[libvirt] [RFC v4] Export KVM Host Power Management capabilities
Srivatsa S. Bhat
srivatsa.bhat at linux.vnet.ibm.com
Tue Aug 9 15:29:54 UTC 2011
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 exploit power management features
such as S3/S4. This was discussed in [3] and [4].
Please let me know your comments and feedback.
Changelog:
---------
v1: The idea of exporting host power management capabilities through
libvirt was discussed in [1].
v2: A working implementation was presented for review in [2].
v3: Omissions and improvements pointed out in v2 were taken care of in [5].
References:
----------
[1] Exporting KVM host power saving capabilities through libvirt
http://thread.gmane.org/gmane.comp.emulators.libvirt/40886
[2] http://www.redhat.com/archives/libvir-list/2011-August/msg00238.html
[3] http://www.redhat.com/archives/libvir-list/2011-August/msg00248.html
[4] http://www.redhat.com/archives/libvir-list/2011-August/msg00302.html
[5] http://www.redhat.com/archives/libvir-list/2011-August/msg00282.html
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat at linux.vnet.ibm.com>
---
docs/formatcaps.html.in | 19 +++++++---
docs/schemas/capability.rng | 18 +++++++++
include/libvirt/virterror.h | 1 +
libvirt.spec.in | 2 +
src/conf/capabilities.c | 27 +++++++++++++-
src/conf/capabilities.h | 4 ++
src/libvirt_private.syms | 1 +
src/qemu/qemu_capabilities.c | 18 +++++++++
src/util/util.c | 82 ++++++++++++++++++++++++++++++++++++++++++
src/util/util.h | 14 +++++++
src/util/virterror.c | 3 ++
11 files changed, 183 insertions(+), 6 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..8238a37 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 +108,21 @@
</zeroOrMore>
</define>
+ <define name='power_management'>
+ <element name='power_management'>
+ <optional>
+ <element name='S3'>
+ <empty/>
+ </element>
+ </optional>
+ <optional>
+ <element name='S4'>
+ <empty/>
+ </element>
+ </optional>
+ </element>
+ </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/libvirt.spec.in b/libvirt.spec.in
index e2b7f65..3193de3 100644
--- a/libvirt.spec.in
+++ b/libvirt.spec.in
@@ -482,6 +482,8 @@ Requires: nc
Requires: gettext
# Needed by virt-pki-validate script.
Requires: gnutls-utils
+# Needed for probing the power management features of the host.
+Requires: pm-utils
%if %{with_sasl}
Requires: cyrus-sasl
# Not technically required, but makes 'out-of-box' config
diff --git a/src/conf/capabilities.c b/src/conf/capabilities.c
index 2f243ae..e8ab599 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:
@@ -201,7 +208,6 @@ virCapabilitiesAddHostFeature(virCapsPtr caps,
return 0;
}
-
/**
* virCapabilitiesAddHostMigrateTransport:
* @caps: capabilities to extend
@@ -686,6 +692,25 @@ virCapabilitiesFormatXML(virCapsPtr caps)
virBufferAddLit(&xml, " </cpu>\n");
+ if(caps->host.powerMgmt_valid) {
+ /* The PM query was successful. */
+ if(caps->host.powerMgmt) {
+ /* The host supports some PM features. */
+ unsigned int pm = caps->host.powerMgmt;
+ virBufferAddLit(&xml, " <power_management>\n");
+ while(pm) {
+ int bit = ffs(pm) - 1;
+ virBufferAsprintf(&xml, " <%s/>\n",
+ virHostPMCapabilityTypeToString(bit));
+ pm &= ~(1U << bit);
+ }
+ virBufferAddLit(&xml, " </power_management>\n");
+ } else {
+ /* 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..c51f220 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 powerMgmt_valid;
+ unsigned int powerMgmt; /* Bitmask of the PM capabilities.
+ * See enum virHostPMCapability.
+ */
int offlineMigrate;
int liveMigrate;
size_t nmigrateTrans;
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 830222b..40fc4d0 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1058,6 +1058,7 @@ virFormatMacAddr;
virGenerateMacAddr;
virGetGroupID;
virGetHostname;
+virGetPMCapabilities;
virGetUserDirectory;
virGetUserID;
virGetUserName;
diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index 3f36212..581b80f 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -794,6 +794,8 @@ virCapsPtr qemuCapsInit(virCapsPtr old_caps)
struct utsname utsname;
virCapsPtr caps;
int i;
+ int status = -1;
+ unsigned int pmbitmask = 0;
char *xenner = NULL;
/* Really, this never fails - look at the man-page. */
@@ -824,6 +826,22 @@ virCapsPtr qemuCapsInit(virCapsPtr old_caps)
old_caps->host.cpu = NULL;
}
+ /* Add the power management features of the host */
+
+ status = virGetPMCapabilities(&pmbitmask);
+ if(status < 0) {
+ caps->host.powerMgmt_valid = false;
+ VIR_WARN("Failed to get host power management capabilities");
+ } else {
+ /* The PM query succeeded. */
+ caps->host.powerMgmt_valid = true;
+
+ /* The power management features supported by the host are
+ * represented as a bitmask by 'pmbitmask'.
+ */
+ caps->host.powerMgmt = pmbitmask;
+ }
+
virCapabilitiesAddHostMigrateTransport(caps,
"tcp");
diff --git a/src/util/util.c b/src/util/util.c
index 03a9e1a..b1a6434 100644
--- a/src/util/util.c
+++ b/src/util/util.c
@@ -2641,3 +2641,85 @@ or other application using the libvirt API.\n\
return 0;
}
+
+/**
+ * Get the Power Management Capabilities of the host system.
+ * The script 'pm-is-supported' (from the pm-utils package) is run
+ * to find out all the power management features supported by the host,
+ * such as Suspend-to-RAM (S3) and Suspend-to-Disk (S4).
+ *
+ * @bitmask: Pointer to the bitmask that must be set appropriately to
+ * indicate all the supported host power management features.
+ * This will be set to zero if the host does not support any
+ * power management feature.
+ *
+ * Return values:
+ * 0 if the query was successful.
+ * -1 on error like 'pm-is-supported' is not found.
+ */
+int
+virGetPMCapabilities(unsigned int * bitmask)
+{
+
+ char *path = NULL;
+ int status = -1;
+ int ret = -1;
+ virCommandPtr cmd;
+
+ *bitmask = 0;
+ if((path = virFindFileInPath("pm-is-supported")) == NULL) {
+ virUtilError(VIR_ERR_INTERNAL_ERROR,
+ "%s", _("Failed to get the path of pm-is-supported"));
+ return -1;
+ }
+
+ /* Check support for Suspend-to-RAM (S3) */
+ cmd = virCommandNew(path);
+ virCommandAddArg(cmd, "--suspend");
+ if(virCommandRun(cmd, &status) < 0) {
+ virUtilError(VIR_ERR_INTERNAL_ERROR,
+ "%s", _("Failed to run command"
+ "'pm-is-supported --suspend'"));
+ virCommandFree(cmd);
+ ret = -1;
+ goto cleanup;
+ } else {
+ ret = 0;
+
+ /* Check return code of command == 0 for success
+ * (i.e., the PM capability is supported)
+ */
+ if(status == 0)
+ *bitmask |= 1U << VIR_HOST_PM_S3;
+
+ virCommandFree(cmd);
+ }
+
+ /* Check support for Suspend-to-Disk (S4) */
+ cmd = virCommandNew(path);
+ virCommandAddArg(cmd, "--hibernate");
+ if(virCommandRun(cmd, &status) < 0) {
+ virUtilError(VIR_ERR_INTERNAL_ERROR,
+ "%s", _("Failed to run command"
+ "'pm-is-supported --hibernate'"));
+
+ virCommandFree(cmd);
+ ret = -1;
+ goto cleanup;
+ } else {
+ ret = 0;
+
+ /* Check return code of command == 0 for success
+ * (i.e., the PM capability is supported)
+ */
+ if(status == 0)
+ *bitmask |= 1U << VIR_HOST_PM_S4;
+
+ virCommandFree(cmd);
+ }
+
+cleanup:
+ VIR_FREE(path);
+ return ret;
+}
+
diff --git a/src/util/util.h b/src/util/util.h
index af8b15d..24a87ff 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 virGetPMCapabilities(unsigned int *);
+
#endif /* __VIR_UTIL_H__ */
diff --git a/src/util/virterror.c b/src/util/virterror.c
index 9a27feb..e07de61 100644
--- a/src/util/virterror.c
+++ b/src/util/virterror.c
@@ -172,6 +172,9 @@ static const char *virErrorDomainName(virErrorDomain domain) {
case VIR_FROM_LOCKING:
dom = "Locking ";
break;
+ case VIR_FROM_CAPABILITIES:
+ dom = "Capabilities ";
+ break;
}
return(dom);
}
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