This patch exports KVM Host Power Management capabilities as XML so that
higher-level systems management software can make use of these features
available in the host.
The script "pm-is-supported" (from pm-utils package) is run to discover if
Suspend-to-RAM (S3) or Suspend-to-Disk (S4) is supported by the host.
If either of them are supported, then a new tag "<power_management>" is
introduced in the XML under the <host> tag.
Eg: When the host supports both S3 and S4, the XML looks like this:
<capabilities>
<host>
<uuid>dc699581-48a2-11cb-b8a8-9a0265a79bbe</uuid>
<cpu>
<arch>i686</arch>
<model>coreduo</model>
<vendor>Intel</vendor>
<topology sockets='1' cores='2' threads='1'/>
<feature name='xtpr'/>
<feature name='tm2'/>
<feature name='est'/>
<feature name='vmx'/>
<feature name='pbe'/>
<feature name='tm'/>
<feature name='ht'/>
<feature name='ss'/>
<feature name='acpi'/>
<feature name='ds'/>
</cpu>
<power_management> <<<=== New host power management features
<S3/>
<S4/>
</power_management>
<migration_features>
<live/>
<uri_transports>
<uri_transport>tcp</uri_transport>
</uri_transports>
</migration_features>
</host>
.
.
.
However in case the query to check for power management features succeeded,
but the host does not support any such feature, then the XML will contain
an empty <power_management/> tag. In the event that the PM query itself
failed, the XML will not contain any "power_management" tag.
Open issues:
-----------
1. Design new APIs in libvirt to actually exploit the host power management
features instead of relying on external programs. This was discussed in
[4].
2. Decide on whether to include "pm-utils" package in the libvirt.spec
file considering the fact that the package name (pm-utils) may differ
from one Linux distribution to another.
Please let me know your comments and feedback.
Changelog:
---------
v1: The idea of exporting host power management capabilities through
libvirt was discussed in [1]. The choice to name the new tag as
"power_management" was discussed in [2].
v2: A working implementation was presented for review in [3].
References:
----------
[1] Exporting KVM host power saving capabilities through libvirt
http://thread.gmane.org/gmane.comp.emulators.libvirt/40886
[2] http://article.gmane.org/gmane.comp.emulators.libvirt/41688
[3] http://www.redhat.com/archives/libvir-list/2011-August/msg00238.html
[4] http://www.redhat.com/archives/libvir-list/2011-August/msg00248.html
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
---
docs/formatcaps.html.in | 19 ++++++++++---
docs/schemas/capability.rng | 23 ++++++++++++++++
include/libvirt/virterror.h | 1 +
src/conf/capabilities.c | 50 ++++++++++++++++++++++++++++++++++
src/conf/capabilities.h | 8 ++++++
src/libvirt_private.syms | 2 +
src/qemu/qemu_capabilities.c | 27 +++++++++++++++++++
src/util/util.c | 61 ++++++++++++++++++++++++++++++++++++++++++
src/util/util.h | 14 ++++++++++
src/util/virterror.c | 3 ++
10 files changed, 203 insertions(+), 5 deletions(-)
diff --git a/docs/formatcaps.html.in b/docs/formatcaps.html.in
index a4297ce..ce6f9a6 100644
--- a/docs/formatcaps.html.in
+++ b/docs/formatcaps.html.in
@@ -28,6 +28,10 @@ BIOS you will see</p>
<feature name='xtpr'/>
...
</cpu>
+ <power_management>
+ <S3/>
+ <S4/>
+ <power_management/>
</host></span>
<!-- xen-3.0-x86_64 -->
@@ -61,11 +65,16 @@ BIOS you will see</p>
...
</capabilities></pre>
<p>The first block (in red) indicates the host hardware capabilities, currently
-it is limited to the CPU properties but other information may be available,
-it shows the CPU architecture, topology, model name, and additional features
-which are not included in the model but the CPU provides them. Features of the
-chip are shown within the feature block (the block is similar to what you will
-find in a Xen fully virtualized domain description).</p>
+it is limited to the CPU properties and the power management features of
+the host platform, but other information may be available, it shows the CPU architecture,
+topology, model name, and additional features which are not included in the model but the
+CPU provides them. Features of the chip are shown within the feature block (the block is
+similar to what you will find in a Xen fully virtualized domain description). Further,
+the power management features supported by the host are shown, such as Suspend-to-RAM (S3)
+and Suspend-to-Disk (S4). In case the query for power management features succeeded but the
+host does not support any such feature, then an empty <power_management/>
+tag will be shown. Otherwise, if the query itself failed, no such tag will
+be displayed (i.e., there will not be any power_management block or empty tag in the XML).</p>
<p>The second block (in blue) indicates the paravirtualization support of the
Xen support, you will see the os_type of xen to indicate a paravirtual
kernel, then architecture information and potential features.</p>
diff --git a/docs/schemas/capability.rng b/docs/schemas/capability.rng
index 99b4a9a..930374c 100644
--- a/docs/schemas/capability.rng
+++ b/docs/schemas/capability.rng
@@ -35,6 +35,9 @@
</optional>
</element>
<optional>
+ <ref name='power_management'/>
+ </optional>
+ <optional>
<ref name='migration'/>
</optional>
<optional>
@@ -105,6 +108,26 @@
</zeroOrMore>
</define>
+ <define name='power_management'>
+ <choice>
+ <element name='power_management'>
+ <optional>
+ <element name='S3'>
+ <empty/>
+ </element>
+ </optional>
+ <optional>
+ <element name='S4'>
+ <empty/>
+ </element>
+ </optional>
+ </element>
+ <element name='power_management'>
+ <empty/>
+ </element>
+ </choice>
+ </define>
+
<define name='migration'>
<element name='migration_features'>
<optional>
diff --git a/include/libvirt/virterror.h b/include/libvirt/virterror.h
index 9cac437..a831c73 100644
--- a/include/libvirt/virterror.h
+++ b/include/libvirt/virterror.h
@@ -82,6 +82,7 @@ typedef enum {
VIR_FROM_EVENT = 40, /* Error from event loop impl */
VIR_FROM_LIBXL = 41, /* Error from libxenlight driver */
VIR_FROM_LOCKING = 42, /* Error from lock manager */
+ VIR_FROM_CAPABILITIES = 43, /* Error from capabilities */
} virErrorDomain;
diff --git a/src/conf/capabilities.c b/src/conf/capabilities.c
index 2f243ae..d39a3f9 100644
--- a/src/conf/capabilities.c
+++ b/src/conf/capabilities.c
@@ -29,6 +29,13 @@
#include "util.h"
#include "uuid.h"
#include "cpu_conf.h"
+#include "virterror_internal.h"
+
+
+#define VIR_FROM_THIS VIR_FROM_CAPABILITIES
+
+VIR_ENUM_IMPL(virHostPMCapability, VIR_HOST_PM_LAST,
+ "S3", "S4")
/**
* virCapabilitiesNew:
@@ -166,6 +173,8 @@ virCapabilitiesFree(virCapsPtr caps) {
virCapabilitiesFreeNUMAInfo(caps);
+ VIR_FREE(caps->host.powerMgmt);
+
for (i = 0 ; i < caps->host.nmigrateTrans ; i++)
VIR_FREE(caps->host.migrateTrans[i]);
VIR_FREE(caps->host.migrateTrans);
@@ -201,6 +210,28 @@ virCapabilitiesAddHostFeature(virCapsPtr caps,
return 0;
}
+/**
+ * virCapabilitiesAddHostPowerManagement:
+ * @caps: capabilities to extend
+ * @feature: the power management feature to be added
+ *
+ * Registers a new host power management feature, eg: 'S3' or 'S4'
+ */
+int
+virCapabilitiesAddHostPowerManagement(virCapsPtr caps,
+ int feature)
+{
+ if(VIR_RESIZE_N(caps->host.powerMgmt, caps->host.npowerMgmt_max,
+ caps->host.npowerMgmt, 1) < 0) {
+ virReportOOMError();
+ return -1;
+ }
+
+ caps->host.powerMgmt[caps->host.npowerMgmt] = feature;
+ caps->host.npowerMgmt++;
+
+ return 0;
+}
/**
* virCapabilitiesAddHostMigrateTransport:
@@ -686,6 +717,25 @@ virCapabilitiesFormatXML(virCapsPtr caps)
virBufferAddLit(&xml, " </cpu>\n");
+ if(caps->host.isPMQuerySuccess) {
+ if(caps->host.npowerMgmt) {
+ /* The PM Query was successful and the host supports
+ * some PM features.
+ */
+ virBufferAddLit(&xml, " <power_management>\n");
+ for (i = 0; i < caps->host.npowerMgmt ; i++) {
+ virBufferAsprintf(&xml, " <%s/>\n",
+ virHostPMCapabilityTypeToString(caps->host.powerMgmt[i]));
+ }
+ virBufferAddLit(&xml, " </power_management>\n");
+ } else {
+ /* The PM Query was successful but the host does not
+ * support any PM feature.
+ */
+ virBufferAddLit(&xml, " <power_management/>\n");
+ }
+ }
+
if (caps->host.offlineMigrate) {
virBufferAddLit(&xml, " <migration_features>\n");
if (caps->host.liveMigrate)
diff --git a/src/conf/capabilities.h b/src/conf/capabilities.h
index e2fa1d6..afbf732 100644
--- a/src/conf/capabilities.h
+++ b/src/conf/capabilities.h
@@ -105,6 +105,10 @@ struct _virCapsHost {
size_t nfeatures;
size_t nfeatures_max;
char **features;
+ bool isPMQuerySuccess;
+ size_t npowerMgmt;
+ size_t npowerMgmt_max;
+ int *powerMgmt; /* enum virHostPMCapability */
int offlineMigrate;
int liveMigrate;
size_t nmigrateTrans;
@@ -186,6 +190,10 @@ virCapabilitiesAddHostFeature(virCapsPtr caps,
const char *name);
extern int
+virCapabilitiesAddHostPowerManagement(virCapsPtr caps,
+ int feature);
+
+extern int
virCapabilitiesAddHostMigrateTransport(virCapsPtr caps,
const char *name);
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 830222b..5754fdd 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -41,6 +41,7 @@ virCapabilitiesAddGuestFeature;
virCapabilitiesAddHostFeature;
virCapabilitiesAddHostMigrateTransport;
virCapabilitiesAddHostNUMACell;
+virCapabilitiesAddHostPowerManagement;
virCapabilitiesAllocMachines;
virCapabilitiesDefaultGuestArch;
virCapabilitiesDefaultGuestEmulator;
@@ -1025,6 +1026,7 @@ safezero;
virArgvToString;
virAsprintf;
virBuildPathInternal;
+virCheckPMCapability;
virDirCreate;
virEmitXMLWarning;
virEnumFromString;
diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index 3f36212..f3d0c0a 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -794,6 +794,7 @@ virCapsPtr qemuCapsInit(virCapsPtr old_caps)
struct utsname utsname;
virCapsPtr caps;
int i;
+ int status = -1;
char *xenner = NULL;
/* Really, this never fails - look at the man-page. */
@@ -824,6 +825,32 @@ virCapsPtr qemuCapsInit(virCapsPtr old_caps)
old_caps->host.cpu = NULL;
}
+ /* Add the power management features of the host */
+
+ /* Check for Suspend-to-RAM support (S3) */
+ status = virCheckPMCapability(VIR_HOST_PM_S3);
+ if(status < 0) {
+ caps->host.isPMQuerySuccess = false;
+ VIR_WARN("Failed to get host power management features");
+ } else {
+ /* The PM Query succeeded */
+ caps->host.isPMQuerySuccess = true;
+ if(status == 1) /* S3 is supported */
+ virCapabilitiesAddHostPowerManagement(caps, VIR_HOST_PM_S3);
+ }
+
+ /* Check for Suspend-to-Disk support (S4) */
+ status = virCheckPMCapability(VIR_HOST_PM_S4);
+ if(status < 0) {
+ caps->host.isPMQuerySuccess = false;
+ VIR_WARN("Failed to get host power management features");
+ } else {
+ /* The PM Query succeeded */
+ caps->host.isPMQuerySuccess = true;
+ if(status == 1) /* S4 is supported */
+ virCapabilitiesAddHostPowerManagement(caps, VIR_HOST_PM_S4);
+ }
+
virCapabilitiesAddHostMigrateTransport(caps,
"tcp");
diff --git a/src/util/util.c b/src/util/util.c
index 03a9e1a..489c4d6 100644
--- a/src/util/util.c
+++ b/src/util/util.c
@@ -2641,3 +2641,64 @@ or other application using the libvirt API.\n\
return 0;
}
+
+/**
+ * Check the Power Management Capabilities of the host system.
+ * The script 'pm-is-supported' (from the pm-utils package) is run
+ * to find out if the capability is supported by the host.
+ *
+ * @capability: capability to check for
+ * VIR_HOST_PM_S3: Check for Suspend-to-RAM support
+ * VIR_HOST_PM_S4: Check for Suspend-to-Disk support
+ *
+ * Return values:
+ * 1 if the capability is supported.
+ * 0 if the query was successful but the capability is
+ * not supported by the host.
+ * -1 on error like 'pm-is-supported' is not found.
+ */
+int
+virCheckPMCapability(int capability)
+{
+
+ char *path = NULL;
+ int status = -1;
+ int ret = -1;
+ virCommandPtr cmd;
+
+ if((path = virFindFileInPath("pm-is-supported")) == NULL) {
+ virUtilError(VIR_ERR_INTERNAL_ERROR,
+ "%s", _("Failed to get the path of pm-is-supported"));
+ return -1;
+ }
+
+ cmd = virCommandNew(path);
+ switch(capability) {
+ case VIR_HOST_PM_S3:
+ /* Check support for suspend (S3) */
+ virCommandAddArg(cmd, "--suspend");
+ break;
+
+ case VIR_HOST_PM_S4:
+ /* Check support for hibernation (S4) */
+ virCommandAddArg(cmd, "--hibernate");
+ break;
+
+ default:
+ goto cleanup;
+ }
+
+ if(virCommandRun(cmd, &status) < 0)
+ goto cleanup;
+
+ /* Check return code of command == 0 for success
+ * (i.e., the PM capability is supported)
+ */
+ ret = (status == 0) ? 1 : 0;
+
+cleanup:
+ virCommandFree(cmd);
+ VIR_FREE(path);
+ return ret;
+}
+
diff --git a/src/util/util.h b/src/util/util.h
index af8b15d..dfb8c1a 100644
--- a/src/util/util.h
+++ b/src/util/util.h
@@ -272,4 +272,18 @@ bool virIsDevMapperDevice(const char *devname) ATTRIBUTE_NONNULL(1);
int virEmitXMLWarning(int fd,
const char *name,
const char *cmd) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3);
+
+/* Power Management Capabilities of the host system */
+
+enum virHostPMCapability {
+ VIR_HOST_PM_S3, /* Suspend-to-RAM */
+ VIR_HOST_PM_S4, /* Suspend-to-Disk */
+
+ VIR_HOST_PM_LAST
+};
+
+VIR_ENUM_DECL(virHostPMCapability)
+
+int virCheckPMCapability(int capability);
+
#endif /* __VIR_UTIL_H__ */
diff --git a/src/util/virterror.c b/src/util/virterror.c
index 9a27feb..26d6011 100644
--- a/src/util/virterror.c
+++ b/src/util/virterror.c
@@ -148,6 +148,9 @@ static const char *virErrorDomainName(virErrorDomain domain) {
case VIR_FROM_CPU:
dom = "CPU ";
break;
+ case VIR_FROM_CAPABILITIES:
+ dom = "Capabilities ";
+ break;
case VIR_FROM_NWFILTER:
dom = "Network Filter ";
break;
--
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