From: Somnath Kotur <somnath.kotur@xxxxxxxxxxxx>
The code determines if the next ring entry is valid before proceeding
further to read the rest of the entry. The CPU can re-order and read
the rest of the entry first, possibly reading a stale entry, if DMA
of a new entry happens right after reading it.
Signed-off-by: Somnath Kotur <somnath.kotur@xxxxxxxxxxxx>
Signed-off-by: Selvin Xavier <selvin.xavier@xxxxxxxxxxxx>
---
drivers/infiniband/hw/bnxt_re/qplib_fp.c | 21 +++++++++++++++++++++
drivers/infiniband/hw/bnxt_re/qplib_rcfw.c | 4 ++++
2 files changed, 25 insertions(+)
diff --git a/drivers/infiniband/hw/bnxt_re/qplib_fp.c b/drivers/infiniband/hw/bnxt_re/qplib_fp.c
index a82044d..31ea9f4 100644
--- a/drivers/infiniband/hw/bnxt_re/qplib_fp.c
+++ b/drivers/infiniband/hw/bnxt_re/qplib_fp.c
@@ -292,6 +292,12 @@ static void bnxt_qplib_service_nq(unsigned long data)
if (!NQE_CMP_VALID(nqe, raw_cons, hwq->max_elements))
break;
+ /*
+ * The valid test of the entry must be done first before
+ * reading any further.
+ */
+ dma_rmb();
+
type = le16_to_cpu(nqe->info10_type) & NQ_BASE_TYPE_MASK;
switch (type) {
case NQ_BASE_TYPE_CQ_NOTIFICATION:
@@ -1113,6 +1119,11 @@ static void __clean_cq(struct bnxt_qplib_cq *cq, u64 qp)
hw_cqe = &hw_cqe_ptr[CQE_PG(i)][CQE_IDX(i)];
if (!CQE_CMP_VALID(hw_cqe, i, cq_hwq->max_elements))
continue;
+ /*
+ * The valid test of the entry must be done first before
+ * reading any further.
+ */
+ dma_rmb();
switch (hw_cqe->cqe_type_toggle & CQ_BASE_CQE_TYPE_MASK) {
case CQ_BASE_CQE_TYPE_REQ:
case CQ_BASE_CQE_TYPE_TERMINAL:
@@ -1896,6 +1907,11 @@ static int do_wa9060(struct bnxt_qplib_qp *qp, struct bnxt_qplib_cq *cq,
/* If the next hwcqe is VALID */
if (CQE_CMP_VALID(peek_hwcqe, peek_raw_cq_cons,
cq->hwq.max_elements)) {
+ /*
+ * The valid test of the entry must be done first before
+ * reading any further.
+ */
+ dma_rmb();
/* If the next hwcqe is a REQ */
if ((peek_hwcqe->cqe_type_toggle &
CQ_BASE_CQE_TYPE_MASK) ==
@@ -2440,6 +2456,11 @@ int bnxt_qplib_poll_cq(struct bnxt_qplib_cq *cq, struct bnxt_qplib_cqe *cqe,
if (!CQE_CMP_VALID(hw_cqe, raw_cons, cq->hwq.max_elements))
break;
+ /*
+ * The valid test of the entry must be done first before
+ * reading any further.
+ */
+ dma_rmb();
/* From the device's respective CQE format to qplib_wc*/
switch (hw_cqe->cqe_type_toggle & CQ_BASE_CQE_TYPE_MASK) {
case CQ_BASE_CQE_TYPE_REQ:
diff --git a/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c b/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c
index 6d11614..751170a 100644
--- a/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c
+++ b/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c
@@ -357,6 +357,10 @@ static void bnxt_qplib_service_creq(unsigned long data)
creqe = &creq_ptr[get_creq_pg(sw_cons)][get_creq_idx(sw_cons)];
if (!CREQ_CMP_VALID(creqe, raw_cons, creq->max_elements))
break;
+ /* The valid test of the entry must be done first before
+ * reading any further.
+ */
+ dma_rmb();
type = creqe->type & CREQ_BASE_TYPE_MASK;
switch (type) {
--
2.5.5
--
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