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 65 void idxd_free_desc(struct idxd_wq *wq, struct idxd_desc *desc) 66 { 67 int cpu = desc->cpu; 68 69 desc->cpu = -1; 70 sbitmap_queue_clear(&wq->sbq, desc->id, cpu); 71 } 72 73 static struct idxd_desc *list_abort_desc(struct idxd_wq *wq, struct idxd_irq_entry *ie, 74 struct idxd_desc *desc) 75 { 76 struct idxd_desc *d, *n; 77 78 lockdep_assert_held(&ie->list_lock); 79 list_for_each_entry_safe(d, n, &ie->work_list, list) { 80 if (d == desc) { 81 list_del(&d->list); 82 return d; 83 } 84 } 85 86 /* 87 * At this point, the desc needs to be aborted is held by the completion 88 * handler where it has taken it off the pending list but has not added to the 89 * work list. It will be cleaned up by the interrupt handler when it sees the 90 * IDXD_COMP_DESC_ABORT for completion status. 91 */ 92 return NULL; 93 } 94 95 static void llist_abort_desc(struct idxd_wq *wq, struct idxd_irq_entry *ie, 96 struct idxd_desc *desc) 97 { 98 struct idxd_desc *d, *t, *found = NULL; 99 struct llist_node *head; 100 LIST_HEAD(flist); 101 102 desc->completion->status = IDXD_COMP_DESC_ABORT; 103 /* 104 * Grab the list lock so it will block the irq thread handler. This allows the 105 * abort code to locate the descriptor need to be aborted. 106 */ 107 spin_lock(&ie->list_lock); 108 head = llist_del_all(&ie->pending_llist); 109 if (head) { 110 llist_for_each_entry_safe(d, t, head, llnode) { 111 if (d == desc) { 112 found = desc; 113 continue; 114 } 115 116 if (d->completion->status) 117 list_add_tail(&d->list, &flist); 118 else 119 list_add_tail(&d->list, &ie->work_list); 120 } 121 } 122 123 if (!found) 124 found = list_abort_desc(wq, ie, desc); 125 spin_unlock(&ie->list_lock); 126 127 if (found) 128 idxd_dma_complete_txd(found, IDXD_COMPLETE_ABORT, false); 129 130 /* 131 * completing the descriptor will return desc to allocator and 132 * the desc can be acquired by a different process and the 133 * desc->list can be modified. Delete desc from list so the 134 * list trasversing does not get corrupted by the other process. 135 */ 136 list_for_each_entry_safe(d, t, &flist, list) { 137 list_del_init(&d->list); 138 idxd_dma_complete_txd(found, IDXD_COMPLETE_ABORT, true); 139 } 140 } 141 142 /* 143 * ENQCMDS typically fail when the WQ is inactive or busy. On host submission, the driver 144 * has better control of number of descriptors being submitted to a shared wq by limiting 145 * the number of driver allocated descriptors to the wq size. However, when the swq is 146 * exported to a guest kernel, it may be shared with multiple guest kernels. This means 147 * the likelihood of getting busy returned on the swq when submitting goes significantly up. 148 * Having a tunable retry mechanism allows the driver to keep trying for a bit before giving 149 * up. The sysfs knob can be tuned by the system administrator. 150 */ 151 int idxd_enqcmds(struct idxd_wq *wq, void __iomem *portal, const void *desc) 152 { 153 int rc, retries = 0; 154 155 do { 156 rc = enqcmds(portal, desc); 157 if (rc == 0) 158 break; 159 cpu_relax(); 160 } while (retries++ < wq->enqcmds_retries); 161 162 return rc; 163 } 164 165 int idxd_submit_desc(struct idxd_wq *wq, struct idxd_desc *desc) 166 { 167 struct idxd_device *idxd = wq->idxd; 168 struct idxd_irq_entry *ie = NULL; 169 u32 desc_flags = desc->hw->flags; 170 void __iomem *portal; 171 int rc; 172 173 if (idxd->state != IDXD_DEV_ENABLED) 174 return -EIO; 175 176 if (!percpu_ref_tryget_live(&wq->wq_active)) { 177 wait_for_completion(&wq->wq_resurrect); 178 if (!percpu_ref_tryget_live(&wq->wq_active)) 179 return -ENXIO; 180 } 181 182 portal = idxd_wq_portal_addr(wq); 183 184 /* 185 * The wmb() flushes writes to coherent DMA data before 186 * possibly triggering a DMA read. The wmb() is necessary 187 * even on UP because the recipient is a device. 188 */ 189 wmb(); 190 191 /* 192 * Pending the descriptor to the lockless list for the irq_entry 193 * that we designated the descriptor to. 194 */ 195 if (desc_flags & IDXD_OP_FLAG_RCI) { 196 ie = &wq->ie; 197 desc->hw->int_handle = ie->int_handle; 198 llist_add(&desc->llnode, &ie->pending_llist); 199 } 200 201 if (wq_dedicated(wq)) { 202 iosubmit_cmds512(portal, desc->hw, 1); 203 } else { 204 rc = idxd_enqcmds(wq, portal, desc->hw); 205 if (rc < 0) { 206 percpu_ref_put(&wq->wq_active); 207 /* abort operation frees the descriptor */ 208 if (ie) 209 llist_abort_desc(wq, ie, desc); 210 return rc; 211 } 212 } 213 214 percpu_ref_put(&wq->wq_active); 215 return 0; 216 } 217