bnx2x_set_features() forces a driver reload if GRO setting is changed.

A reload makes the ethernet port unresponsive for about 5 seconds.

This is not needed in the common case LRO is enabled, as LRO
(TPA_ENABLE_FLAG) has precedence over GRO (GRO_ENABLE_FLAG)

Tested:
 Verified that "ethtool -K eth0 gro {on|off}" doesn't blackout
 the NIC anymore

Google-Bug-Id: 8440442
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Dmitry Kravkov <dmitry@broadcom.com>
Acked-by: NDmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Nithin Nayak Sujir says:

====================
This series adds support for modifying EEE settings via ethtool. Since this can
impact Link Flap Avoidance, the driver pulls the current hardware settings if
LFA is enabled. This is similar to how we do the link settings to avoid a flap.

v2: Fixes pointed out by Ben Hutchings.
 - Use MDIO_AN_EEE_LPABLE to set the lp_advertised field.
 - Check that tx_lpi_timer is within valid range.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Reviewed-by: NBen Li <benli@broadcom.com>
Signed-off-by: NMichael Chan <mchan@broadcom.com>
Signed-off-by: NNithin Nayak Sujir <nsujir@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

eee_config_ok() was checking only for mismatch in advertised settings.
This patch expands the scope of eee_config_ok() to check for mismatch in
the other eee settings. On mismatch we will require a call to
tg3_setup_eee() to push the configured settings to the hardware.
Reviewed-by: NBen Li <benli@broadcom.com>
Signed-off-by: NMichael Chan <mchan@broadcom.com>
Signed-off-by: NNithin Nayak Sujir <nsujir@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add tg3_eee_pull_config() to pull the settings from the hardware and
populate the eee structure.

If Link Flap Avoidance is enabled, we pull the eee settings from the hw
so as not to cause a phy reset on eee config mismatch later. This
requires moving down tg3_setup_eee() below the tg3_pull_config() to not
trample existing settings.
Reviewed-by: NBen Li <benli@broadcom.com>
Signed-off-by: NMichael Chan <mchan@broadcom.com>
Signed-off-by: NNithin Nayak Sujir <nsujir@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add an eee structure and update it with eee settings. This will be used
for set/get_eee operations. Add common function tg3_setup_eee() that
will be used in the subsequent patches.
Reviewed-by: NBen Li <benli@broadcom.com>
Signed-off-by: NMichael Chan <mchan@broadcom.com>
Signed-off-by: NNithin Nayak Sujir <nsujir@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Do not leak starting address of BPF JIT code for non root users,
as it might help intruders to perform an attack.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Cc: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

hpa bringed into my attention some security related issues
with BPF JIT on x86.

This patch makes sure the bpf generated code is marked read only,
as other kernel text sections.

It also splits the unused space (we vmalloc() and only use a fraction of
the page) in two parts, so that the generated bpf code not starts at a
known offset in the page, but a pseudo random one.

Refs:
http://mainisusuallyafunction.blogspot.com/2012/11/attacking-hardened-linux-systems-with.htmlReported-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reviewed-by: NDaniel Borkmann <dborkman@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

tcp_timeout_skb() was intended to trigger fast recovery on timeout,
unfortunately in reality it often causes spurious retransmission
storms during fast recovery. The particular sign is a fast retransmit
over the highest sacked sequence (SND.FACK).

Currently the RTO timer re-arming (as in RFC6298) offers a nice cushion
to avoid spurious timeout: when SND.UNA advances the sender re-arms
RTO and extends the timeout by icsk_rto. The sender does not offset
the time elapsed since the packet at SND.UNA was sent.

But if the next (DUP)ACK arrives later than ~RTTVAR and triggers
tcp_fastretrans_alert(), then tcp_timeout_skb() will mark any packet
sent before the icsk_rto interval lost, including one that's above the
highest sacked sequence. Most likely a large part of scorebard will be
marked.

If most packets are not lost then the subsequent DUPACKs with new SACK
blocks will cause the sender to continue to retransmit packets beyond
SND.FACK spuriously. Even if only one packet is lost the sender may
falsely retransmit almost the entire window.

The situation becomes common in the world of bufferbloat: the RTT
continues to grow as the queue builds up but RTTVAR remains small and
close to the minimum 200ms. If a data packet is lost and the DUPACK
triggered by the next data packet is slightly delayed, then a spurious
retransmission storm forms.

As the original comment on tcp_timeout_skb() suggests: the usefulness
of this feature is questionable. It also wastes cycles walking the
sack scoreboard and is actually harmful because of false recovery.

It's time to remove this.
Signed-off-by: NYuchung Cheng <ycheng@google.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Acked-by: NNeal Cardwell <ncardwell@google.com>
Acked-by: NNandita Dukkipati <nanditad@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch removes mentioning the sysfsf net_device weight attribute
(class/net/<device>/weight)
in Documentation/sysctl/net.txt, since the net sysfs weight attribute
was removed by the following patch:

[NET]: Make NAPI polling independent of struct net_device objects
 bea3348eSigned-off-by: NRami Rosen <ramirose@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds the support of peer address for IPv6. For example, it is
possible to specify the remote end of a 6inY tunnel.
This was already possible in IPv4:
 ip addr add ip1 peer ip2 dev dev1

The peer address is specified with IFA_ADDRESS and the local address with
IFA_LOCAL (like explained in include/uapi/linux/if_addr.h).
Note that the API is not changed, because before this patch, it was not
possible to specify two different addresses in IFA_LOCAL and IFA_REMOTE.
There is a small change for the dump: if the peer is different from ::,
IFA_ADDRESS will contain the peer address instead of the local address.
Signed-off-by: NNicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

module_free()/vfree() takes care of details, we no longer need a wrapper
and a work_struct.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This was added by commit 59b9997b (Revert "net: maintain namespace
isolation between vlan and real device").
In fact, before the initial commit - the one that is reverted -, this
statement was not present.
'skb->dev = dev' is already done in eth_type_trans(), which is call just
after.
Spotted-by: NAlain Ritoux <alain.ritoux@6wind.com>
Signed-off-by: NNicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch enables user to unload netback module, which is useful when user
wants to upgrade to a newer netback module without rebooting the host.

Netfront cannot handle netback removal event. As we cannot fix all possible
frontends we add module get / put along with vif get / put to avoid
mis-unloading of netback. To unload netback module, user needs to shutdown all
VMs or migrate them to another host or unplug all vifs before hand.
Signed-off-by: NWei Liu <wei.liu2@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>¬
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The array mmap_pages is never touched in the initialization function. This is
remnant of mapping mechanism, which does not exist upstream. In current
upstream code this array only tracks usage of pages inside netback. Those
pages are allocated when contructing a SKB and passed directly to network
subsystem.
Signed-off-by: NWei Liu <wei.liu2@citrix.com>
Acked-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It looks like we can call module_free()/vfree() from softirq context,
so no longer need a wrapper and a work_struct.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

module_usb_driver() eliminates boilerplate and simplifies the code.
Signed-off-by: NSachin Kamat <sachin.kamat@linaro.org>
Cc: Realtek linux nic maintainers <nic_swsd@realtek.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

version.h header inclusion is not necessary as detected by
checkversion.pl.
Signed-off-by: NSachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The commit 823aa873
  Author: stephen hemminger <stephen@networkplumber.org>
  Date:   Sat Apr 27 11:31:57 2013 +0000

    vxlan: allow choosing destination port per vxlan

introduced per-vxlan UDP port configuration but only did half of the
necessary work.  It added per vxlan destination for sending, but
overlooked the handling of multiple ports for incoming traffic.

This patch changes the listening port management to handle multiple
incoming UDP ports. The earlier per-namespace structure is now a hash
list per namespace.

It is also now possible to define the same virtual network id
but with different UDP port values which can be useful for migration.
Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Clean up the code a bit to initialize the variables directly when
defining them.
Signed-off-by: NEmilio López <emilio@elopez.com.ar>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Clean up the code a bit to initialize the variables directly when
defining them.
Signed-off-by: NEmilio López <emilio@elopez.com.ar>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Clean up the code a bit to initialize the variables directly when
defining them.
Signed-off-by: NEmilio López <emilio@elopez.com.ar>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Clean up the code a bit to initialize the variables directly when
defining them.
Signed-off-by: NEmilio López <emilio@elopez.com.ar>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Marc Kleine-Budde says:

====================
this is a pull-request for net-next/master. It consists of 4 patches by
Jingoo Han, which remove the unnecessary platform_set_drvdata() and a
patch by Laurent Navet converting the grcan driver to use
devm_ioremap_resource().
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch removes unnecessary #if 0 code from 3c509.c
Signed-off-by: Ngovindarajulu.v <govindarajulu90@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

devm_ioremap_resource does sanity checks on the given resource. No need to
duplicate this in the driver.
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

tcp_fixup_rcvbuf() contains a loop to estimate initial socket
rcv space needed for a given mss. With large MTU (like 64K on lo),
we can loop ~500 times and consume a lot of cpu cycles.

perf top of 200 concurrent netperf -t TCP_CRR

5.62%  netperf  [kernel.kallsyms]  [k] tcp_init_buffer_space
1.71%  netperf  [kernel.kallsyms]  [k] _raw_spin_lock
1.55%  netperf  [kernel.kallsyms]  [k] kmem_cache_free
1.51%  netperf  [kernel.kallsyms]  [k] tcp_transmit_skb
1.50%  netperf  [kernel.kallsyms]  [k] tcp_ack

Lets use a 100% factor, and remove the loop.

100% is needed anyway for tcp_adv_win_scale=1
default value, and is also the maximum factor.

Refs: commit b49960a0
      ("tcp: change tcp_adv_win_scale and tcp_rmem[2]")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Acked-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The driver core clears the driver data to NULL after device_release
or on probe failure, since commit 0998d063
(device-core: Ensure drvdata = NULL when no driver is bound).
Thus, it is not needed to manually clear the device driver data to NULL.
Signed-off-by: NJingoo Han <jg1.han@samsung.com>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

The driver core clears the driver data to NULL after device_release
or on probe failure, since commit 0998d063
(device-core: Ensure drvdata = NULL when no driver is bound).
Thus, it is not needed to manually clear the device driver data to NULL.
Signed-off-by: NJingoo Han <jg1.han@samsung.com>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

The driver core clears the driver data to NULL after device_release
or on probe failure, since commit 0998d063
(device-core: Ensure drvdata = NULL when no driver is bound).
Thus, it is not needed to manually clear the device driver data to NULL.
Signed-off-by: NJingoo Han <jg1.han@samsung.com>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

The driver core clears the driver data to NULL after device_release
or on probe failure, since commit 0998d063
(device-core: Ensure drvdata = NULL when no driver is bound).
Thus, it is not needed to manually clear the device driver data to NULL.
Signed-off-by: NJingoo Han <jg1.han@samsung.com>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

Replace a call to deprecated devm_request_and_ioremap by devm_ioremap_resource.
dev_err() message is no more needed since it's already displayed in
devm_ioremap_resource().
Signed-off-by: NLaurent Navet <laurent.navet@gmail.com>
Acked-by: NAndreas Larsson <andreas@gaisler.com>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

Pull networking fixes from David Miller:
 "Several small bug fixes all over:

   1) be2net driver uses wrong payload length when submitting MAC list
      get requests to the chip.  From Sathya Perla.

   2) Fix mwifiex memory leak on driver unload, from Amitkumar Karwar.

   3) Prevent random memory access in batman-adv, from Marek Lindner.

   4) batman-adv doesn't check for pskb_trim_rcsum() errors, also from
      Marek Lindner.

   5) Fix fec crashes on rapid link up/down, from Frank Li.

   6) Fix inner protocol grovelling in GSO, from Pravin B Shelar.

   7) Link event validation fix in qlcnic from Rajesh Borundia.

   8) Not all FEC chips can support checksum offload, fix from Shawn
      Guo.

   9) EXPORT_SYMBOL + inline doesn't make any sense, from Denis Efremov.

  10) Fix race in passthru mode during device removal in macvlan, from
      Jiri Pirko.

  11) Fix RCU hash table lookup socket state race in ipv6, leading to
      NULL pointer derefs, from Eric Dumazet.

  12) Add several missing HAS_DMA kconfig dependencies, from Geert
      Uyttterhoeven.

  13) Fix bogus PCI resource management in 3c59x driver, from Sergei
      Shtylyov.

  14) Fix info leak in ipv6 GRE tunnel driver, from Amerigo Wang.

  15) Fix device leak in ipv6 IPSEC policy layer, from Cong Wang.

  16) DMA mapping leak fix in qlge from Thadeu Lima de Souza Cascardo.

  17) Missing iounmap on probe failure in bna driver, from Wei Yongjun."

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (40 commits)
  bna: add missing iounmap() on error in bnad_init()
  qlge: fix dma map leak when the last chunk is not allocated
  xfrm6: release dev before returning error
  ipv6,gre: do not leak info to user-space
  virtio_net: use default napi weight by default
  emac: Fix EMAC soft reset on 460EX/GT
  3c59x: fix PCI resource management
  caif: CAIF_VIRTIO should depend on HAS_DMA
  net/ethernet: MACB should depend on HAS_DMA
  net/ethernet: ARM_AT91_ETHER should depend on HAS_DMA
  net/wireless: ATH9K should depend on HAS_DMA
  net/ethernet: STMMAC_ETH should depend on HAS_DMA
  net/ethernet: NET_CALXEDA_XGMAC should depend on HAS_DMA
  ipv6: do not clear pinet6 field
  macvlan: fix passthru mode race between dev removal and rx path
  ipv4: ip_output: remove inline marking of EXPORT_SYMBOL functions
  net/mlx4: Strengthen VLAN tags/priorities enforcement in VST mode
  net/mlx4_core: Add missing report on VST and spoof-checking dev caps
  net: fec: enable hardware checksum only on imx6q-fec
  qlcnic: Fix validation of link event command.
  ...

Add the missing iounmap() before return from bnad_init()
in the error handling case.
Introduced by commit 01b54b14
(bna: tx rx cleanup fix).
Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

qlge allocates chunks from a page that it maps and unmaps that page when
the last chunk is released. When the driver is unloaded or the card is
removed, all chunks are released and the page is unmapped for the last
chunk.

However, when the last chunk of a page is not allocated and the device
is removed, that page is not unmapped. In fact, its last reference is
not put and there's also a page leak. This bug prevents a device from
being properly hotplugged.

When the DMA API debug option is enabled, the following messages show
the pending DMA allocation after we remove the driver.

This patch fixes the bug by unmapping and putting the page from the ring
if its last chunk has not been allocated.

pci 0005:98:00.0: DMA-API: device driver has pending DMA allocations while released from device [count=1]
One of leaked entries details: [device address=0x0000000060a80000] [size=65536 bytes] [mapped with DMA_FROM_DEVICE] [mapped as page]
------------[ cut here ]------------
WARNING: at lib/dma-debug.c:746
Modules linked in: qlge(-) rpadlpar_io rpaphp pci_hotplug fuse [last unloaded: qlge]
NIP: c0000000003fc3ec LR: c0000000003fc3e8 CTR: c00000000054de60
REGS: c0000003ee9c74e0 TRAP: 0700   Tainted: G           O  (3.7.2)
MSR: 8000000000029032 <SF,EE,ME,IR,DR,RI>  CR: 28002424  XER: 00000001
SOFTE: 1
CFAR: c0000000007a39c8
TASK = c0000003ee8d5c90[8406] 'rmmod' THREAD: c0000003ee9c4000 CPU: 31
GPR00: c0000000003fc3e8 c0000003ee9c7760 c000000000c789f8 00000000000000ee
GPR04: 0000000000000000 00000000000000ef 0000000000004000 0000000000010000
GPR08: 00000000000000be c000000000b22088 c000000000c4c218 00000000007c0000
GPR12: 0000000028002422 c00000000ff26c80 0000000000000000 000001001b0f1b40
GPR16: 00000000100cb9d8 0000000010093088 c000000000cdf910 0000000000000001
GPR20: 0000000000000000 c000000000dbfc00 0000000000000000 c000000000dbfb80
GPR24: c0000003fafc9d80 0000000000000001 000000000001ff80 c0000003f38f7888
GPR28: c000000000ddfc00 0000000000000400 c000000000bd7790 c000000000ddfb80
NIP [c0000000003fc3ec] .dma_debug_device_change+0x22c/0x2b0
LR [c0000000003fc3e8] .dma_debug_device_change+0x228/0x2b0
Call Trace:
[c0000003ee9c7760] [c0000000003fc3e8] .dma_debug_device_change+0x228/0x2b0 (unreliable)
[c0000003ee9c7840] [c00000000079a098] .notifier_call_chain+0x78/0xf0
[c0000003ee9c78e0] [c0000000000acc20] .__blocking_notifier_call_chain+0x70/0xb0
[c0000003ee9c7990] [c0000000004a9580] .__device_release_driver+0x100/0x140
[c0000003ee9c7a20] [c0000000004a9708] .driver_detach+0x148/0x150
[c0000003ee9c7ac0] [c0000000004a8144] .bus_remove_driver+0xc4/0x150
[c0000003ee9c7b60] [c0000000004aa58c] .driver_unregister+0x8c/0xe0
[c0000003ee9c7bf0] [c0000000004090b4] .pci_unregister_driver+0x34/0xf0
[c0000003ee9c7ca0] [d000000002231194] .qlge_exit+0x1c/0x34 [qlge]
[c0000003ee9c7d20] [c0000000000e36d8] .SyS_delete_module+0x1e8/0x290
[c0000003ee9c7e30] [c0000000000098d4] syscall_exit+0x0/0x94
Instruction dump:
7f26cb78 e818003a e87e81a0 e8f80028 e9180030 796b1f24 78001f24 7d6a5a14
7d2a002a e94b0020 483a7595 60000000 <0fe00000> 2fb80000 40de0048 80120050
---[ end trace 4294f9abdb01031d ]---
Mapped at:
 [<d000000002222f54>] .ql_update_lbq+0x384/0x580 [qlge]
 [<d000000002227bd0>] .ql_clean_inbound_rx_ring+0x300/0xc60 [qlge]
 [<d0000000022288cc>] .ql_napi_poll_msix+0x39c/0x5a0 [qlge]
 [<c0000000006b3c50>] .net_rx_action+0x170/0x300
 [<c000000000081840>] .__do_softirq+0x170/0x300
Signed-off-by: NThadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>
Acked-by: NJitendra Kalsaria <Jitendra.kalsaria@qlogic.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Pull spi updates from Mark Brown:
 "A few driver specific fixes plus improved error handling in the
  generic DT GPIO chipselect handling - not exciting but useful."

* tag 'spi-v3.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
  spi/spi-atmel: BUG: fix doesn' support 16 bits transfers using PIO
  spi/davinci: fix module build error
  spi: Return error from of_spi_register_master on bad "cs-gpios" property
  spi: Initialize cs_gpio and cs_gpios with -ENOENT
  spi/atmel: fix speed_hz check in atmel_spi_transfer()

Pull drm fixes from Dave Airlie:
 "Just a few straggling fixes I hoovered up, and an intel fixes pull
  from Daniel which fixes some regressions, and some mgag200 fixes from
  Matrox."

* 'drm-next' of git://people.freedesktop.org/~airlied/linux:
  drm/mgag200: Fix framebuffer base address programming
  drm/mgag200: Convert counter delays to jiffies
  drm/mgag200: Fix writes into MGA1064_PIX_CLK_CTL register
  drm/mgag200: Don't change unrelated registers during modeset
  drm: Only print a debug message when the polled connector has changed
  drm: Make the HPD status updates debug logs more readable
  drm: Use names of ioctls in debug traces
  drm: Remove pointless '-' characters from drm_fb_helper documentation
  drm: Add kernel-doc for drm_fb_helper_funcs->initial_config
  drm: refactor call to request_module
  drm: Don't prune modes loudly when a connector is disconnected
  drm: Add missing break in the command line mode parsing code
  drm/i915: clear the stolen fb before resuming
  Revert "drm/i915: Calculate correct stolen size for GEN7+"
  drm/i915: hsw: fix link training for eDP on port-A
  Revert "drm/i915: revert eDP bpp clamping code changes"
  drm: don't check modeset locks in panic handler
  drm/i915: Fix pipe enabled mask for pipe C in WM calculations
  drm/mm: fix dump table BUG
  drm/i915: Always normalize return timeout for wait_timeout_ioctl

Pull virtio/lguest fixes from Rusty Russell:
 "Missing license tag and some fallout from the lguest pagetable rework"

* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
  lguest: clear cached last cpu when guest_set_pgd() called.
  Add missing module license tag to vring helpers.