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