linux-toradex.git/drivers/virtio/virtio_balloon.c, branch v3.4.2

virtio: balloon: let host know of updated balloon size before module removal

2012-05-17T09:14:34+00:00

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outdated balloon values.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 
Signed-off-by: Michael S. Tsirkin

virtio_balloon: fix handling of PAGE_SIZE != 4k

2012-04-15T08:51:06+00:00

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 
Tested-by: David Gibson 
Signed-off-by: Michael S. Tsirkin

virtio_balloon: Fix endian bug

2012-04-15T08:51:05+00:00

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 
Signed-off-by: Michael S. Tsirkin

virtio: drop thaw PM operation

2012-03-31T02:39:50+00:00

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

virtio: balloon: Allow stats update after restore from S4

2012-03-31T02:39:50+00:00

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

virtio: balloon: leak / fill balloon across S4

2012-02-29T22:58:41+00:00

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 
Signed-off-by: Rusty Russell

virtio: balloon: Add freeze, restore handlers to support S4

2012-01-12T05:14:47+00:00

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 
Signed-off-by: Rusty Russell

virtio: balloon: Move vq initialization into separate function

2012-01-12T05:14:46+00:00

The probe and PM restore functions will share this code.

Signed-off-by: Amit Shah 
Signed-off-by: Rusty Russell

virtio: rename virtqueue_add_buf_gfp to virtqueue_add_buf

2012-01-12T05:14:42+00:00

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 
Reviewed-by: Christoph Hellwig

virtio-balloon: Trivial cleanups

2012-01-12T05:14:42+00:00

Trivial changes to remove forgotten junk, format comments, and correct names.

Cc: Rusty Russell 
Cc: "Michael S. Tsirkin" 
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: Sasha Levin 
Signed-off-by: Rusty Russell