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 trasversing 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); 223