On 02/13/2013 11:28 AM, Peter Krempa wrote:
Qemu's implementation of virtio RNG supports rate limiting of the entropy used. This patch exposes the option to tune this fucntionality.
s/fucntionality/functionality
This patch is based on qemu commit 904d6f588063fb5ad2b61998acdf1e73fb4
The rate limiting is exported in the XML as: <devices> ... <rng model='virtio'> <rate period='1234'>4321</rate> <backend model='random'/> </rng> ... --- docs/formatdomain.html.in | 9 +++++++++ docs/schemas/domaincommon.rng | 18 +++++++++++++++++- src/conf/domain_conf.c | 17 +++++++++++++++++ src/conf/domain_conf.h | 2 ++ src/qemu/qemu_command.c | 8 ++++++++ .../qemuxml2argv-virtio-rng-random.args | 2 +- .../qemuxml2argv-virtio-rng-random.xml | 1 + 7 files changed, 55 insertions(+), 2 deletions(-)
diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index e8cd086..b264460 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -4293,6 +4293,7 @@ qemu-kvm -net nic,model=? /dev/null ... <devices> <rng model='virtio'> + <rate period="2000">1234</rate> <backend model='random'>/dev/random</backend> <!-- OR --> <backend model='egd' type='udp'> @@ -4315,6 +4316,14 @@ qemu-kvm -net nic,model=? /dev/null <li>'virtio' — supported by qemu and virtio-rng kernel module</li> </ul> </dd> + <dt><code>rate</code></dt> + <dd> + <p> + The rate parameter allows to limit the rate that the entropy can be + read from the source. The value is in bits that the device is allowed + to read in the selected period. The default period is 1000ms or 1 second. + </p> + </dd>
bits or bytes?
<dt><code>backend</code></dt> <dd> <p> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng index 8330a50..da53095 100644 --- a/docs/schemas/domaincommon.rng +++ b/docs/schemas/domaincommon.rng @@ -3522,7 +3522,12 @@ <value>virtio</value> </choice> </attribute> - <ref name="rng-backend"/> + <interleave> + <ref name="rng-backend"/> + <optional> + <ref name="rng-rate"/> + </optional> + </interleave> </element> </define>
@@ -3546,6 +3551,17 @@ </element> </define>
+ <define name="rng-rate"> + <element name="rate"> + <optional> + <attribute name="period"> + <ref name="positiveInteger"/> + </attribute> + </optional> + <ref name="positiveInteger"/> + </element> + </define> + <define name="usbmaster"> <element name="master"> <attribute name="startport"> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index 53c6b2f..023e92c 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -7445,6 +7445,17 @@ virDomainRNGDefParseXML(const xmlNodePtr node,
ctxt->node = node;
+ if (virXPathUInt("string(./rate)", ctxt, &def->rate) < -1) { + virReportError(VIR_ERR_XML_ERROR, "%s", _("invalid RNG rate value")); + goto error; + } + + if (def->rate > 0 && + virXPathUInt("string(./rate/@period)", ctxt, &def->period) < -1) { + virReportError(VIR_ERR_XML_ERROR, "%s", _("invalid RNG period value")); + goto error; + } + if ((nbackends = virXPathNodeSet("./backend", ctxt, &backends)) < 0) goto error;
@@ -13792,6 +13803,12 @@ virDomainRNGDefFormat(virBufferPtr buf, const char *backend = virDomainRNGBackendTypeToString(def->backend);
virBufferAsprintf(buf, " <rng model='%s'>\n", model); + if (def->rate) { + virBufferAddLit(buf, " <rate"); + if (def->period) + virBufferAsprintf(buf, " period='%u'", def->period); + virBufferAsprintf(buf, ">%u</rate>\n", def->rate); + } virBufferAsprintf(buf, " <backend model='%s'", backend);
switch ((enum virDomainRNGBackend) def->backend) { diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h index b78a04c..b34484c 100644 --- a/src/conf/domain_conf.h +++ b/src/conf/domain_conf.h @@ -1736,6 +1736,8 @@ enum virDomainRNGBackend { struct _virDomainRNGDef { int model; int backend; + unsigned int rate; + unsigned int period;
union { char *file; /* file name for 'random' source */ diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index d3a9b70..14d8f6d 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -4297,6 +4297,14 @@ qemuBuildRNGDeviceArgs(virCommandPtr cmd,
virBufferAsprintf(&buf, "virtio-rng-pci,rng=%s", dev->info.alias);
+ if (dev->rate > 0) { + virBufferAsprintf(&buf, ",max-bytes=%u", dev->rate); + if (dev->period) + virBufferAsprintf(&buf, ",period=%u", dev->period); + else + virBufferAddLit(&buf, ",period=1000"); + } + if (qemuBuildDeviceAddressStr(&buf, &dev->info, qemuCaps) < 0) goto cleanup;
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.args b/tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.args index 4611ae5..428804b 100644 --- a/tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.args +++ b/tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.args @@ -1 +1 @@ -LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu -S -M pc -m 214 -smp 1 -nographic -nodefaults -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -usb -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3 -object rng-random,id=rng0,filename=/test/phile -device virtio-rng-pci,rng=rng0,bus=pci.0,addr=0x4 +LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu -S -M pc -m 214 -smp 1 -nographic -nodefaults -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -usb -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3 -object rng-random,id=rng0,filename=/test/phile -device virtio-rng-pci,rng=rng0,max-bytes=1337,period=1234,bus=pci.0,addr=0x4 diff --git a/tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.xml b/tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.xml index ab1f38c..73e77cd 100644 --- a/tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.xml +++ b/tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.xml @@ -17,6 +17,7 @@ <controller type='usb' index='0'/> <memballoon model='virtio'/> <rng model='virtio'> + <rate period='1234'>1337</rate> <backend model='random'>/test/phile</backend> </rng> </devices>