RDMA/uverbs: Use UMEM attributes for QP creation

Apply the per-attribute UMEM model to the QP create method. Add three optional UMEM attributes that drivers pick from based on how their user ABI lays out the QP rings: - CREATE_QP_BUF_UMEM is a single user buffer that backs both the SQ and RQ of one QP. This is the common case where userspace pins one contiguous WQE region for the QP. - CREATE_QP_SQ_BUF_UMEM and CREATE_QP_RQ_BUF_UMEM are a pair of user buffers backing the SQ and RQ independently, used when the two rings live in physically distinct user allocations and must be pinned and addressed separately. Existing drivers would map their current umems as follows: - mlx5: BUF for normal QPs (one ucmd->buf_addr covers SQ+RQ); for IB_QPT_RAW_PACKET and IB_QP_CREATE_SOURCE_QPN, the RQ side comes from ucmd->buf_addr (RQ-sized) via RQ_BUF and the SQ from ucmd->sq_buf_addr via SQ_BUF. - mlx4: BUF, single ucmd.buf_addr covering SQ+RQ. - hns: BUF, single ucmd.buf_addr covering SQ + ext-SGE + RQ. - erdma: BUF, single ureq.qbuf_va sliced by the kernel into SQ at offset 0 and RQ at rq_offset. - bnxt_re: SQ_BUF (ureq->qpsva) + RQ_BUF (ureq->qprva, the RQ side is skipped when the QP uses an SRQ). - vmw_pvrdma: SQ_BUF (sbuf_addr) + RQ_BUF (rbuf_addr, the RQ side is skipped when the QP uses an SRQ). - qedr: SQ_BUF (sq_addr) + RQ_BUF (rq_addr) for whichever side the QP type actually has (no SQ for XRC_TGT/GSI; no RQ for XRC_INI/XRC_TGT/SRQ). - ionic: SQ_BUF (req.sq.addr) + RQ_BUF (req.rq.addr); both are skipped when the rings are placed in CMB instead of host memory. - mana: raw-packet QP uses SQ_BUF (sq_buf_addr) only; the RC path uses multiple per-queue user buffers (ucmd.queue_buf[]) that do not fit the SQ/RQ pair semantics of these attrs and stays on the legacy UHW path. - efa, irdma, hfi1, ocrdma, mthca, cxgb4 and usnic do not pin a QP WQE buffer via umem; none of these attributes apply.

JPJiri Pirko committed 5 months ago