On 7/3/23 1:30 AM, Lin Ma wrote:
VMX(kernel v6.0) supports Notification VM exit feature under commit 2f4073e0.
QEMU supports it as well since v7.2 under commit e2e69f6b.
Add this feature into libvirt now.
An example of Domain XML snippet to configure this feature:
<features>
<kvm>
<notify-vmexit state='on' mode='run' notify-window='16384'/>
</kvm>
</features>
Signed-off-by: Lin Ma <lma@xxxxxxx>
---
docs/formatdomain.rst | 4 +++
src/conf/domain_conf.c | 32 +++++++++++++++++++++
src/conf/domain_conf.h | 7 +++++
src/conf/schemas/domaincommon.rng | 17 +++++++++++
src/qemu/qemu_command.c | 3 ++
tests/qemuxml2argvdata/kvm-features-off.xml | 1 +
tests/qemuxml2argvdata/kvm-features.xml | 1 +
7 files changed, 65 insertions(+)
diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
index f29449f749..452ee17367 100644
--- a/docs/formatdomain.rst
+++ b/docs/formatdomain.rst
@@ -1976,6 +1976,7 @@ Hypervisors may allow certain CPU / machine features to be toggled on/off.
<poll-control state='on'/>
<pv-ipi state='off'/>
<dirty-ring state='on' size='4096'/>
+ <notify-vmexit state='on' mode='run' notify-window='16384'/>
</kvm>
<xen>
<e820_host state='on'/>
@@ -2088,6 +2089,9 @@ are:
poll-control Decrease IO completion latency by introducing a grace period of busy waiting on, off :since:`6.10.0 (QEMU 4.2)`
pv-ipi Paravirtualized send IPIs on, off :since:`7.10.0 (QEMU 3.1)`
dirty-ring Enable dirty ring feature on, off; size - must be power of 2, range [1024,65536] :since:`8.0.0 (QEMU 6.1)`
+ notify-vmexit Enable notification VM exit(x86 only) with attribute mode(accepted values on, off :since:`9.5.0 (QEMU 7.2)`
+ are 'run', 'internal-error' and 'disable') and optional attribute
+ notify-window (accepted numbered starting from 0)
============== ============================================================================ ====================================================== ============================
Patch 4/4 includes some discussion about the purpose of this feature,
but it only adds it to the NEWS file. In my opinion, this information
should also be in the documentation itself. For example, a description
of the purpose of the feature, a brief discussion of what 'run',
'internal-error', 'disable' values mean, what the 'notify-window' value
means, etc. Otherwise a user will have to go searching elsewhere for how
to properly configure it.
Also, the possible values for the attributes should probably go in the
3rd column similar to the other features above.
``xen``
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 4121b6a054..c00d50d43d 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -216,6 +216,7 @@ VIR_ENUM_IMPL(virDomainKVM,
"poll-control",
"pv-ipi",
"dirty-ring",
+ "notify-vmexit",
);
VIR_ENUM_IMPL(virDomainXen,
@@ -16349,6 +16350,18 @@ virDomainFeaturesKVMDefParse(virDomainDef *def,
}
}
+ if (feature == VIR_DOMAIN_KVM_NOTIFY_VMEXIT &&
+ value == VIR_TRISTATE_SWITCH_ON) {
+
+ if (!(kvm->notify_vmexit.mode = virXMLPropStringRequired(node, "mode"))) {
+ return -1;
+ }
+ if (virXMLPropUInt(node, "notify-window", 0, VIR_XML_PROP_NONE,
+ &kvm->notify_vmexit.notify_window) < 0) {
+ return -1;
+ }
+ }
+
node = xmlNextElementSibling(node);
}
@@ -20738,6 +20751,7 @@ virDomainDefFeaturesCheckABIStability(virDomainDef *src,
case VIR_DOMAIN_KVM_POLLCONTROL:
case VIR_DOMAIN_KVM_PVIPI:
case VIR_DOMAIN_KVM_DIRTY_RING:
+ case VIR_DOMAIN_KVM_NOTIFY_VMEXIT:
if (src->kvm_features->features[i] != dst->kvm_features->features[i]) {
virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
_("State of KVM feature '%1$s' differs: source: '%2$s', destination: '%3$s'"),
@@ -27202,6 +27216,24 @@ virDomainDefFormatFeatures(virBuffer *buf,
}
break;
+ case VIR_DOMAIN_KVM_NOTIFY_VMEXIT:
+ if (def->kvm_features->features[j] != VIR_TRISTATE_SWITCH_ABSENT) {
+ virBufferAsprintf(&childBuf, "<%s state='%s'",
+ virDomainKVMTypeToString(j),
+ virTristateSwitchTypeToString(def->kvm_features->features[j]));
+ if (def->kvm_features->notify_vmexit.mode != NULL) {
+ virBufferAsprintf(&childBuf, " mode='%s'",
+ def->kvm_features->notify_vmexit.mode);
+ if (def->kvm_features->notify_vmexit.notify_window &&
+ STRNEQ(def->kvm_features->notify_vmexit.mode, "disable")) {
+ virBufferAsprintf(&childBuf, " notify-window='%u'",
+ def->kvm_features->notify_vmexit.notify_window);
+ }
+ }
+ virBufferAddLit(&childBuf, "/>\n");
+ }
+ break;
+
case VIR_DOMAIN_KVM_LAST:
break;
}
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index cddaa3824d..5957f66b79 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -2202,6 +2202,7 @@ typedef enum {
VIR_DOMAIN_KVM_POLLCONTROL,
VIR_DOMAIN_KVM_PVIPI,
VIR_DOMAIN_KVM_DIRTY_RING,
+ VIR_DOMAIN_KVM_NOTIFY_VMEXIT,
VIR_DOMAIN_KVM_LAST
} virDomainKVM;
@@ -2389,6 +2390,12 @@ struct _virDomainFeatureKVM {
int features[VIR_DOMAIN_KVM_LAST];
unsigned int dirty_ring_size; /* size of dirty ring for each vCPU, no units */
+ struct {
+ char *mode; /* option of notify vmexit */
+ unsigned int notify_window; /* A specified amount of time to generate
+ a VM exit if no interrupt windows occur
+ in VMX non-root operation */
+ } notify_vmexit;
};
typedef struct _virDomainFeatureTCG virDomainFeatureTCG;
diff --git a/src/conf/schemas/domaincommon.rng b/src/conf/schemas/domaincommon.rng
index fcf9e00600..84ebd2b03c 100644
--- a/src/conf/schemas/domaincommon.rng
+++ b/src/conf/schemas/domaincommon.rng
@@ -7754,6 +7754,23 @@
</optional>
</element>
</optional>
+ <optional>
+ <element name="notify-vmexit">
+ <ref name="featurestate"/>
+ <optional>
+ <attribute name="mode">
+ <data type="string">
+ <param name="pattern">(run|internal-error|disable)</param>
+ </data>
+ </attribute>
+ </optional>
+ <optional>
+ <attribute name="notify-window">
+ <data type="unsignedInt"/>
+ </attribute>
+ </optional>
+ </element>
+ </optional>
</interleave>
</element>
</define>
I'm being a bit picky here, but, as far as I can tell, the following
configurations are valid and don't produce any errors, but are likely to
be a bit confusing to a user. Is there any way to make this
configuration a bit nicer?
state=off, mode=run:
<kvm>
<notify-vmexit state='off' mode='run' notify-window='16384'/>
</kvm>
state=on, mode=disable:
<kvm>
<notify-vmexit state='on' mode='disable'/>
</kvm>
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index cde6ab4dde..656cf55c1e 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -6475,6 +6475,9 @@ qemuBuildCpuCommandLine(virCommand *cmd,
case VIR_DOMAIN_KVM_DIRTY_RING:
break;
+ case VIR_DOMAIN_KVM_NOTIFY_VMEXIT:
+ break;
+
case VIR_DOMAIN_KVM_LAST:
break;
}
diff --git a/tests/qemuxml2argvdata/kvm-features-off.xml b/tests/qemuxml2argvdata/kvm-features-off.xml
index 7ee6525cd9..d51a8324e0 100644
--- a/tests/qemuxml2argvdata/kvm-features-off.xml
+++ b/tests/qemuxml2argvdata/kvm-features-off.xml
@@ -16,6 +16,7 @@
<poll-control state='off'/>
<pv-ipi state='off'/>
<dirty-ring state='off'/>
+ <notify-vmexit state='off'/>
</kvm>
</features>
<cpu mode='host-passthrough' check='none' migratable='off'/>
diff --git a/tests/qemuxml2argvdata/kvm-features.xml b/tests/qemuxml2argvdata/kvm-features.xml
index 8ce3a2b987..c2d4ecf4d1 100644
--- a/tests/qemuxml2argvdata/kvm-features.xml
+++ b/tests/qemuxml2argvdata/kvm-features.xml
@@ -16,6 +16,7 @@
<poll-control state='on'/>
<pv-ipi state='on'/>
<dirty-ring state='on' size='4096'/>
+ <notify-vmexit state='on' mode='run' notify-window='16384'/>
</kvm>
</features>
<cpu mode='host-passthrough' check='none' migratable='off'/>
