RE: [PATCH for-next 2/2] RDMA/hns: Fix alignment problem of the doorbell

Ruhl, Michael J
2017-12-27T17:40:19Z

> -----Original Message-----
> From: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org [mailto:linux-rdma-
> owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org] On Behalf Of Yixian Liu
> Sent: Monday, December 25, 2017 8:37 AM
> To: jgg-uk2M96/98Pc@public.gmane.org; leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org
> Cc: dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org; linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Subject: [PATCH for-next 2/2] RDMA/hns: Fix alignment problem of the
> doorbell
>
> The array defined for doorbell is not guaranteed to be 64 bit
> aligned while we write it to the hardware with 64 bit
> alignment required.
>
> This patch fixes this problem by defining a union for doorbell
> to make sure it 64 bit alignment.
>
> Signed-off-by: Yixian Liu <liuyixian-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Lijun Ou <oulijun-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Wei Hu (Xavier) <xavier.huwei-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
> ---
> drivers/infiniband/hw/hns/hns_roce_device.h | 5 +++++
> drivers/infiniband/hw/hns/hns_roce_hw_v2.c | 16 ++++++++--------
> 2 files changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/infiniband/hw/hns/hns_roce_device.h
> b/drivers/infiniband/hw/hns/hns_roce_device.h
> index dde5178..defc4ee 100644
> --- a/drivers/infiniband/hw/hns/hns_roce_device.h
> +++ b/drivers/infiniband/hw/hns/hns_roce_device.h
> @@ -569,6 +569,11 @@ struct hns_roce_eq_table {
> void __iomem **eqc_base; /* only for hw v1 */
> };
>
> +union hns_roce_db {
> + u64 doorbell64;

Are there any concerns with big endian/little ending for this value?

Mike

> + u32 doorbell[2];
> +};
> +
> struct hns_roce_caps {
> u8 num_ports;
> int gid_table_len[HNS_ROCE_MAX_PORTS];
> diff --git a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
> b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
> index 7f393f6..ee26bbd 100644
> --- a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
> +++ b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
> @@ -3172,33 +3172,33 @@ static int hns_roce_v2_modify_cq(struct ib_cq
> *cq, u16 cq_count, u16 cq_period)
>
> static void set_eq_cons_index_v2(struct hns_roce_eq *eq)
> {
> - u32 doorbell[2];
> + union hns_roce_db db;
>
> - doorbell[0] = 0;
> - doorbell[1] = 0;
> + db.doorbell[0] = 0;
> + db.doorbell[1] = 0;
>
> if (eq->type_flag == HNS_ROCE_AEQ) {
> - roce_set_field(doorbell[0], HNS_ROCE_V2_EQ_DB_CMD_M,
> + roce_set_field(db.doorbell[0],
> HNS_ROCE_V2_EQ_DB_CMD_M,
> HNS_ROCE_V2_EQ_DB_CMD_S,
> eq->arm_st ==
> HNS_ROCE_V2_EQ_ALWAYS_ARMED ?
> HNS_ROCE_EQ_DB_CMD_AEQ :
> HNS_ROCE_EQ_DB_CMD_AEQ_ARMED);
> } else {
> - roce_set_field(doorbell[0], HNS_ROCE_V2_EQ_DB_TAG_M,
> + roce_set_field(db.doorbell[0],
> HNS_ROCE_V2_EQ_DB_TAG_M,
> HNS_ROCE_V2_EQ_DB_TAG_S, eq->eqn);
>
> - roce_set_field(doorbell[0], HNS_ROCE_V2_EQ_DB_CMD_M,
> + roce_set_field(db.doorbell[0],
> HNS_ROCE_V2_EQ_DB_CMD_M,
> HNS_ROCE_V2_EQ_DB_CMD_S,
> eq->arm_st ==
> HNS_ROCE_V2_EQ_ALWAYS_ARMED ?
> HNS_ROCE_EQ_DB_CMD_CEQ :
> HNS_ROCE_EQ_DB_CMD_CEQ_ARMED);
> }
>
> - roce_set_field(doorbell[1], HNS_ROCE_V2_EQ_DB_PARA_M,
> + roce_set_field(db.doorbell[1], HNS_ROCE_V2_EQ_DB_PARA_M,
> HNS_ROCE_V2_EQ_DB_PARA_S,
> (eq->cons_index & HNS_ROCE_V2_CONS_IDX_M));
>
> - hns_roce_write64_k(doorbell, eq->doorbell);
> + hns_roce_write64_k(db.doorbell, eq->doorbell);
>
> /* Make sure we update the consumer index of EQ before
> * accessing it later
> --
> 1.9.1
>
> --
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