net: generalise net_iov chunk owners

Currently net_iov stores a pointer to struct dmabuf_genpool_chunk_owner,
which serves as a useful abstraction to share data and provide a
context. However, it's

net: generalise net_iov chunk owners

Currently net_iov stores a pointer to struct dmabuf_genpool_chunk_owner,
which serves as a useful abstraction to share data and provide a
context. However, it's too devmem specific, and we want to reuse it for
other memory providers, and for that we need to decouple net_iov from
devmem. Make net_iov to point to a new base structure called
net_iov_area, which dmabuf_genpool_chunk_owner extends.

Reviewed-by: Mina Almasry <[email protected]>
Acked-by: Jakub Kicinski <[email protected]>
Signed-off-by: Pavel Begunkov <[email protected]>
Signed-off-by: David Wei <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

netmem: add a couple of page helper wrappers

Add the following netmem counterparts:

* virt_to_netmem() -- simple page_to_netmem(virt_to_page()) wrapper;
* netmem_is_pfmemalloc() -- page_is_pfmemall

netmem: add a couple of page helper wrappers

Add the following netmem counterparts:

* virt_to_netmem() -- simple page_to_netmem(virt_to_page()) wrapper;
* netmem_is_pfmemalloc() -- page_is_pfmemalloc() for page-backed
netmems, false otherwise;

and the following "unsafe" versions:

* __netmem_to_page()
* __netmem_get_pp()
* __netmem_address()

They do the same as their non-underscored buddies, but assume the netmem
is always page-backed. When working with header &page_pools, you don't
need to check whether netmem belongs to the host memory and you can
never get NULL instead of &page. Checks for the LSB, clearing the LSB,
branches take cycles and increase object code size, sometimes
significantly. When you're sure your PP is always host, you can avoid
this by using the underscored counterparts.

Signed-off-by: Alexander Lobakin <[email protected]>
Reviewed-by: Toke Høiland-Jørgensen <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

page_pool: devmem support

Convert netmem to be a union of struct page and struct netmem. Overload
the LSB of struct netmem* to indicate that it's a net_iov, otherwise
it's a page.

Currently these e

page_pool: devmem support

Convert netmem to be a union of struct page and struct netmem. Overload
the LSB of struct netmem* to indicate that it's a net_iov, otherwise
it's a page.

Currently these entries in struct page are rented by the page_pool and
used exclusively by the net stack:

struct {
unsigned long pp_magic;
struct page_pool *pp;
unsigned long _pp_mapping_pad;
unsigned long dma_addr;
atomic_long_t pp_ref_count;
};

Mirror these (and only these) entries into struct net_iov and implement
netmem helpers that can access these common fields regardless of
whether the underlying type is page or net_iov.

Implement checks for net_iov in netmem helpers which delegate to mm
APIs, to ensure net_iov are never passed to the mm stack.

Signed-off-by: Mina Almasry <[email protected]>
Reviewed-by: Pavel Begunkov <[email protected]>
Acked-by: Jakub Kicinski <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

netdev: support binding dma-buf to netdevice

Add a netdev_dmabuf_binding struct which represents the
dma-buf-to-netdevice binding. The netlink API will bind the dma-buf to
rx queues on the netdevice

netdev: support binding dma-buf to netdevice

Add a netdev_dmabuf_binding struct which represents the
dma-buf-to-netdevice binding. The netlink API will bind the dma-buf to
rx queues on the netdevice. On the binding, the dma_buf_attach
& dma_buf_map_attachment will occur. The entries in the sg_table from
mapping will be inserted into a genpool to make it ready
for allocation.

The chunks in the genpool are owned by a dmabuf_chunk_owner struct which
holds the dma-buf offset of the base of the chunk and the dma_addr of
the chunk. Both are needed to use allocations that come from this chunk.

We create a new type that represents an allocation from the genpool:
net_iov. We setup the net_iov allocation size in the
genpool to PAGE_SIZE for simplicity: to match the PAGE_SIZE normally
allocated by the page pool and given to the drivers.

The user can unbind the dmabuf from the netdevice by closing the netlink
socket that established the binding. We do this so that the binding is
automatically unbound even if the userspace process crashes.

The binding and unbinding leaves an indicator in struct netdev_rx_queue
that the given queue is bound, and the binding is actuated by resetting
the rx queue using the queue API.

The netdev_dmabuf_binding struct is refcounted, and releases its
resources only when all the refs are released.

Signed-off-by: Willem de Bruijn <[email protected]>
Signed-off-by: Kaiyuan Zhang <[email protected]>
Signed-off-by: Mina Almasry <[email protected]>
Reviewed-by: Pavel Begunkov <[email protected]> # excluding netlink
Acked-by: Daniel Vetter <[email protected]>
Reviewed-by: Jakub Kicinski <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

page_pool: convert to use netmem

Abstract the memory type from the page_pool so we can later add support
for new memory types. Convert the page_pool to use the new netmem type
abstraction, rather th

page_pool: convert to use netmem

Abstract the memory type from the page_pool so we can later add support
for new memory types. Convert the page_pool to use the new netmem type
abstraction, rather than use struct page directly.

As of this patch the netmem type is a no-op abstraction: it's always a
struct page underneath. All the page pool internals are converted to
use struct netmem instead of struct page, and the page pool now exports
2 APIs:

1. The existing struct page API.
2. The new struct netmem API.

Keeping the existing API is transitional; we do not want to refactor all
the current drivers using the page pool at once.

The netmem abstraction is currently a no-op. The page_pool uses
page_to_netmem() to convert allocated pages to netmem, and uses
netmem_to_page() to convert the netmem back to pages to pass to mm APIs,

Follow up patches to this series add non-paged netmem support to the
page_pool. This change is factored out on its own to limit the code
churn to this 1 patch, for ease of code review.

Signed-off-by: Mina Almasry <[email protected]>
Reviewed-by: Pavel Begunkov <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

net: introduce abstraction for network memory

Add the netmem_ref type, an abstraction for network memory.

To add support for new memory types to the net stack, we must first
abstract the current me

net: introduce abstraction for network memory

Add the netmem_ref type, an abstraction for network memory.

To add support for new memory types to the net stack, we must first
abstract the current memory type. Currently parts of the net stack
use struct page directly:

- page_pool
- drivers
- skb_frag_t

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 compiler type checking we need to introduce a new type.

netmem_ref 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/[email protected]/

netmem_ref can be pointers to different underlying memory types, and the
low bits are set to indicate the memory type. Helpers are provided
to convert netmem pointers to the underlying memory type (currently only
struct page). In the devmem series helpers are provided so that calling
code can use netmem without worrying about the underlying memory type
unless absolutely necessary.

Reviewed-by: Shakeel Butt <[email protected]>
Signed-off-by: Mina Almasry <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>

show more ...