7:57 a.m.
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" pseudoCPU feature in qemu.
https://bugzilla.redhat.com/show_bug.cgi?id=1008989
---
docs/formatdomain.html.in | 7 +++++
docs/schemas/domaincommon.rng | 10 +++++-
src/conf/domain_conf.c | 36 +++++++++++++++++++++-
src/conf/domain_conf.h | 1 +
src/qemu/qemu_command.c | 14 +++++++++
.../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 8c998db..66ea3cf 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -1182,6 +1182,7 @@
<vapic state='on'/>
<spinlocks state='on' retries='4096'/>
</hyperv>
+ <paravirt-spinlock/>
</features>
...</pre>
@@ -1253,6 +1254,12 @@
</tr>
</table>
</dd>
+ <dt><code>paravirt-spinlock</code></dt>
+ <dd>Notify the guest that the host supports paravirtual spinlocks
+ for example by exposing the pvticketlocks mechanism. This feature
+ can be forced of 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..43a0fc8 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="paravirt-spinlock">
+ <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 d308a12..bfbfd3b 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",
+ "paravirt-spinlock")
VIR_ENUM_IMPL(virDomainFeatureState, VIR_DOMAIN_FEATURE_STATE_LAST,
"default",
@@ -11404,6 +11405,22 @@ virDomainDefParseXML(xmlDocPtr xml,
def->features[val] = VIR_DOMAIN_FEATURE_STATE_ON;
break;
+ case VIR_DOMAIN_FEATURE_PARAVIRT_SPINLOCK:
+ 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;
}
@@ -16771,6 +16788,23 @@ virDomainDefFormatInternal(virDomainDefPtr def,
break;
+ case VIR_DOMAIN_FEATURE_PARAVIRT_SPINLOCK:
+ 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/>\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 c7128e2..7f0a5e8 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_PARAVIRT_SPINLOCK,
VIR_DOMAIN_FEATURE_LAST
};
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index ab55914..5908f40 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -6716,6 +6716,20 @@ qemuBuildCpuArgStr(const virQEMUDriverPtr driver,
have_cpu = true;
}
+ if (def->features[VIR_DOMAIN_FEATURE_PARAVIRT_SPINLOCK]) {
+ char sign;
+ if (def->features[VIR_DOMAIN_FEATURE_PARAVIRT_SPINLOCK] ==
+ 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..afb0b41
--- /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/>
+ <paravirt-spinlock 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..f29cade
--- /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/>
+ <paravirt-spinlock/>
+ </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