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
__get_desc(struct idxd_wq * wq,int idx,int cpu)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
idxd_alloc_desc(struct idxd_wq * wq,enum idxd_op_type optype)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
idxd_free_desc(struct idxd_wq * wq,struct idxd_desc * desc)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
list_abort_desc(struct idxd_wq * wq,struct idxd_irq_entry * ie,struct idxd_desc * desc)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
llist_abort_desc(struct idxd_wq * wq,struct idxd_irq_entry * ie,struct idxd_desc * desc)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 */
idxd_enqcmds(struct idxd_wq * wq,void __iomem * portal,const void * desc)151 int idxd_enqcmds(struct idxd_wq *wq, void __iomem *portal, const void *desc)
152 {
153 unsigned int retries = wq->enqcmds_retries;
154 int rc;
155
156 do {
157 rc = enqcmds(portal, desc);
158 if (rc == 0)
159 break;
160 cpu_relax();
161 } while (retries--);
162
163 return rc;
164 }
165
idxd_submit_desc(struct idxd_wq * wq,struct idxd_desc * desc)166 int idxd_submit_desc(struct idxd_wq *wq, struct idxd_desc *desc)
167 {
168 struct idxd_device *idxd = wq->idxd;
169 struct idxd_irq_entry *ie = NULL;
170 u32 desc_flags = desc->hw->flags;
171 void __iomem *portal;
172 int rc;
173
174 if (idxd->state != IDXD_DEV_ENABLED)
175 return -EIO;
176
177 if (!percpu_ref_tryget_live(&wq->wq_active)) {
178 wait_for_completion(&wq->wq_resurrect);
179 if (!percpu_ref_tryget_live(&wq->wq_active))
180 return -ENXIO;
181 }
182
183 portal = idxd_wq_portal_addr(wq);
184
185 /*
186 * Pending the descriptor to the lockless list for the irq_entry
187 * that we designated the descriptor to.
188 */
189 if (desc_flags & IDXD_OP_FLAG_RCI) {
190 ie = &wq->ie;
191 desc->hw->int_handle = ie->int_handle;
192 llist_add(&desc->llnode, &ie->pending_llist);
193 }
194
195 /*
196 * The wmb() flushes writes to coherent DMA data before
197 * possibly triggering a DMA read. The wmb() is necessary
198 * even on UP because the recipient is a device.
199 */
200 wmb();
201
202 if (wq_dedicated(wq)) {
203 iosubmit_cmds512(portal, desc->hw, 1);
204 } else {
205 rc = idxd_enqcmds(wq, portal, desc->hw);
206 if (rc < 0) {
207 percpu_ref_put(&wq->wq_active);
208 /* abort operation frees the descriptor */
209 if (ie)
210 llist_abort_desc(wq, ie, desc);
211 return rc;
212 }
213 }
214
215 percpu_ref_put(&wq->wq_active);
216 return 0;
217 }
218