Re: [libvirt] [PATCH v3 5/5] qemu: Connect to guest agent iff needed

https://bugzilla.redhat.com/show_bug.cgi?id=1293351 Since we already have virtio channel events, we know when guest agent within guest has (dis-)connected. Instead of us blindly connecting to a socket that no one is listening to, we can just follow what qemu-ga does. This has a nice benefit that we don't need to 'guest-ping' the agent just to timeout and find out nobody is listening. The way that this commit is implemented: - don't connect in qemuProcessStart directly, defer that to event callback (which already follows the agent). - after migration is settled, before we resume vCPUs, ask qemu whether somebody is listening on the socket and if so, connect to it. Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- src/qemu/qemu_driver.c | 21 ++++++++++++++++++++- src/qemu/qemu_migration.c | 20 ++++++++++++++++++++ src/qemu/qemu_process.c | 9 +++++++++ 3 files changed, 49 insertions(+), 1 deletion(-) diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 8ccf68b..43ef18a 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -6650,12 +6650,13 @@ qemuDomainSaveImageStartVM(virConnectPtr conn, bool start_paused, qemuDomainAsyncJob asyncJob) { - int ret = -1; + int rc, ret = -1; virObjectEventPtr event; int intermediatefd = -1; virCommandPtr cmd = NULL; char *errbuf = NULL; virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver); + qemuDomainObjPrivatePtr priv = vm->privateData; if ((header->version == 2) && (header->compressed != QEMU_SAVE_FORMAT_RAW)) { @@ -6710,6 +6711,24 @@ qemuDomainSaveImageStartVM(virConnectPtr conn, goto cleanup; } + if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_VSERPORT_CHANGE)) { + /* If QEMU is capable of vserport_change events, we ought to + * refresh channel states here and possibly connect to the guest + * agent too. */ + if (qemuProcessRefreshChannelState(driver, vm) < 0) + goto cleanup; + + if ((rc = qemuConnectAgent(driver, vm)) < 0) { + if (rc == -2) + goto cleanup; + + VIR_WARN("Cannot connect to QEMU guest agent for %s", + vm->def->name); + virResetLastError(); + priv->agentError = true; + } + } +