tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
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
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 /*
25 * Descriptor completion vectors are 1...N for MSIX. We will round
26 * robin through the N vectors.
27 */
28 wq->vec_ptr = desc->vector = (wq->vec_ptr % idxd->num_wq_irqs) + 1;
29 if (!idxd->int_handles) {
30 desc->hw->int_handle = wq->vec_ptr;
31 } else {
32 /*
33 * int_handles are only for descriptor completion. However for device
34 * MSIX enumeration, vec 0 is used for misc interrupts. Therefore even
35 * though we are rotating through 1...N for descriptor interrupts, we
36 * need to acqurie the int_handles from 0..N-1.
37 */
38 desc->hw->int_handle = idxd->int_handles[desc->vector - 1];
39 }
40
41 return desc;
42}
43
44struct idxd_desc *idxd_alloc_desc(struct idxd_wq *wq, enum idxd_op_type optype)
45{
46 int cpu, idx;
47 struct idxd_device *idxd = wq->idxd;
48 DEFINE_SBQ_WAIT(wait);
49 struct sbq_wait_state *ws;
50 struct sbitmap_queue *sbq;
51
52 if (idxd->state != IDXD_DEV_ENABLED)
53 return ERR_PTR(-EIO);
54
55 sbq = &wq->sbq;
56 idx = sbitmap_queue_get(sbq, &cpu);
57 if (idx < 0) {
58 if (optype == IDXD_OP_NONBLOCK)
59 return ERR_PTR(-EAGAIN);
60 } else {
61 return __get_desc(wq, idx, cpu);
62 }
63
64 ws = &sbq->ws[0];
65 for (;;) {
66 sbitmap_prepare_to_wait(sbq, ws, &wait, TASK_INTERRUPTIBLE);
67 if (signal_pending_state(TASK_INTERRUPTIBLE, current))
68 break;
69 idx = sbitmap_queue_get(sbq, &cpu);
70 if (idx > 0)
71 break;
72 schedule();
73 }
74
75 sbitmap_finish_wait(sbq, ws, &wait);
76 if (idx < 0)
77 return ERR_PTR(-EAGAIN);
78
79 return __get_desc(wq, idx, cpu);
80}
81
82void idxd_free_desc(struct idxd_wq *wq, struct idxd_desc *desc)
83{
84 int cpu = desc->cpu;
85
86 desc->cpu = -1;
87 sbitmap_queue_clear(&wq->sbq, desc->id, cpu);
88}
89
90static struct idxd_desc *list_abort_desc(struct idxd_wq *wq, struct idxd_irq_entry *ie,
91 struct idxd_desc *desc)
92{
93 struct idxd_desc *d, *n;
94
95 lockdep_assert_held(&ie->list_lock);
96 list_for_each_entry_safe(d, n, &ie->work_list, list) {
97 if (d == desc) {
98 list_del(&d->list);
99 return d;
100 }
101 }
102
103 /*
104 * At this point, the desc needs to be aborted is held by the completion
105 * handler where it has taken it off the pending list but has not added to the
106 * work list. It will be cleaned up by the interrupt handler when it sees the
107 * IDXD_COMP_DESC_ABORT for completion status.
108 */
109 return NULL;
110}
111
112static void llist_abort_desc(struct idxd_wq *wq, struct idxd_irq_entry *ie,
113 struct idxd_desc *desc)
114{
115 struct idxd_desc *d, *t, *found = NULL;
116 struct llist_node *head;
117 unsigned long flags;
118
119 desc->completion->status = IDXD_COMP_DESC_ABORT;
120 /*
121 * Grab the list lock so it will block the irq thread handler. This allows the
122 * abort code to locate the descriptor need to be aborted.
123 */
124 spin_lock_irqsave(&ie->list_lock, flags);
125 head = llist_del_all(&ie->pending_llist);
126 if (head) {
127 llist_for_each_entry_safe(d, t, head, llnode) {
128 if (d == desc) {
129 found = desc;
130 continue;
131 }
132 list_add_tail(&desc->list, &ie->work_list);
133 }
134 }
135
136 if (!found)
137 found = list_abort_desc(wq, ie, desc);
138 spin_unlock_irqrestore(&ie->list_lock, flags);
139
140 if (found)
141 complete_desc(found, IDXD_COMPLETE_ABORT);
142}
143
144int idxd_submit_desc(struct idxd_wq *wq, struct idxd_desc *desc)
145{
146 struct idxd_device *idxd = wq->idxd;
147 struct idxd_irq_entry *ie = NULL;
148 void __iomem *portal;
149 int rc;
150
151 if (idxd->state != IDXD_DEV_ENABLED)
152 return -EIO;
153
154 if (!percpu_ref_tryget_live(&wq->wq_active))
155 return -ENXIO;
156
157 portal = wq->portal;
158
159 /*
160 * The wmb() flushes writes to coherent DMA data before
161 * possibly triggering a DMA read. The wmb() is necessary
162 * even on UP because the recipient is a device.
163 */
164 wmb();
165
166 /*
167 * Pending the descriptor to the lockless list for the irq_entry
168 * that we designated the descriptor to.
169 */
170 if (desc->hw->flags & IDXD_OP_FLAG_RCI) {
171 ie = &idxd->irq_entries[desc->vector];
172 llist_add(&desc->llnode, &ie->pending_llist);
173 }
174
175 if (wq_dedicated(wq)) {
176 iosubmit_cmds512(portal, desc->hw, 1);
177 } else {
178 /*
179 * It's not likely that we would receive queue full rejection
180 * since the descriptor allocation gates at wq size. If we
181 * receive a -EAGAIN, that means something went wrong such as the
182 * device is not accepting descriptor at all.
183 */
184 rc = enqcmds(portal, desc->hw);
185 if (rc < 0) {
186 if (ie)
187 llist_abort_desc(wq, ie, desc);
188 return rc;
189 }
190 }
191
192 percpu_ref_put(&wq->wq_active);
193 return 0;
194}