[PATCH][hirsute] UBUNTU: SAUCE: RDMA/core: Introduce peer memory interface

Guilherme Piccoli gpiccoli at canonical.com
Thu Apr 8 18:47:31 UTC 2021


On Thu, Apr 8, 2021 at 11:38 AM dann frazier <dann.frazier at canonical.com> wrote:
>
> From: Jason Gunthorpe <jgg at nvidia.com>
>
> The peer_memory_client scheme allows a driver to register with the ib_umem
> system that it has the ability to understand user virtual address ranges
> that are not compatible with get_user_pages(). For instance VMAs created
> with io_remap_pfn_range(), or other driver special VMA.
>
> For ranges the interface understands it can provide a DMA mapped sg_table
> for use by the ib_umem, allowing user virtual ranges that cannot be
> supported by get_user_pages() to be used as umems for RDMA.
>
> This is designed to preserve the kABI, no functions or structures are
> changed, only new symbols are added:
>
>  ib_register_peer_memory_client
>  ib_unregister_peer_memory_client
>  ib_umem_activate_invalidation_notifier
>  ib_umem_get_peer
>
> And a bitfield in struct ib_umem uses more bits.
>
> This interface is compatible with the two out of tree GPU drivers:
>  https://github.com/RadeonOpenCompute/ROCK-Kernel-Driver/blob/master/drivers/gpu/drm/amd/amdkfd/kfd_peerdirect.c
>  https://github.com/Mellanox/nv_peer_memory/blob/master/nv_peer_mem.c
>
> Signed-off-by: Yishai Hadas <yishaih at mellanox.com>
> Signed-off-by: Feras Daoud <ferasda at mellanox.com>
> Signed-off-by: Jason Gunthorpe <jgg at mellanox.com>
> Signed-off-by: Leon Romanovsky <leonro at nvidia.com>
> (cherry picked from commit a42989294cf39d6e829424734ab0e7ec48bebcef git://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git gpu-v5.11)
> Signed-off-by: dann frazier <dann.frazier at canonical.com>

Hi Dann, thanks for the patch. It's a big one..was it discussed
upstream? Do you have a Launchpad bug in which it is discussed?
Usually there's a LP mentioned in the patch as "Buglink", you can
check examples in our trees.

I suppose we need more information and preferably an upstream
discussion link to gather basic information before accepting such a
big change.
Cheers,


Guilherme



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