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