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// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 2019 Intel Corporation. All rights rsvd. */
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <uapi/linux/idxd.h>
#include "idxd.h"
#include "registers.h"
static struct idxd_desc *__get_desc(struct idxd_wq *wq, int idx, int cpu)
{
struct idxd_desc *desc;
struct idxd_device *idxd = wq->idxd;
desc = wq->descs[idx];
memset(desc->hw, 0, sizeof(struct dsa_hw_desc));
memset(desc->completion, 0, idxd->data->compl_size);
desc->cpu = cpu;
if (device_pasid_enabled(idxd))
desc->hw->pasid = idxd->pasid;
return desc;
}
struct idxd_desc *idxd_alloc_desc(struct idxd_wq *wq, enum idxd_op_type optype)
{
int cpu, idx;
struct idxd_device *idxd = wq->idxd;
DEFINE_SBQ_WAIT(wait);
struct sbq_wait_state *ws;
struct sbitmap_queue *sbq;
if (idxd->state != IDXD_DEV_ENABLED)
return ERR_PTR(-EIO);
sbq = &wq->sbq;
idx = sbitmap_queue_get(sbq, &cpu);
if (idx < 0) {
if (optype == IDXD_OP_NONBLOCK)
return ERR_PTR(-EAGAIN);
} else {
return __get_desc(wq, idx, cpu);
}
ws = &sbq->ws[0];
for (;;) {
sbitmap_prepare_to_wait(sbq, ws, &wait, TASK_INTERRUPTIBLE);
if (signal_pending_state(TASK_INTERRUPTIBLE, current))
break;
idx = sbitmap_queue_get(sbq, &cpu);
if (idx >= 0)
break;
schedule();
}
sbitmap_finish_wait(sbq, ws, &wait);
if (idx < 0)
return ERR_PTR(-EAGAIN);
return __get_desc(wq, idx, cpu);
}
void idxd_free_desc(struct idxd_wq *wq, struct idxd_desc *desc)
{
int cpu = desc->cpu;
desc->cpu = -1;
sbitmap_queue_clear(&wq->sbq, desc->id, cpu);
}
static struct idxd_desc *list_abort_desc(struct idxd_wq *wq, struct idxd_irq_entry *ie,
struct idxd_desc *desc)
{
struct idxd_desc *d, *n;
lockdep_assert_held(&ie->list_lock);
list_for_each_entry_safe(d, n, &ie->work_list, list) {
if (d == desc) {
list_del(&d->list);
return d;
}
}
/*
* At this point, the desc needs to be aborted is held by the completion
* handler where it has taken it off the pending list but has not added to the
* work list. It will be cleaned up by the interrupt handler when it sees the
* IDXD_COMP_DESC_ABORT for completion status.
*/
return NULL;
}
static void llist_abort_desc(struct idxd_wq *wq, struct idxd_irq_entry *ie,
struct idxd_desc *desc)
{
struct idxd_desc *d, *t, *found = NULL;
struct llist_node *head;
LIST_HEAD(flist);
desc->completion->status = IDXD_COMP_DESC_ABORT;
/*
* Grab the list lock so it will block the irq thread handler. This allows the
* abort code to locate the descriptor need to be aborted.
*/
spin_lock(&ie->list_lock);
head = llist_del_all(&ie->pending_llist);
if (head) {
llist_for_each_entry_safe(d, t, head, llnode) {
if (d == desc) {
found = desc;
continue;
}
if (d->completion->status)
list_add_tail(&d->list, &flist);
else
list_add_tail(&d->list, &ie->work_list);
}
}
if (!found)
found = list_abort_desc(wq, ie, desc);
spin_unlock(&ie->list_lock);
if (found)
idxd_dma_complete_txd(found, IDXD_COMPLETE_ABORT, false);
/*
* completing the descriptor will return desc to allocator and
* the desc can be acquired by a different process and the
* desc->list can be modified. Delete desc from list so the
* list trasversing does not get corrupted by the other process.
*/
list_for_each_entry_safe(d, t, &flist, list) {
list_del_init(&d->list);
idxd_dma_complete_txd(found, IDXD_COMPLETE_ABORT, true);
}
}
/*
* ENQCMDS typically fail when the WQ is inactive or busy. On host submission, the driver
* has better control of number of descriptors being submitted to a shared wq by limiting
* the number of driver allocated descriptors to the wq size. However, when the swq is
* exported to a guest kernel, it may be shared with multiple guest kernels. This means
* the likelihood of getting busy returned on the swq when submitting goes significantly up.
* Having a tunable retry mechanism allows the driver to keep trying for a bit before giving
* up. The sysfs knob can be tuned by the system administrator.
*/
int idxd_enqcmds(struct idxd_wq *wq, void __iomem *portal, const void *desc)
{
unsigned int retries = wq->enqcmds_retries;
int rc;
do {
rc = enqcmds(portal, desc);
if (rc == 0)
break;
cpu_relax();
} while (retries--);
return rc;
}
int idxd_submit_desc(struct idxd_wq *wq, struct idxd_desc *desc)
{
struct idxd_device *idxd = wq->idxd;
struct idxd_irq_entry *ie = NULL;
u32 desc_flags = desc->hw->flags;
void __iomem *portal;
int rc;
if (idxd->state != IDXD_DEV_ENABLED)
return -EIO;
if (!percpu_ref_tryget_live(&wq->wq_active)) {
wait_for_completion(&wq->wq_resurrect);
if (!percpu_ref_tryget_live(&wq->wq_active))
return -ENXIO;
}
portal = idxd_wq_portal_addr(wq);
/*
* The wmb() flushes writes to coherent DMA data before
* possibly triggering a DMA read. The wmb() is necessary
* even on UP because the recipient is a device.
*/
wmb();
/*
* Pending the descriptor to the lockless list for the irq_entry
* that we designated the descriptor to.
*/
if (desc_flags & IDXD_OP_FLAG_RCI) {
ie = &wq->ie;
desc->hw->int_handle = ie->int_handle;
llist_add(&desc->llnode, &ie->pending_llist);
}
if (wq_dedicated(wq)) {
iosubmit_cmds512(portal, desc->hw, 1);
} else {
rc = idxd_enqcmds(wq, portal, desc->hw);
if (rc < 0) {
percpu_ref_put(&wq->wq_active);
/* abort operation frees the descriptor */
if (ie)
llist_abort_desc(wq, ie, desc);
return rc;
}
}
percpu_ref_put(&wq->wq_active);
return 0;
}
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