netdev - [RFC 0/2] Set steering-tag directly for PCIe P2P memory access

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20251113213712.776234-1-zhipingz@meta.com>
Date: Thu, 13 Nov 2025 13:37:10 -0800
From: Zhiping Zhang <zhipingz@...a.com>
To: Jason Gunthorpe <jgg@...pe.ca>, Leon Romanovsky <leon@...nel.org>,
        Bjorn
 Helgaas <bhelgaas@...gle.com>, <linux-rdma@...r.kernel.org>,
        <linux-pci@...r.kernel.org>, <netdev@...r.kernel.org>,
        Keith Busch
	<kbusch@...nel.org>, Yochai Cohen <yochai@...dia.com>,
        Yishai Hadas
	<yishaih@...dia.com>
CC: Zhiping Zhang <zhipingz@...a.com>
Subject: [RFC 0/2] Set steering-tag directly for PCIe P2P memory access

Currently, the steering tag can be used for a CPU on the motherboard; the
ACPI check is in place to query and obtain the supported steering tag. This
same check is not possible for the accelerator devices because they are 
designed to be plug-and-play to and ownership can not be always confirmed.

We intend to use the steering tag to improve RDMA NIC memory access on a GPU
or accelerator device via PCIe peer-to-peer. An application can construct a
dma handler (DMAH) with the device memory type and a direct steering-tag
value, and this DMAH can be used to register a RDMA memory region with DMABUF
for the RDMA NIC to access the device memory. The steering tag contains
additional instructions or hints to the GPU or accelerator device for
advanced memory operations, such as, read cache selection.

Signed-off-by: Zhiping Zhang <zhipingz@...a.com>

Zhiping Zhang (2):
  PCIe: Add a memory type for P2P memory access
  RDMA: Set steering-tag value directly for P2P memory access

 .../infiniband/core/uverbs_std_types_dmah.c   | 28 +++++++++++++++++++
 drivers/infiniband/core/uverbs_std_types_mr.c |  3 ++
 drivers/infiniband/hw/mlx5/dmah.c             |  5 ++--
 .../net/ethernet/mellanox/mlx5/core/lib/st.c  | 12 +++++---
 drivers/pci/tph.c                             |  4 +++
 include/linux/mlx5/driver.h                   |  4 +--
 include/linux/pci-tph.h                       |  4 ++-
 include/rdma/ib_verbs.h                       |  2 ++
 include/uapi/rdma/ib_user_ioctl_cmds.h        |  1 +
 9 files changed, 53 insertions(+), 10 deletions(-)

-- 
2.47.3