Commit Graph

42 Commits

Author SHA1 Message Date
Linus Torvalds
6ba74014c1 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6: (1443 commits)
  phy/marvell: add 88ec048 support
  igb: Program MDICNFG register prior to PHY init
  e1000e: correct MAC-PHY interconnect register offset for 82579
  hso: Add new product ID
  can: Add driver for esd CAN-USB/2 device
  l2tp: fix export of header file for userspace
  can-raw: Fix skb_orphan_try handling
  Revert "net: remove zap_completion_queue"
  net: cleanup inclusion
  phy/marvell: add 88e1121 interface mode support
  u32: negative offset fix
  net: Fix a typo from "dev" to "ndev"
  igb: Use irq_synchronize per vector when using MSI-X
  ixgbevf: fix null pointer dereference due to filter being set for VLAN 0
  e1000e: Fix irq_synchronize in MSI-X case
  e1000e: register pm_qos request on hardware activation
  ip_fragment: fix subtracting PPPOE_SES_HLEN from mtu twice
  net: Add getsockopt support for TCP thin-streams
  cxgb4: update driver version
  cxgb4: add new PCI IDs
  ...

Manually fix up conflicts in:
 - drivers/net/e1000e/netdev.c: due to pm_qos registration
   infrastructure changes
 - drivers/net/phy/marvell.c: conflict between adding 88ec048 support
   and cleaning up the IDs
 - drivers/net/wireless/ipw2x00/ipw2100.c: trivial ipw2100_pm_qos_req
   conflict (registration change vs marking it static)
2010-08-04 11:47:58 -07:00
David Stevens
8dd014adfe vhost-net: mergeable buffers support
This adds support for mergeable buffers in vhost-net: this is needed
for older guests without indirect buffer support, as well
as for zero copy with some devices.

Includes changes by Michael S. Tsirkin to make the
patch as low risk as possible (i.e., close to no changes
when feature is disabled).

Signed-off-by: David Stevens <dlstevens@us.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-07-28 15:45:36 +03:00
Michael S. Tsirkin
9e3d195720 vhost: apply cgroup to vhost workers
Apply the cgroup of the owner task to the created vhost worker.

Based on patches from Sridhar Samudrala's and Tejun Heo.
Later we'll need to also apply cpumask and probably priority
of the owner process.

Discussion on the best way to do this is still ongoing.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Sridhar Samudrala <samudrala.sridhar@gmail.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
2010-07-28 15:45:18 +03:00
Tejun Heo
c23f3445e6 vhost: replace vhost_workqueue with per-vhost kthread
Replace vhost_workqueue with per-vhost kthread.  Other than callback
argument change from struct work_struct * to struct vhost_work *,
there's no visible change to vhost_poll_*() interface.

This conversion is to make each vhost use a dedicated kthread so that
resource control via cgroup can be applied.

Partially based on Sridhar Samudrala's patch.

* Updated to use sub structure vhost_work instead of directly using
  vhost_poll at Michael's suggestion.

* Added flusher wake_up() optimization at Michael's suggestion.

Changes by MST:
* Converted atomics/barrier use to a spinlock.
* Create thread on SET_OWNER
* Fix flushing

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Sridhar Samudrala <samudrala.sridhar@gmail.com>
2010-07-28 15:44:53 +03:00
David S. Miller
4c3e5edf2f vhost net: Fix warning.
Reported by Stephen Rothwell.

Signed-off-by: David S. Miller <davem@davemloft.net>
2010-07-21 21:09:23 -07:00
David S. Miller
11fe883936 Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6
Conflicts:
	drivers/vhost/net.c
	net/bridge/br_device.c

Fix merge conflict in drivers/vhost/net.c with guidance from
Stephen Rothwell.

Revert the effects of net-2.6 commit 573201f36f
since net-next-2.6 has fixes that make bridge netpoll work properly thus
we don't need it disabled.

Signed-off-by: David S. Miller <davem@davemloft.net>
2010-07-20 18:25:24 -07:00
Linus Torvalds
516bd66415 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (24 commits)
  bridge: Partially disable netpoll support
  tcp: fix crash in tcp_xmit_retransmit_queue
  IPv6: fix CoA check in RH2 input handler (mip6_rthdr_input())
  ibmveth: lost IRQ while closing/opening device leads to service loss
  rt2x00: Fix lockdep warning in rt2x00lib_probe_dev()
  vhost: avoid pr_err on condition guest can trigger
  ipmr: Don't leak memory if fib lookup fails.
  vhost-net: avoid flush under lock
  net: fix problem in reading sock TX queue
  net/core: neighbour update Oops
  net: skb_tx_hash() fix relative to skb_orphan_try()
  rfs: call sock_rps_record_flow() in tcp_splice_read()
  xfrm: do not assume that template resolving always returns xfrms
  hostap_pci: set dev->base_addr during probe
  axnet_cs: use spin_lock_irqsave in ax_interrupt
  dsa: Fix Kconfig dependencies.
  act_nat: not all of the ICMP packets need an IP header payload
  r8169: incorrect identifier for a 8168dp
  Phonet: fix skb leak in pipe endpoint accept()
  Bluetooth: Update sec_level/auth_type for already existing connections
  ...
2010-07-20 16:26:42 -07:00
Michael S. Tsirkin
95c0ec6a97 vhost: avoid pr_err on condition guest can trigger
Guest can trigger packet truncation by posting
a very short buffer and disabling buffer merging.
Convert pr_err to pr_debug to avoid log from filling
up when this happens.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-07-16 12:18:17 +03:00
Michael S. Tsirkin
1680e9063e vhost-net: avoid flush under lock
We flush under vq mutex when changing backends.
This creates a deadlock as workqueue being flushed
needs this lock as well.

https://bugzilla.redhat.com/show_bug.cgi?id=612421

Drop the vq mutex before flush: we have the device mutex
which is sufficient to prevent another ioctl from touching
the vq.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-07-15 15:26:12 +03:00
Linus Torvalds
2aa72f6121 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (35 commits)
  NET: SB1250: Initialize .owner
  vxge: show startup message with KERN_INFO
  ll_temac: Fix missing iounmaps
  bridge: Clear IPCB before possible entry into IP stack
  bridge br_multicast: BUG: unable to handle kernel NULL pointer dereference
  net: Fix definition of netif_vdbg() when VERBOSE_DEBUG is defined
  net/ne: fix memory leak in ne_drv_probe()
  xfrm: fix xfrm by MARK logic
  virtio_net: fix oom handling on tx
  virtio_net: do not reschedule rx refill forever
  s2io: resolve statistics issues
  linux/net.h: fix kernel-doc warnings
  net: decreasing real_num_tx_queues needs to flush qdisc
  sched: qdisc_reset_all_tx is calling qdisc_reset without qdisc_lock
  qlge: fix a eeh handler to not add a pending timer
  qlge: Replacing add_timer() to mod_timer()
  usbnet: Set parent device early for netdev_printk()
  net: Revert "rndis_host: Poll status channel before control channel"
  netfilter: ip6t_REJECT: fix a dst leak in ipv6 REJECT
  drivers: bluetooth: bluecard_cs.c: Fixed include error, changed to linux/io.h
  ...
2010-07-07 19:56:00 -07:00
David S. Miller
597e608a84 Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2010-07-07 15:59:38 -07:00
Michael S. Tsirkin
7b3384fc30 vhost: add unlikely annotations to error path
patch 'break out of polling loop on error' caused
a minor performance regression on my machine: recover
that performance by adding a bunch of unlikely annotations
in the error handling.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-07-01 19:25:40 +03:00
Michael S. Tsirkin
d5675bd204 vhost: break out of polling loop on error
When ring parsing fails, we currently handle this
as ring empty condition. This means that we enable
kicks and recheck ring empty: if this not empty,
we re-start polling which of course will fail again.

Instead, let's return a negative error code and stop polling.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-06-27 11:52:25 +03:00
Alan Cox
79907d89c3 misc: Fix allocation 'borrowed' by vhost_net
10, 233 is allocated officially to /dev/kmview which is shipping in
Ubuntu and Debian distributions.  vhost_net seem to have borrowed it
without making a proper request and this causes regressions in the other
distributions.

vhost_net can use a dynamic minor so use that instead.  Also update the
file with a comment to try and avoid future misunderstandings.

cc: stable@kernel.org
Signed-off-by: Alan Cox <device@lanana.org>
[ We should have caught this before 2.6.34 got released.  - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-06-09 08:50:31 -07:00
David S. Miller
0dea7c12fc Merge branch 'vhost-net-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost 2010-06-02 08:26:36 -07:00
Linus Torvalds
72da3bc0cb Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (22 commits)
  netlink: bug fix: wrong size was calculated for vfinfo list blob
  netlink: bug fix: don't overrun skbs on vf_port dump
  xt_tee: use skb_dst_drop()
  netdev/fec: fix ifconfig eth0 down hang issue
  cnic: Fix context memory init. on 5709.
  drivers/net: Eliminate a NULL pointer dereference
  drivers/net/hamradio: Eliminate a NULL pointer dereference
  be2net: Patch removes redundant while statement in loop.
  ipv6: Add GSO support on forwarding path
  net: fix __neigh_event_send()
  vhost: fix the memory leak which will happen when memory_access_ok fails
  vhost-net: fix to check the return value of copy_to/from_user() correctly
  vhost: fix to check the return value of copy_to/from_user() correctly
  vhost: Fix host panic if ioctl called with wrong index
  net: fix lock_sock_bh/unlock_sock_bh
  net/iucv: Add missing spin_unlock
  net: ll_temac: fix checksum offload logic
  net: ll_temac: fix interrupt bug when interrupt 0 is used
  sctp: dubious bitfields in sctp_transport
  ipmr: off by one in __ipmr_fill_mroute()
  ...
2010-05-28 10:18:40 -07:00
Takuya Yoshikawa
a02c37891a vhost: fix the memory leak which will happen when memory_access_ok fails
We need to free newmem when vhost_set_memory() fails to complete.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-05-27 13:55:17 +03:00
Takuya Yoshikawa
d3553a5249 vhost-net: fix to check the return value of copy_to/from_user() correctly
copy_to/from_user() returns the number of bytes that could not be copied.

So we need to check if it is not zero, and in that case, we should return
the error number -EFAULT rather than directly return the return value from
copy_to/from_user().

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-05-27 13:55:13 +03:00
Takuya Yoshikawa
7ad9c9d270 vhost: fix to check the return value of copy_to/from_user() correctly
copy_to/from_user() returns the number of bytes that could not be copied.

So we need to check if it is not zero, and in that case, we should return
the error number -EFAULT rather than directly return the return value from
copy_to/from_user().

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-05-27 13:54:59 +03:00
Michael S. Tsirkin
f8322fbe04 vhost: whitespace fix
Fix up whitespace in vq_memory_access_ok.

Reported-by: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-05-27 12:28:03 +03:00
Jeff Dike
dd1f4078f0 vhost-net: minor cleanup
Delete a label and goto from vhost_net_set_backend
Inverting a test allows a label and goto to be eliminated.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-05-27 12:25:37 +03:00
Tobias Klauser
373a83a699 vhost: Storage class should be before const qualifier
The C99 specification states in section 6.11.5:

The placement of a storage-class specifier other than at the beginning
of the declaration specifiers in a declaration is an obsolescent
feature.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-05-27 12:23:49 +03:00
Krishna Kumar
0f3d9a1746 vhost: Fix host panic if ioctl called with wrong index
Missed a boundary value check in vhost_set_vring. The host panics if
idx == nvqs is used in ioctl commands in vhost_virtqueue_init.

Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-05-27 12:19:02 +03:00
Alexey Dobriyan
4be929be34 kernel-wide: replace USHORT_MAX, SHORT_MAX and SHORT_MIN with USHRT_MAX, SHRT_MAX and SHRT_MIN
- C99 knows about USHRT_MAX/SHRT_MAX/SHRT_MIN, not
  USHORT_MAX/SHORT_MAX/SHORT_MIN.

- Make SHRT_MIN of type s16, not int, for consistency.

[akpm@linux-foundation.org: fix drivers/dma/timb_dma.c]
[akpm@linux-foundation.org: fix security/keys/keyring.c]
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-05-25 08:07:02 -07:00
David S. Miller
6811d58fc1 Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6
Conflicts:
	include/linux/if_link.h
2010-05-16 22:26:58 -07:00
Michael S. Tsirkin
0d4993563b vhost: fix barrier pairing
According to memory-barriers.txt, an smp memory barrier in guest
should always be paired with an smp memory barrier in host,
and I quote "a lack of appropriate pairing is almost certainly an
error". In case of vhost, failure to flush out used index
update before looking at the interrupt disable flag
could result in missed interrupts, resulting in
networking hang under stress.

This might happen when flags read bypasses used index write.
So we see interrupts disabled and do not interrupt, at the
same time guest writes flags value to enable interrupt,
reads an old used index value, thinks that
used ring is empty and waits for interrupt.

Note: the barrier we pair with here is in
drivers/virtio/virtio_ring.c, function
vring_enable_cb.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Juan Quintela <quintela@redhat.com>
2010-05-12 18:04:04 +03:00
David S. Miller
fea0691526 Merge branch 'vhost' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost 2010-04-14 22:52:46 -07:00
Christoph Hellwig
a8d3782f9e vhost: fix sparse warnings
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-04-14 11:52:08 +03:00
David S. Miller
4a1032faac Merge branch 'master' of /home/davem/src/GIT/linux-2.6/ 2010-04-11 02:44:30 -07:00
Jeff Dike
179b284e2f vhost-net: fix vq_memory_access_ok error checking
vq_memory_access_ok needs to check whether mem == NULL

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-04-07 17:04:45 +03:00
Tejun Heo
5a0e3ad6af include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-30 22:02:32 +09:00
Michael S. Tsirkin
535297a6ae vhost: fix error handling in vring ioctls
Stanse found a locking problem in vhost_set_vring:
several returns from VHOST_SET_VRING_KICK, VHOST_SET_VRING_CALL,
VHOST_SET_VRING_ERR with the vq->mutex held.
Fix these up.

Reported-by: Jiri Slaby <jirislaby@gmail.com>
Acked-by: Laurent Chavey <chavey@google.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-03-17 23:07:35 +02:00
Michael S. Tsirkin
0e25557212 vhost: fix interrupt mitigation with raw sockets
A thinko in code means we never trigger interrupt
mitigation. Fix this.

Reported-by: Juan Quintela <quintela@redhat.com>
Reported-by: Unai Uribarri <unai.uribarri@optenet.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-03-17 16:44:20 +02:00
Jeff Dike
1dace8c801 vhost: fix error path in vhost_net_set_backend
An error could cause vhost_net_set_backend to exit without unlocking
vq->mutex. Fix this.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-03-07 13:28:53 +02:00
Sridhar Samudrala
39286fa41a vhost-net: restart tx poll on sk_sndbuf full
guest to remote communication with vhost net sometimes stops until
guest driver is restarted. This happens when we get guest kick precisely
when the backend send queue is full, as a result handle_tx() returns without
polling backend. This patch fixes this by restarting tx poll on this condition.

Signed-off-by: Sridhar Samudrala <samudrala@us.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Tom Lendacky <toml@us.ibm.com>
2010-02-28 19:50:33 +02:00
Michael S. Tsirkin
d6db3f5c11 vhost: fix get_user_pages_fast error handling
get_user_pages_fast returns number of pages on success, negative value
on failure, but never 0. Fix vhost code to match this logic.

Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-02-28 19:42:36 +02:00
Michael S. Tsirkin
73a99f0830 vhost: initialize log eventfd context pointer
vq log eventfd context pointer needs to be initialized, otherwise
operation may fail or oops if log is enabled but log eventfd not set by
userspace.  When log_ctx for device is created, it is copied to the vq.
This reset was missing.

Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-02-28 19:42:35 +02:00
Michael S. Tsirkin
86e9424d72 vhost: logging thinko fix
vhost was dong some complex math to get
offset to log at, and got it wrong by a couple of bytes,
while in fact it's simple: get address where we write,
subtract start of buffer, add log base.

Do it this way.

Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-02-28 19:42:35 +02:00
Arnd Bergmann
501c774cb1 net/macvtap: add vhost support
This adds support for passing a macvtap file descriptor into
vhost-net, much like we already do for tun/tap.

Most of the new code is taken from the respective patch
in the tun driver and may get consolidated in the future.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-02-18 14:08:38 -08:00
Michael S. Tsirkin
5659338c88 vhost-net: switch to smp barriers
vhost-net only uses memory barriers to control SMP effects
(communication with userspace potentially running on a different CPU),
so it should use SMP barriers and not mandatory barriers for memory
access ordering, as suggested by Documentation/memory-barriers.txt

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-02-14 22:42:53 -08:00
Michael S. Tsirkin
17660f8124 vhost: fix TUN=m VHOST_NET=y
drivers/built-in.o: In function `get_tun_socket':
    net.c:(.text+0x15436e): undefined reference to `tun_get_socket'

If tun is a module, vhost must be a module, too.
If tun is built-in or disabled, vhost can be built-in.

Note: TUN || !TUN might look a bit strange until you realize
that boolean logic rules do not apply for tristate variables.

Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-01-21 01:28:45 -08:00
Michael S. Tsirkin
3a4d5c94e9 vhost_net: a kernel-level virtio server
What it is: vhost net is a character device that can be used to reduce
the number of system calls involved in virtio networking.
Existing virtio net code is used in the guest without modification.

There's similarity with vringfd, with some differences and reduced scope
- uses eventfd for signalling
- structures can be moved around in memory at any time (good for
  migration, bug work-arounds in userspace)
- write logging is supported (good for migration)
- support memory table and not just an offset (needed for kvm)

common virtio related code has been put in a separate file vhost.c and
can be made into a separate module if/when more backends appear.  I used
Rusty's lguest.c as the source for developing this part : this supplied
me with witty comments I wouldn't be able to write myself.

What it is not: vhost net is not a bus, and not a generic new system
call. No assumptions are made on how guest performs hypercalls.
Userspace hypervisors are supported as well as kvm.

How it works: Basically, we connect virtio frontend (configured by
userspace) to a backend. The backend could be a network device, or a tap
device.  Backend is also configured by userspace, including vlan/mac
etc.

Status: This works for me, and I haven't see any crashes.
Compared to userspace, people reported improved latency (as I save up to
4 system calls per packet), as well as better bandwidth and CPU
utilization.

Features that I plan to look at in the future:
- mergeable buffers
- zero copy
- scalability tuning: figure out the best threading model to use

Note on RCU usage (this is also documented in vhost.h, near
private_pointer which is the value protected by this variant of RCU):
what is happening is that the rcu_dereference() is being used in a
workqueue item.  The role of rcu_read_lock() is taken on by the start of
execution of the workqueue item, of rcu_read_unlock() by the end of
execution of the workqueue item, and of synchronize_rcu() by
flush_workqueue()/flush_work(). In the future we might need to apply
some gcc attribute or sparse annotation to the function passed to
INIT_WORK(). Paul's ack below is for this RCU usage.

(Includes fixes by Alan Cox <alan@linux.intel.com>,
David L Stevens <dlstevens@us.ibm.com>,
Chris Wright <chrisw@redhat.com>)

Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-01-15 01:43:29 -08:00