Hey folks, I wanna thank all of you for the kind feedback in my previous RFC. Recently, i have tried my best to do some updates as per your comments. Indeed, not all comments have been addressed for some reasons, i still wish to post this new one to start a new discussion. Outstanding issues: - iova_to_addr() without any kmap/kmap_local_page flows might not always work. # existing issue. - responder should reply error to requested side when it requests a persistence placement type to DRAM ? ------- These patches are going to implement a *NEW* RDMA opcode "RDMA FLUSH". In IB SPEC 1.5[1][2], 2 new opcodes, ATOMIC WRITE and RDMA FLUSH were added in the MEMORY PLACEMENT EXTENSIONS section. FLUSH is used by the requesting node to achieve guarantees on the data placement within the memory subsystem of preceding accesses to a single memory region, such as those performed by RDMA WRITE, Atomics and ATOMIC WRITE requests. The operation indicates the virtual address space of a destination node and where the guarantees should apply. This range must be contiguous in the virtual space of the memory key but it is not necessarily a contiguous range of physical memory. FLUSH packets carry FLUSH extended transport header (see below) to specify the placement type and the selectivity level of the operation and RDMA extended header (RETH, see base document RETH definition) to specify the R_Key VA and Length associated with this request following the BTH in RC, RDETH in RD and XRCETH in XRC. RC FLUSH: +----+------+------+ |BTH | FETH | RETH | +----+------+------+ RD FLUSH: +----+------+------+------+ |BTH | RDETH| FETH | RETH | +----+------+------+------+ XRC FLUSH: +----+-------+------+------+ |BTH | XRCETH| FETH | RETH | +----+-------+------+------+ Currently, we introduce RC and RD services only, since XRC has not been implemented by rxe yet. NOTE: only RC service is tested now, and since other HCAs have not added/implemented FLUSH yet, we can only test FLUSH operation in both SoftRoCE/rxe devices. The corresponding rdma-core and FLUSH example are available on: https://github.com/zhijianli88/rdma-core/tree/rfc Can access the kernel source in: https://github.com/zhijianli88/linux/tree/rdma-flush - We introduce is_pmem attribute to MR(memory region) - We introduce FLUSH placement type attributes to HCA - We introduce FLUSH access flags that users are able to register with Below figure shows the valid access flags uses can register with: +------------------------+------------------+--------------+ | HCA attributes | register access flags | | and +-----------------+---------------+ | MR attribute(is_pmem) |global visibility | persistence | |------------------------+------------------+--------------+ | global visibility(DRAM)| O | X | |------------------------+------------------+--------------+ | global visibility(PMEM)| O | X | |------------------------+------------------+--------------+ | persistence(DRAM) | X | X | |------------------------+------------------+--------------+ | persistence(PMEM) | X | O | +------------------------+------------------+--------------+ O: allow to register such access flag In order to make placement guarentees, we currently reject requesting a persistent flush to a non-pmem. The responder will check the remote requested placement types by checking the registered access flags. +------------------------+------------------+--------------+ | | registered flags | | remote requested types +------------------+--------------+ | |global visibility | persistence | |------------------------+------------------+--------------+ | global visibility | O | x | +------------------------+------------------+--------------+ | persistence | X | O | +------------------------+------------------+--------------+ O: allow to request such placement type Below list some details about FLUSH transport packet: A FLUSH message is built upon FLUSH request packet and is responded successfully by RDMA READ response of zero size. oA19-2: FLUSH shall be single packet message and shall have no payload. oA19-5: FLUSH BTH shall hold the Opcode = 0x1C FLUSH Extended Transport Header(FETH) +-----+-----------+------------------------+----------------------+ |Bits | 31-6 | 5-4 | 3-0 | +-----+-----------+------------------------+----------------------+ | | Reserved | Selectivity Level(SEL) | Placement Type(PLT) | +-----+-----------+------------------------+----------------------+ Selectivity Level (SEL) – defines the memory region scope the FLUSH should apply on. Values are as follows: • b’00 - Memory Region Range: FLUSH applies for all preceding memory updates to the RETH range on this QP. All RETH fields shall be valid in this selectivity mode. RETH:DMALen field shall be between zero and (2 31 -1) bytes (inclusive). • b’01 - Memory Region: FLUSH applies for all preceding memory up- dates to RETH.R_key on this QP. RETH:DMALen and RETH:VA shall be ignored in this mode. • b'10 - Reserved. • b'11 - Reserved. Placement Type (PLT) – Defines the memory placement guarantee of this FLUSH. Multiple bits may be set in this field. Values are as follows: • Bit 0 if set to '1' indicated that the FLUSH should guarantee Global Visibility. • Bit 1 if set to '1' indicated that the FLUSH should guarantee Persistence. • Bits 3:2 are reserved [1]: https://www.infinibandta.org/ibta-specification/ # login required [2]: https://www.infinibandta.org/wp-content/uploads/2021/08/IBTA-Overview-of-IBTA-Volume-1-Release-1.5-and-MPE-2021-08-17-Secure.pptx CC: yangx.jy@xxxxxxxxxxxxxx CC: y-goto@xxxxxxxxxxx CC: Jason Gunthorpe <jgg@xxxxxxxx> CC: Zhu Yanjun <zyjzyj2000@xxxxxxxxx CC: Leon Romanovsky <leon@xxxxxxxxxx> CC: Bob Pearson <rpearsonhpe@xxxxxxxxx> CC: Mark Bloch <mbloch@xxxxxxxxxx> CC: Wenpeng Liang <liangwenpeng@xxxxxxxxxx> CC: Aharon Landau <aharonl@xxxxxxxxxx> CC: Tom Talpey <tom@xxxxxxxxxx> CC: "Gromadzki, Tomasz" <tomasz.gromadzki@xxxxxxxxx> CC: Dan Williams <dan.j.williams@xxxxxxxxx> CC: linux-rdma@xxxxxxxxxxxxxxx CC: linux-kernel@xxxxxxxxxxxxxxx V1: https://lore.kernel.org/lkml/050c3183-2fc6-03a1-eecd-258744750972@xxxxxxxxxxx/T/ or https://github.com/zhijianli88/linux/tree/rdma-flush-rfcv1 Changes log V2: https://github.com/zhijianli88/linux/tree/rdma-flush RDMA: mr: Introduce is_pmem check 1st byte to avoid crossing page boundary new scheme to check is_pmem # Dan RDMA: Allow registering MR with flush access flags combine with [03/10] RDMA/rxe: Allow registering FLUSH flags for supported device only to this patch # Jason split RDMA_FLUSH to 2 capabilities RDMA/rxe: Allow registering persistent flag for pmem MR only update commit message, get rid of confusing ib_check_flush_access_flags() # Tom RDMA/rxe: Implement RC RDMA FLUSH service in requester side extend flush to include length field. # Tom and Tomasz RDMA/rxe: Implement flush execution in responder side adjust start for WHOLE MR level # Tom don't support DMA mr for flush # Tom check flush return value RDMA/rxe: Enable RDMA FLUSH capability for rxe device adjust patch's order. move it here from [04/10] Li Zhijian (9): RDMA: mr: Introduce is_pmem RDMA: Allow registering MR with flush access flags RDMA/rxe: Allow registering persistent flag for pmem MR only RDMA/rxe: Implement RC RDMA FLUSH service in requester side RDMA/rxe: Set BTH's SE to zero for FLUSH packet RDMA/rxe: Implement flush execution in responder side RDMA/rxe: Implement flush completion RDMA/rxe: Enable RDMA FLUSH capability for rxe device RDMA/rxe: Add RD FLUSH service support drivers/infiniband/core/uverbs_cmd.c | 17 +++ drivers/infiniband/sw/rxe/rxe_comp.c | 4 +- drivers/infiniband/sw/rxe/rxe_hdr.h | 52 +++++++++ drivers/infiniband/sw/rxe/rxe_loc.h | 2 + drivers/infiniband/sw/rxe/rxe_mr.c | 37 ++++++- drivers/infiniband/sw/rxe/rxe_opcode.c | 35 +++++++ drivers/infiniband/sw/rxe/rxe_opcode.h | 3 + drivers/infiniband/sw/rxe/rxe_param.h | 4 +- drivers/infiniband/sw/rxe/rxe_req.c | 19 +++- drivers/infiniband/sw/rxe/rxe_resp.c | 133 +++++++++++++++++++++++- include/rdma/ib_pack.h | 3 + include/rdma/ib_verbs.h | 30 +++++- include/uapi/rdma/ib_user_ioctl_verbs.h | 2 + include/uapi/rdma/ib_user_verbs.h | 19 ++++ include/uapi/rdma/rdma_user_rxe.h | 7 ++ 15 files changed, 355 insertions(+), 12 deletions(-) -- 2.31.1
