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