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To eliminate the use of struct page in page pool, the page pool users
should use netmem descriptor and APIs instead.
Make mlx4 access ->pp_ref_count through netmem_desc instead of page.
While at it, add a helper, pp_page_to_nmdesc() and __pp_page_to_nmdesc(),
that can be used to get netmem_desc from page only if it's a pp page.
For now that netmem_desc overlays on page, it can be achieved by just
casting, and use macro and _Generic to cover const casting as well.
Plus, change page_pool_page_is_pp() to check for 'const struct page *'
instead of 'struct page *' since it doesn't modify data and additionally
covers const type.
Signed-off-by: Byungchul Park <byungchul@sk.com>
Link: https://patch.msgid.link/20250721021835.63939-4-byungchul@sk.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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To eliminate the use of the page pool fields in struct page, the page
pool code should use netmem descriptor and APIs instead.
However, __netmem_get_pp() still accesses ->pp via struct page. So
change it to use struct netmem_desc instead, since ->pp no longer will
be available in struct page.
While at it, add a helper, __netmem_to_nmdesc(), that can be used to
unsafely get pointer to netmem_desc backing the netmem_ref, only when
the netmem_ref is always backed by system memory.
Signed-off-by: Byungchul Park <byungchul@sk.com>
Link: https://patch.msgid.link/20250721021835.63939-3-byungchul@sk.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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To simplify struct page, the page pool members of struct page should be
moved to other, allowing these members to be removed from struct page.
Introduce a network memory descriptor to store the members, struct
netmem_desc, and make it union'ed with the existing fields in struct
net_iov, allowing to organize the fields of struct net_iov.
Signed-off-by: Byungchul Park <byungchul@sk.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Harry Yoo <harry.yoo@oracle.com>
Link: https://patch.msgid.link/20250721021835.63939-2-byungchul@sk.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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The current page_to_netmem() doesn't cover const casting resulting in
trying to cast const struct page * to const netmem_ref fails.
To cover the case, change page_to_netmem() to use macro and _Generic.
Signed-off-by: Byungchul Park <byungchul@sk.com>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://patch.msgid.link/20250702053256.4594-5-byungchul@sk.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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This allows calling page_to_netmem() with a const page * argument.
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Reviewed-by: Cosmin Ratiu <cratiu@nvidia.com>
Signed-off-by: Mark Bloch <mbloch@nvidia.com>
Link: https://patch.msgid.link/20250616141441.1243044-2-mbloch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Trivial fix to a couple of outdated netmem comments. No code changes,
just more accurately describing current code.
Signed-off-by: Mina Almasry <almasrymina@google.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250615203511.591438-1-almasrymina@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Drivers need to make sure not to pass netmem dma-addrs to the
dma-mapping API in order to support netmem TX.
Add helpers and netmem_dma_*() helpers that enables special handling of
netmem dma-addrs that drivers can use.
Document in netmem.rst what drivers need to do to support netmem TX.
Signed-off-by: Mina Almasry <almasrymina@google.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250508004830.4100853-7-almasrymina@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Currently net_iovs support only pp ref counts, and do not support a
page ref equivalent.
This is fine for the RX path as net_iovs are used exclusively with the
pp and only pp refcounting is needed there. The TX path however does not
use pp ref counts, thus, support for get_page/put_page equivalent is
needed for netmem.
Support get_netmem/put_netmem. Check the type of the netmem before
passing it to page or net_iov specific code to obtain a page ref
equivalent.
For dmabuf net_iovs, we obtain a ref on the underlying binding. This
ensures the entire binding doesn't disappear until all the net_iovs have
been put_netmem'ed. We do not need to track the refcount of individual
dmabuf net_iovs as we don't allocate/free them from a pool similar to
what the buddy allocator does for pages.
This code is written to be extensible by other net_iov implementers.
get_netmem/put_netmem will check the type of the netmem and route it to
the correct helper:
pages -> [get|put]_page()
dmabuf net_iovs -> net_devmem_[get|put]_net_iov()
new net_iovs -> new helpers
Signed-off-by: Mina Almasry <almasrymina@google.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250508004830.4100853-3-almasrymina@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Later patches in the series adds TX net_iovs where there is no pp
associated, so we can't rely on niov->pp->mp_ops to tell what is the
type of the net_iov.
Add a type enum to the net_iov which tells us the net_iov type.
Signed-off-by: Mina Almasry <almasrymina@google.com>
Link: https://patch.msgid.link/20250508004830.4100853-2-almasrymina@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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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 <almasrymina@google.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: David Wei <dw@davidwei.uk>
Link: https://patch.msgid.link/20250204215622.695511-4-dw@davidwei.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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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 <aleksander.lobakin@intel.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://patch.msgid.link/20241203173733.3181246-8-aleksander.lobakin@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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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 <almasrymina@google.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20240910171458.219195-6-almasrymina@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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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 <willemb@google.com>
Signed-off-by: Kaiyuan Zhang <kaiyuanz@google.com>
Signed-off-by: Mina Almasry <almasrymina@google.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> # excluding netlink
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20240910171458.219195-4-almasrymina@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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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 <almasrymina@google.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://patch.msgid.link/20240628003253.1694510-6-almasrymina@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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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/20231208005250.2910004-1-almasrymina@google.com/
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 <shakeelb@google.com>
Signed-off-by: Mina Almasry <almasrymina@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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