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 <linux/mmu_context.h>
  22 #include <asm/cputable.h>
  23 #include <asm/current.h>
  24 #include <asm/copro.h>
  25
  26 #include "cxl.h"
  27
  28 /*
  29  * Allocates space for a CXL context.
  30  */
  31 struct cxl_context *cxl_context_alloc(void)
  32 {
  33         return kzalloc(sizeof(struct cxl_context), GFP_KERNEL);
  34 }
  35
  36 /*
  37  * Initialises a CXL context.
  38  */
  39 int cxl_context_init(struct cxl_context *ctx, struct cxl_afu *afu, bool master)
  40 {
  41         int i;
  42
  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 = NULL;
  48
  49         if (cxl_is_power8()) {
  50                 spin_lock_init(&ctx->sste_lock);
  51
  52                 /*
  53                  * Allocate the segment table before we put it in the IDR so that we
  54                  * can always access it when dereferenced from IDR. For the same
  55                  * reason, the segment table is only destroyed after the context is
  56                  * removed from the IDR.  Access to this in the IOCTL is protected by
  57                  * Linux filesytem symantics (can't IOCTL until open is complete).
  58                  */
  59                 i = cxl_alloc_sst(ctx);
  60                 if (i)
  61                         return i;
  62         }
  63
  64         INIT_WORK(&ctx->fault_work, cxl_handle_fault);
  65
  66         init_waitqueue_head(&ctx->wq);
  67         spin_lock_init(&ctx->lock);
  68
  69         ctx->irq_bitmap = NULL;
  70         ctx->pending_irq = false;
  71         ctx->pending_fault = false;
  72         ctx->pending_afu_err = false;
  73
  74         INIT_LIST_HEAD(&ctx->irq_names);
  75         INIT_LIST_HEAD(&ctx->extra_irq_contexts);
  76
  77         /*
  78          * When we have to destroy all contexts in cxl_context_detach_all() we
  79          * end up with afu_release_irqs() called from inside a
  80          * idr_for_each_entry(). Hence we need to make sure that anything
  81          * dereferenced from this IDR is ok before we allocate the IDR here.
  82          * This clears out the IRQ ranges to ensure this.
  83          */
  84         for (i = 0; i < CXL_IRQ_RANGES; i++)
  85                 ctx->irqs.range[i] = 0;
  86
  87         mutex_init(&ctx->status_mutex);
  88
  89         ctx->status = OPENED;
  90
  91         /*
  92          * Allocating IDR! We better make sure everything's setup that
  93          * dereferences from it.
  94          */
  95         mutex_lock(&afu->contexts_lock);
  96         idr_preload(GFP_KERNEL);
  97         i = idr_alloc(&ctx->afu->contexts_idr, ctx, ctx->afu->adapter->min_pe,
  98                       ctx->afu->num_procs, GFP_NOWAIT);
  99         idr_preload_end();
 100         mutex_unlock(&afu->contexts_lock);
 101         if (i < 0)
 102                 return i;
 103
 104         ctx->pe = i;
 105         if (cpu_has_feature(CPU_FTR_HVMODE)) {
 106                 ctx->elem = &ctx->afu->native->spa[i];
 107                 ctx->external_pe = ctx->pe;
 108         } else {
 109                 ctx->external_pe = -1; /* assigned when attaching */
 110         }
 111         ctx->pe_inserted = false;
 112
 113         /*
 114          * take a ref on the afu so that it stays alive at-least till
 115          * this context is reclaimed inside reclaim_ctx.
 116          */
 117         cxl_afu_get(afu);
 118         return 0;
 119 }
 120
 121 void cxl_context_set_mapping(struct cxl_context *ctx,
 122                         struct address_space *mapping)
 123 {
 124         mutex_lock(&ctx->mapping_lock);
 125         ctx->mapping = mapping;
 126         mutex_unlock(&ctx->mapping_lock);
 127 }
 128
 129 static int cxl_mmap_fault(struct vm_fault *vmf)
 130 {
 131         struct vm_area_struct *vma = vmf->vma;
 132         struct cxl_context *ctx = vma->vm_file->private_data;
 133         u64 area, offset;
 134
 135         offset = vmf->pgoff << PAGE_SHIFT;
 136
 137         pr_devel("%s: pe: %i address: 0x%lx offset: 0x%llx\n",
 138                         __func__, ctx->pe, vmf->address, offset);
 139
 140         if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
 141                 area = ctx->afu->psn_phys;
 142                 if (offset >= ctx->afu->adapter->ps_size)
 143                         return VM_FAULT_SIGBUS;
 144         } else {
 145                 area = ctx->psn_phys;
 146                 if (offset >= ctx->psn_size)
 147                         return VM_FAULT_SIGBUS;
 148         }
 149
 150         mutex_lock(&ctx->status_mutex);
 151
 152         if (ctx->status != STARTED) {
 153                 mutex_unlock(&ctx->status_mutex);
 154                 pr_devel("%s: Context not started, failing problem state access\n", __func__);
 155                 if (ctx->mmio_err_ff) {
 156                         if (!ctx->ff_page) {
 157                                 ctx->ff_page = alloc_page(GFP_USER);
 158                                 if (!ctx->ff_page)
 159                                         return VM_FAULT_OOM;
 160                                 memset(page_address(ctx->ff_page), 0xff, PAGE_SIZE);
 161                         }
 162                         get_page(ctx->ff_page);
 163                         vmf->page = ctx->ff_page;
 164                         vma->vm_page_prot = pgprot_cached(vma->vm_page_prot);
 165                         return 0;
 166                 }
 167                 return VM_FAULT_SIGBUS;
 168         }
 169
 170         vm_insert_pfn(vma, vmf->address, (area + offset) >> PAGE_SHIFT);
 171
 172         mutex_unlock(&ctx->status_mutex);
 173
 174         return VM_FAULT_NOPAGE;
 175 }
 176
 177 static const struct vm_operations_struct cxl_mmap_vmops = {
 178         .fault = cxl_mmap_fault,
 179 };
 180
 181 /*
 182  * Map a per-context mmio space into the given vma.
 183  */
 184 int cxl_context_iomap(struct cxl_context *ctx, struct vm_area_struct *vma)
 185 {
 186         u64 start = vma->vm_pgoff << PAGE_SHIFT;
 187         u64 len = vma->vm_end - vma->vm_start;
 188
 189         if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
 190                 if (start + len > ctx->afu->adapter->ps_size)
 191                         return -EINVAL;
 192
 193                 if (cxl_is_power9()) {
 194                         /*
 195                          * Make sure there is a valid problem state
 196                          * area space for this AFU.
 197                          */
 198                         if (ctx->master && !ctx->afu->psa) {
 199                                 pr_devel("AFU doesn't support mmio space\n");
 200                                 return -EINVAL;
 201                         }
 202
 203                         /* Can't mmap until the AFU is enabled */
 204                         if (!ctx->afu->enabled)
 205                                 return -EBUSY;
 206                 }
 207         } else {
 208                 if (start + len > ctx->psn_size)
 209                         return -EINVAL;
 210
 211                 /* Make sure there is a valid per process space for this AFU */
 212                 if ((ctx->master && !ctx->afu->psa) || (!ctx->afu->pp_psa)) {
 213                         pr_devel("AFU doesn't support mmio space\n");
 214                         return -EINVAL;
 215                 }
 216
 217                 /* Can't mmap until the AFU is enabled */
 218                 if (!ctx->afu->enabled)
 219                         return -EBUSY;
 220         }
 221
 222         pr_devel("%s: mmio physical: %llx pe: %i master:%i\n", __func__,
 223                  ctx->psn_phys, ctx->pe , ctx->master);
 224
 225         vma->vm_flags |= VM_IO | VM_PFNMAP;
 226         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 227         vma->vm_ops = &cxl_mmap_vmops;
 228         return 0;
 229 }
 230
 231 /*
 232  * Detach a context from the hardware. This disables interrupts and doesn't
 233  * return until all outstanding interrupts for this context have completed. The
 234  * hardware should no longer access *ctx after this has returned.
 235  */
 236 int __detach_context(struct cxl_context *ctx)
 237 {
 238         enum cxl_context_status status;
 239
 240         mutex_lock(&ctx->status_mutex);
 241         status = ctx->status;
 242         ctx->status = CLOSED;
 243         mutex_unlock(&ctx->status_mutex);
 244         if (status != STARTED)
 245                 return -EBUSY;
 246
 247         /* Only warn if we detached while the link was OK.
 248          * If detach fails when hw is down, we don't care.
 249          */
 250         WARN_ON(cxl_ops->detach_process(ctx) &&
 251                 cxl_ops->link_ok(ctx->afu->adapter, ctx->afu));
 252         flush_work(&ctx->fault_work); /* Only needed for dedicated process */
 253
 254         /*
 255          * Wait until no further interrupts are presented by the PSL
 256          * for this context.
 257          */
 258         if (cxl_ops->irq_wait)
 259                 cxl_ops->irq_wait(ctx);
 260
 261         /* release the reference to the group leader and mm handling pid */
 262         put_pid(ctx->pid);
 263
 264         cxl_ctx_put();
 265
 266         /* Decrease the attached context count on the adapter */
 267         cxl_adapter_context_put(ctx->afu->adapter);
 268
 269         /* Decrease the mm count on the context */
 270         cxl_context_mm_count_put(ctx);
 271         if (ctx->mm)
 272                 mm_context_remove_copro(ctx->mm);
 273         ctx->mm = NULL;
 274
 275         return 0;
 276 }
 277
 278 /*
 279  * Detach the given context from the AFU. This doesn't actually
 280  * free the context but it should stop the context running in hardware
 281  * (ie. prevent this context from generating any further interrupts
 282  * so that it can be freed).
 283  */
 284 void cxl_context_detach(struct cxl_context *ctx)
 285 {
 286         int rc;
 287
 288         rc = __detach_context(ctx);
 289         if (rc)
 290                 return;
 291
 292         afu_release_irqs(ctx, ctx);
 293         wake_up_all(&ctx->wq);
 294 }
 295
 296 /*
 297  * Detach all contexts on the given AFU.
 298  */
 299 void cxl_context_detach_all(struct cxl_afu *afu)
 300 {
 301         struct cxl_context *ctx;
 302         int tmp;
 303
 304         mutex_lock(&afu->contexts_lock);
 305         idr_for_each_entry(&afu->contexts_idr, ctx, tmp) {
 306                 /*
 307                  * Anything done in here needs to be setup before the IDR is
 308                  * created and torn down after the IDR removed
 309                  */
 310                 cxl_context_detach(ctx);
 311
 312                 /*
 313                  * We are force detaching - remove any active PSA mappings so
 314                  * userspace cannot interfere with the card if it comes back.
 315                  * Easiest way to exercise this is to unbind and rebind the
 316                  * driver via sysfs while it is in use.
 317                  */
 318                 mutex_lock(&ctx->mapping_lock);
 319                 if (ctx->mapping)
 320                         unmap_mapping_range(ctx->mapping, 0, 0, 1);
 321                 mutex_unlock(&ctx->mapping_lock);
 322         }
 323         mutex_unlock(&afu->contexts_lock);
 324 }
 325
 326 static void reclaim_ctx(struct rcu_head *rcu)
 327 {
 328         struct cxl_context *ctx = container_of(rcu, struct cxl_context, rcu);
 329
 330         if (cxl_is_power8())
 331                 free_page((u64)ctx->sstp);
 332         if (ctx->ff_page)
 333                 __free_page(ctx->ff_page);
 334         ctx->sstp = NULL;
 335
 336         kfree(ctx->irq_bitmap);
 337
 338         /* Drop ref to the afu device taken during cxl_context_init */
 339         cxl_afu_put(ctx->afu);
 340
 341         kfree(ctx);
 342 }
 343
 344 void cxl_context_free(struct cxl_context *ctx)
 345 {
 346         if (ctx->kernelapi && ctx->mapping)
 347                 cxl_release_mapping(ctx);
 348         mutex_lock(&ctx->afu->contexts_lock);
 349         idr_remove(&ctx->afu->contexts_idr, ctx->pe);
 350         mutex_unlock(&ctx->afu->contexts_lock);
 351         call_rcu(&ctx->rcu, reclaim_ctx);
 352 }
 353
 354 void cxl_context_mm_count_get(struct cxl_context *ctx)
 355 {
 356         if (ctx->mm)
 357                 atomic_inc(&ctx->mm->mm_count);
 358 }
 359
 360 void cxl_context_mm_count_put(struct cxl_context *ctx)
 361 {
 362         if (ctx->mm)
 363                 mmdrop(ctx->mm);
 364 }