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RDMA/mlx5: Implement DMABUF export ops

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Enable p2pdma on the mlx5 PCI device to allow DMABUF-based peer-to-peer
DMA mappings.

Add implementation of the mmap_get_pfns and pgoff_to_mmap_entry device
operations required for DMABUF support in the mlx5 RDMA driver.

The pgoff_to_mmap_entry operation converts a page offset to the
corresponding rdma_user_mmap_entry by extracting the command and index
from the offset and looking it up in the ucontext's mmap_xa.

The mmap_get_pfns operation retrieves the physical address and length
from the mmap entry and obtains the p2pdma provider for the underlying
PCI device, which is needed for peer-to-peer DMA operations with
DMABUFs.

Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Edward Srouji <edwards@nvidia.com>
Link: https://patch.msgid.link/20260201-dmabuf-export-v3-3-da238b614fe3@nvidia.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>
This commit is contained in:
Yishai Hadas 2026-02-01 16:34:06 +02:00 • committed by Leon Romanovsky
parent 0ac6f4056c
commit d6c58f4eb3
1 changed files with 72 additions and 0 deletions
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72
drivers/infiniband/hw/mlx5/main.c
View file

@ -2454,6 +2454,70 @@ static int mlx5_ib_mmap_clock_info_page(struct mlx5_ib_dev *dev,
virt_to_page(dev->mdev->clock_info));
}
static int phys_addr_to_bar(struct pci_dev *pdev, phys_addr_t pa)
{
resource_size_t start, end;
int bar;
for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
/* Skip BARs not present or not memory-mapped */
if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
continue;
start = pci_resource_start(pdev, bar);
end = pci_resource_end(pdev, bar);
if (!start || !end)
continue;
if (pa >= start && pa <= end)
return bar;
}
return -1;
}
static int mlx5_ib_mmap_get_pfns(struct rdma_user_mmap_entry *entry,
struct phys_vec *phys_vec,
struct p2pdma_provider **provider)
{
struct mlx5_user_mmap_entry *mentry = to_mmmap(entry);
struct pci_dev *pdev = to_mdev(entry->ucontext->device)->mdev->pdev;
int bar;
phys_vec->paddr = mentry->address;
phys_vec->len = entry->npages * PAGE_SIZE;
bar = phys_addr_to_bar(pdev, phys_vec->paddr);
if (bar < 0)
return -EINVAL;
*provider = pcim_p2pdma_provider(pdev, bar);
/* If the kernel was not compiled with CONFIG_PCI_P2PDMA the
* functionality is not supported.
*/
if (!*provider)
return -EOPNOTSUPP;
return 0;
}
static struct rdma_user_mmap_entry *
mlx5_ib_pgoff_to_mmap_entry(struct ib_ucontext *ucontext, off_t pg_off)
{
unsigned long entry_pgoff;
unsigned long idx;
u8 command;
pg_off = pg_off >> PAGE_SHIFT;
command = get_command(pg_off);
idx = get_extended_index(pg_off);
entry_pgoff = command << 16 | idx;
return rdma_user_mmap_entry_get_pgoff(ucontext, entry_pgoff);
}
static void mlx5_ib_mmap_free(struct rdma_user_mmap_entry *entry)
{
struct mlx5_user_mmap_entry *mentry = to_mmmap(entry);
@ -4419,7 +4483,13 @@ static int mlx5_ib_stage_init_init(struct mlx5_ib_dev *dev)
if (err)
goto err_mp;
err = pcim_p2pdma_init(mdev->pdev);
if (err && err != -EOPNOTSUPP)
goto err_dd;
return 0;
err_dd:
mlx5_ib_data_direct_cleanup(dev);
err_mp:
mlx5_ib_cleanup_multiport_master(dev);
err:
@ -4471,11 +4541,13 @@ static const struct ib_device_ops mlx5_ib_dev_ops = {
.map_mr_sg_pi = mlx5_ib_map_mr_sg_pi,
.mmap = mlx5_ib_mmap,
.mmap_free = mlx5_ib_mmap_free,
.mmap_get_pfns = mlx5_ib_mmap_get_pfns,
.modify_cq = mlx5_ib_modify_cq,
.modify_device = mlx5_ib_modify_device,
.modify_port = mlx5_ib_modify_port,
.modify_qp = mlx5_ib_modify_qp,
.modify_srq = mlx5_ib_modify_srq,
.pgoff_to_mmap_entry = mlx5_ib_pgoff_to_mmap_entry,
.pre_destroy_cq = mlx5_ib_pre_destroy_cq,
.poll_cq = mlx5_ib_poll_cq,
.post_destroy_cq = mlx5_ib_post_destroy_cq,