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