QEMU 2.7 and newer don't allow guests to start unless the initial vCPUs count is a multiple of the vCPU hotplug granularity, so validate it and report an error if needed. Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1283700 Signed-off-by: Andrea Bolognani <abologna@xxxxxxxxxx> --- src/qemu/qemu_domain.c | 41 ++++++++++++++++++++++ tests/qemuxml2argvdata/cpu-hotplug-granularity.xml | 18 ++++++++++ tests/qemuxml2argvtest.c | 3 ++ 3 files changed, 62 insertions(+) create mode 100644 tests/qemuxml2argvdata/cpu-hotplug-granularity.xml diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index 227ba32a7..43bd0fff4 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -3289,6 +3289,36 @@ qemuDomainDefValidateVideo(const virDomainDef *def) } +/** + * qemuDomainDefGetVcpuHotplugGranularity: + * @def: domain definition + * + * With QEMU 2.7 and newer, vCPUs can only be hotplugged in groups that + * respect the guest's hotplug granularity; because of that, QEMU will + * not allow guests to start unless the initial number of vCPUs is a + * multiple of the hotplug granularity. + * + * Returns the vCPU hotplug granularity. + */ +static unsigned int +qemuDomainDefGetVcpuHotplugGranularity(const virDomainDef *def) +{ + /* If the guest CPU topology has not been configured, assume we + * can hotplug vCPUs one at a time */ + if (!def->cpu || def->cpu->sockets == 0) + return 1; + + /* For pSeries guests, hotplug can only be performed one core + * at a time, so the vCPU hotplug granularity is the number + * of threads per core */ + if (qemuDomainIsPSeries(def)) + return def->cpu->threads; + + /* In all other cases, we can hotplug vCPUs one at a time */ + return 1; +} + + #define QEMU_MAX_VCPUS_WITHOUT_EIM 255 @@ -3363,6 +3393,7 @@ qemuDomainDefValidate(const virDomainDef *def, * CPU topology. Verify known constraints are respected */ if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_QUERY_HOTPLUGGABLE_CPUS)) { unsigned int topologycpus; + unsigned int granularity; /* Starting from QEMU 2.5, max vCPU count and overall vCPU topology * must agree. We only actually enforce this with QEMU 2.7+, due @@ -3373,6 +3404,16 @@ qemuDomainDefValidate(const virDomainDef *def, _("CPU topology doesn't match maximum vcpu count")); goto cleanup; } + + /* vCPU hotplug granularity must be respected */ + granularity = qemuDomainDefGetVcpuHotplugGranularity(def); + if ((virDomainDefGetVcpus(def) % granularity) != 0) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, + _("vCPUs count must be a multiple of the vCPU " + "hotplug granularity (%u)"), + granularity); + goto cleanup; + } } if (ARCH_IS_X86(def->os.arch) && diff --git a/tests/qemuxml2argvdata/cpu-hotplug-granularity.xml b/tests/qemuxml2argvdata/cpu-hotplug-granularity.xml new file mode 100644 index 000000000..a94f41e46 --- /dev/null +++ b/tests/qemuxml2argvdata/cpu-hotplug-granularity.xml @@ -0,0 +1,18 @@ +<domain type='qemu'> + <name>guest</name> + <uuid>1ccfd97d-5eb4-478a-bbe6-88d254c16db7</uuid> + <memory unit='KiB'>524288</memory> + <vcpu placement='static' current='2'>8</vcpu> + <os> + <type arch='ppc64' machine='pseries'>hvm</type> + </os> + <cpu> + <topology sockets='1' cores='2' threads='4'/> + </cpu> + <devices> + <emulator>/usr/bin/qemu-system-ppc64</emulator> + <controller type='pci' model='pci-root'/> + <controller type='usb' model='none'/> + <memballoon model='none'/> + </devices> +</domain> diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c index ca24e0bbb..10ab8d787 100644 --- a/tests/qemuxml2argvtest.c +++ b/tests/qemuxml2argvtest.c @@ -2900,6 +2900,9 @@ mymain(void) QEMU_CAPS_DEVICE_INTEL_IOMMU); DO_TEST("cpu-hotplug-startup", QEMU_CAPS_QUERY_HOTPLUGGABLE_CPUS); + DO_TEST_PARSE_ERROR("cpu-hotplug-granularity", + QEMU_CAPS_QUERY_HOTPLUGGABLE_CPUS); + DO_TEST("virtio-options", QEMU_CAPS_VIRTIO_SCSI, QEMU_CAPS_VIRTIO_KEYBOARD, QEMU_CAPS_VIRTIO_MOUSE, QEMU_CAPS_VIRTIO_TABLET, QEMU_CAPS_VIRTIO_INPUT_HOST, -- 2.14.3 -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
