Commit Graph

30 Commits

Author SHA1 Message Date
Michael S. Tsirkin 5786aee8bf vhost: fix log ctx signalling
The log eventfd signalling got put in dead code.
We didn't notice because qemu currently does polling
instead of eventfd select.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-09-22 16:21:33 +02:00
Michael S. Tsirkin 615cc2211c vhost: error handling fix
vhost should set worker to NULL on cgroups attach failure,
so that we won't try to destroy the worker again on close.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-09-06 09:49:39 +03:00
Michael S. Tsirkin 87d6a412bd vhost: fix attach to cgroups regression
Since 2.6.36-rc1, non-root users of vhost-net fail to attach
if they are in any cgroups.

The reason is that when qemu uses vhost, vhost wants to attach
its thread to all cgroups that qemu has.  But we got the API backwards,
so a non-priveledged process (Qemu) tried to control
the priveledged one (vhost), which fails.

Fix this by switching to the new cgroup_attach_task_all,
and running it from the vhost thread.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-09-06 09:49:31 +03:00
Eric Dumazet 78b620ce9e vhost: stop worker only if created
Its currently illegal to call kthread_stop(NULL)

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-09-01 14:26:13 -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 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
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 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
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 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
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 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