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RDMA/rxe: Enable asynchronous prefetch for ODP MRs

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Calling ibv_advise_mr(3) with flags other than IBV_ADVISE_MR_FLAG_FLUSH
invokes an asynchronous request. It is best-effort, and thus can safely be
deferred to the system-wide workqueue.

The reference counter in rxe_mr is used to ensure that the MRs persist and
that rxe is not terminated until the queued work is done.

Signed-off-by: Daisuke Matsuda <dskmtsd@gmail.com>
Link: https://patch.msgid.link/20250522111955.3227-3-dskmtsd@gmail.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>
This commit is contained in:
Daisuke Matsuda 2025-05-22 11:19:55 +00:00 • committed by Leon Romanovsky
parent 3576b0df15
commit 9284bc34c7
1 changed files with 85 additions and 2 deletions
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87
drivers/infiniband/sw/rxe/rxe_odp.c
View file

@ -419,6 +419,52 @@ enum resp_states rxe_odp_do_atomic_write(struct rxe_mr *mr, u64 iova, u64 value)
return RESPST_NONE;
}
struct prefetch_mr_work {
struct work_struct work;
u32 pf_flags;
u32 num_sge;
struct {
u64 io_virt;
struct rxe_mr *mr;
size_t length;
} frags[];
};
static void rxe_ib_prefetch_mr_work(struct work_struct *w)
{
struct prefetch_mr_work *work =
container_of(w, struct prefetch_mr_work, work);
int ret;
u32 i;
/*
* We rely on IB/core that work is executed
* if we have num_sge != 0 only.
*/
WARN_ON(!work->num_sge);
for (i = 0; i < work->num_sge; ++i) {
struct ib_umem_odp *umem_odp;
ret = rxe_odp_do_pagefault_and_lock(work->frags[i].mr,
work->frags[i].io_virt,
work->frags[i].length,
work->pf_flags);
if (ret < 0) {
rxe_dbg_mr(work->frags[i].mr,
"failed to prefetch the mr\n");
goto deref;
}
umem_odp = to_ib_umem_odp(work->frags[i].mr->umem);
mutex_unlock(&umem_odp->umem_mutex);
deref:
rxe_put(work->frags[i].mr);
}
kvfree(work);
}
static int rxe_ib_prefetch_sg_list(struct ib_pd *ibpd,
enum ib_uverbs_advise_mr_advice advice,
u32 pf_flags, struct ib_sge *sg_list,
@ -470,7 +516,11 @@ static int rxe_ib_advise_mr_prefetch(struct ib_pd *ibpd,
u32 flags, struct ib_sge *sg_list,
u32 num_sge)
{
struct rxe_pd *pd = container_of(ibpd, struct rxe_pd, ibpd);
u32 pf_flags = RXE_PAGEFAULT_DEFAULT;
struct prefetch_mr_work *work;
struct rxe_mr *mr;
u32 i;
if (advice == IB_UVERBS_ADVISE_MR_ADVICE_PREFETCH)
pf_flags |= RXE_PAGEFAULT_RDONLY;
@ -483,8 +533,41 @@ static int rxe_ib_advise_mr_prefetch(struct ib_pd *ibpd,
return rxe_ib_prefetch_sg_list(ibpd, advice, pf_flags, sg_list,
num_sge);
/* Asynchronous call is to be added in the next patch */
return -EOPNOTSUPP;
/* Asynchronous call is "best-effort" and allowed to fail */
work = kvzalloc(struct_size(work, frags, num_sge), GFP_KERNEL);
if (!work)
return -ENOMEM;
INIT_WORK(&work->work, rxe_ib_prefetch_mr_work);
work->pf_flags = pf_flags;
work->num_sge = num_sge;
for (i = 0; i < num_sge; ++i) {
/* Takes a reference, which will be released in the queued work */
mr = lookup_mr(pd, IB_ACCESS_LOCAL_WRITE,
sg_list[i].lkey, RXE_LOOKUP_LOCAL);
if (IS_ERR(mr))
goto err;
work->frags[i].io_virt = sg_list[i].addr;
work->frags[i].length = sg_list[i].length;
work->frags[i].mr = mr;
}
queue_work(system_unbound_wq, &work->work);
return 0;
err:
/* rollback reference counts for the invalid request */
while (i > 0) {
i--;
rxe_put(work->frags[i].mr);
}
kvfree(work);
return PTR_ERR(mr);
}
int rxe_ib_advise_mr(struct ib_pd *ibpd,