root/drivers/misc/cxl/context.c

DEFINITIONS

1. cxl_context_alloc
2. cxl_context_init
3. cxl_context_set_mapping
4. cxl_mmap_fault
5. cxl_context_iomap
6. __detach_context
7. cxl_context_detach
8. cxl_context_detach_all
9. reclaim_ctx
10. cxl_context_free
11. cxl_context_mm_count_get
12. cxl_context_mm_count_put

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright 2014 IBM Corp.
   4  */
   5 
   6 #include <linux/module.h>
   7 #include <linux/kernel.h>
   8 #include <linux/bitmap.h>
   9 #include <linux/sched.h>
  10 #include <linux/pid.h>
  11 #include <linux/fs.h>
  12 #include <linux/mm.h>
  13 #include <linux/debugfs.h>
  14 #include <linux/slab.h>
  15 #include <linux/idr.h>
  16 #include <linux/sched/mm.h>
  17 #include <linux/mmu_context.h>
  18 #include <asm/cputable.h>
  19 #include <asm/current.h>
  20 #include <asm/copro.h>
  21 
  22 #include "cxl.h"
  23 
  24 /*
  25  * Allocates space for a CXL context.
  26  */
  27 struct cxl_context *cxl_context_alloc(void)
  28 {
  29         return kzalloc(sizeof(struct cxl_context), GFP_KERNEL);
  30 }
  31 
  32 /*
  33  * Initialises a CXL context.
  34  */
  35 int cxl_context_init(struct cxl_context *ctx, struct cxl_afu *afu, bool master)
  36 {
  37         int i;
  38 
  39         ctx->afu = afu;
  40         ctx->master = master;
  41         ctx->pid = NULL; /* Set in start work ioctl */
  42         mutex_init(&ctx->mapping_lock);
  43         ctx->mapping = NULL;
  44         ctx->tidr = 0;
  45         ctx->assign_tidr = false;
  46 
  47         if (cxl_is_power8()) {
  48                 spin_lock_init(&ctx->sste_lock);
  49 
  50                 /*
  51                  * Allocate the segment table before we put it in the IDR so that we
  52                  * can always access it when dereferenced from IDR. For the same
  53                  * reason, the segment table is only destroyed after the context is
  54                  * removed from the IDR.  Access to this in the IOCTL is protected by
  55                  * Linux filesytem symantics (can't IOCTL until open is complete).
  56                  */
  57                 i = cxl_alloc_sst(ctx);
  58                 if (i)
  59                         return i;
  60         }
  61 
  62         INIT_WORK(&ctx->fault_work, cxl_handle_fault);
  63 
  64         init_waitqueue_head(&ctx->wq);
  65         spin_lock_init(&ctx->lock);
  66 
  67         ctx->irq_bitmap = NULL;
  68         ctx->pending_irq = false;
  69         ctx->pending_fault = false;
  70         ctx->pending_afu_err = false;
  71 
  72         INIT_LIST_HEAD(&ctx->irq_names);
  73 
  74         /*
  75          * When we have to destroy all contexts in cxl_context_detach_all() we
  76          * end up with afu_release_irqs() called from inside a
  77          * idr_for_each_entry(). Hence we need to make sure that anything
  78          * dereferenced from this IDR is ok before we allocate the IDR here.
  79          * This clears out the IRQ ranges to ensure this.
  80          */
  81         for (i = 0; i < CXL_IRQ_RANGES; i++)
  82                 ctx->irqs.range[i] = 0;
  83 
  84         mutex_init(&ctx->status_mutex);
  85 
  86         ctx->status = OPENED;
  87 
  88         /*
  89          * Allocating IDR! We better make sure everything's setup that
  90          * dereferences from it.
  91          */
  92         mutex_lock(&afu->contexts_lock);
  93         idr_preload(GFP_KERNEL);
  94         i = idr_alloc(&ctx->afu->contexts_idr, ctx, 0,
  95                       ctx->afu->num_procs, GFP_NOWAIT);
  96         idr_preload_end();
  97         mutex_unlock(&afu->contexts_lock);
  98         if (i < 0)
  99                 return i;
 100 
 101         ctx->pe = i;
 102         if (cpu_has_feature(CPU_FTR_HVMODE)) {
 103                 ctx->elem = &ctx->afu->native->spa[i];
 104                 ctx->external_pe = ctx->pe;
 105         } else {
 106                 ctx->external_pe = -1; /* assigned when attaching */
 107         }
 108         ctx->pe_inserted = false;
 109 
 110         /*
 111          * take a ref on the afu so that it stays alive at-least till
 112          * this context is reclaimed inside reclaim_ctx.
 113          */
 114         cxl_afu_get(afu);
 115         return 0;
 116 }
 117 
 118 void cxl_context_set_mapping(struct cxl_context *ctx,
 119                         struct address_space *mapping)
 120 {
 121         mutex_lock(&ctx->mapping_lock);
 122         ctx->mapping = mapping;
 123         mutex_unlock(&ctx->mapping_lock);
 124 }
 125 
 126 static vm_fault_t cxl_mmap_fault(struct vm_fault *vmf)
 127 {
 128         struct vm_area_struct *vma = vmf->vma;
 129         struct cxl_context *ctx = vma->vm_file->private_data;
 130         u64 area, offset;
 131         vm_fault_t ret;
 132 
 133         offset = vmf->pgoff << PAGE_SHIFT;
 134 
 135         pr_devel("%s: pe: %i address: 0x%lx offset: 0x%llx\n",
 136                         __func__, ctx->pe, vmf->address, offset);
 137 
 138         if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
 139                 area = ctx->afu->psn_phys;
 140                 if (offset >= ctx->afu->adapter->ps_size)
 141                         return VM_FAULT_SIGBUS;
 142         } else {
 143                 area = ctx->psn_phys;
 144                 if (offset >= ctx->psn_size)
 145                         return VM_FAULT_SIGBUS;
 146         }
 147 
 148         mutex_lock(&ctx->status_mutex);
 149 
 150         if (ctx->status != STARTED) {
 151                 mutex_unlock(&ctx->status_mutex);
 152                 pr_devel("%s: Context not started, failing problem state access\n", __func__);
 153                 if (ctx->mmio_err_ff) {
 154                         if (!ctx->ff_page) {
 155                                 ctx->ff_page = alloc_page(GFP_USER);
 156                                 if (!ctx->ff_page)
 157                                         return VM_FAULT_OOM;
 158                                 memset(page_address(ctx->ff_page), 0xff, PAGE_SIZE);
 159                         }
 160                         get_page(ctx->ff_page);
 161                         vmf->page = ctx->ff_page;
 162                         vma->vm_page_prot = pgprot_cached(vma->vm_page_prot);
 163                         return 0;
 164                 }
 165                 return VM_FAULT_SIGBUS;
 166         }
 167 
 168         ret = vmf_insert_pfn(vma, vmf->address, (area + offset) >> PAGE_SHIFT);
 169 
 170         mutex_unlock(&ctx->status_mutex);
 171 
 172         return ret;
 173 }
 174 
 175 static const struct vm_operations_struct cxl_mmap_vmops = {
 176         .fault = cxl_mmap_fault,
 177 };
 178 
 179 /*
 180  * Map a per-context mmio space into the given vma.
 181  */
 182 int cxl_context_iomap(struct cxl_context *ctx, struct vm_area_struct *vma)
 183 {
 184         u64 start = vma->vm_pgoff << PAGE_SHIFT;
 185         u64 len = vma->vm_end - vma->vm_start;
 186 
 187         if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
 188                 if (start + len > ctx->afu->adapter->ps_size)
 189                         return -EINVAL;
 190 
 191                 if (cxl_is_power9()) {
 192                         /*
 193                          * Make sure there is a valid problem state
 194                          * area space for this AFU.
 195                          */
 196                         if (ctx->master && !ctx->afu->psa) {
 197                                 pr_devel("AFU doesn't support mmio space\n");
 198                                 return -EINVAL;
 199                         }
 200 
 201                         /* Can't mmap until the AFU is enabled */
 202                         if (!ctx->afu->enabled)
 203                                 return -EBUSY;
 204                 }
 205         } else {
 206                 if (start + len > ctx->psn_size)
 207                         return -EINVAL;
 208 
 209                 /* Make sure there is a valid per process space for this AFU */
 210                 if ((ctx->master && !ctx->afu->psa) || (!ctx->afu->pp_psa)) {
 211                         pr_devel("AFU doesn't support mmio space\n");
 212                         return -EINVAL;
 213                 }
 214 
 215                 /* Can't mmap until the AFU is enabled */
 216                 if (!ctx->afu->enabled)
 217                         return -EBUSY;
 218         }
 219 
 220         pr_devel("%s: mmio physical: %llx pe: %i master:%i\n", __func__,
 221                  ctx->psn_phys, ctx->pe , ctx->master);
 222 
 223         vma->vm_flags |= VM_IO | VM_PFNMAP;
 224         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 225         vma->vm_ops = &cxl_mmap_vmops;
 226         return 0;
 227 }
 228 
 229 /*
 230  * Detach a context from the hardware. This disables interrupts and doesn't
 231  * return until all outstanding interrupts for this context have completed. The
 232  * hardware should no longer access *ctx after this has returned.
 233  */
 234 int __detach_context(struct cxl_context *ctx)
 235 {
 236         enum cxl_context_status status;
 237 
 238         mutex_lock(&ctx->status_mutex);
 239         status = ctx->status;
 240         ctx->status = CLOSED;
 241         mutex_unlock(&ctx->status_mutex);
 242         if (status != STARTED)
 243                 return -EBUSY;
 244 
 245         /* Only warn if we detached while the link was OK.
 246          * If detach fails when hw is down, we don't care.
 247          */
 248         WARN_ON(cxl_ops->detach_process(ctx) &&
 249                 cxl_ops->link_ok(ctx->afu->adapter, ctx->afu));
 250         flush_work(&ctx->fault_work); /* Only needed for dedicated process */
 251 
 252         /*
 253          * Wait until no further interrupts are presented by the PSL
 254          * for this context.
 255          */
 256         if (cxl_ops->irq_wait)
 257                 cxl_ops->irq_wait(ctx);
 258 
 259         /* release the reference to the group leader and mm handling pid */
 260         put_pid(ctx->pid);
 261 
 262         cxl_ctx_put();
 263 
 264         /* Decrease the attached context count on the adapter */
 265         cxl_adapter_context_put(ctx->afu->adapter);
 266 
 267         /* Decrease the mm count on the context */
 268         cxl_context_mm_count_put(ctx);
 269         if (ctx->mm)
 270                 mm_context_remove_copro(ctx->mm);
 271         ctx->mm = NULL;
 272 
 273         return 0;
 274 }
 275 
 276 /*
 277  * Detach the given context from the AFU. This doesn't actually
 278  * free the context but it should stop the context running in hardware
 279  * (ie. prevent this context from generating any further interrupts
 280  * so that it can be freed).
 281  */
 282 void cxl_context_detach(struct cxl_context *ctx)
 283 {
 284         int rc;
 285 
 286         rc = __detach_context(ctx);
 287         if (rc)
 288                 return;
 289 
 290         afu_release_irqs(ctx, ctx);
 291         wake_up_all(&ctx->wq);
 292 }
 293 
 294 /*
 295  * Detach all contexts on the given AFU.
 296  */
 297 void cxl_context_detach_all(struct cxl_afu *afu)
 298 {
 299         struct cxl_context *ctx;
 300         int tmp;
 301 
 302         mutex_lock(&afu->contexts_lock);
 303         idr_for_each_entry(&afu->contexts_idr, ctx, tmp) {
 304                 /*
 305                  * Anything done in here needs to be setup before the IDR is
 306                  * created and torn down after the IDR removed
 307                  */
 308                 cxl_context_detach(ctx);
 309 
 310                 /*
 311                  * We are force detaching - remove any active PSA mappings so
 312                  * userspace cannot interfere with the card if it comes back.
 313                  * Easiest way to exercise this is to unbind and rebind the
 314                  * driver via sysfs while it is in use.
 315                  */
 316                 mutex_lock(&ctx->mapping_lock);
 317                 if (ctx->mapping)
 318                         unmap_mapping_range(ctx->mapping, 0, 0, 1);
 319                 mutex_unlock(&ctx->mapping_lock);
 320         }
 321         mutex_unlock(&afu->contexts_lock);
 322 }
 323 
 324 static void reclaim_ctx(struct rcu_head *rcu)
 325 {
 326         struct cxl_context *ctx = container_of(rcu, struct cxl_context, rcu);
 327 
 328         if (cxl_is_power8())
 329                 free_page((u64)ctx->sstp);
 330         if (ctx->ff_page)
 331                 __free_page(ctx->ff_page);
 332         ctx->sstp = NULL;
 333 
 334         kfree(ctx->irq_bitmap);
 335 
 336         /* Drop ref to the afu device taken during cxl_context_init */
 337         cxl_afu_put(ctx->afu);
 338 
 339         kfree(ctx);
 340 }
 341 
 342 void cxl_context_free(struct cxl_context *ctx)
 343 {
 344         if (ctx->kernelapi && ctx->mapping)
 345                 cxl_release_mapping(ctx);
 346         mutex_lock(&ctx->afu->contexts_lock);
 347         idr_remove(&ctx->afu->contexts_idr, ctx->pe);
 348         mutex_unlock(&ctx->afu->contexts_lock);
 349         call_rcu(&ctx->rcu, reclaim_ctx);
 350 }
 351 
 352 void cxl_context_mm_count_get(struct cxl_context *ctx)
 353 {
 354         if (ctx->mm)
 355                 atomic_inc(&ctx->mm->mm_count);
 356 }
 357 
 358 void cxl_context_mm_count_put(struct cxl_context *ctx)
 359 {
 360         if (ctx->mm)
 361                 mmdrop(ctx->mm);
 362 }