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>
>
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