  78          * end up with afu_release_irqs() called from inside a
  79          * idr_for_each_entry(). Hence we need to make sure that anything
  80          * dereferenced from this IDR is ok before we allocate the IDR here.
  81          * This clears out the IRQ ranges to ensure this.
  82          */
  83         for (i = 0; i < CXL_IRQ_RANGES; i++)
  84                 ctx->irqs.range[i] = 0;
  85
  86         mutex_init(&ctx->status_mutex);
  87
  88         ctx->status = OPENED;
  89
  90         /*
  91          * Allocating IDR! We better make sure everything's setup that
  92          * dereferences from it.
  93          */
  94         mutex_lock(&afu->contexts_lock);
  95         idr_preload(GFP_KERNEL);
  96         i = idr_alloc(&ctx->afu->contexts_idr, ctx, ctx->afu->adapter->min_pe,
  97                       ctx->afu->num_procs, GFP_NOWAIT);
  98         idr_preload_end();
  99         mutex_unlock(&afu->contexts_lock);
 100         if (i < 0)
 101                 return i;
 102
 103         ctx->pe = i;
 104         if (cpu_has_feature(CPU_FTR_HVMODE)) {
 105                 ctx->elem = &ctx->afu->native->spa[i];
 106                 ctx->external_pe = ctx->pe;
 107         } else {
 108                 ctx->external_pe = -1; /* assigned when attaching */
 109         }
 110         ctx->pe_inserted = false;
 111
 112         /*
 113          * take a ref on the afu so that it stays alive at-least till
 114          * this context is reclaimed inside reclaim_ctx.
 115          */
 116         cxl_afu_get(afu);
 117         return 0;
 118 }
 119
 120 void cxl_context_set_mapping(struct cxl_context *ctx,
 121                         struct address_space *mapping)
 122 {
 123         mutex_lock(&ctx->mapping_lock);
 124         ctx->mapping = mapping;
 125         mutex_unlock(&ctx->mapping_lock);
 126 }
 127
 128 static int cxl_mmap_fault(struct vm_fault *vmf)
 129 {
 130         struct vm_area_struct *vma = vmf->vma;
 131         struct cxl_context *ctx = vma->vm_file->private_data;
 132         u64 area, offset;
 133
 134         offset = vmf->pgoff << PAGE_SHIFT;
 135
 136         pr_devel("%s: pe: %i address: 0x%lx offset: 0x%llx\n",
 137                         __func__, ctx->pe, vmf->address, offset);
 138
 139         if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
 140                 area = ctx->afu->psn_phys;
 141                 if (offset >= ctx->afu->adapter->ps_size)
 142                         return VM_FAULT_SIGBUS;
 143         } else {
 144                 area = ctx->psn_phys;
 145                 if (offset >= ctx->psn_size)
 146                         return VM_FAULT_SIGBUS;
 147         }
 148
 149         mutex_lock(&ctx->status_mutex);
 150
 151         if (ctx->status != STARTED) {
 152                 mutex_unlock(&ctx->status_mutex);
 153                 pr_devel("%s: Context not started, failing problem state access\n", __func__);
 154                 if (ctx->mmio_err_ff) {
 155                         if (!ctx->ff_page) {
 156                                 ctx->ff_page = alloc_page(GFP_USER);
 157                                 if (!ctx->ff_page)
 158                                         return VM_FAULT_OOM;
 159                                 memset(page_address(ctx->ff_page), 0xff, PAGE_SIZE);
 160                         }
 161                         get_page(ctx->ff_page);
 162                         vmf->page = ctx->ff_page;
 163                         vma->vm_page_prot = pgprot_cached(vma->vm_page_prot);
 164                         return 0;
 165                 }
 166                 return VM_FAULT_SIGBUS;
 167         }
 168
 169         vm_insert_pfn(vma, vmf->address, (area + offset) >> PAGE_SHIFT);
 170
 171         mutex_unlock(&ctx->status_mutex);
 172
 173         return VM_FAULT_NOPAGE;
 174 }
 175
 176 static const struct vm_operations_struct cxl_mmap_vmops = {
 177         .fault = cxl_mmap_fault,
 178 };
 179
 180 /*
 181  * Map a per-context mmio space into the given vma.
 182  */
 183 int cxl_context_iomap(struct cxl_context *ctx, struct vm_area_struct *vma)
 184 {
 185         u64 start = vma->vm_pgoff << PAGE_SHIFT;
 186         u64 len = vma->vm_end - vma->vm_start;
 187
 188         if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
 189                 if (start + len > ctx->afu->adapter->ps_size)
 190                         return -EINVAL;
 191
 192                 if (cxl_is_psl9(ctx->afu)) {
 193                         /*
 194                          * Make sure there is a valid problem state
 195                          * area space for this AFU.
 196                          */
 197                         if (ctx->master && !ctx->afu->psa) {
 198                                 pr_devel("AFU doesn't support mmio space\n");
 199                                 return -EINVAL;
 200                         }
 201
 202                         /* Can't mmap until the AFU is enabled */
 203                         if (!ctx->afu->enabled)
 204                                 return -EBUSY;
 205                 }
 206         } else {
 207                 if (start + len > ctx->psn_size)
 208                         return -EINVAL;
 209
 210                 /* Make sure there is a valid per process space for this AFU */
 211                 if ((ctx->master && !ctx->afu->psa) || (!ctx->afu->pp_psa)) {
 212                         pr_devel("AFU doesn't support mmio space\n");
 213                         return -EINVAL;
 214                 }
 215
 216                 /* Can't mmap until the AFU is enabled */
 217                 if (!ctx->afu->enabled)
 218                         return -EBUSY;
 219         }
 220
 221         pr_devel("%s: mmio physical: %llx pe: %i master:%i\n", __func__,
 222                  ctx->psn_phys, ctx->pe , ctx->master);
 223
 224         vma->vm_flags |= VM_IO | VM_PFNMAP;
 225         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 226         vma->vm_ops = &cxl_mmap_vmops;
 227         return 0;
 228 }
 229
 230 /*
 231  * Detach a context from the hardware. This disables interrupts and doesn't
 232  * return until all outstanding interrupts for this context have completed. The
 233  * hardware should no longer access *ctx after this has returned.
 234  */
 235 int __detach_context(struct cxl_context *ctx)
 236 {
 237         enum cxl_context_status status;
 238
 239         mutex_lock(&ctx->status_mutex);
 240         status = ctx->status;
 241         ctx->status = CLOSED;
 242         mutex_unlock(&ctx->status_mutex);
 243         if (status != STARTED)
 244                 return -EBUSY;
 245
 246         /* Only warn if we detached while the link was OK.
 247          * If detach fails when hw is down, we don't care.
 248          */
 249         WARN_ON(cxl_ops->detach_process(ctx) &&
 250                 cxl_ops->link_ok(ctx->afu->adapter, ctx->afu));
 251         flush_work(&ctx->fault_work); /* Only needed for dedicated process */
 252
 253         /*
 254          * Wait until no further interrupts are presented by the PSL
 255          * for this context.
 256          */
 257         if (cxl_ops->irq_wait)
 258                 cxl_ops->irq_wait(ctx);
 259
 260         /* release the reference to the group leader and mm handling pid */
 261         put_pid(ctx->pid);
 262
 263         cxl_ctx_put();
 264
 265         /* Decrease the attached context count on the adapter */
 266         cxl_adapter_context_put(ctx->afu->adapter);
 267
 268         /* Decrease the mm count on the context */
 269         cxl_context_mm_count_put(ctx);
 270         ctx->mm = NULL;
 271
 272         return 0;
 273 }
 274
 275 /*
 276  * Detach the given context from the AFU. This doesn't actually
 277  * free the context but it should stop the context running in hardware
 278  * (ie. prevent this context from generating any further interrupts
 279  * so that it can be freed).
 280  */
 281 void cxl_context_detach(struct cxl_context *ctx)
 282 {
 283         int rc;
 284
 285         rc = __detach_context(ctx);
 286         if (rc)
 287                 return;
 288
 289         afu_release_irqs(ctx, ctx);
 290         wake_up_all(&ctx->wq);
 291 }
 292
 293 /*
 294  * Detach all contexts on the given AFU.
 295  */
 296 void cxl_context_detach_all(struct cxl_afu *afu)
 297 {
 298         struct cxl_context *ctx;
 299         int tmp;
 300
 301         mutex_lock(&afu->contexts_lock);
 302         idr_for_each_entry(&afu->contexts_idr, ctx, tmp) {
 303                 /*
 304                  * Anything done in here needs to be setup before the IDR is
 305                  * created and torn down after the IDR removed
 306                  */
 307                 cxl_context_detach(ctx);
 308
 309                 /*
 310                  * We are force detaching - remove any active PSA mappings so
 311                  * userspace cannot interfere with the card if it comes back.
 312                  * Easiest way to exercise this is to unbind and rebind the
 313                  * driver via sysfs while it is in use.
 314                  */
 315                 mutex_lock(&ctx->mapping_lock);
 316                 if (ctx->mapping)
 317                         unmap_mapping_range(ctx->mapping, 0, 0, 1);
 318                 mutex_unlock(&ctx->mapping_lock);
 319         }
 320         mutex_unlock(&afu->contexts_lock);
 321 }
 322
 323 static void reclaim_ctx(struct rcu_head *rcu)
 324 {
 325         struct cxl_context *ctx = container_of(rcu, struct cxl_context, rcu);
 326
 327         if (cxl_is_psl8(ctx->afu))
 328                 free_page((u64)ctx->sstp);
 329         if (ctx->ff_page)
 330                 __free_page(ctx->ff_page);
 331         ctx->sstp = NULL;
 332
 333         kfree(ctx->irq_bitmap);
 334
 335         /* Drop ref to the afu device taken during cxl_context_init */
 336         cxl_afu_put(ctx->afu);
 337
 338         kfree(ctx);
 339 }
 340
 341 void cxl_context_free(struct cxl_context *ctx)
 342 {
 343         if (ctx->kernelapi && ctx->mapping)
 344                 cxl_release_mapping(ctx);
 345         mutex_lock(&ctx->afu->contexts_lock);
 346         idr_remove(&ctx->afu->contexts_idr, ctx->pe);
 347         mutex_unlock(&ctx->afu->contexts_lock);
 348         call_rcu(&ctx->rcu, reclaim_ctx);
 349 }
 350
 351 void cxl_context_mm_count_get(struct cxl_context *ctx)
 352 {
 353         if (ctx->mm)
 354                 atomic_inc(&ctx->mm->mm_count);
 355 }
 356
 357 void cxl_context_mm_count_put(struct cxl_context *ctx)
 358 {
 359         if (ctx->mm)
 360                 mmdrop(ctx->mm);
 361 }