RE: [PATCH rdma-core 1/5] verbs: Support dma-buf based memory region

Xiong, Jianxin
2020-11-24T18:00:26Z

> -----Original Message-----
> From: Yishai Hadas <yishaih@nvidia.com>
> Sent: Tuesday, November 24, 2020 2:32 AM
> To: Xiong, Jianxin <jianxin.xiong@intel.com>
> Cc: linux-rdma@vger.kernel.org; dri-devel@lists.freedesktop.org; Doug Ledford <dledford@redhat.com>; Jason Gunthorpe <jgg@ziepe.ca>;
> Leon Romanovsky <leon@kernel.org>; Sumit Semwal <sumit.semwal@linaro.org>; Christian Koenig <christian.koenig@amd.com>; Vetter,
> Daniel <daniel.vetter@intel.com>; Yishai Hadas <yishaih@nvidia.com>
> Subject: Re: [PATCH rdma-core 1/5] verbs: Support dma-buf based memory region
>
> On 11/23/2020 7:53 PM, Jianxin Xiong wrote:
> > Add new API function and new provider method for registering dma-buf
> > based memory region. Update the man page and bump the API version.
> >
> > Signed-off-by: Jianxin Xiong <jianxin.xiong@intel.com>
> > ---
> > kernel-headers/rdma/ib_user_ioctl_cmds.h | 14 ++++++++++++
> > libibverbs/cmd_mr.c | 38 ++++++++++++++++++++++++++++++++
> > libibverbs/driver.h | 7 ++++++
> > libibverbs/dummy_ops.c | 11 +++++++++
> > libibverbs/libibverbs.map.in | 6 +++++
> > libibverbs/man/ibv_reg_mr.3 | 21 ++++++++++++++++--
> > libibverbs/verbs.c | 19 ++++++++++++++++
> > libibverbs/verbs.h | 10 +++++++++
> > 8 files changed, 124 insertions(+), 2 deletions(-)
> >
> > diff --git a/kernel-headers/rdma/ib_user_ioctl_cmds.h
> > b/kernel-headers/rdma/ib_user_ioctl_cmds.h
> > index 7968a18..dafc7eb 100644
> > --- a/kernel-headers/rdma/ib_user_ioctl_cmds.h
> > +++ b/kernel-headers/rdma/ib_user_ioctl_cmds.h
> > @@ -1,5 +1,6 @@
> > /*
> > * Copyright (c) 2018, Mellanox Technologies inc. All rights reserved.
> > + * Copyright (c) 2020, Intel Corporation. All rights reserved.
> > *
> > * This software is available to you under a choice of one of two
> > * licenses. You may choose to be licensed under the terms of the
> > GNU @@ -251,6 +252,7 @@ enum uverbs_methods_mr {
> > UVERBS_METHOD_MR_DESTROY,
> > UVERBS_METHOD_ADVISE_MR,
> > UVERBS_METHOD_QUERY_MR,
> > + UVERBS_METHOD_REG_DMABUF_MR,
> > };
> >
> > enum uverbs_attrs_mr_destroy_ids {
> > @@ -272,6 +274,18 @@ enum uverbs_attrs_query_mr_cmd_attr_ids {
> > UVERBS_ATTR_QUERY_MR_RESP_IOVA,
> > };
> >
> > +enum uverbs_attrs_reg_dmabuf_mr_cmd_attr_ids {
> > + UVERBS_ATTR_REG_DMABUF_MR_HANDLE,
> > + UVERBS_ATTR_REG_DMABUF_MR_PD_HANDLE,
> > + UVERBS_ATTR_REG_DMABUF_MR_OFFSET,
> > + UVERBS_ATTR_REG_DMABUF_MR_LENGTH,
> > + UVERBS_ATTR_REG_DMABUF_MR_IOVA,
> > + UVERBS_ATTR_REG_DMABUF_MR_FD,
> > + UVERBS_ATTR_REG_DMABUF_MR_ACCESS_FLAGS,
> > + UVERBS_ATTR_REG_DMABUF_MR_RESP_LKEY,
> > + UVERBS_ATTR_REG_DMABUF_MR_RESP_RKEY,
> > +};
> > +
> > enum uverbs_attrs_create_counters_cmd_attr_ids {
> > UVERBS_ATTR_CREATE_COUNTERS_HANDLE,
> > };
> > diff --git a/libibverbs/cmd_mr.c b/libibverbs/cmd_mr.c index
> > 42dbe42..91ce2ef 100644
> > --- a/libibverbs/cmd_mr.c
> > +++ b/libibverbs/cmd_mr.c
> > @@ -1,5 +1,6 @@
> > /*
> > * Copyright (c) 2018 Mellanox Technologies, Ltd. All rights reserved.
> > + * Copyright (c) 2020 Intel Corporation. All rights reserved.
> > *
> > * This software is available to you under a choice of one of two
> > * licenses. You may choose to be licensed under the terms of the
> > GNU @@ -116,3 +117,40 @@ int ibv_cmd_query_mr(struct ibv_pd *pd, struct verbs_mr *vmr,
> > return 0;
> > }
> >
> > +int ibv_cmd_reg_dmabuf_mr(struct ibv_pd *pd, uint64_t offset, size_t length,
> > + uint64_t iova, int fd, int access,
> > + struct verbs_mr *vmr)
> > +{
> > + DECLARE_COMMAND_BUFFER(cmdb, UVERBS_OBJECT_MR,
> > + UVERBS_METHOD_REG_DMABUF_MR,
> > + 9);
> > + struct ib_uverbs_attr *handle;
> > + uint32_t lkey, rkey;
> > + int ret;
> > +
> > + handle = fill_attr_out_obj(cmdb, UVERBS_ATTR_REG_DMABUF_MR_HANDLE);
> > + fill_attr_out_ptr(cmdb, UVERBS_ATTR_REG_DMABUF_MR_RESP_LKEY, &lkey);
> > + fill_attr_out_ptr(cmdb, UVERBS_ATTR_REG_DMABUF_MR_RESP_RKEY, &rkey);
> > +
> > + fill_attr_in_obj(cmdb, UVERBS_ATTR_REG_DMABUF_MR_PD_HANDLE, pd->handle);
> > + fill_attr_in_uint64(cmdb, UVERBS_ATTR_REG_DMABUF_MR_OFFSET, offset);
> > + fill_attr_in_uint64(cmdb, UVERBS_ATTR_REG_DMABUF_MR_LENGTH, length);
> > + fill_attr_in_uint64(cmdb, UVERBS_ATTR_REG_DMABUF_MR_IOVA, iova);
> > + fill_attr_in_uint32(cmdb, UVERBS_ATTR_REG_DMABUF_MR_FD, fd);
> > + fill_attr_in_uint32(cmdb, UVERBS_ATTR_REG_DMABUF_MR_ACCESS_FLAGS,
> > +access);
> > +
> > + ret = execute_ioctl(pd->context, cmdb);
> > + if (ret)
> > + return errno;
> > +
> > + vmr->ibv_mr.handle =
> > + read_attr_obj(UVERBS_ATTR_REG_DMABUF_MR_HANDLE, handle);
> > + vmr->ibv_mr.context = pd->context;
> > + vmr->ibv_mr.lkey = lkey;
> > + vmr->ibv_mr.rkey = rkey;
> > + vmr->ibv_mr.pd = pd;
> > + vmr->ibv_mr.addr = (void *)offset;
> > + vmr->ibv_mr.length = length;
> > + vmr->mr_type = IBV_MR_TYPE_MR;
> > + return 0;
> > +}
> > diff --git a/libibverbs/driver.h b/libibverbs/driver.h index
> > ab80f4b..d6a9d0a 100644
> > --- a/libibverbs/driver.h
> > +++ b/libibverbs/driver.h
> > @@ -2,6 +2,7 @@
> > * Copyright (c) 2004, 2005 Topspin Communications. All rights reserved.
> > * Copyright (c) 2005, 2006 Cisco Systems, Inc. All rights reserved.
> > * Copyright (c) 2005 PathScale, Inc. All rights reserved.
> > + * Copyright (c) 2020 Intel Corporation. All rights reserved.
> > *
> > * This software is available to you under a choice of one of two
> > * licenses. You may choose to be licensed under the terms of the
> > GNU @@ -373,6 +374,9 @@ struct verbs_context_ops {
> > struct ibv_mr *(*reg_dm_mr)(struct ibv_pd *pd, struct ibv_dm *dm,
> > uint64_t dm_offset, size_t length,
> > unsigned int access);
> > + struct ibv_mr *(*reg_dmabuf_mr)(struct ibv_pd *pd, uint64_t offset,
> > + size_t length, uint64_t iova,
> > + int fd, int access);
> > struct ibv_mr *(*reg_mr)(struct ibv_pd *pd, void *addr, size_t length,
> > uint64_t hca_va, int access);
> > int (*req_notify_cq)(struct ibv_cq *cq, int solicited_only); @@
> > -498,6 +502,9 @@ int ibv_cmd_advise_mr(struct ibv_pd *pd,
> > uint32_t flags,
> > struct ibv_sge *sg_list,
> > uint32_t num_sge);
> > +int ibv_cmd_reg_dmabuf_mr(struct ibv_pd *pd, uint64_t offset, size_t length,
> > + uint64_t iova, int fd, int access,
> > + struct verbs_mr *vmr);
> > int ibv_cmd_alloc_mw(struct ibv_pd *pd, enum ibv_mw_type type,
> > struct ibv_mw *mw, struct ibv_alloc_mw *cmd,
> > size_t cmd_size,
> > diff --git a/libibverbs/dummy_ops.c b/libibverbs/dummy_ops.c index
> > e5af9e4..dca96d2 100644
> > --- a/libibverbs/dummy_ops.c
> > +++ b/libibverbs/dummy_ops.c
> > @@ -1,5 +1,6 @@
> > /*
> > * Copyright (c) 2017 Mellanox Technologies, Inc. All rights reserved.
> > + * Copyright (c) 2020 Intel Corporation. All rights reserved.
> > *
> > * This software is available to you under a choice of one of two
> > * licenses. You may choose to be licensed under the terms of the
> > GNU @@ -452,6 +453,14 @@ static struct ibv_mr *reg_mr(struct ibv_pd *pd, void *addr, size_t length,
> > return NULL;
> > }
> >
> > +static struct ibv_mr *reg_dmabuf_mr(struct ibv_pd *pd, uint64_t offset,
> > + size_t length, uint64_t iova,
> > + int fd, int access)
> > +{
> > + errno = ENOSYS;
> > + return NULL;
> > +}
> > +
> > static int req_notify_cq(struct ibv_cq *cq, int solicited_only)
> > {
> > return EOPNOTSUPP;
> > @@ -560,6 +569,7 @@ const struct verbs_context_ops verbs_dummy_ops = {
> > query_srq,
> > read_counters,
> > reg_dm_mr,
> > + reg_dmabuf_mr,
> > reg_mr,
> > req_notify_cq,
> > rereg_mr,
> > @@ -689,6 +699,7 @@ void verbs_set_ops(struct verbs_context *vctx,
> > SET_PRIV_OP_IC(vctx, set_ece);
> > SET_PRIV_OP_IC(vctx, unimport_mr);
> > SET_PRIV_OP_IC(vctx, unimport_pd);
> > + SET_OP(vctx, reg_dmabuf_mr);
> >
> > #undef SET_OP
> > #undef SET_OP2
> > diff --git a/libibverbs/libibverbs.map.in
> > b/libibverbs/libibverbs.map.in index b5ccaca..f67e1ef 100644
> > --- a/libibverbs/libibverbs.map.in
> > +++ b/libibverbs/libibverbs.map.in
> > @@ -148,6 +148,11 @@ IBVERBS_1.11 {
> > _ibv_query_gid_table;
> > } IBVERBS_1.10;
> >
> > +IBVERBS_1.12 {
> > + global:
> > + ibv_reg_dmabuf_mr;
> > +} IBVERBS_1.11;
> > +
> > /* If any symbols in this stanza change ABI then the entire staza gets a new symbol
> > version. See the top level CMakeLists.txt for this setting. */
> >
> > @@ -211,6 +216,7 @@ IBVERBS_PRIVATE_@IBVERBS_PABI_VERSION@ {
> > ibv_cmd_query_srq;
> > ibv_cmd_read_counters;
> > ibv_cmd_reg_dm_mr;
> > + ibv_cmd_reg_dmabuf_mr;
> > ibv_cmd_reg_mr;
> > ibv_cmd_req_notify_cq;
> > ibv_cmd_rereg_mr;
> > diff --git a/libibverbs/man/ibv_reg_mr.3 b/libibverbs/man/ibv_reg_mr.3
> > index 2bfc955..4975c79 100644
> > --- a/libibverbs/man/ibv_reg_mr.3
> > +++ b/libibverbs/man/ibv_reg_mr.3
> > @@ -3,7 +3,7 @@
> > .\"
> > .TH IBV_REG_MR 3 2006-10-31 libibverbs "Libibverbs Programmer's Manual"
> > .SH "NAME"
> > -ibv_reg_mr, ibv_reg_mr_iova, ibv_dereg_mr \- register or deregister a
> > memory region (MR)
> > +ibv_reg_mr, ibv_reg_mr_iova, ibv_reg_dmabuf_mr, ibv_dereg_mr \-
> > +register or deregister a memory region (MR)
> > .SH "SYNOPSIS"
> > .nf
> > .B #include <infiniband/verbs.h>
> > @@ -15,6 +15,9 @@ ibv_reg_mr, ibv_reg_mr_iova, ibv_dereg_mr \- register or deregister a memory reg
> > .BI " size_t " "length" ", uint64_t " "hca_va" ,
> > .BI " int " "access" );
> > .sp
> > +.BI "struct ibv_mr *ibv_reg_dmabuf_mr(struct ibv_pd " "*pd" ", uint64_t " "offset" ,
> > +.BI " size_t " "length" ", int " "access" );
> > +.sp
>
>
> This misses the 'fd' parameter.

Thanks. This has been fixed in the new version I am working on (and the github PR).

>
> > .BI "int ibv_dereg_mr(struct ibv_mr " "*mr" );
> > .fi
> > .SH "DESCRIPTION"
> > @@ -71,11 +74,25 @@ a lkey or rkey. The offset in the memory region is computed as 'addr +
> > (iova - hca_va)'. Specifying 0 for hca_va has the same effect as
> > IBV_ACCESS_ZERO_BASED.
> > .PP
> > +.B ibv_reg_dmabuf_mr()
> > +registers a dma-buf based memory region (MR) associated with the
> > +protection domain .I pd\fR.
> > +The MR starts at
> > +.I offset
> > +of the dma-buf and its size is
> > +.I length\fR.
> > +The dma-buf is identified by the file descriptor .I fd\fR.
> > +The argument
> > +.I access
> > +describes the desired memory protection attributes; it is similar to the ibv_reg_mr case except that only the following flags are
> supported:
> > +.B IBV_ACCESS_LOCAL_WRITE, IBV_ACCESS_REMOTE_WRITE, IBV_ACCESS_REMOTE_READ, IBV_ACCESS_REMOTE_ATOMIC,
> IBV_ACCESS_RELAXED_ORDERING.
> > +.PP
> > .B ibv_dereg_mr()
> > deregisters the MR
> > .I mr\fR.
> > .SH "RETURN VALUE"
> > -.B ibv_reg_mr() / ibv_reg_mr_iova()
> > +.B ibv_reg_mr() / ibv_reg_mr_iova() / ibv_reg_dmabuf_mr()
> > returns a pointer to the registered MR, or NULL if the request fails.
> > The local key (\fBL_Key\fR) field
> > .B lkey
> > diff --git a/libibverbs/verbs.c b/libibverbs/verbs.c index
> > 2b0ede8..84ddac7 100644
> > --- a/libibverbs/verbs.c
> > +++ b/libibverbs/verbs.c
> > @@ -1,6 +1,7 @@
> > /*
> > * Copyright (c) 2005 Topspin Communications. All rights reserved.
> > * Copyright (c) 2006, 2007 Cisco Systems, Inc. All rights reserved.
> > + * Copyright (c) 2020 Intel Corperation. All rights reserved.
> > *
> > * This software is available to you under a choice of one of two
> > * licenses. You may choose to be licensed under the terms of the
> > GNU @@ -367,6 +368,24 @@ void ibv_unimport_mr(struct ibv_mr *mr)
> > get_ops(mr->context)->unimport_mr(mr);
> > }
> >
> > +LATEST_SYMVER_FUNC(ibv_reg_dmabuf_mr, 1_12, "IBVERBS_1.12",
> > + struct ibv_mr *,
> > + struct ibv_pd *pd, uint64_t offset,
> > + size_t length, int fd, int access) {
>
>
>  ibv_dereg_mr() -> ibv_dofork_range() doesn't seem to be applicable in this case, right ? if offset / addr won't be 0 it may be activated on
> the address range.

I missed that one. Should add condition to ibv_dereg_mr() to not call ibv_dofork_range()
on dmabuf mr.

>
> Do we rely on applications to *not* turn on fork support in libibverbs ?
> (e.g. call ibv_fork_init()), what if some other registrations may need being fork safe ?
>

If the backing storage is device memory that doesn't have a mapping in the virtual
address space, it's not affected by fork. If the backing storage is shared/system memory
that has user accessible virtual address (e.g. iGPU), the exporter is responsible for handling
fork() -- and in that case, regular memory registration can be used instead, unless for the
purpose of testing dma-buf functionality.

> > + struct ibv_mr *mr;
> > +
> > + mr = get_ops(pd->context)->reg_dmabuf_mr(pd, offset, length, offset,
> > + fd, access);
> > + if (mr) {
> > + mr->context = pd->context;
> > + mr->pd = pd;
> > + mr->addr = (void *)offset;
> > + mr->length = length;
> > + }
> > + return mr;
> > +}
> > +
> > LATEST_SYMVER_FUNC(ibv_rereg_mr, 1_1, "IBVERBS_1.1",
> > int,
> > struct ibv_mr *mr, int flags,
> > diff --git a/libibverbs/verbs.h b/libibverbs/verbs.h index
> > ee57e05..3961b1e 100644
> > --- a/libibverbs/verbs.h
> > +++ b/libibverbs/verbs.h
> > @@ -3,6 +3,7 @@
> > * Copyright (c) 2004, 2011-2012 Intel Corporation. All rights reserved.
> > * Copyright (c) 2005, 2006, 2007 Cisco Systems, Inc. All rights reserved.
> > * Copyright (c) 2005 PathScale, Inc. All rights reserved.
> > + * Copyright (c) 2020 Intel Corporation. All rights reserved.
> > *
> > * This software is available to you under a choice of one of two
> > * licenses. You may choose to be licensed under the terms of the
> > GNU @@ -2133,6 +2134,9 @@ struct verbs_context {
> > struct ibv_xrcd * (*open_xrcd)(struct ibv_context *context,
> > struct ibv_xrcd_init_attr *xrcd_init_attr);
> > int (*close_xrcd)(struct ibv_xrcd *xrcd);
> > + struct ibv_mr * (*reg_dmabuf_mr)(struct ibv_pd *pd, uint64_t offset,
> > + size_t length, uint64_t iova,
> > + int fd, int access);
> > uint64_t _ABI_placeholder3;
> > size_t sz; /* Must be immediately before struct ibv_context */
> > struct ibv_context context; /* Must be last field in the struct */
> > @@ -2535,6 +2539,12 @@ __ibv_reg_mr_iova(struct ibv_pd *pd, void *addr, size_t length, uint64_t iova,
> > __builtin_constant_p( \
> > ((access) & IBV_ACCESS_OPTIONAL_RANGE) == 0))
> >
> > +/**
> > + * ibv_reg_dmabuf_mr - Register a dambuf-based memory region */
> > +struct ibv_mr *ibv_reg_dmabuf_mr(struct ibv_pd *pd, uint64_t offset, size_t length,
> > + int fd, int access);
> > +
> > enum ibv_rereg_mr_err_code {
> > /* Old MR is valid, invalid input */
> > IBV_REREG_MR_ERR_INPUT = -1,
>