net/octeontx2: change default RSS hash calculation

Before C0 HW revision, The RSS adder was computed based the following
static formula.

rss_adder<7:0> = flow_tag<7:0> ^ flow_tag<15:8> ^
flow_tag<23:16> ^ flow_tag<31:24>

The above scheme has the following drawbacks:
1) It is not in line with other standard NIC behavior.
2) There can be an SW use case where SW can compute the hash
upfront using Toeplitz function and predict the queue selection
to optimize some packet lookup function. The nonstandard
way of doing XOR makes the consumer to not predict the queue selection.

C0 HW revision onward, The HW can configure the
rss_adder<7:0> as flow_tag<7:0> to align with standard NICs.

This patch adds an option to select legacy RSS adder mode
using tag_as_xor=1 devargs option while keeping the standard NIC
behavior as default.

Signed-off-by: Jerin Jacob <jerinj@marvell.com>

diff --git a/doc/guides/nics/octeontx2.rst b/doc/guides/nics/octeontx2.rst
index db62a45..2ff1dbd 100644 (file)
--- a/doc/guides/nics/octeontx2.rst
+++ b/doc/guides/nics/octeontx2.rst
@@ -165,7 +165,7 @@ Runtime Config Options
    With the above configuration, each send queue's decscriptor buffer count is
    limited to a maximum of 64 buffers.
 
-- ``switch header enable`` (default ``none``)
+- ``Switch header enable`` (default ``none``)
 
    A port can be configured to a specific switch header type by using
    ``switch_header`` ``devargs`` parameter.
@@ -178,6 +178,23 @@ Runtime Config Options
    traffic on this port should be higig2 traffic only. Supported switch header
    types are "higig2" and "dsa".
 
+- ``RSS tag as XOR`` (default ``0``)
+
+   C0 HW revision onward, The HW gives an option to configure the RSS adder as
+
+   * ``rss_adder<7:0> = flow_tag<7:0> ^ flow_tag<15:8> ^ flow_tag<23:16> ^ flow_tag<31:24>``
+
+   * ``rss_adder<7:0> = flow_tag<7:0>``
+
+   Latter one aligns with standard NIC behavior vs former one is a legacy
+   RSS adder scheme used in OCTEON TX2 products.
+
+   By default, the driver runs in the latter mode from C0 HW revision onward.
+   Setting this flag to 1 to select the legacy mode.
+
+   For example to select the legacy mode(RSS tag adder as XOR)::
+      -w 0002:02:00.0,tag_as_xor=1
+
 .. note::
 
    Above devarg parameters are configurable per device, user needs to pass the

diff --git a/drivers/common/octeontx2/otx2_mbox.h b/drivers/common/octeontx2/otx2_mbox.h
index 4972b8a..e87a53c 100644 (file)
--- a/drivers/common/octeontx2/otx2_mbox.h
+++ b/drivers/common/octeontx2/otx2_mbox.h
@@ -89,7 +89,7 @@ struct mbox_msghdr {
 #define OTX2_MBOX_RSP_SIG (0xbeef)
        /* Signature, for validating corrupted msgs */
        uint16_t __otx2_io sig;
-#define OTX2_MBOX_VERSION (0x0003)
+#define OTX2_MBOX_VERSION (0x0004)
        /* Version of msg's structure for this ID */
        uint16_t __otx2_io ver;
        /* Offset of next msg within mailbox region */
@@ -707,6 +707,8 @@ struct nix_lf_alloc_req {
        uint16_t __otx2_io sso_func;
        uint64_t __otx2_io rx_cfg;   /* See NIX_AF_LF(0..127)_RX_CFG */
        uint64_t __otx2_io way_mask;
+#define NIX_LF_RSS_TAG_LSB_AS_ADDER BIT_ULL(0)
+       uint64_t flags;
 };
 
 struct nix_lf_alloc_rsp {

diff --git a/drivers/net/octeontx2/otx2_ethdev.c b/drivers/net/octeontx2/otx2_ethdev.c
index 11f8c78..1ec234b 100644 (file)
--- a/drivers/net/octeontx2/otx2_ethdev.c
+++ b/drivers/net/octeontx2/otx2_ethdev.c
@@ -70,6 +70,8 @@ nix_lf_alloc(struct otx2_eth_dev *dev, uint32_t nb_rxq, uint32_t nb_txq)
                req->rx_cfg |= BIT_ULL(36 /* CSUM_IL4 */);
        }
        req->rx_cfg |= BIT_ULL(32 /* DROP_RE */);
+       if (dev->rss_tag_as_xor == 0)
+               req->flags = NIX_LF_RSS_TAG_LSB_AS_ADDER;
 
        rc = otx2_mbox_process_msg(mbox, (void *)&rsp);
        if (rc)

diff --git a/drivers/net/octeontx2/otx2_ethdev.h b/drivers/net/octeontx2/otx2_ethdev.h
index c075b8d..49fed95 100644 (file)
--- a/drivers/net/octeontx2/otx2_ethdev.h
+++ b/drivers/net/octeontx2/otx2_ethdev.h
@@ -285,6 +285,7 @@ struct otx2_eth_dev {
        uintptr_t base;
        uintptr_t lmt_addr;
        uint16_t scalar_ena;
+       uint16_t rss_tag_as_xor;
        uint16_t max_sqb_count;
        uint16_t rx_offload_flags; /* Selected Rx offload flags(NIX_RX_*_F) */
        uint64_t rx_offloads;

diff --git a/drivers/net/octeontx2/otx2_ethdev_devargs.c b/drivers/net/octeontx2/otx2_ethdev_devargs.c
index 04da1ab..ab1e14e 100644 (file)
--- a/drivers/net/octeontx2/otx2_ethdev_devargs.c
+++ b/drivers/net/octeontx2/otx2_ethdev_devargs.c
@@ -109,6 +109,7 @@ parse_switch_header_type(const char *key, const char *value, void *extra_args)
 #define OTX2_FLOW_PREALLOC_SIZE "flow_prealloc_size"
 #define OTX2_FLOW_MAX_PRIORITY "flow_max_priority"
 #define OTX2_SWITCH_HEADER_TYPE "switch_header"
+#define OTX2_RSS_TAG_AS_XOR "tag_as_xor"
 
 int
 otx2_ethdev_parse_devargs(struct rte_devargs *devargs, struct otx2_eth_dev *dev)
@@ -119,6 +120,7 @@ otx2_ethdev_parse_devargs(struct rte_devargs *devargs, struct otx2_eth_dev *dev)
        uint16_t switch_header_type = 0;
        uint16_t flow_max_priority = 3;
        uint16_t scalar_enable = 0;
+       uint16_t rss_tag_as_xor = 0;
        struct rte_kvargs *kvlist;
 
        if (devargs == NULL)
@@ -140,10 +142,13 @@ otx2_ethdev_parse_devargs(struct rte_devargs *devargs, struct otx2_eth_dev *dev)
                           &parse_flow_max_priority, &flow_max_priority);
        rte_kvargs_process(kvlist, OTX2_SWITCH_HEADER_TYPE,
                           &parse_switch_header_type, &switch_header_type);
+       rte_kvargs_process(kvlist, OTX2_RSS_TAG_AS_XOR,
+                          &parse_flag, &rss_tag_as_xor);
        rte_kvargs_free(kvlist);
 
 null_devargs:
        dev->scalar_ena = scalar_enable;
+       dev->rss_tag_as_xor = rss_tag_as_xor;
        dev->max_sqb_count = sqb_count;
        dev->rss_info.rss_size = rss_size;
        dev->npc_flow.flow_prealloc_size = flow_prealloc_size;
@@ -161,4 +166,5 @@ RTE_PMD_REGISTER_PARAM_STRING(net_octeontx2,
                              OTX2_MAX_SQB_COUNT "=<8-512>"
                              OTX2_FLOW_PREALLOC_SIZE "=<1-32>"
                              OTX2_FLOW_MAX_PRIORITY "=<1-32>"
-                             OTX2_SWITCH_HEADER_TYPE "=<higig2|dsa>");
+                             OTX2_SWITCH_HEADER_TYPE "=<higig2|dsa>"
+                             OTX2_RSS_TAG_AS_XOR "=1");