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1// SPDX-License-Identifier: GPL-2.02/* 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 11static 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 27struct 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}64EXPORT_SYMBOL_NS_GPL(idxd_alloc_desc, IDXD);65 66void 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}73EXPORT_SYMBOL_NS_GPL(idxd_free_desc, IDXD);74 75static 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 completion90 * handler where it has taken it off the pending list but has not added to the91 * work list. It will be cleaned up by the interrupt handler when it sees the92 * IDXD_COMP_DESC_ABORT for completion status.93 */94 return NULL;95}96 97static 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 the107 * 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 else121 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 and135 * the desc can be acquired by a different process and the136 * desc->list can be modified. Delete desc from list so the137 * 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 driver148 * has better control of number of descriptors being submitted to a shared wq by limiting149 * the number of driver allocated descriptors to the wq size. However, when the swq is150 * exported to a guest kernel, it may be shared with multiple guest kernels. This means151 * 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 giving153 * up. The sysfs knob can be tuned by the system administrator.154 */155int 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 170int 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_entry191 * 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 before201 * possibly triggering a DMA read. The wmb() is necessary202 * 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}222EXPORT_SYMBOL_NS_GPL(idxd_submit_desc, IDXD);223