This is a fix for the port_set_speed method for the Topaz family.
Currently the same method is used as for the Peridot family, but
this is wrong for the SERDES port.

On Topaz, the SERDES port is port 5, not 9 and 10 as in Peridot.
Moreover setting alt_bit on Topaz only makes sense for port 0 (for
(differentiating 100mbps vs 200mbps). The SERDES port does not
support more than 2500mbps, so alt_bit does not make any difference.
Signed-off-by: NMarek Behún <marek.behun@nic.cz>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Sunil Goutham says:

====================
octeontx2-af: NPA and NIX blocks initialization

This patchset is a continuation to earlier submitted patch series
to add a new driver for Marvell's OcteonTX2 SOC's
Resource virtualization unit (RVU) admin function driver.

octeontx2-af: Add RVU Admin Function driver
https://www.spinics.net/lists/netdev/msg528272.html

This patch series adds logic for the following.
- Modified register polling loop to use time_before(jiffies, timeout),
  as suggested by Arnd Bergmann.
- Support to forward interface link status notifications sent by
  firmware to registered PFs mapped to a CGX::LMAC.
- Support to set CGX LMAC in loopback mode, retrieve stats,
  configure DMAC filters at CGX level etc.
- Network pool allocator (NPA) functional block initialization,
  admin queue support, NPALF aura/pool contexts memory allocation, init
  and deinit.
- Network interface controller (NIX) functional block basic init,
  admin queue support, NIXLF RQ/CQ/SQ HW contexts memory allocation,
  init and deinit.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds support for a RVU PF/VF to disable all RQ/SQ/CQ
contexts of a NIX LF via mbox. This will be used by PF/VF drivers
upon teardown or while freeing up HW resources.

A HW context which is not INIT'ed cannot be modified and a
RVU PF/VF driver may or may not INIT all the RQ/SQ/CQ contexts.
So a bitmap is introduced to keep track of enabled NIX RQ/SQ/CQ
contexts, so that only enabled hw contexts are disabled upon LF
teardown.
Signed-off-by: NGeetha sowjanya <gakula@marvell.com>
Signed-off-by: NStanislaw Kardach <skardach@marvell.com>
Signed-off-by: NSunil Goutham <sgoutham@marvell.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add support for a RVU PF/VF to submit instructions to NIX AQ
via mbox. Instructions can be to init/write/read RQ/SQ/CQ/RSS
contexts. In case of read, context will be returned as part of
response to the mbox msg received.
Signed-off-by: NSunil Goutham <sgoutham@marvell.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Allocate bitmaps and memory for PFVF mapping info for
maintaining NIX transmit scheduler queues maintenance.
PF/VF drivers will request for alloc, free e.t.c of
Tx schedulers via mailbox.
Signed-off-by: NSunil Goutham <sgoutham@marvell.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Config LSO formats for TSOv4 and TSOv6 offloads.
These formats tell HW which fields in the TCP packet's
headers have to be updated while performing segmentation
offload.

Also report PF/VF drivers the LSO format indices as part
of response to NIX_LF_ALLOC mbox msg. These indices are
used in SQE extension headers while framing SQE for pkt
transmission with TSO offload.
Signed-off-by: NSunil Goutham <sgoutham@marvell.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Upon receiving NIX_LF_ALLOC mbox message allocate memory for
NIXLF's CQ, SQ, RQ, CINT, QINT and RSS HW contexts and configure
respective base iova HW. Enable caching of contexts into NIX NDC.

Return SQ buffer (SQB) size, this PF/VF MAC address etc info
e.t.c to the mbox msg sender.
Signed-off-by: NSunil Goutham <sgoutham@marvell.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Initialize NIX admin queue (AQ) i.e alloc memory for
AQ instructions and for the results. All NIX LFs will submit
instructions to AQ to init/write/read RQ/SQ/CQ/RSS contexts
and in case of read, get context from result memory.

Also before configuring/using NIX block calibrate X2P bus
and check if NIX interfaces like CGX and LBK are in active
and working state.
Signed-off-by: NSunil Goutham <sgoutham@marvell.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds support for a RVU PF/VF to disable all Aura/Pool
contexts of a NPA LF via mbox. This will be used by PF/VF drivers
upon teardown or while freeing up HW resources.

A HW context which is not INIT'ed cannot be modified and a
RVU PF/VF driver may or may not INIT all the Aura/Pool contexts.
So a bitmap is introduced to keep track of enabled NPA Aura/Pool
contexts, so that only enabled hw contexts are disabled upon LF
teardown.
Signed-off-by: NGeetha sowjanya <gakula@marvell.com>
Signed-off-by: NStanislaw Kardach <skardach@marvell.com>
Signed-off-by: NSunil Goutham <sgoutham@marvell.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add support for a RVU PF/VF to submit instructions to NPA AQ
via mbox. Instructions can be to init/write/read Aura/Pool/Qint
contexts. In case of read, context will be returned as part of
response to the mbox msg received.
Signed-off-by: NSunil Goutham <sgoutham@marvell.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Upon receiving NPA_LF_ALLOC mbox message allocate memory for
NPALF's aura, pool and qint contexts and configure the same
to HW. Enable caching of contexts into NPA NDC.

Return pool related info like stack size, num pointers per
stack page e.t.c to the mbox msg sender.
Signed-off-by: NSunil Goutham <sgoutham@marvell.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Initialize NPA admin queue (AQ) i.e alloc memory for
AQ instructions and for the results. All NPA LFs will submit
instructions to AQ to init/write/read Aura/Pool contexts
and in case of read, get context from result memory.

Added some common APIs for allocating memory for a queue
and get IOVA in return, these APIs will be used by
NIX AQ and for other purposes.
Signed-off-by: NSunil Goutham <sgoutham@marvell.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add support to enable or disable internal loopback mode in CGX.
New mbox IDs CGX_INTLBK_ENABLE/DISABLE added for this.
Signed-off-by: NGeetha sowjanya <gakula@marvell.com>
Signed-off-by: NLinu Cherian <lcherian@marvell.com>
Signed-off-by: NSunil Goutham <sgoutham@marvell.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Upon receiving notification from firmware the CGX event handler
in the AF driver gets the current link info such as status, speed,
duplex etc from CGX driver and sends it across to PFs who have
registered to receive such notifications.

To support above
 - Mbox messaging support for sending msgs from AF to PF has been added.
 - Added mbox msgs so that PFs can register/unregister for link events.
 - Link notifications are sent to PF under two scenarioss.
  1. When a asynchronous link change notification is received from
     firmware with notification flag turned on for that PF.
  2. Upon notification turn on request, the current link status is
     send to the PF.

Also added a new mailbox msg using which RVU PF/VF can retrieve
their mapped CGX LMAC's current link info. Link info includes
status, speed, duplex and lmac type.
Signed-off-by: NLinu Cherian <lcherian@marvell.com>
Signed-off-by: NSunil Goutham <sgoutham@marvell.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds support for setting MAC address filters in CGX
for PF interfaces. Also PF interfaces can be put in promiscuous
mode. Dataplane PFs access this functionality using mailbox
messages to the AF driver.
Signed-off-by: NVidhya Raman <vraman@marvell.com>
Signed-off-by: NStanislaw Kardach <skardach@marvell.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds support for a RVU PF/VF driver to retrieve
it's mapped CGX LMAC Rx and Tx stats from AF via mbox.
New mailbox msg is added is added.
Signed-off-by: NChristina Jacob <cjacob@marvell.com>
Signed-off-by: NSunil Goutham <sgoutham@marvell.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Added new mailbox msgs for RVU PF/VFs to request AF
to enable/disable their mapped CGX::LMAC Rx & Tx.
Signed-off-by: NSunil Goutham <sgoutham@marvell.com>
Signed-off-by: NLinu Cherian <lcherian@marvell.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Instead of looping on a integer timeout, use time_before(jiffies),
so that maximum poll time is capped.
Signed-off-by: NSunil Goutham <sgoutham@marvell.com>
Suggested-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Ido Schimmel says:

====================
mlxsw: Add VxLAN support

This patchset adds support for VxLAN offload in the mlxsw driver.

With regards to the forwarding plane, VxLAN support is composed from two
main parts: Encapsulation and decapsulation.

In the device, NVE encapsulation (and VxLAN in particular) takes place
in the bridge. A packet can be encapsulated using VxLAN either because
it hit an FDB entry that forwards it to the router with the IP of the
remote VTEP or because it was flooded, in which case it is sent to a
list of remote VTEPs (in addition to local ports). In either case, the
VNI is derived from the filtering identifier (FID) the packet was
classified to at ingress and the underlay source IP is taken from a
device global configuration.

VxLAN decapsulation takes place in the underlay router, where packets
that hit a local route that corresponds to the source IP of the local
VTEP are decapsulated and injected to the bridge. The packets are
classified to a FID based on the VNI they came with.

The first six patches export the required APIs in the VxLAN and mlxsw
drivers in order to allow for the introduction of the NVE core in the
next two patches. The NVE core is designed to support a variety of NVE
encapsulations (e.g., VxLAN, NVGRE) and different ASICs, but currently
only VxLAN and Spectrum are supported. Spectrum-2 support will be added
in the future.

The last 10 patches add support for VxLAN decapsulation and
encapsulation and include the addition of the required switchdev APIs in
the VxLAN driver. These APIs allow capable drivers to get a notification
about the addition / deletion of FDB entries to / from the VxLAN's FDB.

Subsequent patchset will add selftests (generic and mlxsw-specific),
data plane learning, FDB extack and vetoing and support for VLAN-aware
bridges (one VNI per VxLAN device model).

v2:
* Implement netif_is_vxlan() using rtnl_link_ops->kind (Jakub & Stephen)
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In the device, VxLAN encapsulation takes place in the FDB table where
certain {MAC, FID} entries are programmed with an underlay unicast IP.
MAC addresses that are not programmed in the FDB are flooded to the
relevant local ports and also to a list of underlay unicast IPs that are
programmed using the all zeros MAC address in the VxLAN driver.

One difference between the hardware and software data paths is the fact
that in the software data path there are two FDB lookups prior to the
encapsulation of the packet. First in the bridge's FDB table using {MAC,
VID} and another in the VxLAN's FDB table using {MAC, VNI}.

Therefore, when a new VxLAN FDB entry is notified, it is only programmed
to the device if there is a corresponding entry in the bridge's FDB
table. Similarly, when a new bridge FDB entry pointing to the VxLAN
device is notified, it is only programmed to the device if there is a
corresponding entry in the VxLAN's FDB table.

Note that the above scheme will result in a discrepancy between both
data paths if only one FDB table is populated in the software data path.
For example, if only the bridge's FDB is populated with an entry
pointing to a VxLAN device, then a packet hitting the entry will only be
flooded by the kernel to remote VTEPs whereas the device will also flood
the packets to other local ports member in the VLAN.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Reviewed-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Enslavement of VxLAN devices to offloaded bridges was never forbidden by
mlxsw, but this patch makes sure the required configuration is performed
in order to allow VxLAN encapsulation and decapsulation to take place in
the device.

The patch handles both the case where a VxLAN device is enslaved to an
already offloaded bridge and the case where the first mlxsw port is
enslaved to a bridge that already has VxLAN device configured.

Invalid configurations are sanitized and an error string is returned via
extack.

Since encapsulation and decapsulation do not occur when the VxLAN device
is down, the driver makes sure to enable / disable these functionalities
based on NETDEV_PRE_UP and NETDEV_DOWN events.

Note that NETDEV_PRE_UP is used in favor of NETDEV_UP, as the former
allows to veto the operation, if necessary.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Reviewed-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently, an FDB entry only ceases being offloaded when it is deleted.
This changes with VxLAN encapsulation.

Devices capable of performing VxLAN encapsulation usually have only one
FDB table, unlike the software data path which has two - one in the
bridge driver and another in the VxLAN driver.

Therefore, bridge FDB entries pointing to a VxLAN device are only
offloaded if there is a corresponding entry in the VxLAN FDB.

Allow clearing the offload indication in case the corresponding entry
was deleted from the VxLAN FDB.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Reviewed-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When notifications are sent about FDB activity, and an FDB entry with
several remotes is removed, the notification is sent only for the first
destination. That makes it impossible to distinguish between the case
where only this first remote is removed, and the one where the FDB entry
is removed as a whole.

Therefore send one notification for each remote of a removed FDB entry.
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>

Offloaded bridge FDB entries are marked with NTF_OFFLOADED. Implement a
similar mechanism for VXLAN, where a given remote destination can be
marked as offloaded.

To that end, introduce a new event, SWITCHDEV_VXLAN_FDB_OFFLOADED,
through which the marking is communicated to the vxlan driver. To
identify which RDST should be marked as offloaded, an
switchdev_notifier_vxlan_fdb_info is passed to the listeners. The
"offloaded" flag in that object determines whether the offloaded mark
should be set or cleared.

When sending offloaded FDB entries over netlink, mark them with
NTF_OFFLOADED.
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>

A switchdev-capable driver that is aware of VXLAN may need to query
VXLAN FDB. In the particular case of mlxsw, this functionality is
limited to querying UC FDBs. Those being easier to deal with than the
general case of RDST chain traversal, introduce an interface to query
specifically UC FDBs: vxlan_fdb_find_uc().
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>

When offloading VXLAN devices, drivers need to know about events in
VXLAN FDB database. Since VXLAN models a bridge, it is natural to
distribute the VXLAN FDB notifications using the pre-existing switchdev
notification mechanism.

To that end, introduce two new notification types:
SWITCHDEV_VXLAN_FDB_ADD_TO_DEVICE and SWITCHDEV_VXLAN_FDB_DEL_TO_DEVICE.
Introduce a new function, vxlan_fdb_switchdev_call_notifiers() to send
the new notifier types, and a struct switchdev_notifier_vxlan_fdb_info
to communicate the details of the FDB entry under consideration.

Invoke the new function from vxlan_fdb_notify().
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>

Add the ability to determine whether a netdev is a VxLAN netdev by
calling the above mentioned function that checks the netdev's
rtnl_link_ops.

This will allow modules to identify netdev events involving a VxLAN
netdev and act accordingly. For example, drivers capable of VxLAN
offload will need to configure the underlying device when a VxLAN netdev
is being enslaved to an offloaded bridge.

Convert nfp to use the newly introduced helper.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Reviewed-by: NPetr Machata <petrm@mellanox.com>
Acked-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When a local route that matches the source IP of an offloaded NVE tunnel
is notified, the driver needs to program it to perform NVE decapsulation
instead of merely trapping packets to the CPU.

This patch complements "mlxsw: spectrum_router: Enable local routes
promotion to perform NVE decap" where existing local routes were
promoted to perform NVE decapsulation.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Reviewed-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

802.1D FIDs are used to represent VLAN-unaware bridges and currently
this is the only type of FID that supports NVE configuration.

Since the NVE tunnel device does not take a reference on the FID, it is
possible for the FID to be destroyed when it still has NVE
configuration.

Therefore, when destroying the FID make sure to disable its NVE
configuration.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Reviewed-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The common NVE core expects each encapsulation type to implement a
certain set of operations that are specific to this type and the
currently used ASIC. These operations include things such as the ability
to determine whether a certain NVE configuration can be offloaded and
ASIC-specific initialization for this type.

Implement these operations for VxLAN on the Spectrum ASIC. Spectrum-2
support will be added by a future patchset.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Reviewed-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The Spectrum ASIC supports different types of NVE encapsulations (e.g.,
VxLAN, NVGRE) with more types to be supported by future ASICs.

Despite being different, all these encapsulations share some common
functionality such as the enablement of NVE encapsulation on a given
filtering identifier (FID) and the addition of remote VTEPs to the
linked-list of VTEPs that traffic should be flooded to.

Implement this common core and allow different ASICs to register
different operations for different encapsulation types.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Reviewed-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Drivers that support tunnel decapsulation (IPinIP or NVE) need to
configure the underlying device to conform to the behavior outlined in
RFC 6040 with respect to the ECN bits.

This behavior is implemented by INET_ECN_decapsulate() which requires an
skb to be passed where the ECN CE bit can be potentially set. Since
these drivers do not need to mark an skb, but only configure the device
to do so, factor out the business logic to __INET_ECN_decapsulate() and
potentially perform the marking in INET_ECN_decapsulate().

This allows drivers to invoke __INET_ECN_decapsulate() and configure the
device.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Suggested-by: NPetr Machata <petrm@mellanox.com>
Reviewed-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Drivers that support VxLAN offload need to be able to sanitize the
configuration of the VxLAN device and accept / reject its offload.

For example, mlxsw requires that the local IP of the VxLAN device be set
and that packets be flooded to unicast IP(s) and not to a multicast
group.

Expose the functions that perform such checks.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Reviewed-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In the device, different VRFs (routing tables) are represented using
different virtual routers (VRs) and thus the kernel's table IDs are
mapped to VR IDs.

Allow internal users of the IP router to query the VR ID based on a
kernel table ID.

This is needed - for example - when configuring the underlay VR where
VxLAN encapsulated packets will undergo an L3 lookup. In this case, the
kernel's table ID is derived from the VxLAN device's configuration.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Reviewed-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When an NVE tunnel with an IP underlay (e.g., VxLAN) is configured the
local route to the tunnel's source IP needs to be promoted to perform
NVE decapsulation.

Expose an API in the unicast IP router to promote / demote local routes.

The case where a local route is configured after the creation of the NVE
tunnel will be handled in a subsequent patch in the set.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Reviewed-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Current APIs only allow looking for a FID and creating it in case it
does not exist.

With VxLAN, in case the bridge to which the VxLAN device was enslaved
does not already have a corresponding FID, then it means that something
went wrong that we need to be aware of.

Add an API to look up a FID, but without creating it in order to catch
above-mentioned situation.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Reviewed-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In the device, the VNI and the list of remote VTEPs a packet should be
flooded to is a property of the filtering identifier (FID).

During encapsulation, the VNI is taken from the FID the packet was
classified to. During decapsulation, the overlay packet is injected into
a bridge and classified to a FID based on the VNI it came with.

Allow NVE configuration for a FID. Currently, this is only supported
with 802.1D FIDs which are used for VLAN-unaware bridges. However, NVE
configuration is going to be supported with 802.1Q FIDs which is why the
related fields are placed in the common FID struct.

Since the device requires a 1:1 mapping between FID and VNI, the driver
maintains a hashtable keyed by VNI and checks if the VNI is already
associated with an existing FID.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Reviewed-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Eric reported that syzkaller triggered a splat in tcp_cleanup_ulp()
where assertion sock_owned_by_me() failed. This happened through
inet_csk_prepare_forced_close() first releasing the socket lock,
then calling into tcp_done(newsk) which is called after the
inet_csk_prepare_forced_close() and therefore without the socket
lock held. The sock_owned_by_me() assertion can generally be
removed as the only place where tcp_cleanup_ulp() is called from
now is out of inet_csk_destroy_sock() -> sk->sk_prot->destroy()
where socket is in dead state and unreachable. Therefore, add a
comment why the check is not needed instead.

Fixes: 8b9088f8 ("tcp, ulp: enforce sock_owned_by_me upon ulp init and cleanup")
Reported-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Yunsheng Lin says:

====================
Some cleanup and bugfix for desc filling

When retransmiting packets, skb_cow_head which is called in
hns3_set_tso may clone a new header. And driver will clear the
checksum of the header after doing DMA map, so HW will read the
old header whose L3 checksum is not cleared and calculate a
wrong L3 checksum.

Also When sending a big fragment using multiple buffer descriptor,
hns3 does one maping, but do multiple unmapping when tx is done,
which may cause unmapping problem.

This patchset does some cleanup before fixing the above problem.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When sending a big fragment using multiple buffer descriptor,
hns3 does one maping, but do multiple unmapping when tx is done,
which may cause unmapping problem.

To fix it, this patch makes sure the value of desc_cb.length of
the non-first bd is zero. If desc_cb.length is zero, we do not
unmap the buffer.

Fixes: 76ad4f0e ("net: hns3: Add support of HNS3 Ethernet Driver for hip08 SoC")
Signed-off-by: NFuyun Liang <liangfuyun1@huawei.com>
Signed-off-by: NPeng Li <lipeng321@huawei.com>
Signed-off-by: NYunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>