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Date: Wed, 20 Dec 2023 13:44:59 -0800
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Message-ID: <20231220214505.2303297-1-almasrymina@google.com>
Subject: [PATCH net-next v3 0/3] Abstract page from net stack
From: Mina Almasry <almasrymina@google.com>
To: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, kvm@vger.kernel.org, 
	virtualization@lists.linux.dev
Cc: Mina Almasry <almasrymina@google.com>, "David S. Miller" <davem@davemloft.net>, 
	Eric Dumazet <edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>, 
	Stefan Hajnoczi <stefanha@redhat.com>, Stefano Garzarella <sgarzare@redhat.com>, 
	David Howells <dhowells@redhat.com>, Jason Gunthorpe <jgg@nvidia.com>, 
	"=?UTF-8?q?Christian=20K=C3=B6nig?=" <christian.koenig@amd.com>, Shakeel Butt <shakeelb@google.com>, 
	Yunsheng Lin <linyunsheng@huawei.com>, Willem de Bruijn <willemdebruijn.kernel@gmail.com>
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Changes in v3:

- Replaced the struct netmem union with an opaque netmem_ref type.
- Added func docs to the netmem helpers and type.
- Renamed the skb_frag_t fields since it's no longer a bio_vec

-----------

Changes in v2:
- Reverted changes to the page_pool. The page pool now retains the same
  API, so that we don't have to touch many existing drivers. The devmem
  TCP series will include the changes to the page pool.

- Addressed comments.

This series is a prerequisite to the devmem TCP series. For a full
snapshot of the code which includes these changes, feel free to check:

https://github.com/mina/linux/commits/tcpdevmem-rfcv5/

-----------

Currently these components in the net stack use the struct page
directly:

1. Drivers.
2. Page pool.
3. skb_frag_t.

To add support for new (non struct page) memory types to the net stack, we
must first abstract the current memory type.

Originally the plan was to reuse struct page* for the new memory types,
and to set the LSB on the page* to indicate it's not really a page.
However, for safe compiler type checking we need to introduce a new type.

struct netmem is introduced to abstract the underlying memory type.
Currently it's a no-op abstraction that is always a struct page underneath.
In parallel there is an undergoing effort to add support for devmem to the
net stack:

https://lore.kernel.org/netdev/20231208005250.2910004-1-almasrymina@google.=
com/

Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Christian K=C3=B6nig <christian.koenig@amd.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Yunsheng Lin <linyunsheng@huawei.com>
Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>

Mina Almasry (3):
  vsock/virtio: use skb_frag_*() helpers
  net: introduce abstraction for network memory
  net: add netmem_ref to skb_frag_t

 include/linux/skbuff.h           | 92 ++++++++++++++++++++++----------
 include/net/netmem.h             | 41 ++++++++++++++
 net/core/skbuff.c                | 22 +++++---
 net/kcm/kcmsock.c                | 10 +++-
 net/vmw_vsock/virtio_transport.c |  6 +--
 5 files changed, 133 insertions(+), 38 deletions(-)
 create mode 100644 include/net/netmem.h

--=20
2.43.0.472.g3155946c3a-goog