[libvirt] [PATCHv2 2/3] qemu: Re-detect virtual cpu threads after cpu hot (un)plug.
After a cpu hotplug the qemu driver did not refresh information about
virtual processors used by qemu and their corresponding threads. This
patch forces a re-detection as is done on start of QEMU.
This ensures that correct information is reported by the
virDomainGetVcpus API and "virsh vcpuinfo".
A failure to obtain the thread<->vcpu mapping is treated non-fatal and
the mapping is not updated in a case of failure as not all versions of
QEMU report this in the info cpus command.
---
Diff to v1:
- don't fail the call if cpu thread detection fails
- fix memory leak when overwriting the priv->vcpupids array
---
src/qemu/qemu_driver.c | 29 +++++++++++++++++++++++++++++
1 files changed, 29 insertions(+), 0 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index b283c8c..a18b4e0 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -3343,6 +3343,8 @@ static int qemudDomainHotplugVcpus(struct qemud_driver *driver,
int ret = -1;
int oldvcpus = vm->def->vcpus;
int vcpus = oldvcpus;
+ pid_t *cpupids = NULL;
+ int ncpupids;
qemuDomainObjEnterMonitor(driver, vm);
@@ -3373,11 +3375,38 @@ static int qemudDomainHotplugVcpus(struct qemud_driver *driver,
}
}
+ /* hotplug succeeded */
+
ret = 0;
+ /* After hotplugging the CPUs we need to re-detect threads corresponding
+ * to the virtual CPUs. Some older versions don't provide the thread ID
+ * or don't have the "info cpus" (and they don't support mutliple
CPUs
+ * anyways) command, so errors in the re-detection will not be treated
+ * fatal */
+ if ((ncpupids = qemuMonitorGetCPUInfo(priv->mon, &cpupids)) <= 0) {
+ virResetLastError();
+ goto cleanup;
+ }
+
+ if (ncpupids != vcpus) {
+ qemuReportError(VIR_ERR_INTERNAL_ERROR,
+ _("got wrong number of vCPU pids from QEMU monitor. "
+ "got %d, wanted %d"),
+ ncpupids, vcpus);
+ ret = -1;
+ goto cleanup;
+ }
+
+ priv->nvcpupids = ncpupids;
+ VIR_FREE(priv->vcpupids);
+ priv->vcpupids = cpupids;
+ cpupids = NULL;
+
cleanup:
qemuDomainObjExitMonitor(driver, vm);
vm->def->vcpus = vcpus;
+ VIR_FREE(cpupids);
virDomainAuditVcpu(vm, oldvcpus, nvcpus, "update", rc == 1);
return ret;
--
1.7.3.4