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commit fc8653228c8588a120f6b5dad6983b7b61ff669e upstream.
When init_vqs runs, virtio_balloon.stats is either uninitialized or
contains stale values. The host updates its state with garbage data
because it has no way of knowing that this is just a marker buffer
used for signaling.
This patch updates the stats before pushing the initial buffer.
Alternative fixes:
* Push an empty buffer in init_vqs. Not easily done with the current
virtio implementation and violates the spec "Driver MUST supply the
same subset of statistics in all buffers submitted to the statsq".
* Push a buffer with invalid tags in init_vqs. Violates the same
spec clause, plus "invalid tag" is not really defined.
Note: the spec says:
When using the legacy interface, the device SHOULD ignore all values in
the first buffer in the statsq supplied by the driver after device
initialization. Note: Historically, drivers supplied an uninitialized
buffer in the first buffer.
Unfortunately QEMU does not seem to implement the recommendation
even for the legacy interface.
Signed-off-by: Ladi Prosek <lprosek@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 37cf99e08c6fb4dcea0f9ad2b13b6daa8c76a711 upstream.
The balloon has a special mechanism that is subscribed to the oom
notification which leads to deflation for a fixed number of pages.
The number is always fixed even when the balloon is fully deflated.
But leak_balloon did not expect that the pages to deflate will be more
than taken, and raise a "BUG" in balloon_page_dequeue when page list
will be empty.
So, the simplest solution would be to check that the number of releases
pages is less or equal to the number taken pages.
Signed-off-by: Konstantin Neumoin <kneumoin@virtuozzo.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 87c9403b0d1de4676b0bd273eea68fcf6de68e68 upstream.
Everything should be LE when using virtio-1, but
the linux balloon driver does not seem to care about that.
Reported-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit f68b992bbb474641881932c61c92dcfa6f5b3689 upstream.
During my compaction-related stuff, I encountered a bug
with ballooning.
With repeated inflating and deflating cycle, guest memory(
ie, cat /proc/meminfo | grep MemTotal) is decreased and
couldn't be recovered.
The reason is balloon_lock doesn't cover release_pages_balloon
so struct virtio_balloon fields could be overwritten by race
of fill_balloon(e,g, vb->*pfns could be critical).
This patch fixes it in my test.
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Balloon device is frequently used as a mean of cooperative memory control
in between guest and host to manage memory overcommitment. This is the
typical case for any hosting workload when KVM guest is provided for
end-user.
Though there is a problem in this setup. The end-user and hosting provider
have signed SLA agreement in which some amount of memory is guaranted for
the guest. The good thing is that this memory will be given to the guest
when the guest will really need it (f.e. with OOM in guest and with
VIRTIO_BALLOON_F_DEFLATE_ON_OOM configuration flag set). The bad thing
is that end-user does not know this.
Balloon by default reduce the amount of memory exposed to the end-user
each time when the page is stolen from guest or returned back by using
adjust_managed_page_count and thus /proc/meminfo shows reduced amount
of memory.
Fortunately the solution is simple, we should just avoid to call
adjust_managed_page_count with VIRTIO_BALLOON_F_DEFLATE_ON_OOM set.
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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and rename it to release_pages_balloon. The function originally takes
arrays of pfns and now it takes pointer to struct virtio_ballon.
This change is necessary to conditionally call adjust_managed_page_count
in the next patch.
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Virtio 1.0 doesn't include a modern balloon device.
But it's not a big change to support a transitional
balloon device: this has the advantage of supporting
existing drivers, transparently.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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virtio balloon has this code:
wait_event_interruptible(vb->config_change,
(diff = towards_target(vb)) != 0
|| vb->need_stats_update
|| kthread_should_stop()
|| freezing(current));
Which is a problem because towards_target() call might block after
wait_event_interruptible sets task state to TAST_INTERRUPTIBLE, causing
the task_struct::state collision typical of nesting of sleeping
primitives
See also http://lwn.net/Articles/628628/ or Thomas's
bug report
http://article.gmane.org/gmane.linux.kernel.virtualization/24846
for a fuller explanation.
To fix, rewrite using wait_woken.
Cc: stable@vger.kernel.org
Reported-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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virtio spec requires that all drivers set DRIVER_OK
before using devices. While balloon isn't yet
included in the virtio 1 spec, previous spec versions
also required this.
virtio balloon might violate this rule: probe calls
kthread_run before setting DRIVER_OK, which might run
immediately and cause balloon to inflate/deflate.
To fix, call virtio_device_ready before running the kthread.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
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Most of our code has
struct foo {
}
Fix two instances where balloon is inconsistent.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Some devices might not implement config space access
(e.g. remoteproc used not to - before 3.9).
virtio/balloon needs config space access so make it
fail gracefully if not there.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Excessive virtio_balloon inflation can cause invocation of OOM-killer,
when Linux is under severe memory pressure. Various mechanisms are
responsible for correct virtio_balloon memory management. Nevertheless
it is often the case that these control tools does not have enough time
to react on fast changing memory load. As a result OS runs out of memory
and invokes OOM-killer. The balancing of memory by use of the virtio
balloon should not cause the termination of processes while there are
pages in the balloon. Now there is no way for virtio balloon driver to
free some memory at the last moment before some process will be get
killed by OOM-killer.
This does not provide a security breach as balloon itself is running
inside guest OS and is working in the cooperation with the host. Thus
some improvements from guest side should be considered as normal.
To solve the problem, introduce a virtio_balloon callback which is
expected to be called from the oom notifier call chain in out_of_memory()
function. If virtio balloon could release some memory, it will make
the system to return and retry the allocation that forced the out of
memory killer to run.
Allocate virtio feature bit for this: it is not set by default,
the the guest will not deflate virtio balloon on OOM without explicit
permission from host.
Signed-off-by: Raushaniya Maksudova <rmaksudova@parallels.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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This value would be useful in the next patch to provide the amount of
the freed memory for OOM killer.
Signed-off-by: Raushaniya Maksudova <rmaksudova@parallels.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Rusty Russell <rusty@rustcorp.com.au>
CC: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
Pull virtio updates from Rusty Russell:
"One cc: stable commit, the rest are a series of minor cleanups which
have been sitting in MST's tree during my vacation. I changed a
function name and made one trivial change, then they spent two days in
linux-next"
* tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: (25 commits)
virtio-rng: refactor probe error handling
virtio_scsi: drop scan callback
virtio_balloon: enable VQs early on restore
virtio_scsi: fix race on device removal
virito_scsi: use freezable WQ for events
virtio_net: enable VQs early on restore
virtio_console: enable VQs early on restore
virtio_scsi: enable VQs early on restore
virtio_blk: enable VQs early on restore
virtio_scsi: move kick event out from virtscsi_init
virtio_net: fix use after free on allocation failure
9p/trans_virtio: enable VQs early
virtio_console: enable VQs early
virtio_blk: enable VQs early
virtio_net: enable VQs early
virtio: add API to enable VQs early
virtio_net: minor cleanup
virtio-net: drop config_mutex
virtio_net: drop config_enable
virtio-blk: drop config_mutex
...
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virtio spec requires drivers to set DRIVER_OK before using VQs.
This is set automatically after resume returns, virtio balloon
violated this rule by adding bufs, which causes the VQ to be used
directly within restore.
To fix, call virtio_device_ready before using VQ.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Always mark pages with PageBalloon even if balloon compaction is disabled
and expose this mark in /proc/kpageflags as KPF_BALLOON.
Also this patch adds three counters into /proc/vmstat: "balloon_inflate",
"balloon_deflate" and "balloon_migrate". They accumulate balloon
activity. Current size of balloon is (balloon_inflate - balloon_deflate)
pages.
All generic balloon code now gathered under option CONFIG_MEMORY_BALLOON.
It should be selected by ballooning driver which wants use this feature.
Currently virtio-balloon is the only user.
Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Now ballooned pages are detected using PageBalloon(). Fake mapping is no
longer required. This patch links ballooned pages to balloon device using
field page->private instead of page->mapping. Also this patch embeds
balloon_dev_info directly into struct virtio_balloon.
Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Sasha Levin reported KASAN splash inside isolate_migratepages_range().
Problem is in the function __is_movable_balloon_page() which tests
AS_BALLOON_MAP in page->mapping->flags. This function has no protection
against anonymous pages. As result it tried to check address space flags
inside struct anon_vma.
Further investigation shows more problems in current implementation:
* Special branch in __unmap_and_move() never works:
balloon_page_movable() checks page flags and page_count. In
__unmap_and_move() page is locked, reference counter is elevated, thus
balloon_page_movable() always fails. As a result execution goes to the
normal migration path. virtballoon_migratepage() returns
MIGRATEPAGE_BALLOON_SUCCESS instead of MIGRATEPAGE_SUCCESS,
move_to_new_page() thinks this is an error code and assigns
newpage->mapping to NULL. Newly migrated page lose connectivity with
balloon an all ability for further migration.
* lru_lock erroneously required in isolate_migratepages_range() for
isolation ballooned page. This function releases lru_lock periodically,
this makes migration mostly impossible for some pages.
* balloon_page_dequeue have a tight race with balloon_page_isolate:
balloon_page_isolate could be executed in parallel with dequeue between
picking page from list and locking page_lock. Race is rare because they
use trylock_page() for locking.
This patch fixes all of them.
Instead of fake mapping with special flag this patch uses special state of
page->_mapcount: PAGE_BALLOON_MAPCOUNT_VALUE = -256. Buddy allocator uses
PAGE_BUDDY_MAPCOUNT_VALUE = -128 for similar purpose. Storing mark
directly in struct page makes everything safer and easier.
PagePrivate is used to mark pages present in page list (i.e. not
isolated, like PageLRU for normal pages). It replaces special rules for
reference counter and makes balloon migration similar to migration of
normal pages. This flag is protected by page_lock together with link to
the balloon device.
Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Link: http://lkml.kernel.org/p/53E6CEAA.9020105@oracle.com
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: <stable@vger.kernel.org> [3.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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A bad implementation of virtio might cause us to mark the virtqueue
broken: we'll dev_err() in that case, and the device is useless, but
let's not BUG().
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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When adding or removing 100G from a balloon:
BUG: soft lockup - CPU#0 stuck for 22s! [vballoon:367]
We have a wait_event_interruptible(), but the condition is always true
(more ballooning to do) so we don't ever sleep. We also have a
wait_event() for the host to ack, but that is also always true as QEMU
is synchronous for balloon operations.
Reported-by: Gopesh Kumar Chaudhary <gopchaud@in.ibm.com>
Cc: stable@kernel.org
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
Pull virtio update from Rusty Russell:
"A few simple fixes. Quiet cycle"
* tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
drivers: virtio: Mark function virtballoon_migratepage() as static in virtio_balloon.c
virtio-scsi: Fix hotcpu_notifier use-after-free with virtscsi_freeze
virtio: pci: remove unnecessary pci_set_drvdata()
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virtio_balloon.c
Mark the function virtballoon_migratepage() as static in
virtio_balloon.c because it is not used outside this file.
This eliminates the following warning in virtio_balloon.c:
drivers/virtio/virtio_balloon.c:372:5: warning: no previous prototype for ‘virtballoon_migratepage’ [-Wmissing-prototypes]
Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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According to the virtio spec, the device configuration field
that should be updated after an inflation or deflation
operation is the 'actual' field, not the 'num_pages' one.
Commit 855e0c5288177bcb193f6f6316952d2490478e1c swapped them
in update_balloon_size(). Fix it.
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Fixes: 855e0c5288177bcb193f6f6316952d2490478e1c
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This lets the transport do endian conversion if necessary, and insulates
the drivers from the difference.
Most drivers can use the simple helpers virtio_cread() and virtio_cwrite().
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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The freeze and restore functions defined in virtio drivers are used
for suspend and hibernate, so CONFIG_PM_SLEEP is more appropriate than
CONFIG_PM. This patch replace all CONFIG_PM with CONFIG_PM_SLEEP for
virtio drivers that implement freeze and restore callbacks.
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
Pull virtio updates from Rusty Russell:
"No real surprises"
* tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
MAINTAINERS: add tools/virtio/ under virtio
tools/virtio: move module license stub to module.h
virtio: include asm/barrier explicitly
virtio: VIRTIO_F_ANY_LAYOUT feature
lguest: fix example launcher compilation for broken glibc headers.
virtio-net: fix the race between channels setting and refill
tools/lguest: real barriers.
tools/lguest: fix missing rmb().
virtio_balloon: leak_balloon(): only tell host if we got pages deflated
virtio-pci: fix leaks of msix_affinity_masks
Fix comment typo "CONFIG_PAE"
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Enhance adjust_managed_page_count() to adjust totalhigh_pages for
highmem pages. And change code which directly adjusts totalram_pages to
use adjust_managed_page_count() because it adjusts totalram_pages,
totalhigh_pages and zone->managed_pages altogether in a safe way.
Remove inc_totalhigh_pages() and dec_totalhigh_pages() from xen/balloon
driver bacause adjust_managed_page_count() has already adjusted
totalhigh_pages.
This patch also fixes two bugs:
1) enhances virtio_balloon driver to adjust totalhigh_pages when
reserve/unreserve pages.
2) enhance memory_hotplug.c to adjust totalhigh_pages when hot-removing
memory.
We still need to deal with modifications of totalram_pages in file
arch/powerpc/platforms/pseries/cmm.c, but need help from PPC experts.
[akpm@linux-foundation.org: remove ifdef, per Wanpeng Li, virtio_balloon.c cleanup, per Sergei]
[akpm@linux-foundation.org: export adjust_managed_page_count() to modules, for drivers/virtio/virtio_balloon.c]
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Minchan Kim <minchan@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <sworddragon2@aol.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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balloon_page_dequeue() can return NULL. If it does for the first page
being freed then leak_balloon() will create a scatter list with len=0.
Which in turn seems to generate an invalid virtio request.
I didn't get this in practice, I found it by code review. On the other
hand, such an invalid virtio request will cause errors in QEMU and
fill_balloon() also performs the same check implemented by this commit.
This bug was introduced in e2250429.
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org # 3.9
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We never add buffers with input and output parts, so use the new accessors.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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CONFIG_HOTPLUG is going away as an option. As a result, the __dev*
markings need to be removed.
This change removes the use of __devinit, __devexit_p, and __devexit
from these drivers.
Based on patches originally written by Bill Pemberton, but redone by me
in order to handle some of the coding style issues better, by hand.
Cc: Bill Pemberton <wfp5p@virginia.edu>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
Pull virtio update from Rusty Russell:
"Some nice cleanups, and even a patch my wife did as a "live" demo for
Latinoware 2012.
There's a slightly non-trivial merge in virtio-net, as we cleaned up
the virtio add_buf interface while DaveM accepted the mq virtio-net
patches."
* tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: (27 commits)
virtio_console: Add support for remoteproc serial
virtio_console: Merge struct buffer_token into struct port_buffer
virtio: add drv_to_virtio to make code clearly
virtio: use dev_to_virtio wrapper in virtio
virtio-mmio: Fix irq parsing in command line parameter
virtio_console: Free buffers from out-queue upon close
virtio: Convert dev_printk(KERN_<LEVEL> to dev_<level>(
virtio_console: Use kmalloc instead of kzalloc
virtio_console: Free buffer if splice fails
virtio: tools: make it clear that virtqueue_add_buf() no longer returns > 0
virtio: scsi: make it clear that virtqueue_add_buf() no longer returns > 0
virtio: rpmsg: make it clear that virtqueue_add_buf() no longer returns > 0
virtio: net: make it clear that virtqueue_add_buf() no longer returns > 0
virtio: console: make it clear that virtqueue_add_buf() no longer returns > 0
virtio: make virtqueue_add_buf() returning 0 on success, not capacity.
virtio: console: don't rely on virtqueue_add_buf() returning capacity.
virtio_net: don't rely on virtqueue_add_buf() returning capacity.
virtio-net: remove unused skb_vnet_hdr->num_sg field
virtio-net: correct capacity math on ring full
virtio: move queue_index and num_free fields into core struct virtqueue.
...
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dev_<level> calls take less code than dev_printk(KERN_<LEVEL>
and reducing object size is good.
Convert if (printk_ratelimit()) dev_printk to dev_<level>_ratelimited.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Memory fragmentation introduced by ballooning might reduce significantly
the number of 2MB contiguous memory blocks that can be used within a guest,
thus imposing performance penalties associated with the reduced number of
transparent huge pages that could be used by the guest workload.
Besides making balloon pages movable at allocation time and introducing
the necessary primitives to perform balloon page migration/compaction,
this patch also introduces the following locking scheme, in order to
enhance the syncronization methods for accessing elements of struct
virtio_balloon, thus providing protection against concurrent access
introduced by parallel memory migration threads.
- balloon_lock (mutex) : synchronizes the access demand to elements of
struct virtio_balloon and its queue operations;
[yongjun_wei@trendmicro.com.cn: fix missing unlock on error in fill_balloon()]
[akpm@linux-foundation.org: avoid having multiple return points in fill_balloon()]
[akpm@linux-foundation.org: fix printk warning]Signed-off-by: Rafael Aquini <aquini@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Since ee7cd8981e15bcb365fc762afe3fc47b8242f630 'virtio: expose added
descriptors immediately.', in virtio balloon virtqueue_get_buf might
now run concurrently with virtqueue_kick. I audited both and this
seems safe in practice but this is not guaranteed by the API.
Additionally, a spurious interrupt might in theory make
virtqueue_get_buf run in parallel with virtqueue_add_buf, which is
racy.
While we might try to protect against spurious callbacks it's
easier to fix the driver: balloon seems to be the only one
(mis)using the API like this, so let's just fix balloon.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (removed unused var)
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The remove and freeze functions have a lot of shared code; put it into a
common function that gets called by both.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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restore_common() was used when there were different thaw and freeze PM
callbacks implemented. We removed thaw in commit
f38f8387cbdc4138a492ce9f2a5f04fd3cd3cf33.
restore_common() can be removed and virtballoon_restore() can itself do
the restore ops.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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When the balloon module is removed, we deflate the balloon, reclaiming
all the pages that were given to the host. However, we don't update the
config values for the new balloon size, resulting in the host showing
outdated balloon values.
The size update is done after each leak and fill operation, only the
module removal case was left out.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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As reported by David Gibson, current code handles PAGE_SIZE != 4k
completely wrong which can lead to guest memory corruption errors:
- page_to_balloon_pfn is wrong: e.g. on system with 64K page size
it gives the same pfn value for 16 different pages.
- we also need to convert back to linux pfns when we free.
- for each linux page we need to tell host about multiple balloon
pages, but code only adds one pfn to the array.
This patch fixes all that, tested with a 64k ppc64 kernel.
Reported-by: David Gibson <david@gibson.dropbear.id.au>
Tested-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Although virtio config space fields are usually in guest-native endian,
the spec for the virtio balloon device explicitly states that both fields
in its config space are little-endian.
However, the current virtio_balloon driver does not have a suitable endian
swap for the 'num_pages' field, although it does have one for the 'actual'
field. This patch corrects the bug, adding sparse annotation while we're
at it.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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The thaw operation was used by the balloon driver, but after the last
commit there's no reason to have separate thaw and restore callbacks.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
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There's no reason stats update after restore can't work. If a host
requested for stats, and before servicing the request, the guest entered
S4, upon restore, the stats request can still be processed and sent off
to the host.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
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commit e562966dbaf49e7804097cd991e5d3a8934fc148 added support for S4 to
the balloon driver. The freeze function did nothing to free the pages,
since reclaiming the pages from the host to immediately give them back
(if S4 was successful) seemed wasteful. Also, if S4 wasn't successful,
the guest would have to re-fill the balloon. On restore, the pages were
supposed to be marked freed and the free page counters were incremented
to reflect the balloon was totally deflated.
However, this wasn't done right. The pages that were earlier taken away
from the guest during a balloon inflation operation were just shown as
used pages after a successful restore from S4. Just a fancy way of
leaking lots of memory.
Instead of trying that, just leak the balloon on freeze and fill it on
restore/thaw paths. This works properly now. The optimisation to not
leak can be added later on after a bit of refactoring of the code.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Handling balloon hibernate / restore is tricky. If the balloon was
inflated before going into the hibernation state, upon resume, the host
will not have any memory of that. Any pages that were passed on to the
host earlier would most likely be invalid, and the host will have to
re-balloon to the previous value to get in the pre-hibernate state.
So the only sane thing for the guest to do here is to discard all the
pages that were put in the balloon. When to discard the pages is the
next question.
One solution is to deflate the balloon just before writing the image to
the disk (in the freeze() PM callback). However, asking for pages from
the host just to discard them immediately after seems wasteful of
resources. Hence, it makes sense to do this by just fudging our
counters soon after wakeup. This means we don't deflate the balloon
before sleep, and also don't put unnecessary pressure on the host.
This also helps in the thaw case: if the freeze fails for whatever
reason, the balloon should continue to remain in the inflated state.
This was tested by issuing 'swapoff -a' and trying to go into the S4
state. That fails, and the balloon stays inflated, as expected. Both
the host and the guest are happy.
Finally, in the restore() callback, we empty the list of pages that were
previously given off to the host, add the appropriate number of pages to
the totalram_pages counter, reset the num_pages counter to 0, and
all is fine.
As a last step, delete the vqs on the freeze callback to prepare for
hibernation, and re-create them in the restore and thaw callbacks to
resume normal operation.
The kthread doesn't race with any operations here, since it's frozen
before the freeze() call and is thawed after the thaw() and restore()
callbacks, so we're safe with that.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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The probe and PM restore functions will share this code.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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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>
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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>
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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>
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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>
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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>
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