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Message-ID: <2806a097-1a8f-595c-fad8-6cb7ec5f4172@gmail.com>
Date: Fri, 19 May 2023 12:09:34 -0500
From: Bob Pearson <rpearsonhpe@...il.com>
To: Daisuke Matsuda <matsuda-daisuke@...itsu.com>,
linux-rdma@...r.kernel.org, leonro@...dia.com, jgg@...dia.com,
zyjzyj2000@...il.com
Cc: linux-kernel@...r.kernel.org, yangx.jy@...itsu.com,
lizhijian@...itsu.com, y-goto@...itsu.com
Subject: Re: [PATCH for-next v5 5/7] RDMA/rxe: Allow registering MRs for
On-Demand Paging
On 5/18/23 03:21, Daisuke Matsuda wrote:
> Allow applications to register an ODP-enabled MR, in which case the flag
> IB_ACCESS_ON_DEMAND is passed to rxe_reg_user_mr(). However, there is no
> RDMA operation supported right now. They will be enabled later in the
> subsequent two patches.
>
> rxe_odp_do_pagefault() is called to initialize an ODP-enabled MR. It syncs
> process address space from the CPU page table to the driver page table
> (dma_list/pfn_list in umem_odp) when called with RXE_PAGEFAULT_SNAPSHOT
> flag. Additionally, It can be used to trigger page fault when pages being
> accessed are not present or do not have proper read/write permissions, and
> possibly to prefetch pages in the future.
>
> Signed-off-by: Daisuke Matsuda <matsuda-daisuke@...itsu.com>
> ---
> drivers/infiniband/sw/rxe/rxe.c | 7 ++
> drivers/infiniband/sw/rxe/rxe_loc.h | 14 +++
> drivers/infiniband/sw/rxe/rxe_mr.c | 9 +-
> drivers/infiniband/sw/rxe/rxe_odp.c | 120 ++++++++++++++++++++++++++
> drivers/infiniband/sw/rxe/rxe_resp.c | 15 +++-
> drivers/infiniband/sw/rxe/rxe_verbs.c | 5 +-
> drivers/infiniband/sw/rxe/rxe_verbs.h | 2 +
> 7 files changed, 166 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/infiniband/sw/rxe/rxe.c b/drivers/infiniband/sw/rxe/rxe.c
> index 54c723a6edda..f2284d27229b 100644
> --- a/drivers/infiniband/sw/rxe/rxe.c
> +++ b/drivers/infiniband/sw/rxe/rxe.c
> @@ -73,6 +73,13 @@ static void rxe_init_device_param(struct rxe_dev *rxe)
> rxe->ndev->dev_addr);
>
> rxe->max_ucontext = RXE_MAX_UCONTEXT;
> +
> + if (IS_ENABLED(CONFIG_INFINIBAND_ON_DEMAND_PAGING)) {
> + rxe->attr.kernel_cap_flags |= IBK_ON_DEMAND_PAGING;
> +
> + /* IB_ODP_SUPPORT_IMPLICIT is not supported right now. */
> + rxe->attr.odp_caps.general_caps |= IB_ODP_SUPPORT;
> + }
> }
>
> /* initialize port attributes */
> diff --git a/drivers/infiniband/sw/rxe/rxe_loc.h b/drivers/infiniband/sw/rxe/rxe_loc.h
> index 00fedd1a4980..93247d123642 100644
> --- a/drivers/infiniband/sw/rxe/rxe_loc.h
> +++ b/drivers/infiniband/sw/rxe/rxe_loc.h
> @@ -202,4 +202,18 @@ static inline unsigned int wr_opcode_mask(int opcode, struct rxe_qp *qp)
> return rxe_wr_opcode_info[opcode].mask[qp->ibqp.qp_type];
> }
>
> +/* rxe_odp.c */
> +#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
> +int rxe_odp_mr_init_user(struct rxe_dev *rxe, u64 start, u64 length,
> + u64 iova, int access_flags, struct rxe_mr *mr);
> +#else /* CONFIG_INFINIBAND_ON_DEMAND_PAGING */
> +static inline int
> +rxe_odp_mr_init_user(struct rxe_dev *rxe, u64 start, u64 length, u64 iova,
> + int access_flags, struct rxe_mr *mr)
> +{
> + return -EOPNOTSUPP;
> +}
> +
> +#endif /* CONFIG_INFINIBAND_ON_DEMAND_PAGING */
> +
> #endif /* RXE_LOC_H */
> diff --git a/drivers/infiniband/sw/rxe/rxe_mr.c b/drivers/infiniband/sw/rxe/rxe_mr.c
> index ffbac6f5e828..cd368cd096c8 100644
> --- a/drivers/infiniband/sw/rxe/rxe_mr.c
> +++ b/drivers/infiniband/sw/rxe/rxe_mr.c
> @@ -318,7 +318,10 @@ int rxe_mr_copy(struct rxe_mr *mr, u64 iova, void *addr,
> return err;
> }
>
> - return rxe_mr_copy_xarray(mr, iova, addr, length, dir);
> + if (mr->odp_enabled)
> + return -EOPNOTSUPP;
> + else
> + return rxe_mr_copy_xarray(mr, iova, addr, length, dir);
> }
>
> /* copy data in or out of a wqe, i.e. sg list
> @@ -527,6 +530,10 @@ int rxe_mr_do_atomic_write(struct rxe_mr *mr, u64 iova, u64 value)
> struct page *page;
> u64 *va;
>
> + /* ODP is not supported right now. WIP. */
> + if (mr->odp_enabled)
> + return RESPST_ERR_UNSUPPORTED_OPCODE;
> +
> /* See IBA oA19-28 */
> if (unlikely(mr->state != RXE_MR_STATE_VALID)) {
> rxe_dbg_mr(mr, "mr not in valid state");
> diff --git a/drivers/infiniband/sw/rxe/rxe_odp.c b/drivers/infiniband/sw/rxe/rxe_odp.c
> index b69b25e0fef6..e5497d09c399 100644
> --- a/drivers/infiniband/sw/rxe/rxe_odp.c
> +++ b/drivers/infiniband/sw/rxe/rxe_odp.c
> @@ -24,6 +24,24 @@ static void rxe_mr_unset_xarray(struct rxe_mr *mr, unsigned long start,
> spin_unlock(&mr->page_list.xa_lock);
> }
>
> +static void rxe_mr_set_xarray(struct rxe_mr *mr, unsigned long start,
> + unsigned long end, unsigned long *pfn_list)
> +{
> + unsigned long lower, upper, idx;
> + struct page *page;
> +
> + lower = rxe_mr_iova_to_index(mr, start);
> + upper = rxe_mr_iova_to_index(mr, end);
> +
> + /* make pages visible in xarray. no sleep while taking the lock */
> + spin_lock(&mr->page_list.xa_lock);
> + for (idx = lower; idx <= upper; idx++) {
> + page = hmm_pfn_to_page(pfn_list[idx]);
> + __xa_store(&mr->page_list, idx, page, GFP_ATOMIC);
> + }
> + spin_unlock(&mr->page_list.xa_lock);
> +}
> +
> static bool rxe_ib_invalidate_range(struct mmu_interval_notifier *mni,
> const struct mmu_notifier_range *range,
> unsigned long cur_seq)
> @@ -54,3 +72,105 @@ static bool rxe_ib_invalidate_range(struct mmu_interval_notifier *mni,
> const struct mmu_interval_notifier_ops rxe_mn_ops = {
> .invalidate = rxe_ib_invalidate_range,
> };
> +
> +#define RXE_PAGEFAULT_RDONLY BIT(1)
> +#define RXE_PAGEFAULT_SNAPSHOT BIT(2)
> +static int rxe_odp_do_pagefault(struct rxe_mr *mr, u64 user_va, int bcnt, u32 flags)
> +{
> + int np;
> + u64 access_mask;
> + bool fault = !(flags & RXE_PAGEFAULT_SNAPSHOT);
> + struct ib_umem_odp *umem_odp = to_ib_umem_odp(mr->umem);
> +
> + access_mask = ODP_READ_ALLOWED_BIT;
> + if (umem_odp->umem.writable && !(flags & RXE_PAGEFAULT_RDONLY))
> + access_mask |= ODP_WRITE_ALLOWED_BIT;
> +
> + /*
> + * ib_umem_odp_map_dma_and_lock() locks umem_mutex on success.
> + * Callers must release the lock later to let invalidation handler
> + * do its work again.
> + */
> + np = ib_umem_odp_map_dma_and_lock(umem_odp, user_va, bcnt,
> + access_mask, fault);
> + if (np < 0)
> + return np;
> +
> + /* umem_mutex is still locked here, so we can use hmm_pfn_to_page()
> + * safely to fetch pages in the range.
> + */
> + rxe_mr_set_xarray(mr, user_va, user_va + bcnt, umem_odp->pfn_list);
> +
> + return np;
> +}
> +
> +static int rxe_odp_init_pages(struct rxe_mr *mr)
> +{
> + int ret;
> + struct ib_umem_odp *umem_odp = to_ib_umem_odp(mr->umem);
> +
> + ret = rxe_odp_do_pagefault(mr, mr->umem->address, mr->umem->length,
> + RXE_PAGEFAULT_SNAPSHOT);
> +
> + if (ret >= 0)
> + mutex_unlock(&umem_odp->umem_mutex);
> +
> + return ret >= 0 ? 0 : ret;
> +}
> +
> +int rxe_odp_mr_init_user(struct rxe_dev *rxe, u64 start, u64 length,
> + u64 iova, int access_flags, struct rxe_mr *mr)
> +{
> + int err;
> + struct ib_umem_odp *umem_odp;
> +
> + if (!IS_ENABLED(CONFIG_INFINIBAND_ON_DEMAND_PAGING))
> + return -EOPNOTSUPP;
> +
> + rxe_mr_init(access_flags, mr);
> +
> + xa_init(&mr->page_list);
> +
> + if (!start && length == U64_MAX) {
> + if (iova != 0)
> + return -EINVAL;
> + if (!(rxe->attr.odp_caps.general_caps & IB_ODP_SUPPORT_IMPLICIT))
> + return -EINVAL;
> +
> + /* Never reach here, for implicit ODP is not implemented. */
> + }
> +
> + umem_odp = ib_umem_odp_get(&rxe->ib_dev, start, length, access_flags,
> + &rxe_mn_ops);
> + if (IS_ERR(umem_odp)) {
> + rxe_dbg_mr(mr, "Unable to create umem_odp err = %d\n",
> + (int)PTR_ERR(umem_odp));
> + return PTR_ERR(umem_odp);
> + }
> +
> + umem_odp->private = mr;
> +
> + mr->odp_enabled = true;
> + mr->umem = &umem_odp->umem;
> + mr->access = access_flags;
> + mr->ibmr.length = length;
> + mr->ibmr.iova = iova;
> + mr->page_offset = ib_umem_offset(&umem_odp->umem);
> +
> + err = rxe_odp_init_pages(mr);
> + if (err) {
> + ib_umem_odp_release(umem_odp);
> + return err;
> + }
> +
> + err = rxe_mr_fill_pages_from_sgt(mr, &umem_odp->umem.sgt_append.sgt);
> + if (err) {
> + ib_umem_odp_release(umem_odp);
> + return err;
> + }
> +
> + mr->state = RXE_MR_STATE_VALID;
> + mr->ibmr.type = IB_MR_TYPE_USER;
> +
> + return err;
> +}
> diff --git a/drivers/infiniband/sw/rxe/rxe_resp.c b/drivers/infiniband/sw/rxe/rxe_resp.c
> index ba0222bfce9e..90c31c4f2944 100644
> --- a/drivers/infiniband/sw/rxe/rxe_resp.c
> +++ b/drivers/infiniband/sw/rxe/rxe_resp.c
> @@ -626,6 +626,10 @@ static enum resp_states process_flush(struct rxe_qp *qp,
> struct rxe_mr *mr = qp->resp.mr;
> struct resp_res *res = qp->resp.res;
>
> + /* ODP is not supported right now. WIP. */
> + if (mr->odp_enabled)
> + return RESPST_ERR_UNSUPPORTED_OPCODE;
> +
> /* oA19-14, oA19-15 */
> if (res && res->replay)
> return RESPST_ACKNOWLEDGE;
> @@ -679,10 +683,13 @@ static enum resp_states atomic_reply(struct rxe_qp *qp,
> if (!res->replay) {
> u64 iova = qp->resp.va + qp->resp.offset;
>
> - err = rxe_mr_do_atomic_op(mr, iova, pkt->opcode,
> - atmeth_comp(pkt),
> - atmeth_swap_add(pkt),
> - &res->atomic.orig_val);
> + if (mr->odp_enabled)
> + err = RESPST_ERR_UNSUPPORTED_OPCODE;
> + else
> + err = rxe_mr_do_atomic_op(mr, iova, pkt->opcode,
> + atmeth_comp(pkt),
> + atmeth_swap_add(pkt),
> + &res->atomic.orig_val);
> if (err)
> return err;
>
> diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.c b/drivers/infiniband/sw/rxe/rxe_verbs.c
> index dea605b7f683..9c23defdc7b5 100644
> --- a/drivers/infiniband/sw/rxe/rxe_verbs.c
> +++ b/drivers/infiniband/sw/rxe/rxe_verbs.c
> @@ -1274,7 +1274,10 @@ static struct ib_mr *rxe_reg_user_mr(struct ib_pd *ibpd, u64 start,
> mr->ibmr.pd = ibpd;
> mr->ibmr.device = ibpd->device;
>
> - err = rxe_mr_init_user(rxe, start, length, iova, access, mr);
> + if (access & IB_ACCESS_ON_DEMAND)
> + err = rxe_odp_mr_init_user(rxe, start, length, iova, access, mr);
> + else
> + err = rxe_mr_init_user(rxe, start, length, iova, access, mr);
> if (err) {
> rxe_dbg_mr(mr, "reg_user_mr failed, err = %d", err);
> goto err_cleanup;
> diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.h b/drivers/infiniband/sw/rxe/rxe_verbs.h
> index b6fbd9b3d086..de5a982c7c7e 100644
> --- a/drivers/infiniband/sw/rxe/rxe_verbs.h
> +++ b/drivers/infiniband/sw/rxe/rxe_verbs.h
> @@ -333,6 +333,8 @@ struct rxe_mr {
> u32 nbuf;
>
> struct xarray page_list;
> +
> + bool odp_enabled;
> };
>
> static inline unsigned int mr_page_size(struct rxe_mr *mr)
Reviewed-by: Bob Pearson <rpearsonhpe@...il.com>
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