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RDMA/core: Add hash functions to calculate RoCEv2 flowlabel and UDP source port

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Add two hash functions to distribute RoCE v2 UDP source and Flowlabel
symmetrically. These are user visible API and any change in the
implementation needs to be tested for inter-operability between old and
new variant.

Link: https://lore.kernel.org/r/20200504051935.269708-2-leon@kernel.org
Signed-off-by: Mark Zhang <markz@mellanox.com>
Reviewed-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
This commit is contained in:
Mark Zhang 2020-05-04 08:19:31 +03:00 committed by Jason Gunthorpe
parent 11a0ae4c4b
commit d5665a2125
1 changed files with 44 additions and 0 deletions
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44
include/rdma/ib_verbs.h
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@ -4709,4 +4709,48 @@ static inline struct ib_device *rdma_device_to_ibdev(struct device *device)
bool rdma_dev_access_netns(const struct ib_device *device,
const struct net *net);
#define IB_ROCE_UDP_ENCAP_VALID_PORT_MIN (0xC000)
#define IB_GRH_FLOWLABEL_MASK (0x000FFFFF)
/**
* rdma_flow_label_to_udp_sport - generate a RoCE v2 UDP src port value based
* on the flow_label
*
* This function will convert the 20 bit flow_label input to a valid RoCE v2
* UDP src port 14 bit value. All RoCE V2 drivers should use this same
* convention.
*/
static inline u16 rdma_flow_label_to_udp_sport(u32 fl)
{
u32 fl_low = fl & 0x03fff, fl_high = fl & 0xFC000;
fl_low ^= fl_high >> 14;
return (u16)(fl_low | IB_ROCE_UDP_ENCAP_VALID_PORT_MIN);
}
/**
* rdma_calc_flow_label - generate a RDMA symmetric flow label value based on
* local and remote qpn values
*
* This function folded the multiplication results of two qpns, 24 bit each,
* fields, and converts it to a 20 bit results.
*
* This function will create symmetric flow_label value based on the local
* and remote qpn values. this will allow both the requester and responder
* to calculate the same flow_label for a given connection.
*
* This helper function should be used by driver in case the upper layer
* provide a zero flow_label value. This is to improve entropy of RDMA
* traffic in the network.
*/
static inline u32 rdma_calc_flow_label(u32 lqpn, u32 rqpn)
{
u64 v = (u64)lqpn * rqpn;
v ^= v >> 20;
v ^= v >> 40;
return (u32)(v & IB_GRH_FLOWLABEL_MASK);
}
#endif /* IB_VERBS_H */