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  1. 18 4月, 2018 26 次提交
  3. 17 4月, 2018 14 次提交
    • D
      Merge branch 'XDP-redirect-memory-return-API' · 684009d4
      由 David S. Miller 提交于 
      Jesper Dangaard Brouer says:

====================
XDP redirect memory return API

Submitted against net-next, as it contains NIC driver changes.

This patchset works towards supporting different XDP RX-ring memory
allocators.  As this will be needed by the AF_XDP zero-copy mode.

The patchset uses mlx5 as the sample driver, which gets implemented
XDP_REDIRECT RX-mode, but not ndo_xdp_xmit (as this API is subject to
change thought the patchset).

A new struct xdp_frame is introduced (modeled after cpumap xdp_pkt).
And both ndo_xdp_xmit and the new xdp_return_frame end-up using this.

Support for a driver supplied allocator is implemented, and a
refurbished version of page_pool is the first return allocator type
introduced.  This will be a integration point for AF_XDP zero-copy.

The mlx5 driver evolve into using the page_pool, and see a performance
increase (with ndo_xdp_xmit out ixgbe driver) from 6Mpps to 12Mpps.

The patchset stop at 16 patches (one over limit), but more API changes
are planned.  Specifically extending ndo_xdp_xmit and xdp_return_frame
APIs to support bulking.  As this will address some known limits.

V2: Updated according to Tariq's feedback
V3: Updated based on feedback from Jason Wang and Alex Duyck
V4: Updated based on feedback from Tariq and Jason
V5: Fix SPDX license, add Tariq's reviews, improve patch desc for perf test
V6: Updated based on feedback from Eric Dumazet and Alex Duyck
V7: Adapt to i40e that got XDP_REDIRECT support in-between
V8:
 Updated based on feedback kbuild test robot, and adjust for mlx5 changes
 page_pool only compiled into kernel when drivers Kconfig 'select' feature
V9:
 Remove some inline statements, let compiler decide what to inline
 Fix return value in virtio_net driver
 Adjust for mlx5 changes in-between submissions
V10:
 Minor adjust for mlx5 requested by Tariq
 Resubmit against net-next
V11: avoid leaking info stored in frame data on page reuse
====================
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      684009d4
    • J
      xdp: avoid leaking info stored in frame data on page reuse · 6dfb970d
      由 Jesper Dangaard Brouer 提交于 
      The bpf infrastructure and verifier goes to great length to avoid
bpf progs leaking kernel (pointer) info.

For queueing an xdp_buff via XDP_REDIRECT, xdp_frame info stores
kernel info (incl pointers) in top part of frame data (xdp->data_hard_start).
Checks are in place to assure enough headroom is available for this.

This info is not cleared, and if the frame is reused, then a
malicious user could use bpf_xdp_adjust_head helper to move
xdp->data into this area.  Thus, making this area readable.

This is not super critical as XDP progs requires root or
CAP_SYS_ADMIN, which are privileged enough for such info.  An
effort (is underway) towards moving networking bpf hooks to the
lesser privileged mode CAP_NET_ADMIN, where leaking such info
should be avoided.  Thus, this patch to clear the info when
needed.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      6dfb970d
    • J
      xdp: transition into using xdp_frame for ndo_xdp_xmit · 44fa2dbd
      由 Jesper Dangaard Brouer 提交于 
      Changing API ndo_xdp_xmit to take a struct xdp_frame instead of struct
xdp_buff.  This brings xdp_return_frame and ndp_xdp_xmit in sync.

This builds towards changing the API further to become a bulk API,
because xdp_buff is not a queue-able object while xdp_frame is.

V4: Adjust for commit 59655a5b ("tuntap: XDP_TX can use native XDP")
V7: Adjust for commit d9314c47 ("i40e: add support for XDP_REDIRECT")
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      44fa2dbd
    • J
      xdp: transition into using xdp_frame for return API · 03993094
      由 Jesper Dangaard Brouer 提交于 
      Changing API xdp_return_frame() to take struct xdp_frame as argument,
seems like a natural choice. But there are some subtle performance
details here that needs extra care, which is a deliberate choice.

When de-referencing xdp_frame on a remote CPU during DMA-TX
completion, result in the cache-line is change to "Shared"
state. Later when the page is reused for RX, then this xdp_frame
cache-line is written, which change the state to "Modified".

This situation already happens (naturally) for, virtio_net, tun and
cpumap as the xdp_frame pointer is the queued object.  In tun and
cpumap, the ptr_ring is used for efficiently transferring cache-lines
(with pointers) between CPUs. Thus, the only option is to
de-referencing xdp_frame.

It is only the ixgbe driver that had an optimization, in which it can
avoid doing the de-reference of xdp_frame.  The driver already have
TX-ring queue, which (in case of remote DMA-TX completion) have to be
transferred between CPUs anyhow.  In this data area, we stored a
struct xdp_mem_info and a data pointer, which allowed us to avoid
de-referencing xdp_frame.

To compensate for this, a prefetchw is used for telling the cache
coherency protocol about our access pattern.  My benchmarks show that
this prefetchw is enough to compensate the ixgbe driver.

V7: Adjust for commit d9314c47 ("i40e: add support for XDP_REDIRECT")
V8: Adjust for commit bd658dda ("net/mlx5e: Separate dma base address
and offset in dma_sync call")
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      03993094
    • J
      mlx5: use page_pool for xdp_return_frame call · 60bbf7ee
      由 Jesper Dangaard Brouer 提交于 
      This patch shows how it is possible to have both the driver local page
cache, which uses elevated refcnt for "catching"/avoiding SKB
put_page returns the page through the page allocator.  And at the
same time, have pages getting returned to the page_pool from
ndp_xdp_xmit DMA completion.

The performance improvement for XDP_REDIRECT in this patch is really
good.  Especially considering that (currently) the xdp_return_frame
API and page_pool_put_page() does per frame operations of both
rhashtable ID-lookup and locked return into (page_pool) ptr_ring.
(It is the plan to remove these per frame operation in a followup
patchset).

The benchmark performed was RX on mlx5 and XDP_REDIRECT out ixgbe,
with xdp_redirect_map (using devmap) . And the target/maximum
capability of ixgbe is 13Mpps (on this HW setup).

Before this patch for mlx5, XDP redirected frames were returned via
the page allocator.  The single flow performance was 6Mpps, and if I
started two flows the collective performance drop to 4Mpps, because we
hit the page allocator lock (further negative scaling occurs).

Two test scenarios need to be covered, for xdp_return_frame API, which
is DMA-TX completion running on same-CPU or cross-CPU free/return.
Results were same-CPU=10Mpps, and cross-CPU=12Mpps.  This is very
close to our 13Mpps max target.

The reason max target isn't reached in cross-CPU test, is likely due
to RX-ring DMA unmap/map overhead (which doesn't occur in ixgbe to
ixgbe testing).  It is also planned to remove this unnecessary DMA
unmap in a later patchset

V2: Adjustments requested by Tariq
 - Changed page_pool_create return codes not return NULL, only
   ERR_PTR, as this simplifies err handling in drivers.
 - Save a branch in mlx5e_page_release
 - Correct page_pool size calc for MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ

V5: Updated patch desc

V8: Adjust for b0cedc84 ("net/mlx5e: Remove rq_headroom field from params")
V9:
 - Adjust for 121e8927 ("net/mlx5e: Refactor RQ XDP_TX indication")
 - Adjust for 73281b78 ("net/mlx5e: Derive Striding RQ size from MTU")
 - Correct handling if page_pool_create fail for MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ

V10: Req from Tariq
 - Change pool_size calc for MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Reviewed-by: NTariq Toukan <tariqt@mellanox.com>
Acked-by: NSaeed Mahameed <saeedm@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      60bbf7ee
    • J
      xdp: allow page_pool as an allocator type in xdp_return_frame · 57d0a1c1
      由 Jesper Dangaard Brouer 提交于 
      New allocator type MEM_TYPE_PAGE_POOL for page_pool usage.

The registered allocator page_pool pointer is not available directly
from xdp_rxq_info, but it could be (if needed).  For now, the driver
should keep separate track of the page_pool pointer, which it should
use for RX-ring page allocation.

As suggested by Saeed, to maintain a symmetric API it is the drivers
responsibility to allocate/create and free/destroy the page_pool.
Thus, after the driver have called xdp_rxq_info_unreg(), it is drivers
responsibility to free the page_pool, but with a RCU free call.  This
is done easily via the page_pool helper page_pool_destroy() (which
avoids touching any driver code during the RCU callback, which could
happen after the driver have been unloaded).

V8: address issues found by kbuild test robot
 - Address sparse should be static warnings
 - Allow xdp.o to be compiled without page_pool.o

V9: Remove inline from .c file, compiler knows best
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      57d0a1c1
    • J
      page_pool: refurbish version of page_pool code · ff7d6b27
      由 Jesper Dangaard Brouer 提交于 
      Need a fast page recycle mechanism for ndo_xdp_xmit API for returning
pages on DMA-TX completion time, which have good cross CPU
performance, given DMA-TX completion time can happen on a remote CPU.

Refurbish my page_pool code, that was presented[1] at MM-summit 2016.
Adapted page_pool code to not depend the page allocator and
integration into struct page.  The DMA mapping feature is kept,
even-though it will not be activated/used in this patchset.

[1] http://people.netfilter.org/hawk/presentations/MM-summit2016/generic_page_pool_mm_summit2016.pdf

V2: Adjustments requested by Tariq
 - Changed page_pool_create return codes, don't return NULL, only
   ERR_PTR, as this simplifies err handling in drivers.

V4: many small improvements and cleanups
- Add DOC comment section, that can be used by kernel-doc
- Improve fallback mode, to work better with refcnt based recycling
  e.g. remove a WARN as pointed out by Tariq
  e.g. quicker fallback if ptr_ring is empty.

V5: Fixed SPDX license as pointed out by Alexei

V6: Adjustments requested by Eric Dumazet
 - Adjust ____cacheline_aligned_in_smp usage/placement
 - Move rcu_head in struct page_pool
 - Free pages quicker on destroy, minimize resources delayed an RCU period
 - Remove code for forward/backward compat ABI interface

V8: Issues found by kbuild test robot
 - Address sparse should be static warnings
 - Only compile+link when a driver use/select page_pool,
   mlx5 selects CONFIG_PAGE_POOL, although its first used in two patches
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      ff7d6b27
    • J
      xdp: rhashtable with allocator ID to pointer mapping · 8d5d8852
      由 Jesper Dangaard Brouer 提交于 
      Use the IDA infrastructure for getting a cyclic increasing ID number,
that is used for keeping track of each registered allocator per
RX-queue xdp_rxq_info.  Instead of using the IDR infrastructure, which
uses a radix tree, use a dynamic rhashtable, for creating ID to
pointer lookup table, because this is faster.

The problem that is being solved here is that, the xdp_rxq_info
pointer (stored in xdp_buff) cannot be used directly, as the
guaranteed lifetime is too short.  The info is needed on a
(potentially) remote CPU during DMA-TX completion time . In an
xdp_frame the xdp_mem_info is stored, when it got converted from an
xdp_buff, which is sufficient for the simple page refcnt based recycle
schemes.

For more advanced allocators there is a need to store a pointer to the
registered allocator.  Thus, there is a need to guard the lifetime or
validity of the allocator pointer, which is done through this
rhashtable ID map to pointer. The removal and validity of of the
allocator and helper struct xdp_mem_allocator is guarded by RCU.  The
allocator will be created by the driver, and registered with
xdp_rxq_info_reg_mem_model().

It is up-to debate who is responsible for freeing the allocator
pointer or invoking the allocator destructor function.  In any case,
this must happen via RCU freeing.

Use the IDA infrastructure for getting a cyclic increasing ID number,
that is used for keeping track of each registered allocator per
RX-queue xdp_rxq_info.

V4: Per req of Jason Wang
- Use xdp_rxq_info_reg_mem_model() in all drivers implementing
  XDP_REDIRECT, even-though it's not strictly necessary when
  allocator==NULL for type MEM_TYPE_PAGE_SHARED (given it's zero).

V6: Per req of Alex Duyck
- Introduce rhashtable_lookup() call in later patch

V8: Address sparse should be static warnings (from kbuild test robot)
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      8d5d8852
    • J
      mlx5: register a memory model when XDP is enabled · 84f5e3fb
      由 Jesper Dangaard Brouer 提交于 
      Now all the users of ndo_xdp_xmit have been converted to use xdp_return_frame.
This enable a different memory model, thus activating another code path
in the xdp_return_frame API.

V2: Fixed issues pointed out by Tariq.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Reviewed-by: NTariq Toukan <tariqt@mellanox.com>
Acked-by: NSaeed Mahameed <saeedm@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      84f5e3fb
    • J
      i40e: convert to use generic xdp_frame and xdp_return_frame API · b411ef11
      由 Jesper Dangaard Brouer 提交于 
      Also convert driver i40e, which very recently got XDP_REDIRECT support
in commit d9314c47 ("i40e: add support for XDP_REDIRECT").

V7: This patch got added in V7 of this patchset.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      b411ef11
    • J
      bpf: cpumap convert to use generic xdp_frame · 70280ed9
      由 Jesper Dangaard Brouer 提交于 
      The generic xdp_frame format, was inspired by the cpumap own internal
xdp_pkt format.  It is now time to convert it over to the generic
xdp_frame format.  The cpumap needs one extra field dev_rx.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      70280ed9
    • J
      virtio_net: convert to use generic xdp_frame and xdp_return_frame API · cac320c8
      由 Jesper Dangaard Brouer 提交于 
      The virtio_net driver assumes XDP frames are always released based on
page refcnt (via put_page).  Thus, is only queues the XDP data pointer
address and uses virt_to_head_page() to retrieve struct page.

Use the XDP return API to get away from such assumptions. Instead
queue an xdp_frame, which allow us to use the xdp_return_frame API,
when releasing the frame.

V8: Avoid endianness issues (found by kbuild test robot)
V9: Change __virtnet_xdp_xmit from bool to int return value (found by Dan Carpenter)
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      cac320c8
    • J
      tun: convert to use generic xdp_frame and xdp_return_frame API · 1ffcbc85
      由 Jesper Dangaard Brouer 提交于 
      The tuntap driver invented it's own driver specific way of queuing
XDP packets, by storing the xdp_buff information in the top of
the XDP frame data.

Convert it over to use the more generic xdp_frame structure.  The
main problem with the in-driver method is that the xdp_rxq_info pointer
cannot be trused/used when dequeueing the frame.

V3: Remove check based on feedback from Jason
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      1ffcbc85
    • J
      xdp: introduce a new xdp_frame type · c0048cff
      由 Jesper Dangaard Brouer 提交于 
      This is needed to convert drivers tuntap and virtio_net.

This is a generalization of what is done inside cpumap, which will be
converted later.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      c0048cff