Commit Graph

772 Commits

Author SHA1 Message Date
Rusty Russell e93300b1af virtio: add debugging if driver doesn't kick.
Under the existing #ifdef DEBUG, check that they don't have more than
1/10 of a second between an add_buf() and a
virtqueue_notify()/virtqueue_kick_prepare() call.

We could get false positives on a really busy system, but good for
development.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-01-12 15:44:43 +10:30
Rusty Russell ee7cd8981e virtio: expose added descriptors immediately.
A virtio driver does virtqueue_add_buf() multiple times before finally
calling virtqueue_kick(); previously we only exposed the added buffers
in the virtqueue_kick() call.  This means we don't need a memory
barrier in virtqueue_add_buf(), but it reduces concurrency as the
device (ie. host) can't see the buffers until the kick.

In the unusual (but now possible) case where a driver does add_buf()
and get_buf() without doing a kick, we do need to insert one before
our counter wraps.  Otherwise we could wrap num_added, and later on
not realize that we have passed the marker where we should have
kicked.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-01-12 15:44:43 +10:30
Rusty Russell 3b720b8c86 virtio: avoid modulus operation.
Since we know vq->vring.num is a power of 2, modulus is lazy (it's asserted
in vring_new_virtqueue()).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-01-12 15:44:43 +10:30
Rusty Russell 41f0377f73 virtio: support unlocked queue kick
Based on patch by Christoph for virtio_blk speedup:

	Split virtqueue_kick to be able to do the actual notification
	outside the lock protecting the virtqueue.  This patch was
	originally done by Stefan Hajnoczi, but I can't find the
	original one anymore and had to recreated it from memory.
	Pointers to the original or corrections for the commit message
	are welcome.

Stefan's patch was here:

	a6d06644e3
	http://www.spinics.net/lists/linux-virtualization/msg14616.html

Third time's the charm!

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-01-12 15:44:43 +10:30
Rusty Russell f96fde41f7 virtio: rename virtqueue_add_buf_gfp to virtqueue_add_buf
Remove wrapper functions. This makes the allocation type explicit in
all callers; I used GPF_KERNEL where it seemed obvious, left it at
GFP_ATOMIC otherwise.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2012-01-12 15:44:42 +10:30
Rusty Russell 5dfc17628d virtio: document functions better.
The old documentation is left over from when we used a structure with
strategy pointers.

And move the documentation to the C file as per kernel practice.
Though I disagree...

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2012-01-12 15:44:42 +10:30
Sasha Levin 1e214a5c1a virtio-balloon: Trivial cleanups
Trivial changes to remove forgotten junk, format comments, and correct names.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-01-12 15:44:42 +10:30
Rusty Russell 7b21e34fd1 virtio: harsher barriers for rpmsg.
We were cheating with our barriers; using the smp ones rather than the
real device ones.  That was fine, until rpmsg came along, which is
used to talk to a real device (a non-SMP CPU).

Unfortunately, just putting back the real barriers (reverting
d57ed95d) causes a performance regression on virtio-pci.  In
particular, Amos reports netbench's TCP_RR over virtio_net CPU
utilization increased up to 35% while throughput went down by up to
14%.

By comparison, this branch is in the noise.

Reference: https://lkml.org/lkml/2011/12/11/22

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-01-12 15:44:42 +10:30
David S. Miller b3613118eb Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2011-12-02 13:49:21 -05:00
Michael S. Tsirkin e6af578c53 virtio-pci: make reset operation safer
virtio pci device reset actually just does an I/O
write, which in PCI is really posted, that is it
can complete on CPU before the device has received it.

Further, interrupts might have been pending on
another CPU, so device callback might get invoked after reset.

This conflicts with how drivers use reset, which is typically:
	reset
	unregister
a callback running after reset completed can race with
unregister, potentially leading to use after free bugs.

Fix by flushing out the write, and flushing pending interrupts.

This assumes that device is never reset from
its vq/config callbacks, or in parallel with being
added/removed, document this assumption.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-11-24 13:04:48 +10:30
Sasha Levin fe1a7fe2c4 virtio-mmio: Correct the name of the guest features selector
Guest features selector spelling mistake.

Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-11-24 13:04:47 +10:30
Heiko Carstens bd20817f73 virtio: add HAS_IOMEM dependency to MMIO platform bus driver
Fix this compile error on s390:

  CC [M]  drivers/virtio/virtio_mmio.o
drivers/virtio/virtio_mmio.c: In function 'vm_get_features':
drivers/virtio/virtio_mmio.c:107:2: error: implicit declaration of function 'writel'

Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Pawel Moll <pawel.moll@arm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-11-24 13:04:47 +10:30
David S. Miller efd0bf97de Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
The forcedeth changes had a conflict with the conversion over
to atomic u64 statistics in net-next.

The libertas cfg.c code had a conflict with the bss reference
counting fix by John Linville in net-next.

Conflicts:
	drivers/net/ethernet/nvidia/forcedeth.c
	drivers/net/wireless/libertas/cfg.c
2011-11-21 13:50:33 -05:00
Rick Jones 66846048f5 enable virtio_net to return bus_info in ethtool -i consistent with emulated NICs
Add a new .bus_name to virtio_config_ops then modify virtio_net to
call through to it in an ethtool .get_drvinfo routine to report
bus_info in ethtool -i output which is consistent with other
emulated NICs and the output of lspci.

Signed-off-by: Rick Jones <rick.jones2@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-11-16 17:26:46 -05:00
Michael S. Tsirkin 72103bd128 virtio-pci: fix use after free
Commit 31a3ddda16 introduced
a use after free in virtio-pci. The main issue is
that the release method signals removal of the virtio device,
while remove signals removal of the pci device.

For example, on driver removal or hot-unplug,
virtio_pci_release_dev is called before virtio_pci_remove.
We then might get a crash as virtio_pci_remove tries to use the
device freed by virtio_pci_release_dev.

We allocate/free all resources together with the
pci device, so we can leave the release method empty.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
2011-11-14 11:16:26 +10:30
Linus Torvalds 32aaeffbd4 Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux
* 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux: (230 commits)
  Revert "tracing: Include module.h in define_trace.h"
  irq: don't put module.h into irq.h for tracking irqgen modules.
  bluetooth: macroize two small inlines to avoid module.h
  ip_vs.h: fix implicit use of module_get/module_put from module.h
  nf_conntrack.h: fix up fallout from implicit moduleparam.h presence
  include: replace linux/module.h with "struct module" wherever possible
  include: convert various register fcns to macros to avoid include chaining
  crypto.h: remove unused crypto_tfm_alg_modname() inline
  uwb.h: fix implicit use of asm/page.h for PAGE_SIZE
  pm_runtime.h: explicitly requires notifier.h
  linux/dmaengine.h: fix implicit use of bitmap.h and asm/page.h
  miscdevice.h: fix up implicit use of lists and types
  stop_machine.h: fix implicit use of smp.h for smp_processor_id
  of: fix implicit use of errno.h in include/linux/of.h
  of_platform.h: delete needless include <linux/module.h>
  acpi: remove module.h include from platform/aclinux.h
  miscdevice.h: delete unnecessary inclusion of module.h
  device_cgroup.h: delete needless include <linux/module.h>
  net: sch_generic remove redundant use of <linux/module.h>
  net: inet_timewait_sock doesnt need <linux/module.h>
  ...

Fix up trivial conflicts (other header files, and  removal of the ab3550 mfd driver) in
 - drivers/media/dvb/frontends/dibx000_common.c
 - drivers/media/video/{mt9m111.c,ov6650.c}
 - drivers/mfd/ab3550-core.c
 - include/linux/dmaengine.h
2011-11-06 19:44:47 -08:00
Pawel Moll edfd52e636 virtio: Add platform bus driver for memory mapped virtio device
This patch, based on virtio PCI driver, adds support for memory
mapped (platform) virtio device. This should allow environments
like qemu to use virtio-based block & network devices even on
platforms without PCI support.

One can define and register a platform device which resources
will describe memory mapped control registers and "mailbox"
interrupt. Such device can be also instantiated using the Device
Tree node with compatible property equal "virtio,mmio".

Cc: Anthony Liguori <aliguori@us.ibm.com>
Cc: Michael S.Tsirkin <mst@redhat.com>
Signed-off-by: Pawel Moll <pawel.moll@arm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-11-02 11:41:01 +10:30
Krishna Kumar 005b20a8e0 virtio: Dont add "config" to list for !per_vq_vector
For the MSI but non-per_vq_vector case, the config/change vq
also gets added to the list of vqs that need to process the
MSI interrupt. This is not needed as config has it's own
handler (vp_config_changed). In any case, vring_interrupt()
finds nothing needs to be done on this vq.

I tested this patch by testing the "Fallback:" and "Finally
fall back" cases in vp_find_vqs(). Please review.

Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-11-02 11:41:01 +10:30
Paul Gortmaker b5a2c4f199 virtio: Add module.h to drivers/virtio users.
Up to now, the module.h header was as hard to keep out as
sunlight.  But we are cleaning that up.  Fix the virtio users
who simply expect module.h to be there in every C file.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2011-10-31 19:32:14 -04:00
Rick Jones 8f9f4668b3 Add ethtool -g support to virtio_net
Add support for reporting ring sizes via ethtool -g to the virtio_net
driver.

Signed-off-by: Rick Jones <rick.jones2@hp.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-10-24 02:07:21 -04:00
Ohad Ben-Cohen e72542191c virtio: expose for non-virtualization users too
virtio has been so far used only in the context of virtualization,
and the virtio Kconfig was sourced directly by the relevant arch
Kconfigs when VIRTUALIZATION was selected.

Now that we start using virtio for inter-processor communications,
we need to source the virtio Kconfig outside of the virtualization
scope too.

Moreover, some architectures might use virtio for both virtualization
and inter-processor communications, so directly sourcing virtio
might yield unexpected results due to conflicting selections.

The simple solution offered by this patch is to always source virtio's
Kconfig in drivers/Kconfig, and remove it from the appropriate arch
Kconfigs. Additionally, a virtio menu entry has been added so virtio
drivers don't show up in the general drivers menu.

This way anyone can use virtio, though it's arguably less accessible
(and neat!) for virtualization users now.

Note: some architectures (mips and sh) seem to have a VIRTUALIZATION
menu merely for sourcing virtio's Kconfig, so that menu is removed too.

Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-07-23 16:20:30 +09:30
Michael S. Tsirkin 7ab358c23c virtio: add api for delayed callbacks
Add an API that tells the other side that callbacks
should be delayed until a lot of work has been done.
Implement using the new event_idx feature.

Note: it might seem advantageous to let the drivers
ask for a callback after a specific capacity has
been reached. However, as a single head can
free many entries in the descriptor table,
we don't really have a clue about capacity
until get_buf is called. The API is the simplest
to implement at the moment, we'll see what kind of
hints drivers can pass when there's more than one
user of the feature.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-05-30 11:14:16 +09:30
Michael S. Tsirkin a5c262c5fd virtio_ring: support event idx feature
Support for the new event idx feature:
1. When enabling interrupts, publish the current avail index
   value to the host to get interrupts on the next update.
2. Use the new avail_event feature to reduce the number
   of exits from the guest.

Simple test with the simulator:

[virtio]# time ./virtio_test
spurious wakeus: 0x7

real    0m0.169s
user    0m0.140s
sys     0m0.019s
[virtio]# time ./virtio_test --no-event-idx
spurious wakeus: 0x11

real    0m0.649s
user    0m0.295s
sys     0m0.335s

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-05-30 11:14:15 +09:30
Dave Hansen bf50e69f63 virtio balloon: kill tell-host-first logic
The virtio balloon driver has a VIRTIO_BALLOON_F_MUST_TELL_HOST
feature bit.  Whenever the bit is set, the guest kernel must
always tell the host before we free pages back to the allocator.
Without this feature, we might free a page (and have another
user touch it) while the hypervisor is unprepared for it.

But, if the bit is _not_ set, we are under no obligation to
reverse the order; we're under no obligation to do _anything_.
As of now, qemu-kvm defines the bit, but doesn't set it.

This patch makes the "tell host first" logic the only case.  This
should make everybody happy, and reduce the amount of untested or
untestable code in the kernel.

This _also_ means that we don't have to preserve a pfn list
after the pages are freed, which should let us get rid of some
temporary storage (vb->pfns) eventually.

Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-05-30 11:14:13 +09:30
Amit Shah 31a3ddda16 virtio_pci: Prevent double-free of pci regions after device hot-unplug
In the case where a virtio-console port is in use (opened by a program)
and a virtio-console device is removed, the port is kept around but all
the virtio-related state is assumed to be gone.

When the port is finally released (close() called), we call
device_destroy() on the port's device.  This results in the parent
device's structures to be freed as well.  This includes the PCI regions
for the virtio-console PCI device.

Once this is done, however, virtio_pci_release_dev() kicks in, as the
last ref to the virtio device is now gone, and attempts to do

     pci_iounmap(pci_dev, vp_dev->ioaddr);
     pci_release_regions(pci_dev);
     pci_disable_device(pci_dev);

which results in a double-free warning.

Move the code that releases regions, etc., to the virtio_pci_remove()
function, and all that's now left in release_dev is the final freeing of
the vp_dev.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-04-21 22:57:00 +09:30
Amit Shah b3258ff1d6 virtio: Decrement avail idx on buffer detach
When detaching a buffer from a vq, the avail.idx value should be
decremented as well.

This was noticed by hot-unplugging a virtio console port and then
plugging in a new one on the same number (re-using the vqs which were
just 'disowned').  qemu reported

   'Guest moved used index from 0 to 256'

when any IO was attempted on the new port.

CC: stable@kernel.org
Reported-by: juzhang <juzhang@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2011-04-21 22:57:00 +09:30
Milton Miller 8b3bb3ecf1 virtio: remove virtio-pci root device
We sometimes need to map between the virtio device and
the given pci device. One such use is OS installer that
gets the boot pci device from BIOS and needs to
find the relevant block device. Since it can't,
installation fails.

Instead of creating a top-level devices/virtio-pci
directory, create each device under the corresponding
pci device node.  Symlinks to all virtio-pci
devices can be found under the pci driver link in
bus/pci/drivers/virtio-pci/devices, and all virtio
devices under drivers/bus/virtio/devices.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Gleb Natapov <gleb@redhat.com>
Tested-by: "Daniel P. Berrange" <berrange@redhat.com>
Cc: stable@kernel.org
2011-01-20 21:37:30 +10:30
Stephen Hemminger be6528b2e5 virtio: fix format of sysfs driver/vendor files
The sysfs files for virtio produce the wrong format and are missing
the required newline. The output for virtio bus vendor/device should
have the same format as the corresponding entries for PCI devices.

Although this technically changes the ABI for sysfs, these files were
broken to start with!

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-11-24 15:21:12 +10:30
Michael S. Tsirkin 7ae4b866f8 virtio: return correct capacity to users
We can't rely on indirect buffers for capacity
calculations because they need a memory allocation
which might fail.  In particular, virtio_net can get
into this situation under stress, and it drops packets
and performs badly.

So return the number of buffers we can guarantee users.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Reported-By: Krishna Kumar2 <krkumar2@in.ibm.com>
2010-11-24 15:21:11 +10:30
Michael S. Tsirkin 1fe9b6fef1 virtio: fix oops on OOM
virtio ring was changed to return an error code on OOM,
but one caller was missed and still checks for vq->vring.num.
The fix is just to check for <0 error code.

Long term it might make sense to change goto add_head to
just return an error on oom instead, but let's apply
a minimal fix for 2.6.35.

Reported-by: Chris Mason <chris.mason@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Tested-by: Chris Mason <chris.mason@oracle.com>
Cc: stable@kernel.org # .34.x
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-07-26 08:05:31 -07:00
Michael S. Tsirkin b03214d559 virtio-pci: disable msi at startup
virtio-pci resets the device at startup by writing to the status
register, but this does not clear the pci config space,
specifically msi enable status which affects register
layout.

This breaks things like kdump when they try to use e.g. virtio-blk.

Fix by forcing msi off at startup. Since pci.c already has
a routine to do this, we export and use it instead of duplicating code.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: linux-pci@vger.kernel.org
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
2010-06-23 22:49:07 +09:30
Michael S. Tsirkin 686d363786 virtio: return ENOMEM on out of memory
add_buf returns ring size on out of memory,
this is not what devices expect.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org # .34.x
2010-06-23 22:49:06 +09:30
Linus Torvalds 1756ac3d3c Merge branch 'virtio' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus
* 'virtio' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus: (27 commits)
  drivers/char: Eliminate use after free
  virtio: console: Accept console size along with resize control message
  virtio: console: Store each console's size in the console structure
  virtio: console: Resize console port 0 on config intr only if multiport is off
  virtio: console: Add support for nonblocking write()s
  virtio: console: Rename wait_is_over() to will_read_block()
  virtio: console: Don't always create a port 0 if using multiport
  virtio: console: Use a control message to add ports
  virtio: console: Move code around for future patches
  virtio: console: Remove config work handler
  virtio: console: Don't call hvc_remove() on unplugging console ports
  virtio: console: Return -EPIPE to hvc_console if we lost the connection
  virtio: console: Let host know of port or device add failures
  virtio: console: Add a __send_control_msg() that can send messages without a valid port
  virtio: Revert "virtio: disable multiport console support."
  virtio: add_buf_gfp
  trans_virtio: use virtqueue_xxx wrappers
  virtio-rng: use virtqueue_xxx wrappers
  virtio_ring: remove a level of indirection
  virtio_net: use virtqueue_xxx wrappers
  ...

Fix up conflicts in drivers/net/virtio_net.c due to new virtqueue_xxx
wrappers changes conflicting with some other cleanups.
2010-05-21 17:22:52 -07:00
Michael S. Tsirkin bbd603efb4 virtio: add_buf_gfp
Add an add_buf variant that gets gfp parameter. Use that
to allocate indirect buffers.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-05-19 22:15:46 +09:30
Michael S. Tsirkin 7c5e9ed0c8 virtio_ring: remove a level of indirection
We have a single virtqueue_ops implementation,
and it seems unlikely we'll get another one
at this point. So let's remove an unnecessary
level of indirection: it would be very easy to
re-add it if another implementation surfaces.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-05-19 22:15:43 +09:30
Michael S. Tsirkin 946cfe0e05 virtio_balloon: use virtqueue_xxx wrappers
Switch virtio_balloon to new virtqueue_xxx wrappers.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-05-19 22:15:41 +09:30
Jiri Kosina 6c9468e9eb Merge branch 'master' into for-next 2010-04-23 02:08:44 +02:00
Balbir Singh 61fb06cc8e virtio: Fix GFP flags passed from the virtio balloon driver
The virtio balloon driver can dig into the reservation pools of the OS
to satisfy a balloon request.  This is not advisable and other balloon
drivers (drivers/xen/balloon.c) avoid this as well.

The patch also adds changes to avoid printing a warning if allocation
fails, since we retry after sometime anyway.

Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: kvm <kvm@vger.kernel.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-04-22 07:34:05 -07:00
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
Thomas Weber 8839316121 Fix typos in comments
[Ss]ytem => [Ss]ystem
udpate => update
paramters => parameters
orginal => original

Signed-off-by: Thomas Weber <swirl@gmx.li>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2010-03-16 11:47:56 +01:00
Michael S. Tsirkin bc505f3739 virtio: set pci bus master enable bit
As all virtio devices perform DMA, we
must enable bus mastering for them to be
spec compliant.

This patch fixes hotplug of virtio devices
with Linux guests and qemu 0.11-0.12.

Tested-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-03-02 13:41:14 +02:00
Michael S. Tsirkin 3119815912 virtio: fix out of range array access
I have observed the following error on virtio-net module unload:

------------[ cut here ]------------
WARNING: at kernel/irq/manage.c:858 __free_irq+0xa0/0x14c()
Hardware name: Bochs
Trying to free already-free IRQ 0
Modules linked in: virtio_net(-) virtio_blk virtio_pci virtio_ring
virtio af_packet e1000 shpchp aacraid uhci_hcd ohci_hcd ehci_hcd [last
unloaded: scsi_wait_scan]
Pid: 1957, comm: rmmod Not tainted 2.6.33-rc8-vhost #24
Call Trace:
 [<ffffffff8103e195>] warn_slowpath_common+0x7c/0x94
 [<ffffffff8103e204>] warn_slowpath_fmt+0x41/0x43
 [<ffffffff810a7a36>] ? __free_pages+0x5a/0x70
 [<ffffffff8107cc00>] __free_irq+0xa0/0x14c
 [<ffffffff8107cceb>] free_irq+0x3f/0x65
 [<ffffffffa0081424>] vp_del_vqs+0x81/0xb1 [virtio_pci]
 [<ffffffffa0091d29>] virtnet_remove+0xda/0x10b [virtio_net]
 [<ffffffffa0075200>] virtio_dev_remove+0x22/0x4a [virtio]
 [<ffffffff812709ee>] __device_release_driver+0x66/0xac
 [<ffffffff81270ab7>] driver_detach+0x83/0xa9
 [<ffffffff8126fc66>] bus_remove_driver+0x91/0xb4
 [<ffffffff81270fcf>] driver_unregister+0x6c/0x74
 [<ffffffffa0075418>] unregister_virtio_driver+0xe/0x10 [virtio]
 [<ffffffffa0091c4d>] fini+0x15/0x17 [virtio_net]
 [<ffffffff8106997b>] sys_delete_module+0x1c3/0x230
 [<ffffffff81007465>] ? old_ich_force_enable_hpet+0x117/0x164
 [<ffffffff813bb720>] ? do_page_fault+0x29c/0x2cc
 [<ffffffff81028e58>] sysenter_dispatch+0x7/0x27
---[ end trace 15e88e4c576cc62b ]---

The bug is in virtio-pci: we use msix_vector as array index to get irq
entry, but some vqs do not have a dedicated vector so this causes an out
of bounds access.  By chance, we seem to often get 0 value, which
results in this error.

Fix by verifying that vector is legal before using it as index.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Anthony Liguori <aliguori@us.ibm.com>
Acked-by: Shirley Ma <xma@us.ibm.com>
Acked-by: Amit Shah <amit.shah@redhat.com>
2010-02-28 20:39:11 +02:00
Amit Shah 3b8706240e virtio: Initialize vq->data entries to NULL
vq operations depend on vq->data[i] being NULL to figure out if the vq
entry is in use (since the previous patch).

We have to initialize them to NULL to ensure we don't work with junk
data and trigger false BUG_ONs.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Shirley Ma <xma@us.ibm.com>
2010-02-24 14:22:29 +10:30
Shirley Ma c021eac414 virtio: Add ability to detach unused buffers from vrings
There's currently no way for a virtio driver to ask for unused
buffers, so it has to keep a list itself to reclaim them at shutdown.
This is redundant, since virtio_ring stores that information.  So
add a new hook to do this.

Signed-off-by: Shirley Ma <xma@us.ibm.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-24 14:22:27 +10:30
Michael S. Tsirkin d57ed95da4 virtio: use smp_XX barriers on SMP
virtio is communicating with a virtual "device" that actually runs on
another host processor. Thus SMP barriers can be used to control
memory access ordering.

Where possible, we should use SMP barriers which are more lightweight than
mandatory barriers, because mandatory barriers also control MMIO effects on
accesses through relaxed memory I/O windows (which virtio does not use)
(compare specifically smp_rmb and rmb on x86_64).

We can't just use smp_mb and friends though, because
we must force memory ordering even if guest is UP since host could be
running on another CPU, but SMP barriers are defined to barrier() in
that configuration. So, for UP fall back to mandatory barriers instead.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-24 14:22:25 +10:30
Rusty Russell 97a545ab6c virtio: remove bogus barriers from DEBUG version of virtio_ring.c
With DEBUG defined, we add an ->in_use flag to detect if the caller
invokes two virtio methods in parallel.  The barriers attempt to ensure
timely update of the ->in_use flag.

But they're voodoo: if we need these barriers it implies that the
calling code doesn't have sufficient synchronization to ensure the
code paths aren't invoked at the same time anyway, and we want to
detect it.

Also, adding barriers changes timing, so turning on debug has more
chance of hiding real problems.

Thanks to MST for drawing my attention to this code...

CC: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-24 14:22:24 +10:30
Rusty Russell 169c246a30 virtio: fix balloon without VIRTIO_BALLOON_F_STATS_VQ
When running under qemu-kvm-0.11.0:

	BUG: unable to handle kernel paging request at 56e58955
	...
	Process vballoon (pid: 1297, ti=c7976000 task=c70a6ca0 task.ti=c7
	...
	Call Trace:
	 [<c88253a3>] ? balloon+0x1b3/0x440 [virtio_balloon]
	 [<c041c2d7>] ? schedule+0x327/0x9d0
	 [<c88251f0>] ? balloon+0x0/0x440 [virtio_balloon]
	 [<c014a2d4>] ? kthread+0x74/0x80
	 [<c014a260>] ? kthread+0x0/0x80
	 [<c0103b36>] ? kernel_thread_helper+0x6/0x30

need_stats_update should be zero-initialized.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Adam Litke <agl@us.ibm.com>
2010-02-24 14:22:17 +10:30
Adam Litke 1f34c71afe virtio: Fix scheduling while atomic in virtio_balloon stats
This is a fix for my earlier patch: "virtio: Add memory statistics reporting to
the balloon driver (V4)".

I discovered that all_vm_events() can sleep and therefore stats collection
cannot be done in interrupt context.  One solution is to handle the interrupt
by noting that stats need to be collected and waking the existing vballoon
kthread which will complete the work via stats_handle_request().  Rusty, is
this a saner way of doing business?

There is one issue that I would like a broader opinion on.  In stats_request, I
update vb->need_stats_update and then wake up the kthread.  The kthread uses
vb->need_stats_update as a condition variable.  Do I need a memory barrier
between the update and wake_up to ensure that my kthread sees the correct
value?  My testing suggests that it is not needed but I would like some
confirmation from the experts.

Signed-off-by: Adam Litke <agl@us.ibm.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Anthony Liguori <aliguori@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-24 14:22:14 +10:30
Adam Litke 9564e138b1 virtio: Add memory statistics reporting to the balloon driver (V4)
Changes since V3:
 - Do not do endian conversions as they will be done in the host
 - Report stats that reference a quantity of memory in bytes
 - Minor coding style updates

Changes since V2:
 - Increase stat field size to 64 bits
 - Report all sizes in kb (not pages)
 - Drop anon_pages stat and fix endianness conversion

Changes since V1:
 - Use a virtqueue instead of the device config space

When using ballooning to manage overcommitted memory on a host, a system for
guests to communicate their memory usage to the host can provide information
that will minimize the impact of ballooning on the guests.  The current method
employs a daemon running in each guest that communicates memory statistics to a
host daemon at a specified time interval.  The host daemon aggregates this
information and inflates and/or deflates balloons according to the level of
host memory pressure.  This approach is effective but overly complex since a
daemon must be installed inside each guest and coordinated to communicate with
the host.  A simpler approach is to collect memory statistics in the virtio
balloon driver and communicate them directly to the hypervisor.

This patch enables the guest-side support by adding stats collection and
reporting to the virtio balloon driver.

Signed-off-by: Adam Litke <agl@us.ibm.com>
Cc: Anthony Liguori <anthony@codemonkey.ws>
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (minor fixes)
2010-02-24 14:22:08 +10:30
Jamie Lokier 1f08b833dd Add __devexit_p around reference to virtio_pci_remove
This is needed to compile with CONFIG_VIRTIO_PCI=y,
because virtio_pci_remove is marked __devexit.

Signed-off-by: Jamie Lokier <jamie@shareable.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2010-02-24 14:22:04 +10:30
Jeff Mahoney d817cd5255 virtio: fix section mismatch warnings
Fix fixes the following warnings by renaming the driver structures to be
suffixed with _driver.

WARNING: drivers/virtio/virtio_balloon.o(.data+0x88): Section mismatch in reference from the variable virtio_balloon to the function .devexit.text:virtballoon_remove()

WARNING: drivers/char/hw_random/virtio-rng.o(.data+0x88): Section mismatch in reference from the variable virtio_rng to the function .devexit.text:virtrng_remove()

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-01-16 12:15:39 -08:00
Michael S. Tsirkin 2d61ba9503 virtio: order used ring after used index read
On SMP guests, reads from the ring might bypass used index reads. This
causes guest crashes because host writes to used index to signal ring
data readiness.  Fix this by inserting rmb before used ring reads.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
2009-10-29 08:50:37 +10:30
Michael S. Tsirkin 0b22bd0ba0 virtio-pci: fix per-vq MSI-X request logic
Commit f68d24082e
in 2.6.32-rc1 broke requesting IRQs for per-VQ MSI-X vectors:
- vector number was used instead of the vector itself
- we try to request an IRQ for VQ which does not
  have a callback handler

This is a regression that causes warnings in kernel log,
potentially lower performance as we need to scan vq list,
and might cause system failure if the interrupt
requested is in fact needed by another system.

This was not noticed earlier because in most cases
we were falling back on shared interrupt for all vqs.

The warnings often look like this:

virtio-pci 0000:00:03.0: irq 26 for MSI/MSI-X
virtio-pci 0000:00:03.0: irq 27 for MSI/MSI-X
virtio-pci 0000:00:03.0: irq 28 for MSI/MSI-X
IRQ handler type mismatch for IRQ 1
current handler: i8042
Pid: 2400, comm: modprobe Tainted: G        W
2.6.32-rc3-11952-gf3ed8d8-dirty #1
Call Trace:
 [<ffffffff81072aed>] ? __setup_irq+0x299/0x304
 [<ffffffff81072ff3>] ? request_threaded_irq+0x144/0x1c1
 [<ffffffff813455af>] ? vring_interrupt+0x0/0x30
 [<ffffffff81346598>] ? vp_try_to_find_vqs+0x583/0x5c7
 [<ffffffffa0015188>] ? skb_recv_done+0x0/0x34 [virtio_net]
 [<ffffffff81346609>] ? vp_find_vqs+0x2d/0x83
 [<ffffffff81345d00>] ? vp_get+0x3c/0x4e
 [<ffffffffa0016373>] ? virtnet_probe+0x2f1/0x428 [virtio_net]
 [<ffffffffa0015188>] ? skb_recv_done+0x0/0x34 [virtio_net]
 [<ffffffffa00150d8>] ? skb_xmit_done+0x0/0x39 [virtio_net]
 [<ffffffff8110ab92>] ? sysfs_do_create_link+0xcb/0x116
 [<ffffffff81345cc2>] ? vp_get_status+0x14/0x16
 [<ffffffff81345464>] ? virtio_dev_probe+0xa9/0xc8
 [<ffffffff8122b11c>] ? driver_probe_device+0x8d/0x128
 [<ffffffff8122b206>] ? __driver_attach+0x4f/0x6f
 [<ffffffff8122b1b7>] ? __driver_attach+0x0/0x6f
 [<ffffffff8122a9f9>] ? bus_for_each_dev+0x43/0x74
 [<ffffffff8122a374>] ? bus_add_driver+0xea/0x22d
 [<ffffffff8122b4a3>] ? driver_register+0xa7/0x111
 [<ffffffffa001a000>] ? init+0x0/0xc [virtio_net]
 [<ffffffff81009051>] ? do_one_initcall+0x50/0x148
 [<ffffffff8106e117>] ? sys_init_module+0xc5/0x21a
 [<ffffffff8100af02>] ? system_call_fastpath+0x16/0x1b
virtio-pci 0000:00:03.0: irq 26 for MSI/MSI-X
virtio-pci 0000:00:03.0: irq 27 for MSI/MSI-X

Reported-by: Marcelo Tosatti <mtosatti@redhat.com>
Reported-by: Shirley Ma <xma@us.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-10-29 08:50:36 +10:30
Uwe Kleine-König 1e65175c2c move virtballoon_remove to .devexit.text
The function virtballoon_remove is used only wrapped by __devexit_p so
define it using __devexit.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-10-22 16:39:31 +10:30
Christian Borntraeger e95646c3ec virtio: let header files include virtio_ids.h
Rusty,

commit 3ca4f5ca73
    virtio: add virtio IDs file
moved all device IDs into a single file. While the change itself is
a very good one, it can break userspace applications. For example
if a userspace tool wanted to get the ID of virtio_net it used to
include virtio_net.h. This does no longer work, since virtio_net.h
does not include virtio_ids.h.
This patch moves all "#include <linux/virtio_ids.h>" from the C
files into the header files, making the header files compatible with
the old ones.

In addition, this patch exports virtio_ids.h to userspace.

CC: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-10-22 16:39:28 +10:30
Fernando Luis Vazquez Cao 3ca4f5ca73 virtio: add virtio IDs file
Virtio IDs are spread all over the tree which makes assigning new IDs
bothersome. Putting them together should make the process less error-prone.

Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-09-23 22:26:32 +09:30
Rusty Russell 3c1b27d504 virtio: make add_buf return capacity remaining
This API change means that virtio_net can tell how much capacity
remains for buffers.  It's necessarily fuzzy, since
VIRTIO_RING_F_INDIRECT_DESC means we can fit any number of descriptors
in one, *if* we can kmalloc.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dinesh Subhraveti <dineshs@us.ibm.com>
2009-09-23 22:26:31 +09:30
Rusty Russell f68d24082e virtio_pci: minor MSI-X cleanups
1) Rename vp_request_vectors to vp_request_msix_vectors, and take
   non-MSI-X case out to caller.
2) Comment weird pci_enable_msix API
3) Rename vp_find_vq to setup_vq.
4) Fix spaces to tabs
5) Make nvectors calc internal to vp_try_to_find_vqs()
6) Rename vector to msix_vector for more clarity.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
2009-09-23 22:26:31 +09:30
Michael S. Tsirkin e969fed542 virtio: refactor find_vqs
This refactors find_vqs, making it more readable and robust, and fixing
two regressions from 2.6.30:
- double free_irq causing BUG_ON on device removal
- probe failure when vq can't be assigned to msi-x vector
  (reported on old host kernels)

Tested-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-07-30 16:03:45 +09:30
Michael S. Tsirkin f6c8250703 virtio: delete vq from list
This makes delete vq the reverse of find vq.
This is required to make it possible to retry find_vqs
after a failure, otherwise the list gets corrupted.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-07-30 16:03:44 +09:30
Michael S. Tsirkin ff52c3fc71 virtio: fix memory leak on device removal
Make vp_free_vectors do the reverse of vq_request_vectors.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-07-30 16:03:44 +09:30
Mark McLoughlin 4b892e6582 virtio-pci: correctly unregister root device on error
If pci_register_driver() fails we're incorrectly unregistering the root
device with device_unregister() rather than root_device_unregister().

Reported-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-07-17 21:47:47 +09:30
Christian Borntraeger e335385373 virtio: enhance id_matching for virtio drivers
This patch allows a virtio driver to use VIRTIO_DEV_ANY_ID for the
device id. This will be used by a test module that can be bound to
any virtio device.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:16:40 +09:30
Christian Borntraeger c89e80168b virtio: fix id_matching for virtio drivers
This bug never appeared, since all current virtio drivers use
VIRTIO_DEV_ANY_ID for the vendor field. If a real vendor would be used,
the check in virtio_id_match is wrong - it returns 0 if
id->vendor == dev->id.vendor.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:16:40 +09:30
Mark McLoughlin 9fa29b9df3 virtio: indirect ring entries (VIRTIO_RING_F_INDIRECT_DESC)
Add a new feature flag for indirect ring entries. These are ring
entries which point to a table of buffer descriptors.

The idea here is to increase the ring capacity by allowing a larger
effective ring size whereby the ring size dictates the number of
requests that may be outstanding, rather than the size of those
requests.

This should be most effective in the case of block I/O where we can
potentially benefit by concurrently dispatching a large number of
large requests. Even in the simple case of single segment block
requests, this results in a threefold increase in ring capacity.

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:16:39 +09:30
Rusty Russell a92892825a virtio: expose features in sysfs
Each device negotiates feature bits; expose these in sysfs to help
diagnostics and debugging.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:16:38 +09:30
Michael S. Tsirkin 82af8ce84e virtio_pci: optional MSI-X support
This implements optional MSI-X support in virtio_pci.
MSI-X is used whenever the host supports at least 2 MSI-X
vectors: 1 for configuration changes and 1 for virtqueues.
Per-virtqueue vectors are allocated if enough vectors
available.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (+ whitespace, style)
2009-06-12 22:16:37 +09:30
Michael S. Tsirkin 77cf524654 virtio_pci: split up vp_interrupt
This reorganizes virtio-pci code in vp_interrupt slightly, so that
it's easier to add per-vq MSI support on top.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:16:37 +09:30
Michael S. Tsirkin d2a7ddda9f virtio: find_vqs/del_vqs virtio operations
This replaces find_vq/del_vq with find_vqs/del_vqs virtio operations,
and updates all drivers. This is needed for MSI support, because MSI
needs to know the total number of vectors upfront.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (+ lguest/9p compile fixes)
2009-06-12 22:16:36 +09:30
Rusty Russell 9499f5e7ed virtio: add names to virtqueue struct, mapping from devices to queues.
Add a linked list of all virtqueues for a virtio device: this helps for
debugging and is also needed for upcoming interface change.

Also, add a "name" field for clearer debug messages.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:16:36 +09:30
Rusty Russell ef688e151c virtio: meet virtio spec by finalizing features before using device
Virtio devices are supposed to negotiate features before they start using
the device, but the current code doesn't do this.  This is because the
driver's probe() function invariably has to add buffers to a virtqueue,
or probe the disk (virtio_blk).

This currently doesn't matter since no existing backend is strict about
the feature negotiation.  But it's possible to imagine a future feature
which completely changes how a device operates: in this case, we'd need
to acknowledge it before using the device.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-06-12 22:16:35 +09:30
Marcelo Tosatti 84a139a985 virtio: fix suspend when using virtio_balloon
Break out of wait_event_interruptible() if freezing has been requested,
in the vballoon thread. Without this change vballoon refuses to stop and
the system can't suspend.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
2009-04-19 23:14:01 +09:30
Rusty Russell c5f841f178 virtio: more neatening of virtio_ring macros.
Impact: cleanup

Roel Kluin drew attention to these macros with his patch: here I
neaten them a little further:
1) Add a comment on what START_USE and END_USE are checking,
2) Brackets around _vq in BAD_RING,
3) Neaten formatting for START_USE so it's less than 80 cols.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-03-30 21:55:23 +10:30
Roel Kluin 3a35ce7dce virtio: fix BAD_RING, START_US and END_USE macros
Impact: cleanup

fix BAD_RING, START_US and END_USE macros

When these macros aren't called with a variable named vq as first
argument, this would result in a build failure.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-03-30 21:55:22 +10:30
Mark McLoughlin 3fff0179e3 virtio-pci: do not oops on config change if driver not loaded
The host really shouldn't be notifying us of config changes
before the device status is VIRTIO_CONFIG_S_DRIVER or
VIRTIO_CONFIG_S_DRIVER_OK.

However, if we do happen to be interrupted while we're not
attached to a driver, we really shouldn't oops. Prevent
this simply by checking that device->driver is non-NULL
before trying to notify the driver of config changes.

Problem observed by doing a "set_link virtio.0 down" with
QEMU before the net driver had been loaded.

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-02-02 19:17:56 -08:00
Mark McLoughlin 63d1255670 virtio: do not statically allocate root device
We shouldn't be statically allocating the root device object,
so dynamically allocate it using root_device_register()
instead.

Also avoids this warning from 'rmmod virtio_pci':

  Device 'virtio-pci' does not have a release() function, it is broken and must be fixed

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-01-06 10:44:34 -08:00
Mark McLoughlin 29f9f12ec7 virtio: add PCI device release() function
Add a release() function for virtio_pci devices so as to avoid:

  Device 'virtio0' does not have a release() function, it is broken and must be fixed

Move the code to free the resources associated with the device
from virtio_pci_remove() into this new function. virtio_pci_remove()
now merely unregisters the device which should cause the final
ref to be dropped and virtio_pci_release_dev() to be called.

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Reported-by: Michael Tokarev <mjt@tls.msk.ru>
Cc: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-12-30 09:26:10 +10:30
Hollis Blanchard 1b4aa2faec virtio: avoid implicit use of Linux page size in balloon interface
Make the balloon interface always use 4K pages, and convert Linux pfns if
necessary. This patch assumes that Linux's PAGE_SHIFT will never be less than
12.

Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (modified)
2008-12-30 09:26:04 +10:30
Rusty Russell 87c7d57c17 virtio: hand virtio ring alignment as argument to vring_new_virtqueue
This allows each virtio user to hand in the alignment appropriate to
their virtio_ring structures.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
2008-12-30 09:26:03 +10:30
Rusty Russell 498af14783 virtio: Don't use PAGE_SIZE for vring alignment in virtio_pci.
That doesn't work for non-4k guests which are now appearing.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-12-30 09:25:58 +10:30
Rusty Russell 480daab42c virtio: Don't use PAGE_SIZE in virtio_pci.c
The virtio PCI devices don't depend on the guest page size.  This matters
now PowerPC virtio is gaining ground (they like 64k pages).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-12-30 09:25:57 +10:30
Kay Sievers 99e0b6c8e3 virtio: struct device - replace bus_id with dev_name(), dev_set_name()
This patch is part of a larger patch series which will remove
the "char bus_id[20]" name string from struct device. The device
name is managed in the kobject anyway, and without any size
limitation, and just needlessly copied into "struct device".

To set and read the device name dev_name(dev) and dev_set_name(dev)
must be used. If your code uses static kobjects, which it shouldn't
do, "const char *init_name" can be used to statically provide the
name the registered device should have. At registration time, the
init_name field is cleared, to enforce the use of dev_name(dev) to
access the device name at a later time.

We need to get rid of all occurrences of bus_id in the entire tree
to be able to enable the new interface. Please apply this patch,
and possibly convert any remaining remaining occurrences of bus_id.

We want to submit a patch to -next, which will remove bus_id from
"struct device", to find the remaining pieces to convert, and finally
switch over to the new api, which will remove the 20 bytes array
and does no longer have a size limitation.

Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-12-30 09:25:56 +10:30
Hollis Blanchard 13b1eb333b virtio-pci queue allocation not page-aligned
kzalloc() does not guarantee page alignment, and in fact this broke when
I enabled CONFIG_SLUB_DEBUG_ON.

(Thanks to Anthony Liguori for spotting the missing kfree sub)

Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (fixed kfree)
Tested-by: Anthony Liguori <aliguori@us.ibm.com>
2008-12-30 09:25:56 +10:30
Anthony Liguori 532a6086e3 virtio_balloon: fix towards_target when deflating balloon
Both v and vb->num_pages are u32 and unsigned int respectively.  If v is less
than vb->num_pages (and it is, when deflating the balloon), the result is a
very large 32-bit number.  Since we're returning a s64, instead of getting the
same negative number we desire, we get a very large positive number.

This handles the case where v < vb->num_pages and ensures we get a small,
negative, s64 as the result.

Rusty: please push this for 2.6.27-rc4.  It's probably appropriate for the
stable tree too as it will cause an unexpected OOM when ballooning.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (simplified)
2008-08-26 00:19:25 +10:00
Rusty Russell e34f872567 virtio: Add transport feature handling stub for virtio_ring.
To prepare for virtio_ring transport feature bits, hook in a call in
all the users to manipulate them.  This currently just clears all the
bits, since it doesn't understand any features.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-25 12:06:14 +10:00
Rusty Russell c624896e48 virtio: Rename set_features to finalize_features
Rather than explicitly handing the features to the lower-level, we just
hand the virtio_device and have it set the features.  This make it clear
that it has the chance to manipulate the features of the device at this
point (and that all feature negotiation is already done).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-25 12:06:12 +10:00
Rusty Russell dd7c7bc462 virtio: Formally reserve bits 28-31 to be 'transport' features.
We assign feature bits as required, but it makes sense to reserve some
for the particular transport, rather than the particular device.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-25 12:06:07 +10:00
Mark McLoughlin e962fa660d virtio: Use bus_type probe and remove methods
Hook up to the probe() and remove() methods in bus_type
rather than device_driver. The latter has been preferred
since 2.6.16.

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-25 12:06:05 +10:00
Rusty Russell 44653eae14 virtio: don't always force a notification when ring is full
We force notification when the ring is full, even if the host has
indicated it doesn't want to know.  This seemed like a good idea at
the time: if we fill the transmit ring, we should tell the host
immediately.

Unfortunately this logic also applies to the receiving ring, which is
refilled constantly.  We should introduce real notification thesholds
to replace this logic.  Meanwhile, removing the logic altogether breaks
the heuristics which KVM uses, so we use a hack: only notify if there are
outgoing parts of the new buffer.

Here are the number of exits with lguest's crappy network implementation:
Before:
	network xmit 7859051 recv 236420
After:
	network xmit 7858610 recv 118136

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-25 12:06:04 +10:00
Mark McLoughlin b92dea67cc virtio: Complete feature negotation before updating status
lguest (in rusty's use-tun-ringfd patch) assumes that the
guest has updated its feature bits before setting its status
to VIRTIO_CONFIG_S_DRIVER_OK.

That's pretty reasonable, so let's make it so.

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-06-15 13:46:16 -07:00
Rusty Russell b4f68be6c5 virtio: force callback on empty.
virtio allows drivers to suppress callbacks (ie. interrupts) for
efficiency (no locking, it's just an optimization).

There's a similar mechanism for the host to suppress notifications
coming from the guest: in that case, we ignore the suppression if the
ring is completely full.

It turns out that life is simpler if the host similarly ignores
callback suppression when the ring is completely empty: the network
driver wants to free up old packets in a timely manner, and otherwise
has to use a timer to poll.

We have to remove the code which ignores interrupts when the driver
has disabled them (again, it had no locking and hence was unreliable
anyway).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-05-30 15:09:46 +10:00
Christian Borntraeger 52a3a05f3a virtio_net: another race with virtio_net and enable_cb
Hello Rusty,

seems that we still have a problem with virtio_net and the enable_cb callback.
During a long running network stress tests with virtio and got the following
oops:

------------[ cut here ]------------
kernel BUG at drivers/virtio/virtio_ring.c:230!
illegal operation: 0001 [#1] SMP
Modules linked in:
CPU: 0 Not tainted 2.6.26-rc2-kvm-00436-gc94c08b-dirty #34
Process netserver (pid: 2582, task: 000000000fbc4c68, ksp: 000000000f42b990)
Krnl PSW : 0704c00180000000 00000000002d0ec8 (vring_enable_cb+0x1c/0x60)
           R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 EA:3
Krnl GPRS: 0000000000000000 0000000000000000 000000000ef3d000 0000000010009800
           0000000000000000 0000000000419ce0 0000000000000080 000000000000007b
           000000000adb5538 000000000ef40900 000000000ef40000 000000000ef40920
           0000000000000000 0000000000000005 000000000029c1b0 000000000fea7d18
Krnl Code: 00000000002d0ebc: a7110001           tmll    %r1,1
           00000000002d0ec0: a7740004           brc     7,2d0ec8
           00000000002d0ec4: a7f40001           brc     15,2d0ec6
          >00000000002d0ec8: a517fffe           nill    %r1,65534
           00000000002d0ecc: 40103000           sth     %r1,0(%r3)
           00000000002d0ed0: 07f0               bcr     15,%r0
           00000000002d0ed2: e31020380004       lg      %r1,56(%r2)
           00000000002d0ed8: a7480000           lhi     %r4,0
Call Trace:
([<000000000029c0fc>] virtnet_poll+0x290/0x3b8)
 [<0000000000333fb8>] net_rx_action+0x9c/0x1b8
 [<00000000001394bc>] __do_softirq+0x74/0x108
 [<000000000010d16a>] do_softirq+0x92/0xac
 [<0000000000139826>] irq_exit+0x72/0xc8
 [<000000000010a7b6>] do_extint+0xe2/0x104
 [<0000000000110508>] ext_no_vtime+0x16/0x1a
Last Breaking-Event-Address:
 [<00000000002d0ec4>] vring_enable_cb+0x18/0x60

I looked into the virtio_net code for some time and I think the following
scenario happened. Please look at virtnet_poll:
[...]
        /* Out of packets? */
        if (received < budget) {
                netif_rx_complete(vi->dev, napi);
                if (unlikely(!vi->rvq->vq_ops->enable_cb(vi->rvq))
                    && napi_schedule_prep(napi)) {
                        vi->rvq->vq_ops->disable_cb(vi->rvq);
                        __netif_rx_schedule(vi->dev, napi);
                        goto again;
                }
        }

If an interrupt arrives after netif_rx_complete, a second poll routine can run
on a different cpu. The second check for napi_schedule_prep would prevent any
harm in the network stack, but we have called enable_cb possibly after the
disable_cb in skb_recv_done.

static void skb_recv_done(struct virtqueue *rvq)
{
        struct virtnet_info *vi = rvq->vdev->priv;
        /* Schedule NAPI, Suppress further interrupts if successful. */
        if (netif_rx_schedule_prep(vi->dev, &vi->napi)) {
                rvq->vq_ops->disable_cb(rvq);
                __netif_rx_schedule(vi->dev, &vi->napi);
        }
}

That means that the second poll routine runs with interrupts enabled, which is
ok, since we can handle additional interrupts. The problem is now that the
second poll routine might also call enable_cb, triggering the BUG.

The only solution I can come up with, is to remove the BUG statement in
enable_cb - similar to disable_cb. Opinions or better ideas where the oops
could come from?

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-05-30 15:09:45 +10:00
Rusty Russell b769f57908 virtio: set device index in common code.
Anthony Liguori points out that three different transports use the virtio code,
but each one keeps its own counter to set the virtio_device's index field.  In
theory (though not in current practice) this means that names could be
duplicated, and that risk grows as more transports are created.

So we move the selection of the unique virtio_device.index into the common code
in virtio.c, which has the side-benefit of removing duplicate code.

The only complexity is that lguest and S/390 use the index to uniquely identify
the device in case of catastrophic failure before register_virtio_device() is
called: now we use the offset within the descriptor page as a unique identifier
for the printks.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Carsten Otte <cotte@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Chris Lalancette <clalance@redhat.com>
Cc: Anthony Liguori <anthony@codemonkey.ws>
2008-05-30 15:09:42 +10:00
Rusty Russell 5610bd1524 virtio: virtio_pci should not set bus_id.
The common virtio code sets the bus_id, overriding anything virtio_pci
sets anyway.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Carsten Otte <cotte@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Chris Lalancette <clalance@redhat.com>
Cc: Anthony Liguori <anthony@codemonkey.ws>
2008-05-30 15:09:42 +10:00
Rusty Russell 2ad3cfbac5 virtio: bus_id for devices should contain 'virtio'
Chris Lalancette <clalance@redhat.com> points out that virtio.c sets all device
names to '0', '1', etc, which looks silly in /proc/interrupts.  We change this
from '%d' to 'virtio%d'.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Carsten Otte <cotte@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Chris Lalancette <clalance@redhat.com>
Cc: Anthony Liguori <anthony@codemonkey.ws>
2008-05-30 15:09:42 +10:00
Rusty Russell c45a6816c1 virtio: explicit advertisement of driver features
A recent proposed feature addition to the virtio block driver revealed
some flaws in the API: in particular, we assume that feature
negotiation is complete once a driver's probe function returns.

There is nothing in the API to require this, however, and even I
didn't notice when it was violated.

So instead, we require the driver to specify what features it supports
in a table, we can then move the feature negotiation into the virtio
core.  The intersection of device and driver features are presented in
a new 'features' bitmap in the struct virtio_device.

Note that this highlights the difference between Linux unsigned-long
bitmaps where each unsigned long is in native endian, and a
straight-forward little-endian array of bytes.

Drivers can still remove feature bits in their probe routine if they
really have to.

API changes:
- dev->config->feature() no longer gets and acks a feature.
- drivers should advertise their features in the 'feature_table' field
- use virtio_has_feature() for extra sanity when checking feature bits

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-05-02 21:50:50 +10:00
Rusty Russell 72e61eb40b virtio: change config to guest endian.
A recent proposed feature addition to the virtio block driver revealed
some flaws in the API, in particular how easy it is to break big
endian machines.

The virtio config space was originally chosen to be little-endian,
because we thought the config might be part of the PCI config space
for virtio_pci.  It's actually a separate mmio region, so that
argument holds little water; as only x86 is currently using the virtio
mechanism, we can change this (but must do so now, before the
impending s390 merge).

API changes:
- __virtio_config_val() just becomes a striaght vdev->config_get() call.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-05-02 21:50:50 +10:00
Harvey Harrison 597d56e4b5 virtio: fix sparse return void-valued expression warnings
drivers/virtio/virtio_pci.c:148:2: warning: returning void-valued expression
drivers/virtio/virtio_pci.c:155:2: warning: returning void-valued expression

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-05-02 21:50:44 +10:00
Rusty Russell 5ef827526f virtio: ignore corrupted virtqueues rather than spinning.
A corrupt virtqueue (caused by the other end screwing up) can have
strange results such as a driver spinning: just bail when we try to
get a buffer from a known-broken queue.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-05-02 21:50:43 +10:00
Rusty Russell 2557a933b7 virtio: remove overzealous BUG_ON.
The 'disable_cb' callback is designed as an optimization to tell the host
we don't need callbacks now.  As it is not reliable, the debug check is
overzealous: it can happen on two CPUs at the same time.  Document this.

Even if it were reliable, the virtio_net driver doesn't disable
callbacks on transmit so the START_USE/END_USE debugging reentrance
protection can be easily tripped even on UP.

Thanks to Balaji Rao for the bug report and testing.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
CC: Balaji Rao <balajirrao@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-07 13:14:22 -07:00
Al Viro 97968358ab virtio_pci iomem annotations
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-03-30 14:20:23 -07:00
Anthony Liguori bd6c26900b virtio_pci: unregister virtio device at device remove
Make sure to call unregister_virtio_device() when a virtio device is removed.
Otherwise, virtio_pci.ko cannot be rmmod'd.

This was spotted by Marcelo Tosatti.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-03-28 11:05:51 +11:00
Christian Borntraeger 4265f161b6 virtio: fix race in enable_cb
There is a race in virtio_net, dealing with disabling/enabling the callback.
I saw the following oops:

kernel BUG at /space/kvm/drivers/virtio/virtio_ring.c:218!
illegal operation: 0001 [#1] SMP
Modules linked in: sunrpc dm_mod
CPU: 2 Not tainted 2.6.25-rc1zlive-host-10623-gd358142-dirty #99
Process swapper (pid: 0, task: 000000000f85a610, ksp: 000000000f873c60)
Krnl PSW : 0404300180000000 00000000002b81a6 (vring_disable_cb+0x16/0x20)
           R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:0 CC:3 PM:0 EA:3
Krnl GPRS: 0000000000000001 0000000000000001 0000000010005800 0000000000000001
           000000000f3a0900 000000000f85a610 0000000000000000 0000000000000000
           0000000000000000 000000000f870000 0000000000000000 0000000000001237
           000000000f3a0920 000000000010ff74 00000000002846f6 000000000fa0bcd8
Krnl Code: 00000000002b819a: a7110001           tmll    %r1,1
           00000000002b819e: a7840004           brc     8,2b81a6
           00000000002b81a2: a7f40001           brc     15,2b81a4
          >00000000002b81a6: a51b0001           oill    %r1,1
           00000000002b81aa: 40102000           sth     %r1,0(%r2)
           00000000002b81ae: 07fe               bcr     15,%r14
           00000000002b81b0: eb7ff0380024       stmg    %r7,%r15,56(%r15)
           00000000002b81b6: a7f13e00           tmll    %r15,15872
Call Trace:
([<000000000fa0bcd0>] 0xfa0bcd0)
 [<00000000002b8350>] vring_interrupt+0x5c/0x6c
 [<000000000010ab08>] do_extint+0xb8/0xf0
 [<0000000000110716>] ext_no_vtime+0x16/0x1a
 [<0000000000107e72>] cpu_idle+0x1c2/0x1e0

The problem can be triggered with a high amount of host->guest traffic.
I think its the following race:

poll says netif_rx_complete
poll calls enable_cb
enable_cb opens the interrupt mask
a new packet comes, an interrupt is triggered----\
enable_cb sees that there is more work           |
enable_cb disables the interrupt                 |
       .                                         V
       .                            interrupt is delivered
       .                            skb_recv_done does atomic napi test, ok
 some waiting                       disable_cb is called->check fails->bang!
       .
poll would do napi check
poll would do disable_cb

The fix is to let enable_cb not disable the interrupt again, but expect the
caller to do the cleanup if it returns false. In that case, the interrupt is
only disabled, if the napi test_set_bit was successful.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (cleaned up doco)
2008-03-17 22:58:21 +11:00
Rusty Russell bdc1681cdf virtio: handle > 2 billion page balloon targets
If the host asks for a huge target towards_target() can overflow, and
we up oops as we try to release more pages than we have.  The simple
fix is to use a 64-bit value.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-03-17 22:58:19 +11:00
Anthony Liguori 27ebe308af virtio: Use spin_lock_irqsave/restore for virtio-pci
virtio-pci acquires its spin lock in an interrupt context so it's necessary
to use spin_lock_irqsave/restore variants.  This patch fixes guest SMP when
using virtio devices in KVM.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-03-17 22:58:13 +11:00
Johann Felix Soden 6659a0f0bb virtio: add missing #include <linux/delay.h>
Include linux/delay.h to fix compiler error:

drivers/virtio/virtio_balloon.c: In function 'fill_balloon':
drivers/virtio/virtio_balloon.c:98: error: implicit declaration of function 'msleep'

Signed-off-by: Johann Felix Soden <johfel@users.sourceforge.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-06 10:41:21 -08:00
Rusty Russell 6b35e40767 virtio: balloon driver
After discussions with Anthony Liguori, it seems that the virtio
balloon can be made even simpler.  Here's my attempt.

The device configuration tells the driver how much memory it should
take from the guest (ie. balloon size).  The guest feeds the page
numbers it has taken via one virtqueue.

A second virtqueue feeds the page numbers the driver wants back: if
the device has the VIRTIO_BALLOON_F_MUST_TELL_HOST bit, then this
queue is compulsory, otherwise it's advisory (and the guest can simply
fault the pages back in).

This driver can be enhanced later to deflate the balloon via a
shrinker, oom callback or we could even go for a complete set of
in-guest regulators.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-02-04 23:50:13 +11:00
Anthony Liguori 55a7c06604 virtio: Use PCI revision field to indicate virtio PCI ABI version
As Avi pointed out, as we continue to massage the virtio PCI ABI, we can make
things a little more friendly to users by utilizing the PCI revision field to
indicate which version of the ABI we're using.  This is a hard ABI version
and incrementing it will cause the guest driver to break.

This is the necessary changes to virtio_pci to support this.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-02-04 23:50:12 +11:00
Anthony Liguori 3343660d8c virtio: PCI device
This is a PCI device that implements a transport for virtio.  It allows virtio
devices to be used by QEMU based VMMs like KVM or Xen.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-02-04 23:50:11 +11:00
Rusty Russell c6fd47011b virtio: Allow virtio to be modular and used by modules
This is needed for the virtio PCI device to be compiled as a module.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-02-04 23:50:06 +11:00
Rusty Russell 15f9c8903c virtio: Use the sg_phys convenience function.
Simple cleanup.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-02-04 23:50:05 +11:00
Rusty Russell 81a8deab1c virtio: handle interrupts after callbacks turned off
Anthony Liguori found double interrupt suppression in the virtio_net
driver, triggered by two skb_recv_done's in a row.  This is because
virtio_ring's interrupt suppression is a best-effort optimization: it
contains no synchronization so the host can miss it and still send
interrupts.

But it's certainly nicer for virtio users if calling disable_cb
actually disables callbacks, so we check for the race in the interrupt
routine.

Note: SMP guests might require syncronization here, but since
disable_cb is actually called from interrupt context, there has to be
some form of synchronization before the next same interrupt handler is
called (Linux guarantees that the same device's irq handler will never
run simultanously on multiple CPUs).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-02-04 23:50:04 +11:00
Rusty Russell 6e5aa7efb2 virtio: reset function
A reset function solves three problems:

1) It allows us to renegotiate features, eg. if we want to upgrade a
   guest driver without rebooting the guest.

2) It gives us a clean way of shutting down virtqueues: after a reset,
   we know that the buffers won't be used by the host, and

3) It helps the guest recover from messed-up drivers.

So we remove the ->shutdown hook, and the only way we now remove
feature bits is via reset.

We leave it to the driver to do the reset before it deletes queues:
the balloon driver, for example, needs to chat to the host in its
remove function.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-02-04 23:50:03 +11:00
Rusty Russell 426e3e0af5 virtio: clarify NO_NOTIFY flag usage
The other side (host) can set the NO_NOTIFY flag as an optimization,
to say "no need to kick me when you add things".  Make it clear that
this is advisory only; especially that we should always notify when
the ring is full.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-02-04 23:50:00 +11:00
Rusty Russell 18445c4d50 virtio: explicit enable_cb/disable_cb rather than callback return.
It seems that virtio_net wants to disable callbacks (interrupts) before
calling netif_rx_schedule(), so we can't use the return value to do so.

Rename "restart" to "cb_enable" and introduce "cb_disable" hook: callback
now returns void, rather than a boolean.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-02-04 23:49:58 +11:00
Rusty Russell a586d4f601 virtio: simplify config mechanism.
Previously we used a type/len pair within the config space, but this
seems overkill.  We now simply define a structure which represents the
layout in the config space: the config space can now only be extended
at the end.

The main driver-visible changes:
1) We indicate what fields are present with an explicit feature bit.
2) Virtqueues are explicitly numbered, and not in the config space.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-02-04 23:49:57 +11:00
Rusty Russell 74b2553f1d virtio: fix module/device unloading
The virtio code never hooked through the ->remove callback.  Although
noone supports device removal at the moment, this code is already
needed for module unloading.

This of course also revealed bugs in virtio_blk, virtio_net and lguest
unloading paths.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-11-19 11:20:42 +11:00
Rusty Russell 42b36cc0ce virtio: Force use of power-of-two for descriptor ring sizes
The virtio descriptor rings of size N-1 were nicely set up to be
aligned to an N-byte boundary.  But as Anthony Liguori points out, the
free-running indices used by virtio require that the sizes be a power
of 2, otherwise we get problems on wrap (demonstrated with lguest).

So we replace the clever "2^n-1" scheme with a simple "align to page
boundary" scheme: this means that all virtio rings take at least two
pages, but it's safer than guessing cache alignment.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-11-12 13:59:40 +11:00
Anthony Liguori 1bc4953ed4 virtio: Fix used_idx wrap-around
The more_used() function compares the vq->vring.used->idx with last_used_idx.
Since vq->vring.used->idx is a 16-bit integer, and last_used_idx is an
unsigned int, this results in unpredictable behavior when vq->vring.used->idx
wraps around.

This patch corrects this by changing last_used_idx to the correct type.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-11-12 13:59:09 +11:00
Rusty Russell 0a8a69dd77 Virtio helper routines for a descriptor ringbuffer implementation
These helper routines supply most of the virtqueue_ops for hypervisors
which want to use a ring for virtio.  Unlike the previous lguest
implementation:

1) The rings are variable sized (2^n-1 elements).
2) They have an unfortunate limit of 65535 bytes per sg element.
3) The page numbers are always 64 bit (PAE anyone?)
4) They no longer place used[] on a separate page, just a separate
   cacheline.
5) We do a modulo on a variable.  We could be tricky if we cared.
6) Interrupts and notifies are suppressed using flags within the rings.

Users need only get the ring pages and provide a notify hook (KVM
wants the guest to allocate the rings, lguest does it sanely).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dor Laor <dor.laor@qumranet.com>
2007-10-23 15:49:55 +10:00
Rusty Russell b01d9f2863 Module autoprobing support for virtio drivers.
This adds the logic to convert the virtio ids into module aliases, and
includes a modalias entry in sysfs and the env var to make probing work.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-10-23 15:49:55 +10:00
Rusty Russell ec3d41c4db Virtio interface
This attempts to implement a "virtual I/O" layer which should allow
common drivers to be efficiently used across most virtual I/O
mechanisms.  It will no-doubt need further enhancement.

The virtio drivers add buffers to virtio queues; as the buffers are consumed
the driver "interrupt" callbacks are invoked.

There is also a generic implementation of config space which drivers can query
to get setup information from the host.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dor Laor <dor.laor@qumranet.com>
Cc: Arnd Bergmann <arnd@arndb.de>
2007-10-23 15:49:54 +10:00