diff options
Diffstat (limited to 'drivers/dma/idxd/submit.c')
| -rw-r--r-- | drivers/dma/idxd/submit.c | 31 |
1 files changed, 24 insertions, 7 deletions
diff --git a/drivers/dma/idxd/submit.c b/drivers/dma/idxd/submit.c index 776fa81db61d..569815a84e95 100644 --- a/drivers/dma/idxd/submit.c +++ b/drivers/dma/idxd/submit.c @@ -123,6 +123,29 @@ static void llist_abort_desc(struct idxd_wq *wq, struct idxd_irq_entry *ie, idxd_dma_complete_txd(found, IDXD_COMPLETE_ABORT, false); } +/* + * 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) +{ + int rc, retries = 0; + + do { + rc = enqcmds(portal, desc); + if (rc == 0) + break; + cpu_relax(); + } while (retries++ < wq->enqcmds_retries); + + return rc; +} + int idxd_submit_desc(struct idxd_wq *wq, struct idxd_desc *desc) { struct idxd_device *idxd = wq->idxd; @@ -166,13 +189,7 @@ int idxd_submit_desc(struct idxd_wq *wq, struct idxd_desc *desc) if (wq_dedicated(wq)) { iosubmit_cmds512(portal, desc->hw, 1); } else { - /* - * It's not likely that we would receive queue full rejection - * since the descriptor allocation gates at wq size. If we - * receive a -EAGAIN, that means something went wrong such as the - * device is not accepting descriptor at all. - */ - rc = enqcmds(portal, desc->hw); + rc = idxd_enqcmds(wq, portal, desc->hw); if (rc < 0) { percpu_ref_put(&wq->wq_active); /* abort operation frees the descriptor */ |