When data is received on the READ channel, the matching logic for cmds
that are waiting for a reply is currently hard-coded into the channel's
main IO callback.
Move this into a per-cmd callback, so that we can apply custom matching
logic for each individual cmd.

This also allows us to remove the coarse-grained check for unexpected
non-IPA replies, since they will no longer match against _all_ pending
cmds.

Note that IDX cmds use _no_ matcher, since their reply is synchronously
received as part of the cmd's IO.
Signed-off-by: NJulian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Large parts of the online/offline code are identical now, and cleaning
up the remaining stuff is easier with a shared core.
Signed-off-by: NJulian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Move some duplicated logic into a shared code path.
Signed-off-by: NJulian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

qeth_l2_setup_bridgeport_attrs() is entirely unrelated to sysfs
functionality, move it where it belongs.
While at it merge all the bridgeport-specific code in the set-online
path together.
Signed-off-by: NJulian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: NAlexandra Winter <wintera@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Jeff Kirsher says:

====================
100GbE Intel Wired LAN Driver Updates 2020-01-25

This series contains updates to the ice driver to add support for RSS.

Henry and Tony enable the driver to write the filtering hardware tables
to allow for changing of RSS rules, also introduced and initialized the
structures for storing the configuration.  Then followed it up by
creating an extraction sequence based on the packet header protocols to
be programmed.  Next was storing the TCAM entry with the profile data
and VSI group in the respective software structures.

Md Fahad sets up the configuration to support RSS tables for the virtual
function (VF) driver (iavf).  Add support for flow types TCP4, TCP6,
UDP4, UDP6, SCTP4 and SCTP6 for RSS via ethtool.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Minor conflict in mlx5 because changes happened to code that has
moved meanwhile.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Bump version to 0.8.2-k
Signed-off-by: NTony Nguyen <anthony.l.nguyen@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

Provide support to change or retrieve RSS hash options for a flow type.
The supported flow-types are: tcp4, tcp6, udp4, udp6, sctp4, sctp6.
Signed-off-by: NMd Fahad Iqbal Polash <md.fahad.iqbal.polash@intel.com>
Signed-off-by: NTony Nguyen <anthony.l.nguyen@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

Set configuration for hardware RSS tables for VFs.
Signed-off-by: NMd Fahad Iqbal Polash <md.fahad.iqbal.polash@intel.com>
Signed-off-by: NTony Nguyen <anthony.l.nguyen@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

Attempt to optimize TCAM entries and reduce table resource usage by
searching for profiles that can be reused. Provide resource cleanup
of both hardware and software structures.
Signed-off-by: NTony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: NHenry Tieman <henry.w.tieman@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

Write the hardware tables based on the populated software structures.
Signed-off-by: NTony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: NHenry Tieman <henry.w.tieman@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

Store the TCAM entry with the profile data and the VSI group in the
respective SW structures. This will be subsequently used to write out
the tables to hardware.
Signed-off-by: NTony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: NHenry Tieman <henry.w.tieman@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

Pull ARM fixes from Russell King:

 - fix ftrace relocation type filtering

 - relax arch timer version check

* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: 8955/1: virt: Relax arch timer version check during early boot
  ARM: 8950/1: ftrace/recordmcount: filter relocation types

Pull networking fixes from David Miller:

 1) Off by one in mt76 airtime calculation, from Dan Carpenter.

 2) Fix TLV fragment allocation loop condition in iwlwifi, from Luca
    Coelho.

 3) Don't confirm neigh entries when doing ipsec pmtu updates, from Xu
    Wang.

 4) More checks to make sure we only send TSO packets to lan78xx chips
    that they can actually handle. From James Hughes.

 5) Fix ip_tunnel namespace move, from William Dauchy.

 6) Fix unintended packet reordering due to cooperation between
    listification done by GRO and non-GRO paths. From Maxim
    Mikityanskiy.

 7) Add Jakub Kicincki formally as networking co-maintainer.

 8) Info leak in airo ioctls, from Michael Ellerman.

 9) IFLA_MTU attribute needs validation during rtnl_create_link(), from
    Eric Dumazet.

10) Use after free during reload in mlxsw, from Ido Schimmel.

11) Dangling pointers are possible in tp->highest_sack, fix from Eric
    Dumazet.

12) Missing *pos++ in various networking seq_next handlers, from Vasily
    Averin.

13) CHELSIO_GET_MEM operation neds CAP_NET_ADMIN check, from Michael
    Ellerman.

* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (109 commits)
  firestream: fix memory leaks
  net: cxgb3_main: Add CAP_NET_ADMIN check to CHELSIO_GET_MEM
  net: bcmgenet: Use netif_tx_napi_add() for TX NAPI
  tipc: change maintainer email address
  net: stmmac: platform: fix probe for ACPI devices
  net/mlx5e: kTLS, Do not send decrypted-marked SKBs via non-accel path
  net/mlx5e: kTLS, Remove redundant posts in TX resync flow
  net/mlx5e: kTLS, Fix corner-case checks in TX resync flow
  net/mlx5e: Clear VF config when switching modes
  net/mlx5: DR, use non preemptible call to get the current cpu number
  net/mlx5: E-Switch, Prevent ingress rate configuration of uplink rep
  net/mlx5: DR, Enable counter on non-fwd-dest objects
  net/mlx5: Update the list of the PCI supported devices
  net/mlx5: Fix lowest FDB pool size
  net: Fix skb->csum update in inet_proto_csum_replace16().
  netfilter: nf_tables: autoload modules from the abort path
  netfilter: nf_tables: add __nft_chain_type_get()
  netfilter: nf_tables_offload: fix check the chain offload flag
  netfilter: conntrack: sctp: use distinct states for new SCTP connections
  ipv6_route_seq_next should increase position index
  ...

Pull ARM SoC fixes from Olof Johansson:
 "A couple of fixes have come in that would be good to include in this
  release:

   - A fix for amount of memory on Beaglebone Black. Surfaced now since
     GRUB2 doesn't update memory size in the booted kernel.

   - A fix to make SPI interfaces work on am43x-epos-evm.

   - Small Kconfig fix for OPTEE (adds a depend on MMU) to avoid build
     failures"

* tag 'armsoc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc:
  ARM: dts: am43x-epos-evm: set data pin directions for spi0 and spi1
  tee: optee: Fix compilation issue with nommu
  ARM: dts: am335x-boneblack-common: fix memory size

In fs_open(), 'vcc' is allocated through kmalloc() and assigned to
'atm_vcc->dev_data.' In the following execution, if an error occurs, e.g.,
there is no more free channel, an error code EBUSY or ENOMEM will be
returned. However, 'vcc' is not deallocated, leading to memory leaks. Note
that, in normal cases where fs_open() returns 0, 'vcc' will be deallocated
in fs_close(). But, if fs_open() fails, there is no guarantee that
fs_close() will be invoked.

To fix this issue, deallocate 'vcc' before the error code is returned.
Signed-off-by: NWenwen Wang <wenwen@cs.uga.edu>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Pablo Neira Ayuso says:

====================
Netfilter fixes for net

The following patchset contains Netfilter fixes for net:

1) Missing netlink attribute sanity check for NFTA_OSF_DREG,
   from Florian Westphal.

2) Use bitmap infrastructure in ipset to fix KASAN slab-out-of-bounds
   reads, from Jozsef Kadlecsik.

3) Missing initial CLOSED state in new sctp connection through
   ctnetlink events, from Jiri Wiesner.

4) Missing check for NFT_CHAIN_HW_OFFLOAD in nf_tables offload
   indirect block infrastructure, from wenxu.

5) Add __nft_chain_type_get() to sanity check family and chain type.

6) Autoload modules from the nf_tables abort path to fix races
   reported by syzbot.

7) Remove unnecessary skb->csum update on inet_proto_csum_replace16(),
   from Praveen Chaudhary.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Pull btrfs fix from David Sterba:
 "Here's a last minute fix for a regression introduced in this
  development cycle.

  There's a small chance of a silent corruption when device replace and
  NOCOW data writes happen at the same time in one block group. Metadata
  or COW data writes are unaffected.

  The extra fixup patch is there to silence an unnecessary warning"

* tag 'for-5.5-rc8-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: dev-replace: remove warning for unknown return codes when finished
  btrfs: scrub: Require mandatory block group RO for dev-replace

Pull pin control fix from Linus Walleij:
 "A single fix for the Intel Sunrisepoint pin controller that makes the
  interrupts work properly on it"

* tag 'pinctrl-v5.5-5' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: sunrisepoint: Add missing Interrupt Status register offset

Saeed Mahameed says:

====================
Mellanox, mlx5 fixes 2020-01-24

This series introduces some fixes to mlx5 driver.

Please pull and let me know if there is any problem.

Merge conflict: once merge with net-next, a contextual conflict will
appear in drivers/net/ethernet/mellanox/mlx5/core/eswitch_offloads.c
since the code moved in net-next.
To resolve, just delete ALL of the conflicting hunk from net.
So sorry for the small mess ..

For -stable v5.4:
 ('net/mlx5: Update the list of the PCI supported devices')
 ('net/mlx5: Fix lowest FDB pool size')
 ('net/mlx5e: kTLS, Fix corner-case checks in TX resync flow')
 ('net/mlx5e: kTLS, Do not send decrypted-marked SKBs via non-accel path')
 ('net/mlx5: Eswitch, Prevent ingress rate configuration of uplink rep')
 ('net/mlx5e: kTLS, Remove redundant posts in TX resync flow')
 ('net/mlx5: DR, Enable counter on non-fwd-dest objects')
 ('net/mlx5: DR, use non preemptible call to get the current cpu number')
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The fstests btrfs/011 triggered a warning at the end of device replace,

  [ 1891.998975] BTRFS warning (device vdd): failed setting block group ro: -28
  [ 1892.038338] BTRFS error (device vdd): btrfs_scrub_dev(/dev/vdd, 1, /dev/vdb) failed -28
  [ 1892.059993] ------------[ cut here ]------------
  [ 1892.063032] WARNING: CPU: 2 PID: 2244 at fs/btrfs/dev-replace.c:506 btrfs_dev_replace_start.cold+0xf9/0x140 [btrfs]
  [ 1892.074346] CPU: 2 PID: 2244 Comm: btrfs Not tainted 5.5.0-rc7-default+ #942
  [ 1892.079956] RIP: 0010:btrfs_dev_replace_start.cold+0xf9/0x140 [btrfs]

  [ 1892.096576] RSP: 0018:ffffbb58c7b3fd10 EFLAGS: 00010286
  [ 1892.098311] RAX: 00000000ffffffe4 RBX: 0000000000000001 RCX: 8888888888888889
  [ 1892.100342] RDX: 0000000000000001 RSI: ffff9e889645f5d8 RDI: ffffffff92821080
  [ 1892.102291] RBP: ffff9e889645c000 R08: 000001b8878fe1f6 R09: 0000000000000000
  [ 1892.104239] R10: ffffbb58c7b3fd08 R11: 0000000000000000 R12: ffff9e88a0017000
  [ 1892.106434] R13: ffff9e889645f608 R14: ffff9e88794e1000 R15: ffff9e88a07b5200
  [ 1892.108642] FS:  00007fcaed3f18c0(0000) GS:ffff9e88bda00000(0000) knlGS:0000000000000000
  [ 1892.111558] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [ 1892.113492] CR2: 00007f52509ff420 CR3: 00000000603dd002 CR4: 0000000000160ee0

  [ 1892.115814] Call Trace:
  [ 1892.116896]  btrfs_dev_replace_by_ioctl+0x35/0x60 [btrfs]
  [ 1892.118962]  btrfs_ioctl+0x1d62/0x2550 [btrfs]

caused by the previous patch ("btrfs: scrub: Require mandatory block
group RO for dev-replace"). Hitting ENOSPC is possible and could happen
when the block group is set read-only, preventing NOCOW writes to the
area that's being accessed by dev-replace.

This has happend with scratch devices of size 12G but not with 5G and
20G, so this is depends on timing and other activity on the filesystem.
The whole replace operation is restartable, the space state should be
examined by the user in any case.

The error code is propagated back to the ioctl caller so the kernel
warning is causing false alerts.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Ido Schimmel says:

====================
mlxsw: Offload TBF

Petr says:

In order to allow configuration of shapers on Spectrum family of
machines, recognize TBF either as root Qdisc, or as a child of ETS or
PRIO. Configure rate of maximum shaper according to TBF rate setting,
and maximum shaper burst size according to TBF burst setting.

- Patches #1 and #2 make the TBF shaper suitable for offloading.
- Patches #3, #4 and #5 are refactoring aimed at easier support of leaf
  Qdiscs in general.
- Patches #6 to #10 gradually introduce TBF offload.
- Patches #11 to #14 add selftests.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a test that runs traffic across a port throttled with TBF. The test
checks that the observed throughput is within +-5% from the installed
shaper.

To allow checking both the software datapath and the offloaded one, make
the test suitable for inclusion from driver-specific wrapper. Introduce
such wrappers for mlxsw.
Signed-off-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The function tc_rule_stats_get() fetches a packet counter of a given TC
rule. Extend it to support byte counters as well by adding an optional
argument with selector.
Signed-off-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The function busywait() is handy as a safety-latched variant of a while
loop. Many selftests deal specifically with counter values, and busywaiting
on them is likely to be rather common (it is not quite common now, but
busywait() has not been around for very long). To facilitate expressing
simply what is tested, introduce two helpers:

- until_counter_is(), which can be used as a predicate passed to
  busywait(), which holds when expression, which is itself passed as an
  argument to until_counter_is(), reaches a desired value.

- busywait_for_counter(), which is useful for waiting until a given counter
  changes "by" (as opposed to "to") a certain amount.
Signed-off-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The function humanize() is used for converting value in bits/s to a
human-friendly approximate value in Kbps, Mbps or Gbps. There is nothing
hardware-specific in that, so move the function to lib.sh.

Similarly for the rate() function, which just does a bit of math to
calculate a rate, given two counter values and a time interval.
Signed-off-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

React to the TC messages that were introduced in a preceding patch and
configure egress maximum shaper as appropriate. TBF can be used as a root
qdisc or under one of PRIO or strict ETS bands.
Signed-off-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In order to allow configuration of burst size together with shaper rate,
extend mlxsw_sp_port_ets_maxrate_set() with a burst_size argument. Convert
call sites to pass 0 (for default).
Signed-off-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Lower limit of burst size configuration is dependent on system type. Add a
datum to track the value. Initialize as appropriate in mlxsw_spX_init().
Signed-off-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As the port speeds grow, the current value of "unlimited shaper",
200000000Kbps, might become lower than the actually supported speeds. Bump
it to the maximum value that fits in the corresponding QEEC field, which is
about 2.1Tbps.
Signed-off-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The QEEC register configures scheduling elements. One of the bits of
configuration is the burst size to use for the shaper installed on the
element. Add the necessary fields to support this configuration.
Signed-off-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When the RED Qdisc is unoffloaded, it needs to reduce the reported backlog
by the amount that is in the HW, so that only the SW backlog is contained
in the counter. The same thing will need to be done by TBF, and likely any
other leaf Qdisc as well.

Extract a helper mlxsw_sp_qdisc_leaf_unoffload() and call it from
mlxsw_sp_qdisc_red_unoffload().
Signed-off-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a wrapper around mlxsw_sp_qdisc_collect_tc_stats() and
mlxsw_sp_qdisc_update_stats() for the simple case of doing both in one go:
mlxsw_sp_qdisc_get_class_stats(). Dispatch to that function from
mlxsw_sp_qdisc_get_red_stats(). This new function will be useful for other
leaf Qdiscs as well.
Signed-off-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Extract from mlxsw_sp_qdisc_get_prio_stats() two new functions:
mlxsw_sp_qdisc_collect_tc_stats() to accumulate stats for that one TC only,
and mlxsw_sp_qdisc_update_stats() that makes the stats relative to base
values stored earlier. Use them from mlxsw_sp_qdisc_get_red_stats().
Signed-off-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Invoke ndo_setup_tc as appropriate to signal init / replacement, destroying
and dumping of TBF Qdisc.
Signed-off-by: NPetr Machata <petrm@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In 2011, in commit b0460e44 ("sch_tbf: report backlog information"),
TBF started copying backlog depth from the child Qdisc before dumping, with
the motivation that the backlog was otherwise not visible in "tc -s qdisc
show".

Later, in 2016, in commit 8d5958f4 ("sch_tbf: update backlog as well"),
TBF got a full-blown backlog tracking. However it kept copying the child's
backlog over before dumping.

That line is now unnecessary, so remove it.

As shown in the following example, backlog is still reported correctly:

    # tc -s qdisc show dev veth0 invisible
    qdisc tbf 1: root refcnt 2 rate 1Mbit burst 128Kb lat 82.8s
     Sent 505475370 bytes 406985 pkt (dropped 0, overlimits 812544 requeues 0)
     backlog 81972b 66p requeues 0
    qdisc bfifo 0: parent 1:1 limit 10Mb
     Sent 505475370 bytes 406985 pkt (dropped 0, overlimits 0 requeues 0)
     backlog 81972b 66p requeues 0
Signed-off-by: NPetr Machata <petrm@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The cxgb3 driver for "Chelsio T3-based gigabit and 10Gb Ethernet
adapters" implements a custom ioctl as SIOCCHIOCTL/SIOCDEVPRIVATE in
cxgb_extension_ioctl().

One of the subcommands of the ioctl is CHELSIO_GET_MEM, which appears
to read memory directly out of the adapter and return it to userspace.
It's not entirely clear what the contents of the adapter memory
contains, but the assumption is that it shouldn't be accessible to all
users.

So add a CAP_NET_ADMIN check to the CHELSIO_GET_MEM case. Put it after
the is_offload() check, which matches two of the other subcommands in
the same function which also check for is_offload() and CAP_NET_ADMIN.

Found by Ilja by code inspection, not tested as I don't have the
required hardware.
Reported-by: NIlja Van Sprundel <ivansprundel@ioactive.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Haiyang Zhang says:

====================
hv_netvsc: Add XDP support

Add XDP support and update related document.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Added the new section in the document regarding XDP support
by hv_netvsc driver.
Signed-off-by: NHaiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds support of XDP in native mode for hv_netvsc driver, and
transparently sets the XDP program on the associated VF NIC as well.

Setting / unsetting XDP program on synthetic NIC (netvsc) propagates to
VF NIC automatically. Setting / unsetting XDP program on VF NIC directly
is not recommended, also not propagated to synthetic NIC, and may be
overwritten by setting of synthetic NIC.

The Azure/Hyper-V synthetic NIC receive buffer doesn't provide headroom
for XDP. We thought about re-use the RNDIS header space, but it's too
small. So we decided to copy the packets to a page buffer for XDP. And,
most of our VMs on Azure have Accelerated  Network (SRIOV) enabled, so
most of the packets run on VF NIC. The synthetic NIC is considered as a
fallback data-path. So the data copy on netvsc won't impact performance
significantly.

XDP program cannot run with LRO (RSC) enabled, so you need to disable LRO
before running XDP:
        ethtool -K eth0 lro off

XDP actions not yet supported:
        XDP_REDIRECT
Signed-off-by: NHaiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>