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         ctx->tidr = 0;
  49         ctx->assign_tidr = false;
  50
  51         if (cxl_is_power8()) {
  52                 spin_lock_init(&ctx->sste_lock);
  53
  54                 /*
  55                  * Allocate the segment table before we put it in the IDR so that we
  56                  * can always access it when dereferenced from IDR. For the same
  57                  * reason, the segment table is only destroyed after the context is
  58                  * removed from the IDR.  Access to this in the IOCTL is protected by
  59                  * Linux filesytem symantics (can't IOCTL until open is complete).
  60                  */
  61                 i = cxl_alloc_sst(ctx);
  62                 if (i)
  63                         return i;
  64         }
  65
  66         INIT_WORK(&ctx->fault_work, cxl_handle_fault);
  67
  68         init_waitqueue_head(&ctx->wq);
  69         spin_lock_init(&ctx->lock);
  70
  71         ctx->irq_bitmap = NULL;
  72         ctx->pending_irq = false;
  73         ctx->pending_fault = false;
  74         ctx->pending_afu_err = false;
  75
  76         INIT_LIST_HEAD(&ctx->irq_names);
  77         INIT_LIST_HEAD(&ctx->extra_irq_contexts);
  78
  79         /*
  80          * When we have to destroy all contexts in cxl_context_detach_all() we
  81          * end up with afu_release_irqs() called from inside a
  82          * idr_for_each_entry(). Hence we need to make sure that anything
  83          * dereferenced from this IDR is ok before we allocate the IDR here.
  84          * This clears out the IRQ ranges to ensure this.
  85          */
  86         for (i = 0; i < CXL_IRQ_RANGES; i++)
  87                 ctx->irqs.range[i] = 0;
  88
  89         mutex_init(&ctx->status_mutex);
  90
  91         ctx->status = OPENED;
  92
  93         /*
  94          * Allocating IDR! We better make sure everything's setup that
  95          * dereferences from it.
  96          */
  97         mutex_lock(&afu->contexts_lock);
  98         idr_preload(GFP_KERNEL);
  99         i = idr_alloc(&ctx->afu->contexts_idr, ctx, ctx->afu->adapter->min_pe,
 100                       ctx->afu->num_procs, GFP_NOWAIT);
 101         idr_preload_end();
 102         mutex_unlock(&afu->contexts_lock);
 103         if (i < 0)
 104                 return i;
 105
 106         ctx->pe = i;
 107         if (cpu_has_feature(CPU_FTR_HVMODE)) {
 108                 ctx->elem = &ctx->afu->native->spa[i];
 109                 ctx->external_pe = ctx->pe;
 110         } else {
 111                 ctx->external_pe = -1; /* assigned when attaching */
 112         }
 113         ctx->pe_inserted = false;
 114
 115         /*
 116          * take a ref on the afu so that it stays alive at-least till
 117          * this context is reclaimed inside reclaim_ctx.
 118          */
 119         cxl_afu_get(afu);
 120         return 0;
 121 }
 122
 123 void cxl_context_set_mapping(struct cxl_context *ctx,
 124                         struct address_space *mapping)
 125 {
 126         mutex_lock(&ctx->mapping_lock);
 127         ctx->mapping = mapping;
 128         mutex_unlock(&ctx->mapping_lock);
 129 }
 130
 131 static int cxl_mmap_fault(struct vm_fault *vmf)
 132 {
 133         struct vm_area_struct *vma = vmf->vma;
 134         struct cxl_context *ctx = vma->vm_file->private_data;
 135         u64 area, offset;
 136
 137         offset = vmf->pgoff << PAGE_SHIFT;
 138
 139         pr_devel("%s: pe: %i address: 0x%lx offset: 0x%llx\n",
 140                         __func__, ctx->pe, vmf->address, offset);
 141
 142         if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
 143                 area = ctx->afu->psn_phys;
 144                 if (offset >= ctx->afu->adapter->ps_size)
 145                         return VM_FAULT_SIGBUS;
 146         } else {
 147                 area = ctx->psn_phys;
 148                 if (offset >= ctx->psn_size)
 149                         return VM_FAULT_SIGBUS;
 150         }
 151
 152         mutex_lock(&ctx->status_mutex);
 153
 154         if (ctx->status != STARTED) {
 155                 mutex_unlock(&ctx->status_mutex);
 156                 pr_devel("%s: Context not started, failing problem state access\n", __func__);
 157                 if (ctx->mmio_err_ff) {
 158                         if (!ctx->ff_page) {
 159                                 ctx->ff_page = alloc_page(GFP_USER);
 160                                 if (!ctx->ff_page)
 161                                         return VM_FAULT_OOM;
 162                                 memset(page_address(ctx->ff_page), 0xff, PAGE_SIZE);
 163                         }
 164                         get_page(ctx->ff_page);
 165                         vmf->page = ctx->ff_page;
 166                         vma->vm_page_prot = pgprot_cached(vma->vm_page_prot);
 167                         return 0;
 168                 }
 169                 return VM_FAULT_SIGBUS;
 170         }
 171
 172         vm_insert_pfn(vma, vmf->address, (area + offset) >> PAGE_SHIFT);
 173
 174         mutex_unlock(&ctx->status_mutex);
 175
 176         return VM_FAULT_NOPAGE;
 177 }
 178
 179 static const struct vm_operations_struct cxl_mmap_vmops = {
 180         .fault = cxl_mmap_fault,
 181 };
 182
 183 /*
 184  * Map a per-context mmio space into the given vma.
 185  */
 186 int cxl_context_iomap(struct cxl_context *ctx, struct vm_area_struct *vma)
 187 {
 188         u64 start = vma->vm_pgoff << PAGE_SHIFT;
 189         u64 len = vma->vm_end - vma->vm_start;
 190
 191         if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
 192                 if (start + len > ctx->afu->adapter->ps_size)
 193                         return -EINVAL;
 194
 195                 if (cxl_is_power9()) {
 196                         /*
 197                          * Make sure there is a valid problem state
 198                          * area space for this AFU.
 199                          */
 200                         if (ctx->master && !ctx->afu->psa) {
 201                                 pr_devel("AFU doesn't support mmio space\n");
 202                                 return -EINVAL;
 203                         }
 204
 205                         /* Can't mmap until the AFU is enabled */
 206                         if (!ctx->afu->enabled)
 207                                 return -EBUSY;
 208                 }
 209         } else {
 210                 if (start + len > ctx->psn_size)
 211                         return -EINVAL;
 212
 213                 /* Make sure there is a valid per process space for this AFU */
 214                 if ((ctx->master && !ctx->afu->psa) || (!ctx->afu->pp_psa)) {
 215                         pr_devel("AFU doesn't support mmio space\n");
 216                         return -EINVAL;
 217                 }
 218
 219                 /* Can't mmap until the AFU is enabled */
 220                 if (!ctx->afu->enabled)
 221                         return -EBUSY;
 222         }
 223
 224         pr_devel("%s: mmio physical: %llx pe: %i master:%i\n", __func__,
 225                  ctx->psn_phys, ctx->pe , ctx->master);
 226
 227         vma->vm_flags |= VM_IO | VM_PFNMAP;
 228         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 229         vma->vm_ops = &cxl_mmap_vmops;
 230         return 0;
 231 }
 232
 233 /*
 234  * Detach a context from the hardware. This disables interrupts and doesn't
 235  * return until all outstanding interrupts for this context have completed. The
 236  * hardware should no longer access *ctx after this has returned.
 237  */
 238 int __detach_context(struct cxl_context *ctx)
 239 {
 240         enum cxl_context_status status;
 241
 242         mutex_lock(&ctx->status_mutex);
 243         status = ctx->status;
 244         ctx->status = CLOSED;
 245         mutex_unlock(&ctx->status_mutex);
 246         if (status != STARTED)
 247                 return -EBUSY;
 248
 249         /* Only warn if we detached while the link was OK.
 250          * If detach fails when hw is down, we don't care.
 251          */
 252         WARN_ON(cxl_ops->detach_process(ctx) &&
 253                 cxl_ops->link_ok(ctx->afu->adapter, ctx->afu));
 254         flush_work(&ctx->fault_work); /* Only needed for dedicated process */
 255
 256         /*
 257          * Wait until no further interrupts are presented by the PSL
 258          * for this context.
 259          */
 260         if (cxl_ops->irq_wait)
 261                 cxl_ops->irq_wait(ctx);
 262
 263         /* release the reference to the group leader and mm handling pid */
 264         put_pid(ctx->pid);
 265
 266         cxl_ctx_put();
 267
 268         /* Decrease the attached context count on the adapter */
 269         cxl_adapter_context_put(ctx->afu->adapter);
 270
 271         /* Decrease the mm count on the context */
 272         cxl_context_mm_count_put(ctx);
 273         if (ctx->mm)
 274                 mm_context_remove_copro(ctx->mm);
 275         ctx->mm = NULL;
 276
 277         return 0;
 278 }
 279
 280 /*
 281  * Detach the given context from the AFU. This doesn't actually
 282  * free the context but it should stop the context running in hardware
 283  * (ie. prevent this context from generating any further interrupts
 284  * so that it can be freed).
 285  */
 286 void cxl_context_detach(struct cxl_context *ctx)
 287 {
 288         int rc;
 289
 290         rc = __detach_context(ctx);
 291         if (rc)
 292                 return;
 293
 294         afu_release_irqs(ctx, ctx);
 295         wake_up_all(&ctx->wq);
 296 }
 297
 298 /*
 299  * Detach all contexts on the given AFU.
 300  */
 301 void cxl_context_detach_all(struct cxl_afu *afu)
 302 {
 303         struct cxl_context *ctx;
 304         int tmp;
 305
 306         mutex_lock(&afu->contexts_lock);
 307         idr_for_each_entry(&afu->contexts_idr, ctx, tmp) {
 308                 /*
 309                  * Anything done in here needs to be setup before the IDR is
 310                  * created and torn down after the IDR removed
 311                  */
 312                 cxl_context_detach(ctx);
 313
 314                 /*
 315                  * We are force detaching - remove any active PSA mappings so
 316                  * userspace cannot interfere with the card if it comes back.
 317                  * Easiest way to exercise this is to unbind and rebind the
 318                  * driver via sysfs while it is in use.
 319                  */
 320                 mutex_lock(&ctx->mapping_lock);
 321                 if (ctx->mapping)
 322                         unmap_mapping_range(ctx->mapping, 0, 0, 1);
 323                 mutex_unlock(&ctx->mapping_lock);
 324         }
 325         mutex_unlock(&afu->contexts_lock);
 326 }
 327
 328 static void reclaim_ctx(struct rcu_head *rcu)
 329 {
 330         struct cxl_context *ctx = container_of(rcu, struct cxl_context, rcu);
 331
 332         if (cxl_is_power8())
 333                 free_page((u64)ctx->sstp);
 334         if (ctx->ff_page)
 335                 __free_page(ctx->ff_page);
 336         ctx->sstp = NULL;
 337
 338         kfree(ctx->irq_bitmap);
 339
 340         /* Drop ref to the afu device taken during cxl_context_init */
 341         cxl_afu_put(ctx->afu);
 342
 343         kfree(ctx);
 344 }
 345
 346 void cxl_context_free(struct cxl_context *ctx)
 347 {
 348         if (ctx->kernelapi && ctx->mapping)
 349                 cxl_release_mapping(ctx);
 350         mutex_lock(&ctx->afu->contexts_lock);
 351         idr_remove(&ctx->afu->contexts_idr, ctx->pe);
 352         mutex_unlock(&ctx->afu->contexts_lock);
 353         call_rcu(&ctx->rcu, reclaim_ctx);
 354 }
 355
 356 void cxl_context_mm_count_get(struct cxl_context *ctx)
 357 {
 358         if (ctx->mm)
 359                 atomic_inc(&ctx->mm->mm_count);
 360 }
 361
 362 void cxl_context_mm_count_put(struct cxl_context *ctx)
 363 {
 364         if (ctx->mm)
 365                 mmdrop(ctx->mm);
 366 }