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 = 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         ctx->elem = &ctx->afu->spa[i];
  99         ctx->pe_inserted = false;
 100         return 0;
 101 }
 102
 103 static int cxl_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 104 {
 105         struct cxl_context *ctx = vma->vm_file->private_data;
 106         unsigned long address = (unsigned long)vmf->virtual_address;
 107         u64 area, offset;
 108
 109         offset = vmf->pgoff << PAGE_SHIFT;
 110
 111         pr_devel("%s: pe: %i address: 0x%lx offset: 0x%llx\n",
 112                         __func__, ctx->pe, address, offset);
 113
 114         if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
 115                 area = ctx->afu->psn_phys;
 116                 if (offset >= ctx->afu->adapter->ps_size)
 117                         return VM_FAULT_SIGBUS;
 118         } else {
 119                 area = ctx->psn_phys;
 120                 if (offset >= ctx->psn_size)
 121                         return VM_FAULT_SIGBUS;
 122         }
 123
 124         mutex_lock(&ctx->status_mutex);
 125
 126         if (ctx->status != STARTED) {
 127                 mutex_unlock(&ctx->status_mutex);
 128                 pr_devel("%s: Context not started, failing problem state access\n", __func__);
 129                 if (ctx->mmio_err_ff) {
 130                         if (!ctx->ff_page) {
 131                                 ctx->ff_page = alloc_page(GFP_USER);
 132                                 if (!ctx->ff_page)
 133                                         return VM_FAULT_OOM;
 134                                 memset(page_address(ctx->ff_page), 0xff, PAGE_SIZE);
 135                         }
 136                         get_page(ctx->ff_page);
 137                         vmf->page = ctx->ff_page;
 138                         vma->vm_page_prot = pgprot_cached(vma->vm_page_prot);
 139                         return 0;
 140                 }
 141                 return VM_FAULT_SIGBUS;
 142         }
 143
 144         vm_insert_pfn(vma, address, (area + offset) >> PAGE_SHIFT);
 145
 146         mutex_unlock(&ctx->status_mutex);
 147
 148         return VM_FAULT_NOPAGE;
 149 }
 150
 151 static const struct vm_operations_struct cxl_mmap_vmops = {
 152         .fault = cxl_mmap_fault,
 153 };
 154
 155 /*
 156  * Map a per-context mmio space into the given vma.
 157  */
 158 int cxl_context_iomap(struct cxl_context *ctx, struct vm_area_struct *vma)
 159 {
 160         u64 start = vma->vm_pgoff << PAGE_SHIFT;
 161         u64 len = vma->vm_end - vma->vm_start;
 162
 163         if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
 164                 if (start + len > ctx->afu->adapter->ps_size)
 165                         return -EINVAL;
 166         } else {
 167                 if (start + len > ctx->psn_size)
 168                         return -EINVAL;
 169         }
 170
 171         if (ctx->afu->current_mode != CXL_MODE_DEDICATED) {
 172                 /* make sure there is a valid per process space for this AFU */
 173                 if ((ctx->master && !ctx->afu->psa) || (!ctx->afu->pp_psa)) {
 174                         pr_devel("AFU doesn't support mmio space\n");
 175                         return -EINVAL;
 176                 }
 177
 178                 /* Can't mmap until the AFU is enabled */
 179                 if (!ctx->afu->enabled)
 180                         return -EBUSY;
 181         }
 182
 183         pr_devel("%s: mmio physical: %llx pe: %i master:%i\n", __func__,
 184                  ctx->psn_phys, ctx->pe , ctx->master);
 185
 186         vma->vm_flags |= VM_IO | VM_PFNMAP;
 187         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 188         vma->vm_ops = &cxl_mmap_vmops;
 189         return 0;
 190 }
 191
 192 /*
 193  * Detach a context from the hardware. This disables interrupts and doesn't
 194  * return until all outstanding interrupts for this context have completed. The
 195  * hardware should no longer access *ctx after this has returned.
 196  */
 197 int __detach_context(struct cxl_context *ctx)
 198 {
 199         enum cxl_context_status status;
 200
 201         mutex_lock(&ctx->status_mutex);
 202         status = ctx->status;
 203         ctx->status = CLOSED;
 204         mutex_unlock(&ctx->status_mutex);
 205         if (status != STARTED)
 206                 return -EBUSY;
 207
 208         /* Only warn if we detached while the link was OK.
 209          * If detach fails when hw is down, we don't care.
 210          */
 211         WARN_ON(cxl_detach_process(ctx) &&
 212                 cxl_adapter_link_ok(ctx->afu->adapter));
 213         flush_work(&ctx->fault_work); /* Only needed for dedicated process */
 214         put_pid(ctx->pid);
 215         cxl_ctx_put();
 216         return 0;
 217 }
 218
 219 /*
 220  * Detach the given context from the AFU. This doesn't actually
 221  * free the context but it should stop the context running in hardware
 222  * (ie. prevent this context from generating any further interrupts
 223  * so that it can be freed).
 224  */
 225 void cxl_context_detach(struct cxl_context *ctx)
 226 {
 227         int rc;
 228
 229         rc = __detach_context(ctx);
 230         if (rc)
 231                 return;
 232
 233         afu_release_irqs(ctx, ctx);
 234         wake_up_all(&ctx->wq);
 235 }
 236
 237 /*
 238  * Detach all contexts on the given AFU.
 239  */
 240 void cxl_context_detach_all(struct cxl_afu *afu)
 241 {
 242         struct cxl_context *ctx;
 243         int tmp;
 244
 245         mutex_lock(&afu->contexts_lock);
 246         idr_for_each_entry(&afu->contexts_idr, ctx, tmp) {
 247                 /*
 248                  * Anything done in here needs to be setup before the IDR is
 249                  * created and torn down after the IDR removed
 250                  */
 251                 cxl_context_detach(ctx);
 252
 253                 /*
 254                  * We are force detaching - remove any active PSA mappings so
 255                  * userspace cannot interfere with the card if it comes back.
 256                  * Easiest way to exercise this is to unbind and rebind the
 257                  * driver via sysfs while it is in use.
 258                  */
 259                 mutex_lock(&ctx->mapping_lock);
 260                 if (ctx->mapping)
 261                         unmap_mapping_range(ctx->mapping, 0, 0, 1);
 262                 mutex_unlock(&ctx->mapping_lock);
 263         }
 264         mutex_unlock(&afu->contexts_lock);
 265 }
 266
 267 static void reclaim_ctx(struct rcu_head *rcu)
 268 {
 269         struct cxl_context *ctx = container_of(rcu, struct cxl_context, rcu);
 270
 271         free_page((u64)ctx->sstp);
 272         if (ctx->ff_page)
 273                 __free_page(ctx->ff_page);
 274         ctx->sstp = NULL;
 275         if (ctx->kernelapi)
 276                 kfree(ctx->mapping);
 277
 278         if (ctx->irq_bitmap)
 279                 kfree(ctx->irq_bitmap);
 280
 281         kfree(ctx);
 282 }
 283
 284 void cxl_context_free(struct cxl_context *ctx)
 285 {
 286         mutex_lock(&ctx->afu->contexts_lock);
 287         idr_remove(&ctx->afu->contexts_idr, ctx->pe);
 288         mutex_unlock(&ctx->afu->contexts_lock);
 289         call_rcu(&ctx->rcu, reclaim_ctx);
 290 }