File libvirt-virtio-rng-Add-rate-limiting-options-for-virtio-RNG.patch of Package libvirt
From 749c3cc62cf480d507d545d1d62362eace504500 Mon Sep 17 00:00:00 2001
Message-Id: <749c3cc62cf480d507d545d1d62362eace504500@dist-git>
From: Peter Krempa <pkrempa@redhat.com>
Date: Fri, 28 Mar 2014 22:54:00 +0100
Subject: [PATCH] virtio-rng: Add rate limiting options for virtio-RNG
https://bugzilla.redhat.com/show_bug.cgi?id=786408
Qemu's implementation of virtio RNG supports rate limiting of the
entropy used. This patch exposes the option to tune this functionality.
This patch is based on qemu commit 904d6f588063fb5ad2b61998acdf1e73fb4
The rate limiting is exported in the XML as:
<devices>
...
<rng model='virtio'>
<rate bytes='123' period='1234'/>
<backend model='random'/>
</rng>
...
(cherry picked from commit 32bd699f5547841677608577a5c9c597ed0f6647)
Conflicts:
src/qemu/qemu_command.c - context from previous changes
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
---
docs/formatdomain.html.in | 13 +++++++++++++
docs/schemas/domaincommon.rng | 21 ++++++++++++++++++++-
src/conf/domain_conf.c | 19 +++++++++++++++++++
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, 64 insertions(+), 2 deletions(-)
diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index 31a1a07..e2e5b89 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -4192,6 +4192,7 @@ qemu-kvm -net nic,model=? /dev/null
...
<devices>
<rng model='virtio'>
+ <rate period="2000" bytes="1234"/>
<backend model='random'>/dev/random</backend>
<!-- OR -->
<backend model='egd' type='udp'>
@@ -4214,6 +4215,18 @@ 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 optional <code>rate</code> element allows limiting the rate at
+ which entropy can be consumed from the source. The mandatory
+ attribute <code>bytes</code> specifies how many bytes are permitted
+ to be consumed per period. An optional <code>period</code> attribute
+ specifies the duration of a period in milliseconds; if omitted, the
+ period is taken as 1000 milliseconds (1 second).
+ <span class='since'>Since 1.0.4</span>
+ </p>
+ </dd>
<dt><code>backend</code></dt>
<dd>
<p>
diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
index d5685d5..fbb6f0d 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -3423,7 +3423,12 @@
<value>virtio</value>
</choice>
</attribute>
- <ref name="rng-backend"/>
+ <interleave>
+ <ref name="rng-backend"/>
+ <optional>
+ <ref name="rng-rate"/>
+ </optional>
+ </interleave>
</element>
</define>
@@ -3451,6 +3456,20 @@
</element>
</define>
+ <define name="rng-rate">
+ <element name="rate">
+ <attribute name="bytes">
+ <ref name="positiveInteger"/>
+ </attribute>
+ <optional>
+ <attribute name="period">
+ <ref name="positiveInteger"/>
+ </attribute>
+ </optional>
+ <empty/>
+ </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 a95aacf..ca0e4ef 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -7142,6 +7142,19 @@ virDomainRNGDefParseXML(const xmlNodePtr node,
ctxt->node = node;
+ if (virXPathUInt("string(./rate/@bytes)", ctxt, &def->rate) < -1) {
+ virReportError(VIR_ERR_XML_ERROR, "%s",
+ _("invalid RNG rate bytes value"));
+ goto error;
+ }
+
+ if (def->rate > 0 &&
+ virXPathUInt("string(./rate/@period)", ctxt, &def->period) < -1) {
+ virReportError(VIR_ERR_XML_ERROR, "%s",
+ _("invalid RNG rate period value"));
+ goto error;
+ }
+
if ((nbackends = virXPathNodeSet("./backend", ctxt, &backends)) < 0)
goto error;
@@ -13385,6 +13398,12 @@ virDomainRNGDefFormat(virBufferPtr buf,
const char *backend = virDomainRNGBackendTypeToString(def->backend);
virBufferAsprintf(buf, " <rng model='%s'>\n", model);
+ if (def->rate) {
+ virBufferAsprintf(buf, " <rate bytes='%u'", def->rate);
+ if (def->period)
+ virBufferAsprintf(buf, " period='%u'", def->period);
+ virBufferAddLit(buf, "/>\n");
+ }
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 27bc881..d2ae8a0 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -1701,6 +1701,8 @@ enum virDomainRNGBackend {
struct _virDomainRNGDef {
int model;
int backend;
+ unsigned int rate; /* bytes per period */
+ unsigned int period; /* milliseconds */
union {
char *file; /* file name for 'random' source */
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 4346123..4296ea3 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -4206,6 +4206,14 @@ 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, caps) < 0)
goto cleanup;
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.args b/tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.args
index 7ab9dbc..5d296e8 100644
--- a/tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.args
+++ b/tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.args
@@ -3,4 +3,4 @@ LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu \
-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=/dev/hwrng \
--device virtio-rng-pci,rng=rng0,bus=pci.0,addr=0x4
+-device virtio-rng-pci,rng=rng0,max-bytes=123,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 1e2c4be..354ae42 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 bytes='123' period='1234'/>
<backend model='random'>/dev/hwrng</backend>
</rng>
</devices>
--
1.9.1
