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