[libvirt] [PATCHv2 7/8] qemu: Add support for paravirtual spinlocks in the guest

The linux kernel recently added support for paravirtual spinlock handling to avoid performance regressions on overcomitted hosts. This feature needs to be turned in the hypervisor so that the guest OS is notified about the possible support. This patch adds a new feature "paravirt-spinlock" to the XML and supporting code to enable the "kvm_pv_unhalt" pseudo CPU feature in qemu. https://bugzilla.redhat.com/show_bug.cgi?id=1008989 --- Notes: Version 2: - s/paravirt-spinlock/pvspinlock/ docs/formatdomain.html.in | 8 +++++ docs/schemas/domaincommon.rng | 10 +++++- src/conf/domain_conf.c | 36 +++++++++++++++++++++- src/conf/domain_conf.h | 1 + src/qemu/qemu_command.c | 13 ++++++++ .../qemuxml2argv-pv-spinlock-disabled.args | 5 +++ .../qemuxml2argv-pv-spinlock-disabled.xml | 26 ++++++++++++++++ .../qemuxml2argv-pv-spinlock-enabled.args | 5 +++ .../qemuxml2argv-pv-spinlock-enabled.xml | 26 ++++++++++++++++ tests/qemuxml2argvtest.c | 2 ++ tests/qemuxml2xmltest.c | 2 ++ 11 files changed, 132 insertions(+), 2 deletions(-) create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-pv-spinlock-disabled.args create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-pv-spinlock-disabled.xml create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-pv-spinlock-enabled.args create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-pv-spinlock-enabled.xml diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index c5a3fa8..14fe84e 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -1184,6 +1184,7 @@ &lt;vapic state='on'/&gt; &lt;spinlocks state='on' retries='4096'/&gt; &lt;/hyperv&gt; + &lt;pvspinlock/&gt; &lt;/features&gt; ...</pre> @@ -1255,6 +1256,13 @@ </tr> </table> </dd> + <dt><code>pvspinlock</code></dt> + <dd>Notify the guest that the host supports paravirtual spinlocks + for example by exposing the pvticketlocks mechanism. This feature + can be explicitly disabled by using <code>state='off'</code> + attribute. + </dd> + </dl> <h3><a name="elementsTime">Time keeping</a></h3> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng index 14b6700..cc3096d 100644 --- a/docs/schemas/domaincommon.rng +++ b/docs/schemas/domaincommon.rng @@ -3561,7 +3561,7 @@ </define> <!-- A set of optional features: PAE, APIC, ACPI, - HyperV Enlightenment and HAP support + HyperV Enlightenment, paravirtual spinlocks and HAP support --> <define name="features"> <optional> @@ -3607,6 +3607,14 @@ <empty/> </element> </optional> + <optional> + <element name="pvspinlock"> + <optional> + <ref name="featurestate"/> + </optional> + <empty/> + </element> + </optional> </interleave> </element> </optional> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index 6a99e3f..adc27e3 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -142,7 +142,8 @@ VIR_ENUM_IMPL(virDomainFeature, VIR_DOMAIN_FEATURE_LAST, "hap", "viridian", "privnet", - "hyperv") + "hyperv", + "pvspinlock") VIR_ENUM_IMPL(virDomainFeatureState, VIR_DOMAIN_FEATURE_STATE_LAST, "default", @@ -11435,6 +11436,22 @@ virDomainDefParseXML(xmlDocPtr xml, def->features[val] = VIR_DOMAIN_FEATURE_STATE_ON; break; + case VIR_DOMAIN_FEATURE_PVSPINLOCK: + node = ctxt->node; + ctxt->node = nodes[i]; + if ((tmp = virXPathString("string(./@state)", ctxt))) { + if ((def->features[val] = virDomainFeatureStateTypeFromString(tmp)) == -1) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, + _("unknown state atribute '%s' of feature '%s'"), + tmp, virDomainFeatureTypeToString(val)); + goto error; + } + } else { + def->features[val] = VIR_DOMAIN_FEATURE_STATE_ON; + } + ctxt->node = node; + break; + case VIR_DOMAIN_FEATURE_LAST: break; } @@ -16802,6 +16819,23 @@ virDomainDefFormatInternal(virDomainDefPtr def, break; + case VIR_DOMAIN_FEATURE_PVSPINLOCK: + switch ((enum virDomainFeatureState) def->features[i]) { + case VIR_DOMAIN_FEATURE_STATE_LAST: + case VIR_DOMAIN_FEATURE_STATE_DEFAULT: + break; + + case VIR_DOMAIN_FEATURE_STATE_ON: + virBufferAsprintf(buf, " <%s state='on'/>\n", name); + break; + + case VIR_DOMAIN_FEATURE_STATE_OFF: + virBufferAsprintf(buf, " <%s state='off'/>\n", name); + break; + } + + break; + case VIR_DOMAIN_FEATURE_APIC: if (def->features[i] == VIR_DOMAIN_FEATURE_STATE_ON) { virBufferAddLit(buf, " <apic"); diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h index ffd7e9d..05c2a84 100644 --- a/src/conf/domain_conf.h +++ b/src/conf/domain_conf.h @@ -1619,6 +1619,7 @@ enum virDomainFeature { VIR_DOMAIN_FEATURE_VIRIDIAN, VIR_DOMAIN_FEATURE_PRIVNET, VIR_DOMAIN_FEATURE_HYPERV, + VIR_DOMAIN_FEATURE_PVSPINLOCK, VIR_DOMAIN_FEATURE_LAST }; diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index 91ffacc..c1ceed2 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -6718,6 +6718,19 @@ qemuBuildCpuArgStr(virQEMUDriverPtr driver, have_cpu = true; } + if (def->features[VIR_DOMAIN_FEATURE_PVSPINLOCK]) { + char sign; + if (def->features[VIR_DOMAIN_FEATURE_PVSPINLOCK] == VIR_DOMAIN_FEATURE_STATE_ON) + sign = '+'; + else + sign = '-'; + + virBufferAsprintf(&buf, "%s,%ckvm_pv_unhalt", + have_cpu ? "" : default_model, + sign); + have_cpu = true; + } + if (def->features[VIR_DOMAIN_FEATURE_HYPERV] == VIR_DOMAIN_FEATURE_STATE_ON) { if (!have_cpu) { virBufferAdd(&buf, default_model, -1); diff --git a/tests/qemuxml2argvdata/qemuxml2argv-pv-spinlock-disabled.args b/tests/qemuxml2argvdata/qemuxml2argv-pv-spinlock-disabled.args new file mode 100644 index 0000000..80047f9 --- /dev/null +++ b/tests/qemuxml2argvdata/qemuxml2argv-pv-spinlock-disabled.args @@ -0,0 +1,5 @@ +LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=none \ +/usr/bin/qemu -S -M pc \ +-cpu qemu32,-kvm_pv_unhalt -m 214 -smp 6 -nographic -monitor \ +unix:/tmp/test-monitor,server,nowait -boot n -usb -net none -serial \ +none -parallel none diff --git a/tests/qemuxml2argvdata/qemuxml2argv-pv-spinlock-disabled.xml b/tests/qemuxml2argvdata/qemuxml2argv-pv-spinlock-disabled.xml new file mode 100644 index 0000000..4820476 --- /dev/null +++ b/tests/qemuxml2argvdata/qemuxml2argv-pv-spinlock-disabled.xml @@ -0,0 +1,26 @@ +<domain type='qemu'> + <name>QEMUGuest1</name> + <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid> + <memory unit='KiB'>219100</memory> + <currentMemory unit='KiB'>219100</currentMemory> + <vcpu placement='static'>6</vcpu> + <os> + <type arch='i686' machine='pc'>hvm</type> + <boot dev='network'/> + </os> + <features> + <acpi/> + <pae/> + <pvspinlock state='off'/> + </features> + <clock offset='utc'/> + <on_poweroff>destroy</on_poweroff> + <on_reboot>restart</on_reboot> + <on_crash>destroy</on_crash> + <devices> + <emulator>/usr/bin/qemu</emulator> + <controller type='usb' index='0'/> + <controller type='pci' index='0' model='pci-root'/> + <memballoon model='virtio'/> + </devices> +</domain> diff --git a/tests/qemuxml2argvdata/qemuxml2argv-pv-spinlock-enabled.args b/tests/qemuxml2argvdata/qemuxml2argv-pv-spinlock-enabled.args new file mode 100644 index 0000000..70db173 --- /dev/null +++ b/tests/qemuxml2argvdata/qemuxml2argv-pv-spinlock-enabled.args @@ -0,0 +1,5 @@ +LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=none \ +/usr/bin/qemu -S -M pc \ +-cpu qemu32,+kvm_pv_unhalt -m 214 -smp 6 -nographic -monitor \ +unix:/tmp/test-monitor,server,nowait -boot n -usb -net none -serial \ +none -parallel none diff --git a/tests/qemuxml2argvdata/qemuxml2argv-pv-spinlock-enabled.xml b/tests/qemuxml2argvdata/qemuxml2argv-pv-spinlock-enabled.xml new file mode 100644 index 0000000..ac8781b --- /dev/null +++ b/tests/qemuxml2argvdata/qemuxml2argv-pv-spinlock-enabled.xml @@ -0,0 +1,26 @@ +<domain type='qemu'> + <name>QEMUGuest1</name> + <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid> + <memory unit='KiB'>219100</memory> + <currentMemory unit='KiB'>219100</currentMemory> + <vcpu placement='static'>6</vcpu> + <os> + <type arch='i686' machine='pc'>hvm</type> + <boot dev='network'/> + </os> + <features> + <acpi/> + <pae/> + <pvspinlock state='on'/> + </features> + <clock offset='utc'/> + <on_poweroff>destroy</on_poweroff> + <on_reboot>restart</on_reboot> + <on_crash>destroy</on_crash> + <devices> + <emulator>/usr/bin/qemu</emulator> + <controller type='usb' index='0'/> + <controller type='pci' index='0' model='pci-root'/> + <memballoon model='virtio'/> + </devices> +</domain> diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c index 060acf2..d716c58 100644 --- a/tests/qemuxml2argvtest.c +++ b/tests/qemuxml2argvtest.c @@ -448,6 +448,8 @@ mymain(void) QEMU_CAPS_CHARDEV_SPICEVMC, QEMU_CAPS_SPICE, QEMU_CAPS_HDA_DUPLEX); DO_TEST("eoi-disabled", NONE); DO_TEST("eoi-enabled", NONE); + DO_TEST("pv-spinlock-disabled", NONE); + DO_TEST("pv-spinlock-enabled", NONE); DO_TEST("kvmclock+eoi-disabled", QEMU_CAPS_ENABLE_KVM); DO_TEST("hyperv", NONE); diff --git a/tests/qemuxml2xmltest.c b/tests/qemuxml2xmltest.c index 4e308b4..ffff3b5 100644 --- a/tests/qemuxml2xmltest.c +++ b/tests/qemuxml2xmltest.c @@ -159,6 +159,8 @@ mymain(void) DO_TEST("cpu-eoi-enabled"); DO_TEST("eoi-disabled"); DO_TEST("eoi-enabled"); + DO_TEST("pv-spinlock-disabled"); + DO_TEST("pv-spinlock-enabled"); DO_TEST("hyperv"); DO_TEST("hyperv-off"); -- 1.8.3.2