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 <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  */
  29 struct 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  */
  37 int 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
 116 void 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
 124 static int cxl_mmap_fault(struct vm_fault *vmf)
 125 {
 126         struct vm_area_struct *vma = vmf->vma;
 127         struct cxl_context *ctx = vma->vm_file->private_data;
 128         u64 area, offset;
 129
 130         offset = vmf->pgoff << PAGE_SHIFT;
 131
 132         pr_devel("%s: pe: %i address: 0x%lx offset: 0x%llx\n",
 133                         __func__, ctx->pe, vmf->address, offset);
 134
 135         if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
 136                 area = ctx->afu->psn_phys;
 137                 if (offset >= ctx->afu->adapter->ps_size)
 138                         return VM_FAULT_SIGBUS;
 139         } else {
 140                 area = ctx->psn_phys;
 141                 if (offset >= ctx->psn_size)
 142                         return VM_FAULT_SIGBUS;
 143         }
 144
 145         mutex_lock(&ctx->status_mutex);
 146
 147         if (ctx->status != STARTED) {
 148                 mutex_unlock(&ctx->status_mutex);
 149                 pr_devel("%s: Context not started, failing problem state access\n", __func__);
 150                 if (ctx->mmio_err_ff) {
 151                         if (!ctx->ff_page) {
 152                                 ctx->ff_page = alloc_page(GFP_USER);
 153                                 if (!ctx->ff_page)
 154                                         return VM_FAULT_OOM;
 155                                 memset(page_address(ctx->ff_page), 0xff, PAGE_SIZE);
 156                         }
 157                         get_page(ctx->ff_page);
 158                         vmf->page = ctx->ff_page;
 159                         vma->vm_page_prot = pgprot_cached(vma->vm_page_prot);
 160                         return 0;
 161                 }
 162                 return VM_FAULT_SIGBUS;
 163         }
 164
 165         vm_insert_pfn(vma, vmf->address, (area + offset) >> PAGE_SHIFT);
 166
 167         mutex_unlock(&ctx->status_mutex);
 168
 169         return VM_FAULT_NOPAGE;
 170 }
 171
 172 static const struct vm_operations_struct cxl_mmap_vmops = {
 173         .fault = cxl_mmap_fault,
 174 };
 175
 176 /*
 177  * Map a per-context mmio space into the given vma.
 178  */
 179 int cxl_context_iomap(struct cxl_context *ctx, struct vm_area_struct *vma)
 180 {
 181         u64 start = vma->vm_pgoff << PAGE_SHIFT;
 182         u64 len = vma->vm_end - vma->vm_start;
 183
 184         if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
 185                 if (start + len > ctx->afu->adapter->ps_size)
 186                         return -EINVAL;
 187         } else {
 188                 if (start + len > ctx->psn_size)
 189                         return -EINVAL;
 190         }
 191
 192         if (ctx->afu->current_mode != CXL_MODE_DEDICATED) {
 193                 /* make sure there is a valid per process space for this AFU */
 194                 if ((ctx->master && !ctx->afu->psa) || (!ctx->afu->pp_psa)) {
 195                         pr_devel("AFU doesn't support mmio space\n");
 196                         return -EINVAL;
 197                 }
 198
 199                 /* Can't mmap until the AFU is enabled */
 200                 if (!ctx->afu->enabled)
 201                         return -EBUSY;
 202         }
 203
 204         pr_devel("%s: mmio physical: %llx pe: %i master:%i\n", __func__,
 205                  ctx->psn_phys, ctx->pe , ctx->master);
 206
 207         vma->vm_flags |= VM_IO | VM_PFNMAP;
 208         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 209         vma->vm_ops = &cxl_mmap_vmops;
 210         return 0;
 211 }
 212
 213 /*
 214  * Detach a context from the hardware. This disables interrupts and doesn't
 215  * return until all outstanding interrupts for this context have completed. The
 216  * hardware should no longer access *ctx after this has returned.
 217  */
 218 int __detach_context(struct cxl_context *ctx)
 219 {
 220         enum cxl_context_status status;
 221
 222         mutex_lock(&ctx->status_mutex);
 223         status = ctx->status;
 224         ctx->status = CLOSED;
 225         mutex_unlock(&ctx->status_mutex);
 226         if (status != STARTED)
 227                 return -EBUSY;
 228
 229         /* Only warn if we detached while the link was OK.
 230          * If detach fails when hw is down, we don't care.
 231          */
 232         WARN_ON(cxl_ops->detach_process(ctx) &&
 233                 cxl_ops->link_ok(ctx->afu->adapter, ctx->afu));
 234         flush_work(&ctx->fault_work); /* Only needed for dedicated process */
 235
 236         /*
 237          * Wait until no further interrupts are presented by the PSL
 238          * for this context.
 239          */
 240         if (cxl_ops->irq_wait)
 241                 cxl_ops->irq_wait(ctx);
 242
 243         /* release the reference to the group leader and mm handling pid */
 244         put_pid(ctx->pid);
 245         put_pid(ctx->glpid);
 246
 247         cxl_ctx_put();
 248
 249         /* Decrease the attached context count on the adapter */
 250         cxl_adapter_context_put(ctx->afu->adapter);
 251         return 0;
 252 }
 253
 254 /*
 255  * Detach the given context from the AFU. This doesn't actually
 256  * free the context but it should stop the context running in hardware
 257  * (ie. prevent this context from generating any further interrupts
 258  * so that it can be freed).
 259  */
 260 void cxl_context_detach(struct cxl_context *ctx)
 261 {
 262         int rc;
 263
 264         rc = __detach_context(ctx);
 265         if (rc)
 266                 return;
 267
 268         afu_release_irqs(ctx, ctx);
 269         wake_up_all(&ctx->wq);
 270 }
 271
 272 /*
 273  * Detach all contexts on the given AFU.
 274  */
 275 void cxl_context_detach_all(struct cxl_afu *afu)
 276 {
 277         struct cxl_context *ctx;
 278         int tmp;
 279
 280         mutex_lock(&afu->contexts_lock);
 281         idr_for_each_entry(&afu->contexts_idr, ctx, tmp) {
 282                 /*
 283                  * Anything done in here needs to be setup before the IDR is
 284                  * created and torn down after the IDR removed
 285                  */
 286                 cxl_context_detach(ctx);
 287
 288                 /*
 289                  * We are force detaching - remove any active PSA mappings so
 290                  * userspace cannot interfere with the card if it comes back.
 291                  * Easiest way to exercise this is to unbind and rebind the
 292                  * driver via sysfs while it is in use.
 293                  */
 294                 mutex_lock(&ctx->mapping_lock);
 295                 if (ctx->mapping)
 296                         unmap_mapping_range(ctx->mapping, 0, 0, 1);
 297                 mutex_unlock(&ctx->mapping_lock);
 298         }
 299         mutex_unlock(&afu->contexts_lock);
 300 }
 301
 302 static void reclaim_ctx(struct rcu_head *rcu)
 303 {
 304         struct cxl_context *ctx = container_of(rcu, struct cxl_context, rcu);
 305
 306         free_page((u64)ctx->sstp);
 307         if (ctx->ff_page)
 308                 __free_page(ctx->ff_page);
 309         ctx->sstp = NULL;
 310
 311         kfree(ctx->irq_bitmap);
 312
 313         /* Drop ref to the afu device taken during cxl_context_init */
 314         cxl_afu_put(ctx->afu);
 315
 316         kfree(ctx);
 317 }
 318
 319 void cxl_context_free(struct cxl_context *ctx)
 320 {
 321         if (ctx->kernelapi && ctx->mapping)
 322                 cxl_release_mapping(ctx);
 323         mutex_lock(&ctx->afu->contexts_lock);
 324         idr_remove(&ctx->afu->contexts_idr, ctx->pe);
 325         mutex_unlock(&ctx->afu->contexts_lock);
 326         call_rcu(&ctx->rcu, reclaim_ctx);
 327 }