[libvirt] [PATCH 2/3] qemu: add hypervisor feature cpu-pm support for kvm
Ján Tomko
jtomko at redhat.com
Wed Aug 21 16:12:58 UTC 2019
On Mon, Aug 19, 2019 at 10:32:25AM +0200, Menno Lageman wrote:
>From: Wim ten Have <wim.ten.have at oracle.com>
>
>QEMU introduced a CPU power management feature with commit 6f131f13e68d
>("kvm: support -overcommit cpu-pm=on|off").
>
>This patch series adds support for controlling QEMU's "-overcommit"
>command line switch: "-overcommit cpu-pm=[on|off]". By default "cpu-pm" is off.
>
>To turn the CPU power management feature on, the following
>XML needs to be added to the guest's domain description:
>
> <features>
> <kvm>
> <cpu-pm state='on'/>
> </kvm>
> </features>
>
>Note that the "cpu-pm" element is only available if the CPU
>mode is set to "host-passthrough":
>
> <cpu mode='host-passthrough ... />
>
>Signed-off-by: Wim ten Have <wim.ten.have at oracle.com>
>Signed-off-by: Menno Lageman <menno.lageman at oracle.com>
>---
> docs/formatdomain.html.in | 7 +++++++
> docs/schemas/domaincommon.rng | 5 +++++
> src/conf/domain_conf.c | 4 ++++
> src/conf/domain_conf.h | 1 +
> src/libvirt_private.syms | 1 +
> src/qemu/qemu_command.c | 16 +++++++++++++++-
> src/qemu/qemu_domain.c | 25 ++++++++++++++++++-------
> 7 files changed, 51 insertions(+), 8 deletions(-)
>
>diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
>index a18119f9a08e..7ea819ef6fb2 100644
>--- a/docs/formatdomain.html.in
>+++ b/docs/formatdomain.html.in
>@@ -2045,6 +2045,7 @@
> <kvm>
> <hidden state='on'/>
> <hint-dedicated state='on'/>
>+ <cpu-pm state='on'/>
> </kvm>
> <pvspinlock state='on'/>
> <gic version='2'/>
>@@ -2224,6 +2225,12 @@
> <td>on, off</td>
> <td><span class="since">5.7.0 (QEMU 2.12.1)</span></td>
> </tr>
Hmm, seems we did not bother to document hint-dedicated
>+ <tr>
>+ <td>cpu-pm</td>
>+ <td>Enable guest management of the host CPU's power state. Note that enabling this will increase latency for other processes running on the same host CPU.</td>
>+ <td>on, off</td>
>+ <td><span class="since">5.7.0 (QEMU 2.12.1)</span></td>
>+ </tr>
> </table>
> </dd>
> <dt><code>pmu</code></dt>
>diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
>index 08853f9d9e92..51c9e434aa35 100644
>--- a/docs/schemas/domaincommon.rng
>+++ b/docs/schemas/domaincommon.rng
>@@ -5970,6 +5970,11 @@
> <ref name="featurestate"/>
> </element>
> </optional>
>+ <optional>
>+ <element name="cpu-pm">
>+ <ref name="featurestate"/>
>+ </element>
>+ </optional>
> </interleave>
> </element>
> </define>
>diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
>index 8642927d6bf3..e348aa0bcb5f 100644
>--- a/src/conf/domain_conf.c
>+++ b/src/conf/domain_conf.c
>@@ -203,6 +203,7 @@ VIR_ENUM_IMPL(virDomainKVM,
> VIR_DOMAIN_KVM_LAST,
> "hidden",
> "hint-dedicated",
>+ "cpu-pm",
> );
>
> VIR_ENUM_IMPL(virDomainMsrsUnknown,
>@@ -20412,6 +20413,7 @@ virDomainDefParseXML(xmlDocPtr xml,
> switch ((virDomainKVM) feature) {
> case VIR_DOMAIN_KVM_HIDDEN:
> case VIR_DOMAIN_KVM_DEDICATED:
>+ case VIR_DOMAIN_KVM_CPU_PM:
> if (!(tmp = virXMLPropString(nodes[i], "state"))) {
> virReportError(VIR_ERR_XML_ERROR,
> _("missing 'state' attribute for "
>@@ -22625,6 +22627,7 @@ virDomainDefFeaturesCheckABIStability(virDomainDefPtr src,
> switch ((virDomainKVM) i) {
> case VIR_DOMAIN_KVM_HIDDEN:
> case VIR_DOMAIN_KVM_DEDICATED:
>+ case VIR_DOMAIN_KVM_CPU_PM:
> if (src->kvm_features[i] != dst->kvm_features[i]) {
> virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> _("State of KVM feature '%s' differs: "
>@@ -28126,6 +28129,7 @@ virDomainDefFormatFeatures(virBufferPtr buf,
> switch ((virDomainKVM) j) {
> case VIR_DOMAIN_KVM_HIDDEN:
> case VIR_DOMAIN_KVM_DEDICATED:
>+ case VIR_DOMAIN_KVM_CPU_PM:
> if (def->kvm_features[j])
> virBufferAsprintf(&childBuf, "<%s state='%s'/>\n",
> virDomainKVMTypeToString(j),
>diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
>index f7423b1b6f89..b5a4cee46c1e 100644
>--- a/src/conf/domain_conf.h
>+++ b/src/conf/domain_conf.h
>@@ -1766,6 +1766,7 @@ typedef enum {
> typedef enum {
> VIR_DOMAIN_KVM_HIDDEN = 0,
> VIR_DOMAIN_KVM_DEDICATED,
>+ VIR_DOMAIN_KVM_CPU_PM,
>
> VIR_DOMAIN_KVM_LAST
> } virDomainKVM;
>diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
>index 9db4ac7933e5..67a3a14c9b36 100644
>--- a/src/libvirt_private.syms
>+++ b/src/libvirt_private.syms
>@@ -446,6 +446,7 @@ virDomainIOThreadIDDel;
> virDomainIOThreadIDFind;
> virDomainKeyWrapCipherNameTypeFromString;
> virDomainKeyWrapCipherNameTypeToString;
>+virDomainKVMTypeToString;
> virDomainLeaseDefFree;
> virDomainLeaseIndex;
> virDomainLeaseInsert;
>diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
>index 922456ec679e..163c98bc7d0f 100644
>--- a/src/qemu/qemu_command.c
>+++ b/src/qemu/qemu_command.c
>@@ -7217,6 +7217,8 @@ qemuBuildCpuCommandLine(virCommandPtr cmd,
> virBufferAddLit(&buf, ",kvm-hint-dedicated=on");
> break;
>
>+ /* Not a -cpu option */
>+ case VIR_DOMAIN_KVM_CPU_PM:
> /* coverity[dead_error_begin] */
> case VIR_DOMAIN_KVM_LAST:
> break;
>@@ -7852,8 +7854,20 @@ qemuBuildOvercommitCommandLine(virCommandPtr cmd,
> virQEMUCapsPtr qemuCaps)
> {
> if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_OVERCOMMIT)) {
>+ virBuffer buf = VIR_BUFFER_INITIALIZER;
>+ char *overcommit;
>+
>+ virBufferAsprintf(&buf, "mem-lock=%s", def->mem.locked ? "on" : "off");
>+
>+ if (def->features[VIR_DOMAIN_FEATURE_KVM] == VIR_TRISTATE_SWITCH_ON)
>+ virBufferAsprintf(&buf, ",cpu-pm=%s",
>+ def->kvm_features[VIR_DOMAIN_KVM_CPU_PM] == VIR_TRISTATE_SWITCH_ON ? "on" : "off");
const char *cpu_pm = NULL;
if (def->kvm_features[VIR_DOMAIN_KVM_CPU_PM] != VIR_TRISTATE_SWITCH_DEFAULT)
cpu_pm = virTristateBoolTypeToString(def->kvm_features[VIR_DOMAIN_KVM_CPU_PM])
if (cpu_pm)
virBufferAsprintf...
to avoid the super long line.
>+
>+ overcommit = virBufferContentAndReset(&buf);
> virCommandAddArg(cmd, "-overcommit");
>- virCommandAddArgFormat(cmd, "mem-lock=%s", def->mem.locked ? "on" : "off");
>+ virCommandAddArgFormat(cmd, "%s", overcommit);
You can use virCommandAddArgBuffer and avoid the temporary char*
variable
>+
>+ VIR_FREE(overcommit);
> }
> return 0;
> }
>diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
>index a06672333cf7..5571f52fec47 100644
>--- a/src/qemu/qemu_domain.c
>+++ b/src/qemu/qemu_domain.c
>@@ -4442,7 +4442,7 @@ static int
> qemuDomainDefValidateFeatures(const virDomainDef *def,
> virQEMUCapsPtr qemuCaps)
> {
>- size_t i;
>+ size_t i, j;
>
> for (i = 0; i < VIR_DOMAIN_FEATURE_LAST; i++) {
> const char *featureName = virDomainFeatureTypeToString(i);
>@@ -4499,12 +4499,23 @@ qemuDomainDefValidateFeatures(const virDomainDef *def,
> break;
>
> case VIR_DOMAIN_FEATURE_KVM:
>- if (def->kvm_features[VIR_DOMAIN_KVM_DEDICATED] == VIR_TRISTATE_SWITCH_ON &&
>- (!def->cpu || def->cpu->mode != VIR_CPU_MODE_HOST_PASSTHROUGH)) {
>- virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
>- _("kvm-hint-dedicated=on is only applicable "
>- "for cpu host-passthrough"));
>- return -1;
>+ for (j = 0; j < VIR_DOMAIN_KVM_LAST; j++) {
>+ switch ((virDomainKVM) j) {
>+ case VIR_DOMAIN_KVM_DEDICATED:
>+ case VIR_DOMAIN_KVM_CPU_PM:
>+ if (def->kvm_features[j] == VIR_TRISTATE_SWITCH_ON &&
>+ (!def->cpu || def->cpu->mode != VIR_CPU_MODE_HOST_PASSTHROUGH)) {
>+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
>+ _("%s=on is only applicable for cpu host-passthrough"),
>+ virDomainKVMTypeToString(j));
>+ return -1;
>+ }
What if the user asks for cpu-pm but QEMU_CAPS_OVERCOMMIT is not
available?
Jano
>+ break;
>+
>+ case VIR_DOMAIN_KVM_HIDDEN:
>+ case VIR_DOMAIN_KVM_LAST:
>+ break;
>+ }
> }
> break;
>
>--
>2.21.0
>
>--
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>libvir-list at redhat.com
>https://www.redhat.com/mailman/listinfo/libvir-list
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