xen/netfront: Decouple XENNET tags from mbuf lifetimes

netmap's generic mode tries to improve performance by minimizing mbuf
allocations. In service of this goal, it maintains an extra reference
to

xen/netfront: Decouple XENNET tags from mbuf lifetimes

netmap's generic mode tries to improve performance by minimizing mbuf
allocations. In service of this goal, it maintains an extra reference
to the mbuf and polls the counter to see if the driver has released its
reference by calling m_freem(). As a result, the extref destructor is
not called when expected by the netfront driver, and mbufs tags are not
freed.

Modify the tx path to release its mbuf tags promptly when reclaiming tx
descriptors. They are drawn from a fixed-size pool, so otherwise are
quickly exhausted when a netfront interface is in netmap generic mode.

Co-authored by: royger
MFC after: 2 weeks
Fixes: dabb3db7a817 ("xen/netfront: deal with mbuf data crossing a page boundary")
Sponsored by: Cloud Software Group
Sponsored by: Klara, Inc.
Sponsored by: Zenarmor

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xen-netfront: attempt to make cleanup idempotent

Current cleanup code assumes that all the fields are allocated and/or setup by
the time cleanup is called, but this is not always true: a failure in

xen-netfront: attempt to make cleanup idempotent

Current cleanup code assumes that all the fields are allocated and/or setup by
the time cleanup is called, but this is not always true: a failure in mid-setup
of the device will cause the functions to be called with possibly uninitialized
fields.

Fix the functions to cope with such sate, while also attempting to make the
cleanup idempotent.

Finally fix an error path during setup that would not mark the device as
closed, and hence prevents the kernel from finishing booting.

Fixes: 96375eac945c ("xen-netfront: add multiqueue support")
Sponsored by: Citrix Systems R&D

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netfront: fix the support for disabling LRO at boot time

The driver has a tunable hw.xn.enable_lro which is intended to control
whether LRO is enabled. This is currently non-functional - even if its

netfront: fix the support for disabling LRO at boot time

The driver has a tunable hw.xn.enable_lro which is intended to control
whether LRO is enabled. This is currently non-functional - even if its
set to zero, the driver still requests LRO support from the backend.
This change fixes the feature so that if enable_lro is set to zero, LRO
no longer appears in the interface capabilities and LRO is not requested
from the backend.

PR: 273046
MFC after: 1 week
Reviewed by: royger
Differential Revision: https://reviews.freebsd.org/D41439

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sys: Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

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Mechanically convert Xen netfront/netback(4) to IfAPI

Reviewed by: zlei
Sponsored by: Juniper Networks, Inc.
Differential Revision: https://reviews.freebsd.org/D37800

xen/netfront: deal with mbuf data crossing a page boundary

There's been a report recently of mbufs with data that crosses a page
boundary. It seems those mbufs are generated by the iSCSI target
syst

xen/netfront: deal with mbuf data crossing a page boundary

There's been a report recently of mbufs with data that crosses a page
boundary. It seems those mbufs are generated by the iSCSI target
system:

https://lists.xenproject.org/archives/html/xen-devel/2021-12/msg01581.html

In order to handle those mbufs correctly on netfront use the bus_dma
interface and explicitly request that segments must not cross a page
boundary. No other requirements are necessary, so it's expected that
bus_dma won't need to bounce the data and hence it shouldn't
introduce a too big performance penalty.

Using bus_dma requires some changes to netfront, mainly in order to
accommodate for the fact that now ring slots no longer have a 1:1
match with mbufs, as a single mbuf can use two ring slots if the data
buffer crosses a page boundary. Store the first packet of the mbuf
chain in every ring slot that's used, and use a mbuf tag in order to
store the bus_dma related structures and a refcount to keep track of
the pending slots before the mbuf chain can be freed.

Reported by: G.R.
Tested by: G.R.
MFC: 1 week
Differential revision: https://reviews.freebsd.org/D33876

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xen: Remove unused devclass arguments to DRIVER_MODULE.

xen: switch to use headers in contrib

These headers originate with the Xen project and shouldn't be mixed with
the main portion of the FreeBSD kernel. Notably they shouldn't be the
target of clean-u

xen: switch to use headers in contrib

These headers originate with the Xen project and shouldn't be mixed with
the main portion of the FreeBSD kernel. Notably they shouldn't be the
target of clean-up commits.

Switch to use the headers in sys/contrib/xen.

Reviewed by: royger

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xen: plug some of set-but-not-used vars

Sponsored by: Rubicon Communications, LLC ("Netgate")

xen/netfront: introduce xen_pv_nics_disabled()

ARM guest is considered as HVM but it only supports PV nics (no
emulation available).

Submitted by: Elliott Mitchell <ehem+freebsd@m5p.com>
Reviewed b

xen/netfront: introduce xen_pv_nics_disabled()

ARM guest is considered as HVM but it only supports PV nics (no
emulation available).

Submitted by: Elliott Mitchell <ehem+freebsd@m5p.com>
Reviewed by: royger
Differential Revision: https://reviews.freebsd.org/D29405

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dev/xen: clean up empty lines in .c and .h files

Merge ^/head r338026 through r338297, and resolve conflicts.

xen/netfront: Ensure curvnet is set

netfront_backend_changed() is called from the xenwatch_thread(), which means
that the curvnet is not set. We have to set it before we can call things like
arp_ifi

xen/netfront: Ensure curvnet is set

netfront_backend_changed() is called from the xenwatch_thread(), which means
that the curvnet is not set. We have to set it before we can call things like
arp_ifinit().

PR: 230845

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ifnet: Replace if_addr_lock rwlock with epoch + mutex

Run on LLNW canaries and tested by pho@

gallatin:
Using a 14-core, 28-HTT single socket E5-2697 v3 with a 40GbE MLX5
based ConnectX 4-LX NIC, I

ifnet: Replace if_addr_lock rwlock with epoch + mutex

Run on LLNW canaries and tested by pho@

gallatin:
Using a 14-core, 28-HTT single socket E5-2697 v3 with a 40GbE MLX5
based ConnectX 4-LX NIC, I see an almost 12% improvement in received
packet rate, and a larger improvement in bytes delivered all the way
to userspace.

When the host receiving 64 streams of netperf -H $DUT -t UDP_STREAM -- -m 1,
I see, using nstat -I mce0 1 before the patch:

InMpps OMpps InGbs OGbs err TCP Est %CPU syscalls csw irq GBfree
4.98 0.00 4.42 0.00 4235592 33 83.80 4720653 2149771 1235 247.32
4.73 0.00 4.20 0.00 4025260 33 82.99 4724900 2139833 1204 247.32
4.72 0.00 4.20 0.00 4035252 33 82.14 4719162 2132023 1264 247.32
4.71 0.00 4.21 0.00 4073206 33 83.68 4744973 2123317 1347 247.32
4.72 0.00 4.21 0.00 4061118 33 80.82 4713615 2188091 1490 247.32
4.72 0.00 4.21 0.00 4051675 33 85.29 4727399 2109011 1205 247.32
4.73 0.00 4.21 0.00 4039056 33 84.65 4724735 2102603 1053 247.32

After the patch

InMpps OMpps InGbs OGbs err TCP Est %CPU syscalls csw irq GBfree
5.43 0.00 4.20 0.00 3313143 33 84.96 5434214 1900162 2656 245.51
5.43 0.00 4.20 0.00 3308527 33 85.24 5439695 1809382 2521 245.51
5.42 0.00 4.19 0.00 3316778 33 87.54 5416028 1805835 2256 245.51
5.42 0.00 4.19 0.00 3317673 33 90.44 5426044 1763056 2332 245.51
5.42 0.00 4.19 0.00 3314839 33 88.11 5435732 1792218 2499 245.52
5.44 0.00 4.19 0.00 3293228 33 91.84 5426301 1668597 2121 245.52

Similarly, netperf reports 230Mb/s before the patch, and 270Mb/s after the patch

Reviewed by: gallatin
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D15366

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sys/dev: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error

sys/dev: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

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MFhead@r320180

Merge ^/head r319973 through 321382.

Merge ^/head r320398 through r320572.

netfront.c: avoid gcc variably-modified warning

gcc produces a "variably modified X at file scope" warning for
structures that use these size definitions. I think the definitions are
actually fine

netfront.c: avoid gcc variably-modified warning

gcc produces a "variably modified X at file scope" warning for
structures that use these size definitions. I think the definitions are
actually fine but can be rephrased with the __CONST_RING_SIZE macro more
cleanly anyway.

Reviewed by: markj, royger
Approved by: markj (mentor)
Sponsored by: Dell EMC Isilon
Differential revision: https://reviews.freebsd.org/D11417

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Merge ^/head r319480 through r319547.

Skip setting the MTU in the netfront driver (xn# devices) if the new MTU
is the same as the old MTU. In particular, on Amazon EC2 "T2" instances
without this change, the network interface is reiniti

Skip setting the MTU in the netfront driver (xn# devices) if the new MTU
is the same as the old MTU. In particular, on Amazon EC2 "T2" instances
without this change, the network interface is reinitialized every 30
minutes due to the MTU being (re)set when a new DHCP lease is obtained,
causing packets to be dropped, along with annoying syslog messages about
the link state changing.

As a side note, the behaviour this commit fixes was responsible for
exposing the locking problems fixed via r318523 and r318631.

Maintainers of other network interface drivers may wish to consider making
the corresponding change; the handling of SIOCSIFMTU does not seem to
exhibit a great deal of consistency between drivers.

MFC after: 1 week

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Merge ^/head r318560 through r318657.

xen/netfront: don't drop the RX lock in xn_rxeof

Since netfront uses different locks for the RX and TX paths there's no need to
drop the RX lock before calling if_input.

Suggested by: jhb
Tested by

xen/netfront: don't drop the RX lock in xn_rxeof

Since netfront uses different locks for the RX and TX paths there's no need to
drop the RX lock before calling if_input.

Suggested by: jhb
Tested by: cperciva
Sponsored by: Citrix Systems R&D
MFC with: r318523

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Merge ^/head r318380 through r318559.