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 {
  39         int i;
  40
  41         spin_lock_init(&ctx->sste_lock);
  42         ctx->afu = afu;
  43         ctx->master = master;
  44         ctx->pid = NULL; /* Set in start work ioctl */
  45
  46         /*
  47          * Allocate the segment table before we put it in the IDR so that we
  48          * can always access it when dereferenced from IDR. For the same
  49          * reason, the segment table is only destroyed after the context is
  50          * removed from the IDR.  Access to this in the IOCTL is protected by
  51          * Linux filesytem symantics (can't IOCTL until open is complete).
  52          */
  53         i = cxl_alloc_sst(ctx);
  54         if (i)
  55                 return i;
  56
  57         INIT_WORK(&ctx->fault_work, cxl_handle_fault);
  58
  59         init_waitqueue_head(&ctx->wq);
  60         spin_lock_init(&ctx->lock);
  61
  62         ctx->irq_bitmap = NULL;
  63         ctx->pending_irq = false;
  64         ctx->pending_fault = false;
  65         ctx->pending_afu_err = false;
  66
  67         /*
  68          * When we have to destroy all contexts in cxl_context_detach_all() we
  69          * end up with afu_release_irqs() called from inside a
  70          * idr_for_each_entry(). Hence we need to make sure that anything
  71          * dereferenced from this IDR is ok before we allocate the IDR here.
  72          * This clears out the IRQ ranges to ensure this.
  73          */
  74         for (i = 0; i < CXL_IRQ_RANGES; i++)
  75                 ctx->irqs.range[i] = 0;
  76
  77         mutex_init(&ctx->status_mutex);
  78
  79         ctx->status = OPENED;
  80
  81         /*
  82          * Allocating IDR! We better make sure everything's setup that
  83          * dereferences from it.
  84          */
  85         idr_preload(GFP_KERNEL);
  86         spin_lock(&afu->contexts_lock);
  87         i = idr_alloc(&ctx->afu->contexts_idr, ctx, 0,
  88                       ctx->afu->num_procs, GFP_NOWAIT);
  89         spin_unlock(&afu->contexts_lock);
  90         idr_preload_end();
  91         if (i < 0)
  92                 return i;
  93
  94         ctx->pe = i;
  95         ctx->elem = &ctx->afu->spa[i];
  96         ctx->pe_inserted = false;
  97         return 0;
  98 }
  99
 100 /*
 101  * Map a per-context mmio space into the given vma.
 102  */
 103 int cxl_context_iomap(struct cxl_context *ctx, struct vm_area_struct *vma)
 104 {
 105         u64 len = vma->vm_end - vma->vm_start;
 106         len = min(len, ctx->psn_size);
 107
 108         if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
 109                 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 110                 return vm_iomap_memory(vma, ctx->afu->psn_phys, ctx->afu->adapter->ps_size);
 111         }
 112
 113         /* make sure there is a valid per process space for this AFU */
 114         if ((ctx->master && !ctx->afu->psa) || (!ctx->afu->pp_psa)) {
 115                 pr_devel("AFU doesn't support mmio space\n");
 116                 return -EINVAL;
 117         }
 118
 119         /* Can't mmap until the AFU is enabled */
 120         if (!ctx->afu->enabled)
 121                 return -EBUSY;
 122
 123         pr_devel("%s: mmio physical: %llx pe: %i master:%i\n", __func__,
 124                  ctx->psn_phys, ctx->pe , ctx->master);
 125
 126         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 127         return vm_iomap_memory(vma, ctx->psn_phys, len);
 128 }
 129
 130 /*
 131  * Detach a context from the hardware. This disables interrupts and doesn't
 132  * return until all outstanding interrupts for this context have completed. The
 133  * hardware should no longer access *ctx after this has returned.
 134  */
 135 static void __detach_context(struct cxl_context *ctx)
 136 {
 137         enum cxl_context_status status;
 138
 139         mutex_lock(&ctx->status_mutex);
 140         status = ctx->status;
 141         ctx->status = CLOSED;
 142         mutex_unlock(&ctx->status_mutex);
 143         if (status != STARTED)
 144                 return;
 145
 146         WARN_ON(cxl_detach_process(ctx));
 147         afu_release_irqs(ctx);
 148         flush_work(&ctx->fault_work); /* Only needed for dedicated process */
 149         wake_up_all(&ctx->wq);
 150 }
 151
 152 /*
 153  * Detach the given context from the AFU. This doesn't actually
 154  * free the context but it should stop the context running in hardware
 155  * (ie. prevent this context from generating any further interrupts
 156  * so that it can be freed).
 157  */
 158 void cxl_context_detach(struct cxl_context *ctx)
 159 {
 160         __detach_context(ctx);
 161 }
 162
 163 /*
 164  * Detach all contexts on the given AFU.
 165  */
 166 void cxl_context_detach_all(struct cxl_afu *afu)
 167 {
 168         struct cxl_context *ctx;
 169         int tmp;
 170
 171         rcu_read_lock();
 172         idr_for_each_entry(&afu->contexts_idr, ctx, tmp)
 173                 /*
 174                  * Anything done in here needs to be setup before the IDR is
 175                  * created and torn down after the IDR removed
 176                  */
 177                 __detach_context(ctx);
 178         rcu_read_unlock();
 179 }
 180
 181 void cxl_context_free(struct cxl_context *ctx)
 182 {
 183         spin_lock(&ctx->afu->contexts_lock);
 184         idr_remove(&ctx->afu->contexts_idr, ctx->pe);
 185         spin_unlock(&ctx->afu->contexts_lock);
 186         synchronize_rcu();
 187
 188         free_page((u64)ctx->sstp);
 189         ctx->sstp = NULL;
 190
 191         put_pid(ctx->pid);
 192         kfree(ctx);
 193 }