block/backup: Fix hang for unaligned image size

When doing a block backup of an image with an unaligned size (with
respect to the BACKUP_CLUSTER_SIZE), qemu would check the allocation
status of sectors after the end of the image. bdrv_is_allocated()
returns a result that is valid for 0 sectors in this case, so the backup
job ran into an endless loop.

Stop looping when seeing a result valid for 0 sectors, we're at EOF then.

The test case looks somewhat unrelated at first sight because I
originally tried to reproduce a different suspected bug that turned out
to not exist. Still a good test case and it accidentally found this one.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
block: Fix bdrv_is_allocated() return value

bdrv_is_allocated() should return either 0 or 1 in successful cases.
We're lucky that currently, the callers that rely on this (e.g. because
they check for ret == 1) don't seem to break badly. They just might skip
some optimisation or in the case of qemu-io 'map' print separate lines
where a single line would suffice. In theory, a wrong allocation status
could lead to image corruption with certain operations, so let's fix
this quickly.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
block: prefer aio_poll to qemu_aio_wait

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
block: drop aio functions that operate on the main AioContext

The main AioContext should be accessed explicitly via qemu_get_aio_context().
Most of the time, using it is not the right thing to do.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
test-aio: fix GSource-based timer test

The current test depends too much on the implementation of the AioContext
GSource.  Just iterate on the main loop until the callback has been invoked
the right number of times.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
AioContext: speed up aio_notify

In many cases, the call to event_notifier_set in aio_notify is unnecessary.
In particular, if we are executing aio_dispatch, or if aio_poll is not
blocking, we know that we will soon get to the next loop iteration (if
necessary); the thread that hosts the AioContext's event loop does not
need any nudging.

The patch includes a Promela formal model that shows that this really
works and does not need any further complication such as generation
counts.  It needs a memory barrier though.

The generation counts are not needed because any change to
ctx->dispatching after the memory barrier is okay for aio_notify.
If it changes from zero to one, it is the right thing to skip
event_notifier_set.  If it changes from one to zero, the
event_notifier_set is unnecessary but harmless.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
s390x/kvm: synchronize guest floating point registers

Add code to kvm_arch_get_registers and kvm_arch_put_registers to
save/restore floating point registers. This missing sync was
unnoticed until migration of userspace that uses fprs.

Signed-off-by: Jason J. Herne <jjherne@us.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
[Update patch to latest upstream]
Cc: qemu-stable@nongnu.org
Reviewed-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
block: Make qiov match the request size until EOF

If a read request goes across EOF, the block driver sees a shortened
request that stops at EOF (the rest is memsetted in block.c), however
the original qiov was used for this request.

This patch makes the qiov size match the request size, avoiding a
potential buffer overflow in raw-posix.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
qcow2: Make qiov match request size until backing file EOF

If a qcow2 image has a shorter backing file and a read request to
unallocated clusters goes across EOF of the backing file, the backing
file sees a shortened request and the rest is filled with zeros.
However, the original too long qiov was used with the shortened request.

This patch makes the qiov size match the request size, avoiding a
potential buffer overflow in raw-posix.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
qed: Make qiov match request size until backing file EOF

If a QED image has a shorter backing file and a read request to
unallocated clusters goes across EOF of the backing file, the backing
file sees a shortened request and the rest is filled with zeros.
However, the original too long qiov was used with the shortened request.

This patch makes the qiov size match the request size, avoiding a
potential buffer overflow in raw-posix.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
block: Assert qiov length matches request length

At least raw-posix relies on this because it can allocate bounce buffers
based on the request length, but access it using all of the qiov entries
later.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
virtio-blk: avoid dataplane VirtIOBlockReq early free

VirtIOBlockReq is freed later by virtio_blk_free_request() in
hw/block/virtio-blk.c.  Remove this extraneous g_slice_free().

This patch fixes the following segfault:

  0x00005555556373af in virtio_blk_rw_complete (opaque=0x5555565ff5e0, ret=0) at hw/block/virtio-blk.c:99
  99          bdrv_acct_done(req->dev->bs, &req->acct);
  (gdb) print req
  $1 = (VirtIOBlockReq *) 0x5555565ff5e0
  (gdb) print req->dev
  $2 = (VirtIOBlock *) 0x0
  (gdb) bt
  #0  0x00005555556373af in virtio_blk_rw_complete (opaque=0x5555565ff5e0, ret=0) at hw/block/virtio-blk.c:99
  #1  0x0000555555840ebe in bdrv_co_em_bh (opaque=0x5555566152d0) at block.c:4675
  #2  0x000055555583de77 in aio_bh_poll (ctx=ctx@entry=0x5555563a8150) at async.c:81
  #3  0x000055555584b7a7 in aio_poll (ctx=0x5555563a8150, blocking=blocking@entry=true) at aio-posix.c:188
  #4  0x00005555556e520e in iothread_run (opaque=0x5555563a7fd8) at iothread.c:41
  #5  0x00007ffff42ba124 in start_thread () from /usr/lib/libpthread.so.0
  #6  0x00007ffff16d14bd in clone () from /usr/lib/libc.so.6

Reported-by: Max Reitz <mreitz@redhat.com>
Cc: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
dataplane: do not free VirtQueueElement in vring_push()

VirtQueueElement is allocated in vring_pop() so it seems to make sense
that vring_push() should free it.  Alas, virtio-blk frees
VirtQueueElement itself in virtio_blk_free_request().

This patch solves a double-free assertion in glib's g_slice_free().

Rename vring_free_element() to vring_unmap_element() since it no longer
frees the VirtQueueElement.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
virtio-blk: avoid g_slice_new0() for VirtIOBlockReq and VirtQueueElement

In commit de6c8042ec55da18702fa51f09072fcaa315edc3 ("virtio-blk: Avoid
zeroing every request structure") we avoided the 40 KB memset when
allocating VirtIOBlockReq.

The memset was reintroduced in commit
671ec3f056559f22a2531a91dce3a258b9b5eb8a ("virtio-blk: Convert
VirtIOBlockReq.elem to pointer").

It must be fixed again to avoid a performance regression.

Cc: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
virtio-blk: embed VirtQueueElement in VirtIOBlockReq

The memory allocation between hw/block/virtio-blk.c,
hw/block/dataplane/virtio-blk.c, and hw/virtio/dataplane/vring.c is
messy.  Structs are allocated in different files than they are freed in.
This is risky and makes memory leaks easier.

Embed VirtQueueElement in VirtIOBlockReq to reduce the amount of memory
allocation we need to juggle.  This also makes vring.c and virtio.c
slightly more similar.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
AioContext: do not rely on aio_poll(ctx, true) result to end a loop

Currently, whenever aio_poll(ctx, true) has completed all pending
work it returns true *and* the next call to aio_poll(ctx, true)
will not block.

This invariant has its roots in qemu_aio_flush()'s implementation
as "while (qemu_aio_wait()) {}".  However, qemu_aio_flush() does
not exist anymore and bdrv_drain_all() is implemented differently;
and this invariant is complicated to maintain and subtly different
from the return value of GMainLoop's g_main_context_iteration.

All calls to aio_poll(ctx, true) except one are guarded by a
while() loop checking for a request to be incomplete, or a
BlockDriverState to be idle.  The one remaining call (in
iothread.c) uses this to delay the aio_context_release/acquire
pair until the AioContext is quiescent, however:

- we can do the same just by using non-blocking aio_poll,
  similar to how vl.c invokes main_loop_wait

- it is buggy, because it does not ensure that the AioContext
  is released between an aio_notify and the next time the
  iothread goes to sleep.  This leads to hangs when stopping
  the dataplane thread.

In the end, these semantics are a bad match for the current
users of AioContext.  So modify that one exception in iothread.c,
which also fixes the hangs, as well as the testcase so that
it use the same idiom as the actual QEMU code.

Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
tests: Fix unterminated string output visitor enum human string

The buffer was being allocated of size string length plus two.
Around the string two quotes were being added, but no terminating NUL.
It was then compared using g_assert_cmpstr(), resulting in fairly random
assertion failures:

 ERROR:tests/test-string-output-visitor.c:213:test_visitor_out_enum: assertion failed (str == str_human): ("\"value1\"" == "\"value1\"\001EEEEEEEEEEEEEE\0171")

There is no g_assert_cmpnstr() counterpart, so use g_strdup_printf()
for safely assembling the string in the first place.

Cc: Hu Tao <hutao@cn.fujitsu.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Suggested-by: Eric Blake <eblake@redhat.com>
Fixes: b4900c0 tests: add human format test for string output visitor
Signed-off-by: Andreas Färber <afaerber@suse.de>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
qtest: fix vhost-user-test compilation with old GLib

Mising G_TIME_SPAN_SECOND definition breaks the RHEL6 compilation as GLib
version before 2.26 does not have it. In such case just define it.

Reported-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
Tested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
dma-helpers: Fix too long qiov

If the size of the scatter/gather list isn't a multiple of 512, the
number of sectors for the block layer request is rounded down, resulting
in a qiov that doesn't match the request length. Truncate the qiov to the
new length of the request.

This fixes the IDE qtest case /x86_64/ide/bmdma/short_prdt.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
virtio-blk: Factor common checks out of virtio_blk_handle_read/write()

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>