Mellanox has contacted Canonical so we could include Connect-X 4 support in kernels for Trusty, Utopic and Vivid. They have used Vivid kernel tree to backport their upstream patches and provided us the following list:
1 - 7835bfb5261501590a508b3de3379e2231cb4853 infiniband: mlx5: avoid a compile-time warning
2 - 7eae20db6adf721d0c14ad2a37208278ce4f11dc IB/mlx5: Update the dev in reg_create
3 - 1707cb4ab723cc07c5f6b83e21e142fa196c9e72 IB/mlx5: Enable the ODP capability query verb
4 - c3c6c9c810e100ab92c782e855f9ab9991065f4e net/mlx5_core: Fix call to mlx5_core_qp_modify
5 - 7bef7ad24b9aa15cb06870f78ba8bd84bb7e1407 net/mlx5_core: Coding style fix
6 - b812b5441e359adb9bd44108f7f91e5b0ba4a768 net/mlx5_core: Clear doorbell record inside mlx5_db_alloc()
7 - 6cf0a15f07a5a4600beb72f3a246fcd9325e86aa IB/mlx5: Fix Mellanox copyright note
8 - 233d05d28ad942929b6b4fbc48aa8dd083c16484 net/mlx5_core: Move completion eqs from mlx5_ib to mlx5_core
9 - ce0f75093282c5dca1e79ae3e3e893deaea86166 net/mlx5_core: Modify arm CQ in preparation for upcoming Ethernet driver
10 - 64613d9499c4887485d4350387919ea507330d90 net/mlx5_core: Extend struct mlx5_interface to support multiple protocols
11 - f4f01b542c027b0df57109140c3ee48321705c88 infiniband: Remove duplicated KERN_<LEVEL> from pr_<level> uses
12 - 64ffaa2159b752e6c263dc57eaaaed7367d37493 net/mlx5_core,mlx5_ib: Do not use vmap() on coherent memory
13 - 938fe83c8dcbbf294d167e6163200a8540ae43c4 net/mlx5_core: New device capabilities handling
14 - f62b8bb8f2d30582f30f51e85a8c0e1260125d7e net/mlx5: Extend mlx5_core to support ConnectX-4 Ethernet functionality
15 - 01949d0109ee5fae33752f0db99a36f1619e1873 net/mlx5_core: Enable XRCs and SRQs when using ISSI > 0
16 - 1b5daf11b015123108686a9060ee6de705a03e76 IB/mlx5: Avoid using the MAD_IFC command under ISSI > 0 mode
17 - 647241ea10db87ed0448853fa510177dd89a7a63 IB/mlx5: Don't create IB instance over Ethernet ports
18 - 4aa17b2879f66e478aa9b81cc3bbade6416126aa mlx5: Enable mutual support for IB and Ethernet
19 - facc9699f0fe7d65a92cc09e175662659306066d net/mlx5e: Fix HW MTU settings
20 - 43c6116573ca0f9fc907e6b46861f2f142acb33b IB/core: Add support for extended query device caps
21 - 64599cca51de08cef94bc13a0f98351e5bb01f41 net/mlx5_core: Use coherent memory for command interface page
22 - 302bdf68fc56a6330bc6b10ce435b4d466417537 net/mlx5_core: Fix Mellanox copyright note
23 - 233d05d28ad942929b6b4fbc48aa8dd083c16484 net/mlx5_core: Move completion eqs from mlx5_ib to mlx5_core
24 - ce0f75093282c5dca1e79ae3e3e893deaea86166 net/mlx5_core: Modify arm CQ in preparation for upcoming Ethernet driver
25 - 64613d9499c4887485d4350387919ea507330d90 net/mlx5_core: Extend struct mlx5_interface to support multiple protocols
26 - 64ffaa2159b752e6c263dc57eaaaed7367d37493 net/mlx5_core,mlx5_ib: Do not use vmap() on coherent memory
27 - db058a186f98b057c19c42f7b10d9a96fd3b5d59 net/mlx5_core: Set irq affinity hints
28 - e281682bf29438848daac11627216bceb1507b71 net/mlx5_core: HW data structs/types definitions cleanup
29 - 938fe83c8dcbbf294d167e6163200a8540ae43c4 net/mlx5_core: New device capabilities handling
30 - adb0c9545bce6f1b1d563e988e6ee5531861d449 net/mlx5_core: Implement access functions of ptys register fields
31 - 4c916a798058c1acf5a980438416020932c24aca net/mlx5_core: Implement get/set port status
32 - 90b3e38d048f09b22fb50bcd460cea65fd00b2d7 net/mlx5_core: Modify CQ moderation parameters
33 - e725440e75da8c4d617a31c4e38216acc55c24e3 net/mlx5_core: Set/Query port MTU commands
34 - afb736e9330ad6b2b6935d2f53ded784eb73f12d net/mlx5: Ethernet resource handling files
35 - f62b8bb8f2d30582f30f51e85a8c0e1260125d7e net/mlx5: Extend mlx5_core to support ConnectX-4 Ethernet functionality
36 - 01949d0109ee5fae33752f0db99a36f1619e1873 net/mlx5_core: Enable XRCs and SRQs when using ISSI > 0
37 - d18a9470f89727f870db944a36223bf1bb15bdc1 net/mlx5_core: Make the vport helpers available for the IB driver too
38 - 707c4602cda6624940761b66a4119f1909492385 net/mlx5_core: Add new query HCA vport commands
39 - 211e6c80e5a68ef39a81484583e8efbf9774627d net/mlx5_core: Get vendor-id using the query adapter command
40 - e760152d08da78aa160e68ac90bf8f3f10aff462 net/mlx5_core: Use port number in the query port mtu helpers
41 - a05bdefa4081d43f9c86c3bb693d0492a21590da net/mlx5_core: Use port number when querying port ptys
42 - a124d13ef59e09941fc0924fd7c29ae6d7cd77a3 net/mlx5_core: Add more query port helpers
43 - 7cf7fa529d0b6b514949cc67b39e3ce406c37006 net/mlx5_core: Fix static checker warnings around system guid query flow
44 - facc9699f0fe7d65a92cc09e175662659306066d net/mlx5e: Fix HW MTU settings
45 - fc11fbf9a785b25c5d07f05a30d4169ec39818da net/mlx5e: Add HW cacheline start padding
46 - 065bd8c28ba37d04c9a5b732173c1508954b1f58 mlx5: avoid build warnings on 32-bit
47 - 1c755cc5be5023c9523d558de0c507316efa6c62 net/mlx5_core: Move to use hex PCI device IDs
48 - 1d966d03a37f7f58abf12e87203d03f96950cfd0 net: Mellanox: Delete unnecessary checks before the function call "vunmap"
49 - 6b9f53bc102d4e61b73c13f661de4a1c358768c1 net/mlx5_core: don't export static symbol
50 - ad1891062adcdacb5818e104707dca8c193c33d8 net/mlx5_core: Allocate firmware pages from device's NUMA node
51 - 9ef9baa2acda077f3831f6e7cdf751bc8691f78f net/mlx5_core: Avoid setting DC requestor/responder resources
52 - b812b5441e359adb9bd44108f7f91e5b0ba4a768 net/mlx5_core: Clear doorbell record inside mlx5_db_alloc()
53 - 60722c2ba02be052140998bc80ed77d74e3c03df net/mlx5_core: Use the right inbox struct in destroy mkey command
54 - 64599cca51de08cef94bc13a0f98351e5bb01f41 net/mlx5_core: Use coherent memory for command interface page
55 - 05e4ecd1dc8b085a9010f20dcb5409b25488480a net/mlx5_core: Avoid copying outbox in aysnc command completion
56 - 21db507439ec3a76a9587f2ad50ad3e4d13f4440 net/mlx5_core: Avoid usage command work entry after
57 - 4cbdd27c9c3abf87d6fe88cdd749218193ed3e12 net/mlx5_core: Fix a bug in alloc_token
58 - 302bdf68fc56a6330bc6b10ce435b4d466417537 net/mlx5_core: Fix Mellanox copyright note
59 - 4ae6c18c59f1419202ab5e2a918e551099d88f9f net/mlx5_core: Update module info macros for ConnectX4 Support
60 - 233d05d28ad942929b6b4fbc48aa8dd083c16484 net/mlx5_core: Move completion eqs from mlx5_ib to mlx5_core
61 - 64613d9499c4887485d4350387919ea507330d90 net/mlx5_core: Extend struct mlx5_interface to support multiple protocols
62 - 12b3375f3963536ba3ad47d2db49f72067b4905e mlx4/mlx5: Use dma_wmb/rmb where appropriate
63 - 59d2d18cc4e9ba30b370db18d0e02d792699da96 mlx5: wrong page mask if CONFIG_ARCH_DMA_ADDR_T_64BIT
64 - 64ffaa2159b752e6c263dc57eaaaed7367d37493 net/mlx5_core,mlx5_ib: Do not use vmap() on coherent memory
65 - db058a186f98b057c19c42f7b10d9a96fd3b5d59 net/mlx5_core: Set irq affinity hints
66 - e281682bf29438848daac11627216bceb1507b71 net/mlx5_core: HW data structs/types definitions cleanup
67 - 938fe83c8dcbbf294d167e6163200a8540ae43c4 net/mlx5_core: New device capabilities handling
68 - adb0c9545bce6f1b1d563e988e6ee5531861d449 net/mlx5_core: Implement access functions of ptys register fields
69 - 4c916a798058c1acf5a980438416020932c24aca net/mlx5_core: Implement get/set port status
70 - 90b3e38d048f09b22fb50bcd460cea65fd00b2d7 net/mlx5_core: Modify CQ moderation parameters
71 - e725440e75da8c4d617a31c4e38216acc55c24e3 net/mlx5_core: Set/Query port MTU commands
72 - e586b3b0baee89f4998efd9cc97001c63e3bc744 net/mlx5: Ethernet Datapath files
73 - afb736e9330ad6b2b6935d2f53ded784eb73f12d net/mlx5: Ethernet resource handling files
74 - f62b8bb8f2d30582f30f51e85a8c0e1260125d7e net/mlx5: Extend mlx5_core to support ConnectX-4 Ethernet functionality
75 - 5e24851ec502334986c2ac775beb4b7184a0b6c5 net/mlx5_en: Add missing check for memory allocation failure
76 - 7db22ffb5b09d9b77baf057ca034d966e58df1e1 net/mlx5_core: Apply proper name convention to helpers
77 - 01949d0109ee5fae33752f0db99a36f1619e1873 net/mlx5_core: Enable XRCs and SRQs when using ISSI > 0
78 - e74a1db03326ecdc7c3f54a581b197a26ce5eebe net/mlx5_core: Check the return bitmask when querying ISSI
79 - d18a9470f89727f870db944a36223bf1bb15bdc1 net/mlx5_core: Make the vport helpers available for the IB driver too
80 - 707c4602cda6624940761b66a4119f1909492385 net/mlx5_core: Add new query HCA vport commands
81 - 211e6c80e5a68ef39a81484583e8efbf9774627d net/mlx5_core: Get vendor-id using the query adapter command
82 - e760152d08da78aa160e68ac90bf8f3f10aff462 net/mlx5_core: Use port number in the query port mtu helpers
83 - a05bdefa4081d43f9c86c3bb693d0492a21590da net/mlx5_core: Use port number when querying port ptys
84 - a124d13ef59e09941fc0924fd7c29ae6d7cd77a3 net/mlx5_core: Add more query port helpers
85 - 4aa17b2879f66e478aa9b81cc3bbade6416126aa mlx5: Enable mutual support for IB and Ethernet
86 - 7cf7fa529d0b6b514949cc67b39e3ce406c37006 net/mlx5_core: Fix static checker warnings around system guid query flow
87 - 7ec0bb227aa6fb8c622bec91933e865b37dc58f2 net/mlx5_core: fix an error code
88 - facc9699f0fe7d65a92cc09e175662659306066d net/mlx5e: Fix HW MTU settings
89 - fc11fbf9a785b25c5d07f05a30d4169ec39818da net/mlx5e: Add HW cacheline start padding
90 - cd58c714acb98a186051dc7e620d1b7ef4843311 net/mlx5e: Disable client vlan TX acceleration
91 - 796a27ec2d9f722ce5a08bd5b33f3c7712fb6127 net/mlx5e: Enforce max flow-tables level >= 3
92 - 56508b5013718e9df783ebb8495461357a97ceda net/mlx5_core: Add transport domain alloc/dealloc support
93 - 3191e05feafaae58c04973ae8a157393eaa30519 net/mlx5e: Add transport domain to the ethernet TIRs/TISs
Since this is a huge list it might be appropriate to include those commits into Vivid and make Trusty depend on the Vivid HWE kernel for supporting ConnectX-4 (since that is what HWE kernel is all about).
After talking to kernel team it was decided it is better to wait for Wily LTS kernel to enable this type of HW in Trusty, Utopic and Vivid.