[dpdk-dev] [PATCH 0/6] introduce DMA memory mapping for external memory

Shahaf Shuler shahafs at mellanox.com
Wed Feb 13 10:10:20 CET 2019


This series is in continue to RFC[1].

The DPDK APIs expose 3 different modes to work with memory used for DMA:
    
1. Use the DPDK owned memory (backed by the DPDK provided hugepages).
This memory is allocated by the DPDK libraries, included in the DPDK    
memory system (memseg lists) and automatically DMA mapped by the DPDK
layers.
      
2. Use memory allocated by the user and register to the DPDK memory  
systems. This is also referred as external memory. Upon registration of
the external memory, the DPDK layers will DMA map it to all needed
devices.
  
3. Use memory allocated by the user and not registered to the DPDK memory
system. This is for users who wants to have tight control on this  
memory. The user will need to explicitly call DMA map function in order
to register such memory to the different devices.
                                
The scope of the patch focus on #3 above.
            
Currently the only way to map external memory is through VFIO        
(rte_vfio_dma_map). While VFIO is common, there are other vendors
which use different ways to map memory (e.g. Mellanox and NXP).
    
The work in this patch moves the DMA mapping to vendor agnostic APIs.  
A new map and unmap ops were added to rte_bus structure. Implementation
of those was done currently only on the PCI bus. The implementation takes
the driver map and umap implementation as bypass to the VFIO mapping.
That is, in case of no specific map/unmap from the PCI driver,
VFIO mapping, if possible, will be used.
                         
Application use with those APIs is quite simple:
* allocate memory                               
* take a device, and query its rte_device.                             
* call the bus map function for this device.
   
Future work will deprecate the rte_vfio_dma_map and rte_vfio_dma_unmap
APIs, leaving the PCI device APIs as the preferred option for the user.

[1] https://patches.dpdk.org/patch/47796/

Shahaf Shuler (6):
  vfio: allow DMA map of memory for the default vfio fd
  vfio: don't fail to DMA map if memory is already mapped
  bus: introduce DMA memory mapping for external memory
  net/mlx5: refactor external memory registration
  net/mlx5: support PCI device DMA map and unmap
  doc: deprecate VFIO DMA map APIs

 doc/guides/prog_guide/env_abstraction_layer.rst |   2 +-
 doc/guides/rel_notes/deprecation.rst            |   4 +
 drivers/bus/pci/pci_common.c                    |  78 +++++++
 drivers/bus/pci/rte_bus_pci.h                   |  14 ++
 drivers/net/mlx5/mlx5.c                         |   2 +
 drivers/net/mlx5/mlx5_mr.c                      | 232 ++++++++++++++++---
 drivers/net/mlx5/mlx5_rxtx.h                    |   5 +
 lib/librte_eal/common/eal_common_bus.c          |  22 ++
 lib/librte_eal/common/include/rte_bus.h         |  57 +++++
 lib/librte_eal/common/include/rte_vfio.h        |  12 +-
 lib/librte_eal/linuxapp/eal/eal_vfio.c          |  26 ++-
 lib/librte_eal/rte_eal_version.map              |   2 +
 12 files changed, 418 insertions(+), 38 deletions(-)

-- 
2.12.0



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