diff options
Diffstat (limited to 'drivers/dma')
| -rw-r--r-- | drivers/dma/idxd/device.c | 1 | ||||
| -rw-r--r-- | drivers/dma/idxd/idxd.h | 20 | ||||
| -rw-r--r-- | drivers/dma/idxd/submit.c | 2 |
3 files changed, 22 insertions, 1 deletions
diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c index 99350ac9a292..41f67a195eb6 100644 --- a/drivers/dma/idxd/device.c +++ b/drivers/dma/idxd/device.c @@ -320,6 +320,7 @@ void idxd_wq_unmap_portal(struct idxd_wq *wq) devm_iounmap(dev, wq->portal); wq->portal = NULL; + wq->portal_offset = 0; } void idxd_wqs_unmap_portal(struct idxd_device *idxd) diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h index 4e4dc0110e77..94983bced189 100644 --- a/drivers/dma/idxd/idxd.h +++ b/drivers/dma/idxd/idxd.h @@ -11,6 +11,7 @@ #include <linux/idr.h> #include <linux/pci.h> #include <linux/perf_event.h> +#include <uapi/linux/idxd.h> #include "registers.h" #define IDXD_DRIVER_VERSION "1.00" @@ -162,6 +163,7 @@ struct idxd_dma_chan { struct idxd_wq { void __iomem *portal; + u32 portal_offset; struct percpu_ref wq_active; struct completion wq_dead; struct idxd_dev idxd_dev; @@ -468,6 +470,24 @@ static inline int idxd_get_wq_portal_full_offset(int wq_id, return ((wq_id * 4) << PAGE_SHIFT) + idxd_get_wq_portal_offset(prot); } +#define IDXD_PORTAL_MASK (PAGE_SIZE - 1) + +/* + * Even though this function can be accessed by multiple threads, it is safe to use. + * At worst the address gets used more than once before it gets incremented. We don't + * hit a threshold until iops becomes many million times a second. So the occasional + * reuse of the same address is tolerable compare to using an atomic variable. This is + * safe on a system that has atomic load/store for 32bit integers. Given that this is an + * Intel iEP device, that should not be a problem. + */ +static inline void __iomem *idxd_wq_portal_addr(struct idxd_wq *wq) +{ + int ofs = wq->portal_offset; + + wq->portal_offset = (ofs + sizeof(struct dsa_raw_desc)) & IDXD_PORTAL_MASK; + return wq->portal + ofs; +} + static inline void idxd_wq_get(struct idxd_wq *wq) { wq->client_count++; diff --git a/drivers/dma/idxd/submit.c b/drivers/dma/idxd/submit.c index 65b0130ab2db..92ae9a157cc9 100644 --- a/drivers/dma/idxd/submit.c +++ b/drivers/dma/idxd/submit.c @@ -146,7 +146,7 @@ int idxd_submit_desc(struct idxd_wq *wq, struct idxd_desc *desc) if (!percpu_ref_tryget_live(&wq->wq_active)) return -ENXIO; - portal = wq->portal; + portal = idxd_wq_portal_addr(wq); /* * The wmb() flushes writes to coherent DMA data before |