drivers/dma/idxd/submit.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright(c) 2019 Intel Corporation. All rights rsvd. */
   3 #include <linux/init.h>
   4 #include <linux/kernel.h>
   5 #include <linux/module.h>
   6 #include <linux/pci.h>
   7 #include <uapi/linux/idxd.h>
   8 #include "idxd.h"
   9 #include "registers.h"
  10
  11 static struct idxd_desc *__get_desc(struct idxd_wq *wq, int idx, int cpu)
  12 {
  13         struct idxd_desc *desc;
  14         struct idxd_device *idxd = wq->idxd;
  15
  16         desc = wq->descs[idx];
  17         memset(desc->hw, 0, sizeof(struct dsa_hw_desc));
  18         memset(desc->completion, 0, idxd->data->compl_size);
  19         desc->cpu = cpu;
  20
  21         if (device_pasid_enabled(idxd))
  22                 desc->hw->pasid = idxd->pasid;
  23
  24         return desc;
  25 }
  26
  27 struct idxd_desc *idxd_alloc_desc(struct idxd_wq *wq, enum idxd_op_type optype)
  28 {
  29         int cpu, idx;
  30         struct idxd_device *idxd = wq->idxd;
  31         DEFINE_SBQ_WAIT(wait);
  32         struct sbq_wait_state *ws;
  33         struct sbitmap_queue *sbq;
  34
  35         if (idxd->state != IDXD_DEV_ENABLED)
  36                 return ERR_PTR(-EIO);
  37
  38         sbq = &wq->sbq;
  39         idx = sbitmap_queue_get(sbq, &cpu);
  40         if (idx < 0) {
  41                 if (optype == IDXD_OP_NONBLOCK)
  42                         return ERR_PTR(-EAGAIN);
  43         } else {
  44                 return __get_desc(wq, idx, cpu);
  45         }
  46
  47         ws = &sbq->ws[0];
  48         for (;;) {
  49                 sbitmap_prepare_to_wait(sbq, ws, &wait, TASK_INTERRUPTIBLE);
  50                 if (signal_pending_state(TASK_INTERRUPTIBLE, current))
  51                         break;
  52                 idx = sbitmap_queue_get(sbq, &cpu);
  53                 if (idx >= 0)
  54                         break;
  55                 schedule();
  56         }
  57
  58         sbitmap_finish_wait(sbq, ws, &wait);
  59         if (idx < 0)
  60                 return ERR_PTR(-EAGAIN);
  61
  62         return __get_desc(wq, idx, cpu);
  63 }
  64 EXPORT_SYMBOL_NS_GPL(idxd_alloc_desc, IDXD);
  65
  66 void idxd_free_desc(struct idxd_wq *wq, struct idxd_desc *desc)
  67 {
  68         int cpu = desc->cpu;
  69
  70         desc->cpu = -1;
  71         sbitmap_queue_clear(&wq->sbq, desc->id, cpu);
  72 }
  73 EXPORT_SYMBOL_NS_GPL(idxd_free_desc, IDXD);
  74
  75 static struct idxd_desc *list_abort_desc(struct idxd_wq *wq, struct idxd_irq_entry *ie,
  76                                          struct idxd_desc *desc)
  77 {
  78         struct idxd_desc *d, *n;
  79
  80         lockdep_assert_held(&ie->list_lock);
  81         list_for_each_entry_safe(d, n, &ie->work_list, list) {
  82                 if (d == desc) {
  83                         list_del(&d->list);
  84                         return d;
  85                 }
  86         }
  87
  88         /*
  89          * At this point, the desc needs to be aborted is held by the completion
  90          * handler where it has taken it off the pending list but has not added to the
  91          * work list. It will be cleaned up by the interrupt handler when it sees the
  92          * IDXD_COMP_DESC_ABORT for completion status.
  93          */
  94         return NULL;
  95 }
  96
  97 static void llist_abort_desc(struct idxd_wq *wq, struct idxd_irq_entry *ie,
  98                              struct idxd_desc *desc)
  99 {
 100         struct idxd_desc *d, *t, *found = NULL;
 101         struct llist_node *head;
 102         LIST_HEAD(flist);
 103
 104         desc->completion->status = IDXD_COMP_DESC_ABORT;
 105         /*
 106          * Grab the list lock so it will block the irq thread handler. This allows the
 107          * abort code to locate the descriptor need to be aborted.
 108          */
 109         spin_lock(&ie->list_lock);
 110         head = llist_del_all(&ie->pending_llist);
 111         if (head) {
 112                 llist_for_each_entry_safe(d, t, head, llnode) {
 113                         if (d == desc) {
 114                                 found = desc;
 115                                 continue;
 116                         }
 117
 118                         if (d->completion->status)
 119                                 list_add_tail(&d->list, &flist);
 120                         else
 121                                 list_add_tail(&d->list, &ie->work_list);
 122                 }
 123         }
 124
 125         if (!found)
 126                 found = list_abort_desc(wq, ie, desc);
 127         spin_unlock(&ie->list_lock);
 128
 129         if (found)
 130                 idxd_dma_complete_txd(found, IDXD_COMPLETE_ABORT, false,
 131                                       NULL, NULL);
 132
 133         /*
 134          * completing the descriptor will return desc to allocator and
 135          * the desc can be acquired by a different process and the
 136          * desc->list can be modified.  Delete desc from list so the
 137          * list traversing does not get corrupted by the other process.
 138          */
 139         list_for_each_entry_safe(d, t, &flist, list) {
 140                 list_del_init(&d->list);
 141                 idxd_dma_complete_txd(found, IDXD_COMPLETE_ABORT, true,
 142                                       NULL, NULL);
 143         }
 144 }
 145
 146 /*
 147  * ENQCMDS typically fail when the WQ is inactive or busy. On host submission, the driver
 148  * has better control of number of descriptors being submitted to a shared wq by limiting
 149  * the number of driver allocated descriptors to the wq size. However, when the swq is
 150  * exported to a guest kernel, it may be shared with multiple guest kernels. This means
 151  * the likelihood of getting busy returned on the swq when submitting goes significantly up.
 152  * Having a tunable retry mechanism allows the driver to keep trying for a bit before giving
 153  * up. The sysfs knob can be tuned by the system administrator.
 154  */
 155 int idxd_enqcmds(struct idxd_wq *wq, void __iomem *portal, const void *desc)
 156 {
 157         unsigned int retries = wq->enqcmds_retries;
 158         int rc;
 159
 160         do {
 161                 rc = enqcmds(portal, desc);
 162                 if (rc == 0)
 163                         break;
 164                 cpu_relax();
 165         } while (retries--);
 166
 167         return rc;
 168 }
 169
 170 int idxd_submit_desc(struct idxd_wq *wq, struct idxd_desc *desc)
 171 {
 172         struct idxd_device *idxd = wq->idxd;
 173         struct idxd_irq_entry *ie = NULL;
 174         u32 desc_flags = desc->hw->flags;
 175         void __iomem *portal;
 176         int rc;
 177
 178         if (idxd->state != IDXD_DEV_ENABLED)
 179                 return -EIO;
 180
 181         if (!percpu_ref_tryget_live(&wq->wq_active)) {
 182                 wait_for_completion(&wq->wq_resurrect);
 183                 if (!percpu_ref_tryget_live(&wq->wq_active))
 184                         return -ENXIO;
 185         }
 186
 187         portal = idxd_wq_portal_addr(wq);
 188
 189         /*
 190          * Pending the descriptor to the lockless list for the irq_entry
 191          * that we designated the descriptor to.
 192          */
 193         if (desc_flags & IDXD_OP_FLAG_RCI) {
 194                 ie = &wq->ie;
 195                 desc->hw->int_handle = ie->int_handle;
 196                 llist_add(&desc->llnode, &ie->pending_llist);
 197         }
 198
 199         /*
 200          * The wmb() flushes writes to coherent DMA data before
 201          * possibly triggering a DMA read. The wmb() is necessary
 202          * even on UP because the recipient is a device.
 203          */
 204         wmb();
 205
 206         if (wq_dedicated(wq)) {
 207                 iosubmit_cmds512(portal, desc->hw, 1);
 208         } else {
 209                 rc = idxd_enqcmds(wq, portal, desc->hw);
 210                 if (rc < 0) {
 211                         percpu_ref_put(&wq->wq_active);
 212                         /* abort operation frees the descriptor */
 213                         if (ie)
 214                                 llist_abort_desc(wq, ie, desc);
 215                         return rc;
 216                 }
 217         }
 218
 219         percpu_ref_put(&wq->wq_active);
 220         return 0;
 221 }
 222 EXPORT_SYMBOL_NS_GPL(idxd_submit_desc, IDXD);