Re: [PATCH 01/17] qemuProcessStartWithMemoryState: Don't setup qemu for incoming migration when reverting internal snapshot

From: Peter Krempa <pkrempa(a)redhat.com&gt; The memory/device state of the VM for an internal snapshot is restored by qemu itself via a QMP command and is taken from the qcow2 image, thus we don't actually do any form of incoming migration. Commit 5b324c0a739fe00 which refactored the setup of the incoming migration state didn't take the above into account and inadvertently caused that qemu is being started with '-incoming defer' also when libvirt would want to revert an internal snapshot. Now when qemu expects incoming migration it doesn't activate the block backends as that would cause locking problems and image inconsistency, but also doesn't allow the use of the images. Since the block backends are not activated qemu then thinks that they don't actually support internal snapshots and reports: error: operation failed: load of internal snapshot 'foo1' job failed: Device 'libvirt-1-format' is writable but does not support snapshots Due to the above bug it's not possible to revert to internal snapshots in libvirt-11.2 and libvirt-11.3. Fixes: 5b324c0a739fe00cbec209219db4488742492112 Resolves: https://issues.redhat.com/browse/RHEL-88747 Closes: https://gitlab.com/libvirt/libvirt/-/issues/771 Signed-off-by: Peter Krempa <pkrempa(a)redhat.com&gt; --- src/qemu/qemu_process.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c index 1af91c5909..5f2203dd13 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -8636,9 +8636,13 @@ qemuProcessStartWithMemoryState(virConnectPtr conn, /* The fd passed to qemuProcessIncomingDefNew is used to create the migration * URI, so it must be called after starting the decompression program. */ - incoming = qemuProcessIncomingDefNew(driver, vm, NULL, "stdio", fd, path, data, migParams); - if (!incoming) - return -1; + if (!snapshot) { + /* Internal snapshots are reverted by a QMP command after qemu is started, + * so we don't actually want to setup incoming migration. */ + if (!(incoming = qemuProcessIncomingDefNew(driver, vm, NULL, "stdio", + fd, path, data, migParams))) + return -1; + } /* No cookie means libvirt which saved the domain was too old to mess up * the CPU definitions.