Re: [RFC PATCH v2 2/2] RDMA/rxe: Add dma-buf support
From: Shunsuke Mie
Date: Wed Oct 13 2021 - 19:10:39 EST
2021年10月13日(水) 20:42 Daniel Vetter <daniel@xxxxxxxx>:
>
> On Fri, Oct 01, 2021 at 12:56:48PM +0900, Shunsuke Mie wrote:
> > 2021年9月30日(木) 23:41 Daniel Vetter <daniel@xxxxxxxx>:
> > >
> > > On Wed, Sep 29, 2021 at 01:19:05PM +0900, Shunsuke Mie wrote:
> > > > Implement a ib device operation ‘reg_user_mr_dmabuf’. Generate a
> > > > rxe_map from the memory space linked the passed dma-buf.
> > > >
> > > > Signed-off-by: Shunsuke Mie <mie@xxxxxxxxxx>
> > > > ---
> > > > drivers/infiniband/sw/rxe/rxe_loc.h | 2 +
> > > > drivers/infiniband/sw/rxe/rxe_mr.c | 118 ++++++++++++++++++++++++++
> > > > drivers/infiniband/sw/rxe/rxe_verbs.c | 34 ++++++++
> > > > drivers/infiniband/sw/rxe/rxe_verbs.h | 2 +
> > > > 4 files changed, 156 insertions(+)
> > > >
> > > > diff --git a/drivers/infiniband/sw/rxe/rxe_loc.h b/drivers/infiniband/sw/rxe/rxe_loc.h
> > > > index 1ca43b859d80..8bc19ea1a376 100644
> > > > --- a/drivers/infiniband/sw/rxe/rxe_loc.h
> > > > +++ b/drivers/infiniband/sw/rxe/rxe_loc.h
> > > > @@ -75,6 +75,8 @@ u8 rxe_get_next_key(u32 last_key);
> > > > void rxe_mr_init_dma(struct rxe_pd *pd, int access, struct rxe_mr *mr);
> > > > int rxe_mr_init_user(struct rxe_pd *pd, u64 start, u64 length, u64 iova,
> > > > int access, struct rxe_mr *mr);
> > > > +int rxe_mr_dmabuf_init_user(struct rxe_pd *pd, int fd, u64 start, u64 length,
> > > > + u64 iova, int access, struct rxe_mr *mr);
> > > > int rxe_mr_init_fast(struct rxe_pd *pd, int max_pages, struct rxe_mr *mr);
> > > > int rxe_mr_copy(struct rxe_mr *mr, u64 iova, void *addr, int length,
> > > > enum rxe_mr_copy_dir dir);
> > > > diff --git a/drivers/infiniband/sw/rxe/rxe_mr.c b/drivers/infiniband/sw/rxe/rxe_mr.c
> > > > index 53271df10e47..af6ef671c3a5 100644
> > > > --- a/drivers/infiniband/sw/rxe/rxe_mr.c
> > > > +++ b/drivers/infiniband/sw/rxe/rxe_mr.c
> > > > @@ -4,6 +4,7 @@
> > > > * Copyright (c) 2015 System Fabric Works, Inc. All rights reserved.
> > > > */
> > > >
> > > > +#include <linux/dma-buf.h>
> > > > #include "rxe.h"
> > > > #include "rxe_loc.h"
> > > >
> > > > @@ -245,6 +246,120 @@ int rxe_mr_init_user(struct rxe_pd *pd, u64 start, u64 length, u64 iova,
> > > > return err;
> > > > }
> > > >
> > > > +static int rxe_map_dmabuf_mr(struct rxe_mr *mr,
> > > > + struct ib_umem_dmabuf *umem_dmabuf)
> > > > +{
> > > > + struct rxe_map_set *set;
> > > > + struct rxe_phys_buf *buf = NULL;
> > > > + struct rxe_map **map;
> > > > + void *vaddr, *vaddr_end;
> > > > + int num_buf = 0;
> > > > + int err;
> > > > + size_t remain;
> > > > +
> > > > + mr->dmabuf_map = kzalloc(sizeof &mr->dmabuf_map, GFP_KERNEL);
> > >
> > > dmabuf_maps are just tagged pointers (and we could shrink them to actually
> > > just a tagged pointer if anyone cares about the overhead of the separate
> > > bool), allocating them seperately is overkill.
> >
> > I agree with you. However, I think it is needed to unmap by
> > dma_buf_vunmap(). If there is another simple way to unmap it. It is not
> > needed I think. What do you think about it?
>
> dma_buf_vunmap does not kfree the dma_buf_map argument, so that's no
> reason to allocate it separately. Or I'm confused.
I had a misunderstood. Yes, It is not needed to allocate an object.
Actually some
implementations don't alloc/free the argument.
e.g. gpu/drm/drm_gem_cma_helper.c
I'll fix it.
> Also apologies, I'm way behind on mails.
No problem. Thank you for your answer.
Thanks,
Shunsuke
> -Daniel
>
> >
> > > > + if (!mr->dmabuf_map) {
> > > > + err = -ENOMEM;
> > > > + goto err_out;
> > > > + }
> > > > +
> > > > + err = dma_buf_vmap(umem_dmabuf->dmabuf, mr->dmabuf_map);
> > > > + if (err)
> > > > + goto err_free_dmabuf_map;
> > > > +
> > > > + set = mr->cur_map_set;
> > > > + set->page_shift = PAGE_SHIFT;
> > > > + set->page_mask = PAGE_SIZE - 1;
> > > > +
> > > > + map = set->map;
> > > > + buf = map[0]->buf;
> > > > +
> > > > + vaddr = mr->dmabuf_map->vaddr;
> > >
> > > dma_buf_map can be an __iomem too, you shouldn't dig around in this, but
> > > use the dma-buf-map.h helpers instead. On x86 (and I think also on most
> > > arm) it doesn't matter, but it's kinda not very nice in a pure software
> > > driver.
> > >
> > > If anything is missing in dma-buf-map.h wrappers just add more.
> > >
> > > Or alternatively you need to fail the import if you can't handle __iomem.
> > >
> > > Aside from these I think the dma-buf side here for cpu access looks
> > > reasonable now.
> > > -Daniel
> > I'll see the dma-buf-map.h and consider the error handling that you suggested.
> > I appreciate your support.
> >
> > Thanks a lot,
> > Shunsuke.
> >
> > > > + vaddr_end = vaddr + umem_dmabuf->dmabuf->size;
> > > > + remain = umem_dmabuf->dmabuf->size;
> > > > +
> > > > + for (; remain; vaddr += PAGE_SIZE) {
> > > > + if (num_buf >= RXE_BUF_PER_MAP) {
> > > > + map++;
> > > > + buf = map[0]->buf;
> > > > + num_buf = 0;
> > > > + }
> > > > +
> > > > + buf->addr = (uintptr_t)vaddr;
> > > > + if (remain >= PAGE_SIZE)
> > > > + buf->size = PAGE_SIZE;
> > > > + else
> > > > + buf->size = remain;
> > > > + remain -= buf->size;
> > > > +
> > > > + num_buf++;
> > > > + buf++;
> > > > + }
> > > > +
> > > > + return 0;
> > > > +
> > > > +err_free_dmabuf_map:
> > > > + kfree(mr->dmabuf_map);
> > > > +err_out:
> > > > + return err;
> > > > +}
> > > > +
> > > > +static void rxe_unmap_dmabuf_mr(struct rxe_mr *mr)
> > > > +{
> > > > + struct ib_umem_dmabuf *umem_dmabuf = to_ib_umem_dmabuf(mr->umem);
> > > > +
> > > > + dma_buf_vunmap(umem_dmabuf->dmabuf, mr->dmabuf_map);
> > > > + kfree(mr->dmabuf_map);
> > > > +}
> > > > +
> > > > +int rxe_mr_dmabuf_init_user(struct rxe_pd *pd, int fd, u64 start, u64 length,
> > > > + u64 iova, int access, struct rxe_mr *mr)
> > > > +{
> > > > + struct ib_umem_dmabuf *umem_dmabuf;
> > > > + struct rxe_map_set *set;
> > > > + int err;
> > > > +
> > > > + umem_dmabuf = ib_umem_dmabuf_get(pd->ibpd.device, start, length, fd,
> > > > + access, NULL);
> > > > + if (IS_ERR(umem_dmabuf)) {
> > > > + err = PTR_ERR(umem_dmabuf);
> > > > + goto err_out;
> > > > + }
> > > > +
> > > > + rxe_mr_init(access, mr);
> > > > +
> > > > + err = rxe_mr_alloc(mr, ib_umem_num_pages(&umem_dmabuf->umem), 0);
> > > > + if (err) {
> > > > + pr_warn("%s: Unable to allocate memory for map\n", __func__);
> > > > + goto err_release_umem;
> > > > + }
> > > > +
> > > > + mr->ibmr.pd = &pd->ibpd;
> > > > + mr->umem = &umem_dmabuf->umem;
> > > > + mr->access = access;
> > > > + mr->state = RXE_MR_STATE_VALID;
> > > > + mr->type = IB_MR_TYPE_USER;
> > > > +
> > > > + set = mr->cur_map_set;
> > > > + set->length = length;
> > > > + set->iova = iova;
> > > > + set->va = start;
> > > > + set->offset = ib_umem_offset(mr->umem);
> > > > +
> > > > + err = rxe_map_dmabuf_mr(mr, umem_dmabuf);
> > > > + if (err)
> > > > + goto err_free_map_set;
> > > > +
> > > > + return 0;
> > > > +
> > > > +err_free_map_set:
> > > > + rxe_mr_free_map_set(mr->num_map, mr->cur_map_set);
> > > > +err_release_umem:
> > > > + ib_umem_release(&umem_dmabuf->umem);
> > > > +err_out:
> > > > + return err;
> > > > +}
> > > > +
> > > > int rxe_mr_init_fast(struct rxe_pd *pd, int max_pages, struct rxe_mr *mr)
> > > > {
> > > > int err;
> > > > @@ -703,6 +818,9 @@ void rxe_mr_cleanup(struct rxe_pool_entry *arg)
> > > > {
> > > > struct rxe_mr *mr = container_of(arg, typeof(*mr), pelem);
> > > >
> > > > + if (mr->umem && mr->umem->is_dmabuf)
> > > > + rxe_unmap_dmabuf_mr(mr);
> > > > +
> > > > ib_umem_release(mr->umem);
> > > >
> > > > if (mr->cur_map_set)
> > > > diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.c b/drivers/infiniband/sw/rxe/rxe_verbs.c
> > > > index 9d0bb9aa7514..6191bb4f434d 100644
> > > > --- a/drivers/infiniband/sw/rxe/rxe_verbs.c
> > > > +++ b/drivers/infiniband/sw/rxe/rxe_verbs.c
> > > > @@ -916,6 +916,39 @@ static struct ib_mr *rxe_reg_user_mr(struct ib_pd *ibpd,
> > > > return ERR_PTR(err);
> > > > }
> > > >
> > > > +static struct ib_mr *rxe_reg_user_mr_dmabuf(struct ib_pd *ibpd, u64 start,
> > > > + u64 length, u64 iova, int fd,
> > > > + int access, struct ib_udata *udata)
> > > > +{
> > > > + int err;
> > > > + struct rxe_dev *rxe = to_rdev(ibpd->device);
> > > > + struct rxe_pd *pd = to_rpd(ibpd);
> > > > + struct rxe_mr *mr;
> > > > +
> > > > + mr = rxe_alloc(&rxe->mr_pool);
> > > > + if (!mr) {
> > > > + err = -ENOMEM;
> > > > + goto err2;
> > > > + }
> > > > +
> > > > + rxe_add_index(mr);
> > > > +
> > > > + rxe_add_ref(pd);
> > > > +
> > > > + err = rxe_mr_dmabuf_init_user(pd, fd, start, length, iova, access, mr);
> > > > + if (err)
> > > > + goto err3;
> > > > +
> > > > + return &mr->ibmr;
> > > > +
> > > > +err3:
> > > > + rxe_drop_ref(pd);
> > > > + rxe_drop_index(mr);
> > > > + rxe_drop_ref(mr);
> > > > +err2:
> > > > + return ERR_PTR(err);
> > > > +}
> > > > +
> > > > static struct ib_mr *rxe_alloc_mr(struct ib_pd *ibpd, enum ib_mr_type mr_type,
> > > > u32 max_num_sg)
> > > > {
> > > > @@ -1081,6 +1114,7 @@ static const struct ib_device_ops rxe_dev_ops = {
> > > > .query_qp = rxe_query_qp,
> > > > .query_srq = rxe_query_srq,
> > > > .reg_user_mr = rxe_reg_user_mr,
> > > > + .reg_user_mr_dmabuf = rxe_reg_user_mr_dmabuf,
> > > > .req_notify_cq = rxe_req_notify_cq,
> > > > .resize_cq = rxe_resize_cq,
> > > >
> > > > diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.h b/drivers/infiniband/sw/rxe/rxe_verbs.h
> > > > index c807639435eb..0aa95ab06b6e 100644
> > > > --- a/drivers/infiniband/sw/rxe/rxe_verbs.h
> > > > +++ b/drivers/infiniband/sw/rxe/rxe_verbs.h
> > > > @@ -334,6 +334,8 @@ struct rxe_mr {
> > > >
> > > > struct rxe_map_set *cur_map_set;
> > > > struct rxe_map_set *next_map_set;
> > > > +
> > > > + struct dma_buf_map *dmabuf_map;
> > > > };
> > > >
> > > > enum rxe_mw_state {
> > > > --
> > > > 2.17.1
> > > >
> > >
> > > --
> > > Daniel Vetter
> > > Software Engineer, Intel Corporation
> > > http://blog.ffwll.ch
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch