Record hash results for each sampled page, crc32 is taken to calculate
hash results for each sampled length in TARGET_PAGE_SIZE.
Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
Signed-off-by: YanYing Zhuang <ann.zhuangyanying@huawei.com>
Reviewed-by: David Edmondson <david.edmondson@oracle.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Message-Id: <1600237327-33618-7-git-send-email-zhengchuan@huawei.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
RAMBLOCK_FOREACH_MIGRATABLE is need in dirtyrate measure,
move the existing definition up into migration/ram.h
Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: David Edmondson <david.edmondson@oracle.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Message-Id: <1600237327-33618-6-git-send-email-zhengchuan@huawei.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Add dirtyrate statistics functions to record/update dirtyrate info.
Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Message-Id: <1600237327-33618-5-git-send-email-zhengchuan@huawei.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Add RamblockDirtyInfo to store sampled page info of each ramblock.
Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: David Edmondson <david.edmondson@oracle.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Message-Id: <1600237327-33618-4-git-send-email-zhengchuan@huawei.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
add DirtyRateStatus to denote calculating status.
Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Message-Id: <1600237327-33618-3-git-send-email-zhengchuan@huawei.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
atomic name fixup
Add get_dirtyrate_thread() functions to setup query-dirtyrate
framework.
Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
Signed-off-by: YanYing Zhuang <ann.zhuangyanying@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: David Edmondson <david.edmondson@oracle.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Message-Id: <1600237327-33618-2-git-send-email-zhengchuan@huawei.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
We duplicated the logic of maintaining the last_rb variable at both callers of
this function. Pass *rb pointer into the function so that we can avoid
duplicating the logic. Also, when we have the rb pointer, it's also easier to
remove the original 2nd & 4th parameters, because both of them (name of the
ramblock when needed, or the page size) can be fetched from the ramblock
pointer too.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20200908203022.341615-3-peterx@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
In migration_incoming_state_destroy(), we've got a few variables that aren't
destroyed properly, namely:
main_thread_load_event
postcopy_pause_sem_dst
postcopy_pause_sem_fault
rp_mutex
Destroy them properly.
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20200908203022.341615-2-peterx@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
clang's C11 atomic_fetch_*() functions only take a C11 atomic type
pointer argument. QEMU uses direct types (int, etc) and this causes a
compiler error when a QEMU code calls these functions in a source file
that also included <stdatomic.h> via a system header file:
$ CC=clang CXX=clang++ ./configure ... && make
../util/async.c:79:17: error: address argument to atomic operation must be a pointer to _Atomic type ('unsigned int *' invalid)
Avoid using atomic_*() names in QEMU's atomic.h since that namespace is
used by <stdatomic.h>. Prefix QEMU's APIs with 'q' so that atomic.h
and <stdatomic.h> can co-exist. I checked /usr/include on my machine and
searched GitHub for existing "qatomic_" users but there seem to be none.
This patch was generated using:
$ git grep -h -o '\<atomic\(64\)\?_[a-z0-9_]\+' include/qemu/atomic.h | \
sort -u >/tmp/changed_identifiers
$ for identifier in $(</tmp/changed_identifiers); do
sed -i "s%\<$identifier\>%q$identifier%g" \
$(git grep -I -l "\<$identifier\>")
done
I manually fixed line-wrap issues and misaligned rST tables.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200923105646.47864-1-stefanha@redhat.com>
Test aio_disable_external(), which switches from fdmon-epoll back to
fdmon-poll. This resulted in an assertion failure that was fixed in the
previous patch.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20200915120339.702938-3-stefanha@redhat.com>
npfd keeps track of how many pollfds are currently being monitored. It
must be reset to 0 when fdmon_poll_wait() returns.
When npfd reaches a treshold we switch to fdmon-epoll because it scales
better.
This patch resets npfd in the case where we switch to fdmon-epoll.
Forgetting to do so results in the following assertion failure:
util/fdmon-poll.c:65: fdmon_poll_wait: Assertion `npfd == 0' failed.
Fixes: 1f050a4690 ("aio-posix: extract ppoll(2) and epoll(7) fd monitoring")
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1869952
Message-Id: <20200915120339.702938-2-stefanha@redhat.com>
The vbootrom module is needed for the new NPCM7xx ARM SoCs. The
vbootrom.git repo is now mirrored on qemu.org. QEMU mirrors third-party
code to ensure that users can always build QEMU even if the dependency
goes offline and so QEMU meets its responsibilities to provide full
source code under software licenses.
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Cc: Havard Skinnemoen <hskinnemoen@google.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20200915130834.706758-4-stefanha@redhat.com>
QEMU now hosts a mirror of meson.git. QEMU mirrors third-party code to
ensure that users can always build QEMU even if the dependency goes
offline and so QEMU meets its responsibilities to provide full source
code under software licenses.
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200915130834.706758-3-stefanha@redhat.com>
QEMU now hosts a mirror of qboot.git. QEMU mirrors third-party code to
ensure that users can always build QEMU even if the dependency goes
offline and so QEMU meets its responsibilities to provide full source
code under software licenses.
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200915130834.706758-2-stefanha@redhat.com>
The sentence explaining the deprecation schedule is ambiguous. Make it
clear that a feature deprecated in the Nth release is guaranteed to
remain available in the N+1th release. Removal can occur in the N+2nd
release or later.
As an example of this in action, see commit
25956af3fe ("block: Finish deprecation of
'qemu-img convert -n -o'"). The feature was deprecated in QEMU 4.2.0. It
was present in the 5.0.0 release and removed in the 5.1.0 release.
Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200915150734.711426-1-stefanha@redhat.com>
A number of iov_discard_front/back() operations are made by
virtio-crypto. The elem->in/out_sg iovec arrays are modified by these
operations, resulting virtqueue_unmap_sg() calls on different addresses
than were originally mapped.
This is problematic because dirty memory may not be logged correctly,
MemoryRegion refcounts may be leaked, and the non-RAM bounce buffer can
be leaked.
Take a copy of the elem->in/out_sg arrays so that the originals are
preserved. The iov_discard_undo() API could be used instead (with better
performance) but requires careful auditing of the code, so do the simple
thing instead.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Message-Id: <20200917094455.822379-4-stefanha@redhat.com>
Fuzzing discovered that virtqueue_unmap_sg() is being called on modified
req->in/out_sg iovecs. This means dma_memory_map() and
dma_memory_unmap() calls do not have matching memory addresses.
Fuzzing discovered that non-RAM addresses trigger a bug:
void address_space_unmap(AddressSpace *as, void *buffer, hwaddr len,
bool is_write, hwaddr access_len)
{
if (buffer != bounce.buffer) {
^^^^^^^^^^^^^^^^^^^^^^^
A modified iov->iov_base is no longer recognized as a bounce buffer and
the wrong branch is taken.
There are more potential bugs: dirty memory is not tracked correctly and
MemoryRegion refcounts can be leaked.
Use the new iov_discard_undo() API to restore elem->in/out_sg before
virtqueue_push() is called.
Fixes: 827805a249 ("virtio-blk: Convert VirtIOBlockReq.out to structrue")
Reported-by: Alexander Bulekov <alxndr@bu.edu>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Buglink: https://bugs.launchpad.net/qemu/+bug/1890360
Message-Id: <20200917094455.822379-3-stefanha@redhat.com>
The iov_discard_front/back() operations are useful for parsing iovecs
but they modify the array elements. If the original array is needed
after parsing finishes there is currently no way to restore it.
Although g_memdup() can be used before performing destructive
iov_discard_front/back() operations, this is inefficient.
Introduce iov_discard_undo() to restore the array to the state prior to
an iov_discard_front/back() operation.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Message-Id: <20200917094455.822379-2-stefanha@redhat.com>
Wire up the CCW device for vhost-user-fs.
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Message-id: 20200901150019.29229-2-mhartmay@linux.ibm.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Since virtio existed even before it got standardized, the virtio
standard defines the following types of virtio devices:
+ legacy device (pre-virtio 1.0)
+ non-legacy or VIRTIO 1.0 device
+ transitional device (which can act both as legacy and non-legacy)
Virtio 1.0 defines the fields of the virtqueues as little endian,
while legacy uses guest's native endian [1]. Currently libvhost-user
does not handle virtio endianness at all, i.e. it works only if the
native endianness matches with whatever is actually needed. That means
things break spectacularly on big-endian targets. Let us handle virtio
endianness for non-legacy as required by the virtio specification [1]
and fence legacy virtio, as there is no safe way to figure out the
needed endianness conversions for all cases. The fencing of legacy
virtio devices is done in `vu_set_features_exec`.
[1] https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/virtio-v1.1-cs01.html#x1-210003
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Message-id: 20200901150019.29229-3-mhartmay@linux.ibm.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Development of the userspace NVMe block driver picked up again recently.
After talking with Fam I am stepping up as block/nvme.c maintainer.
Patches will be merged through my 'block' tree.
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Klaus Jensen <k.jensen@samsung.com>
Cc: Fam Zheng <fam@euphon.net>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Klaus Jensen <k.jensen@samsung.com>
Acked-by: Fam Zheng <fam@euphon.net>
Message-id: 20200907111632.90499-1-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Handle the spice special case in audio_init instead.
With the qemu_spice_audio_init() symbol dependency being
gone we can build spiceaudio as module.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 20200916084117.21828-2-kraxel@redhat.com
Run the downstream playback queue even if there are no samples
in the mixing engine buffer. The downstream queue may still have
queued samples.
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Message-id: 20200920171729.15861-7-vr_qemu@t-online.de
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
The function audio_generic_write should work exactly like
audio_pcm_hw_run_out. It's a very similar function working on a
different buffer.
This patch significantly reduces the number of drop-outs with
the DirectSound backend. To hear the difference start qemu with
-audiodev dsound,id=audio0,out.mixing-engine=off and play a
song in the guest with and without this patch.
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Message-id: 20200920171729.15861-6-vr_qemu@t-online.de
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This patch removes unnecessary calls to the pcm_ops function
put_buffer_in(). No audio backend needs this call if the
returned length of pcm_ops function get_buffer_in() is zero.
For the DirectSound backend this prevents a call to
dsound_unlock_in() without a preceding call to dsound_lock_in().
While Windows doesn't complain it seems wrong anyway.
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Message-id: 20200920171729.15861-5-vr_qemu@t-online.de
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
The function audio_generic_read should work exactly like
audio_pcm_hw_run_in. It's a very similar function working
on a different buffer.
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Message-id: 20200920171729.15861-4-vr_qemu@t-online.de
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
The playback rate with the spiceaudio backend is currently too
fast if there's no spice client connected or the spice client
can't play audio. Rate limit the audio playback stream in all
cases. To calculate the rate correctly the limiter has to know
the maximum buffer size.
Fixes: 8c198ff065 ("spiceaudio: port to the new audio backend api")
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Message-id: 20200920171729.15861-3-vr_qemu@t-online.de
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This patch allows the audio backends get_buffer_out() functions
to drop audio data and mitigates a bug reported on the qemu-devel
mailing list.
https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg03832.html
The new rules for the variables buf and size returned by
get_buffer_out() are:
size == 0: Downstream playback buffer is full. Retry later.
size > 0, buf != NULL: Copy size bytes to buf for playback.
size > 0, buf == NULL: Drop size bytes.
The audio playback rate with spiceaudio for the no audio case is
too fast, but that's what we had before commit fb35c2cec5
"audio/dsound: fix invalid parameters error". The complete fix
comes with the next patch.
Reported-by: Qi Zhou <atmgnd@outlook.com>
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Message-id: 20200920171729.15861-2-vr_qemu@t-online.de
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
With the next patch all audio backends put_buffer_out() functions
have to handle the buf == NULL case, provided the get_buffer_out()
function may return buf = NULL and size > 0.
It turns out that all audio backends get_buffer_out() functions
either can't return buf = NULL or return buf = NULL and size = 0
at the same time. The only exception is the spiceaudio backend
where size may be uninitialized.
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Message-id: 20200920171729.15861-1-vr_qemu@t-online.de
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Class properties make QOM introspection simpler and easier, as
they don't require an object to be instantiated.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20200921221045.699690-25-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Class properties make QOM introspection simpler and easier, as
they don't require an object to be instantiated.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20200921221045.699690-24-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Class properties make QOM introspection simpler and easier, as
they don't require an object to be instantiated.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20200921221045.699690-23-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Class properties make QOM introspection simpler and easier, as
they don't require an object to be instantiated.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20200921221045.699690-21-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Class properties make QOM introspection simpler and easier, as
they don't require an object to be instantiated.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20200921221045.699690-20-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Class properties make QOM introspection simpler and easier, as
they don't require an object to be instantiated.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20200921221045.699690-18-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Class properties make QOM introspection simpler and easier, as
they don't require an object to be instantiated.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20200921221045.699690-13-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Class properties make QOM introspection simpler and easier, as
they don't require an object to be instantiated.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Gonglei <arei.gonglei@huawei.com>
Message-Id: <20200921221045.699690-3-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Class properties make QOM introspection simpler and easier, as
they don't require an object to be instantiated.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Gonglei <arei.gonglei@huawei.com>
Message-Id: <20200921221045.699690-2-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
it's was deprecated since 3.1
Support for invalid topologies is removed, the user must ensure
that topologies described with -smp include all possible cpus,
i.e. (sockets * cores * threads) == maxcpus or QEMU will
exit with error.
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20200911133202.938754-1-imammedo@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
When debugging QEMU it is often useful to put a breakpoint on the
error_setg_internal method impl.
Unfortunately the object_property_add / object_class_property_add
methods call object_property_find / object_class_property_find methods
to check if a property exists already before adding the new property.
As a result there are a huge number of calls to error_setg_internal
on startup of most QEMU commands, making it very painful to set a
breakpoint on this method.
Most callers of object_find_property and object_class_find_property,
however, pass in a NULL for the Error parameter. This simplifies the
methods to remove the Error parameter entirely, and then adds some
new wrapper methods that are able to raise an Error when needed.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200914135617.1493072-1-berrange@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
If you have the chain 'base.qcow2 <- top.qcow2' and want to merge a
bitmap from top into base, qemu-img was failing with:
qemu-img: Could not open 'top.qcow2': Could not open backing file: Failed to get shared "write" lock
Is another process using the image [base.qcow2]?
The easiest fix is to not open the entire backing chain of either
image (source or destination); after all, the point of 'qemu-img
bitmap' is solely to manipulate bitmaps directly within a single qcow2
image, and this is made more precise if we don't pay attention to
other images in the chain that may happen to have a bitmap by the same
name.
However, note that on a case-by-case analysis, there _are_ times where
we treat it as a feature that we can access a bitmap from a backing
layer in association with an overlay BDS. A demonstration of this is
using NBD to expose both an overlay BDS (for constant contents) and a
bitmap (for learning which blocks are interesting) during an
incremental backup:
Base <- Active <- Temporary
\--block job ->/
where Temporary is being fed by a backup 'sync=none' job. When
exposing Temporary over NBD, referring to a bitmap that lives only in
Active is less effort than having to copy a bitmap into Temporary [1].
So the testsuite additions in this patch check both where bitmaps get
allocated (the qemu-img info output), and that qemu-nbd is indeed able
to access a bitmap inherited from the backing chain since it is a
different use case than 'qemu-img bitmap'.
[1] Full disclosure: prior to the recent commit 374eedd1c4 and
friends, we were NOT able to see bitmaps through filters, which meant
that we actually did not have nice clean semantics for uniformly being
able to pick up bitmaps from anywhere in the backing chain (seen as a
change in behavior between qemu 4.1 and 4.2 at commit 00e30f05de, when
block-copy swapped from a one-off to a filter). Which means libvirt
was already coded to copy bitmaps around for the sake of older qemu,
even though modern qemu no longer needs it. Oh well.
Fixes: http://bugzilla.redhat.com/1877209
Reported-by: Eyal Shenitzky <eshenitz@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200914191009.644842-1-eblake@redhat.com>
[eblake: more commit message tweaks, per Max Reitz review]
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>