Re: [dpdk-dev] [PATCH v2 3/3] net/mlx4: add secondary process support

[Shahaf Shuler <shahafs@mellanox.com>]

Monday, March 25, 2019 9:18 PM, Yongseok Koh:
> To: Shahaf Shuler <shahafs@mellanox.com>
> Cc: dev@dpdk.org
> Subject: [PATCH v2 3/3] net/mlx4: add secondary process support
> 
> In order to support secondary process, a few features are required.
> 
> a) rdma-core library should allocate device resources using DPDK's memory
>    allocator.
> 
> b) UAR should be remapped for secondary processes. Currently, in order not
>    to use different data structure for secondary processes, PMD tries to
>    reserve identical virtual address space for both primary and secondary
>    processes.
> 
> c) IPC channel is necessary, which can be easily set with rte_mp APIs.
>    Through the channel, Verbs command FD is delivered to the secondary
>    process and the device stop/start event is also broadcast from primary
>    process.
> 
> Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
> ---
>  doc/guides/nics/features/mlx4.ini |   1 +
>  doc/guides/nics/mlx4.rst          |  10 +
>  drivers/net/mlx4/Makefile         |   6 +
>  drivers/net/mlx4/meson.build      |   3 +
>  drivers/net/mlx4/mlx4.c           | 378
> ++++++++++++++++++++++++++++++++++++--
>  drivers/net/mlx4/mlx4.h           |  60 ++++++
>  drivers/net/mlx4/mlx4_mp.c        | 304
> ++++++++++++++++++++++++++++++
>  drivers/net/mlx4/mlx4_mr.c        |  32 +++-
>  drivers/net/mlx4/mlx4_prm.h       |   4 +-
>  drivers/net/mlx4/mlx4_rxtx.c      |   2 +
>  drivers/net/mlx4/mlx4_rxtx.h      |   1 +
>  drivers/net/mlx4/mlx4_txq.c       | 111 +++++++++++
>  12 files changed, 890 insertions(+), 22 deletions(-)  create mode 100644
> drivers/net/mlx4/mlx4_mp.c
> 
> diff --git a/doc/guides/nics/features/mlx4.ini
> b/doc/guides/nics/features/mlx4.ini
> index a211aef332..4502aa2a87 100644
> --- a/doc/guides/nics/features/mlx4.ini
> +++ b/doc/guides/nics/features/mlx4.ini
> @@ -29,6 +29,7 @@ Packet type parsing  = Y
>  Basic stats          = Y
>  Stats per queue      = Y
>  FW version           = Y
> +Multiprocess aware   = Y
>  Other kdrv           = Y
>  Power8               = Y
>  x86-32               = Y
> diff --git a/doc/guides/nics/mlx4.rst b/doc/guides/nics/mlx4.rst index
> 4ad361a2c2..cd34838f41 100644
> --- a/doc/guides/nics/mlx4.rst
> +++ b/doc/guides/nics/mlx4.rst
> @@ -145,6 +145,16 @@ below.
>  Limitations
>  -----------
> 
> +- For secondary process:
> +
> +  - Forked secondary process not supported.
> +  - All mempools must be initialized before rte_eth_dev_start().
> +  - External memory unregistered in EAL memseg list cannot be used for
> DMA
> +    unless such memory has been registered by
> ``mlx4_mr_update_ext_mp()`` in
> +    primary process and remapped to the same virtual address in secondary
> +    process. If the external memory is registered by primary process but has
> +    different virtual address in secondary process, unexpected error may
> happen.
> +
>  - CRC stripping is supported by default and always reported as "true".
>    The ability to enable/disable CRC stripping requires OFED version
>    4.3-1.5.0.0 and above  or rdma-core version v18 and above.
> diff --git a/drivers/net/mlx4/Makefile b/drivers/net/mlx4/Makefile index
> b527efd625..8126b0dfc6 100644
> --- a/drivers/net/mlx4/Makefile
> +++ b/drivers/net/mlx4/Makefile
> @@ -18,6 +18,7 @@ ifneq ($(CONFIG_RTE_IBVERBS_LINK_DLOPEN),y)
>  SRCS-$(CONFIG_RTE_LIBRTE_MLX4_PMD) += mlx4_glue.c  endif
>  SRCS-$(CONFIG_RTE_LIBRTE_MLX4_PMD) += mlx4_intr.c
> +SRCS-$(CONFIG_RTE_LIBRTE_MLX4_PMD) += mlx4_mp.c
>  SRCS-$(CONFIG_RTE_LIBRTE_MLX4_PMD) += mlx4_mr.c
>  SRCS-$(CONFIG_RTE_LIBRTE_MLX4_PMD) += mlx4_rxq.c
>  SRCS-$(CONFIG_RTE_LIBRTE_MLX4_PMD) += mlx4_rxtx.c @@ -93,6 +94,11
> @@ mlx4_autoconf.h.new: $(RTE_SDK)/buildtools/auto-config-h.sh
>  		enum MLX4DV_SET_CTX_ATTR_BUF_ALLOCATORS \
>  		$(AUTOCONF_OUTPUT)
>  	$Q sh -- '$<' '$@' \
> +		HAVE_IBV_MLX4_UAR_MMAP_OFFSET \
> +		infiniband/mlx4dv.h \
> +		enum MLX4DV_QP_MASK_UAR_MMAP_OFFSET \
> +		$(AUTOCONF_OUTPUT)
> +	$Q sh -- '$<' '$@' \
>  		HAVE_IBV_MLX4_WQE_LSO_SEG \
>  		infiniband/mlx4dv.h \
>  		type 'struct mlx4_wqe_lso_seg' \
> diff --git a/drivers/net/mlx4/meson.build b/drivers/net/mlx4/meson.build
> index 650e2c8fbc..de020701d1 100644
> --- a/drivers/net/mlx4/meson.build
> +++ b/drivers/net/mlx4/meson.build
> @@ -33,6 +33,7 @@ if build
>  		'mlx4_ethdev.c',
>  		'mlx4_flow.c',
>  		'mlx4_intr.c',
> +		'mlx4_mp.c',
>  		'mlx4_mr.c',
>  		'mlx4_rxq.c',
>  		'mlx4_rxtx.c',
> @@ -76,6 +77,8 @@ if build
>  	has_sym_args = [
>  		[ 'HAVE_IBV_MLX4_BUF_ALLOCATORS',
> 'infiniband/mlx4dv.h',
>  		'MLX4DV_SET_CTX_ATTR_BUF_ALLOCATORS' ],
> +		[ 'HAVE_IBV_MLX4_UAR_MMAP_OFFSET',
> 'infiniband/mlx4dv.h',
> +		'MLX4DV_QP_MASK_UAR_MMAP_OFFSET' ],
>  	]
>  	config = configuration_data()
>  	foreach arg:has_sym_args
> diff --git a/drivers/net/mlx4/mlx4.c b/drivers/net/mlx4/mlx4.c index
> 0e0b035df0..a5cfcdbee3 100644
> --- a/drivers/net/mlx4/mlx4.c
> +++ b/drivers/net/mlx4/mlx4.c
> @@ -17,6 +17,7 @@
>  #include <stdio.h>
>  #include <stdlib.h>
>  #include <string.h>
> +#include <sys/mman.h>
>  #include <unistd.h>
> 
>  /* Verbs headers do not support -pedantic. */ @@ -48,10 +49,21 @@
> #include "mlx4_rxtx.h"
>  #include "mlx4_utils.h"
> 
> -struct mlx4_dev_list mlx4_mem_event_cb_list =
> -	LIST_HEAD_INITIALIZER(mlx4_mem_event_cb_list);
> +#if defined(HAVE_IBV_MLX4_UAR_MMAP_OFFSET) && \
> +	defined(HAVE_IBV_MLX4_BUF_ALLOCATORS)
> +#define HAVE_IBV_MLX4_SECONDARY_PROCESS #endif

Features should not be detected on compilation time rather by run time based on capabilities. 
On this case, 
If you are able to register the external allocator (dv call returns w/ success) and the mmap for the uar index also succeed, then you have support for secondary.