Re: [libvirt] [PATCH v3 3/3] qemu: add memfd source type

From: Marc-André Lureau <marcandre.lureau(a)redhat.com&gt; Add a new memoryBacking source type "memfd", supported by QEMU (when the capability is available). A memfd is a specialized anonymous memory kind. As such, an anonymous source type could be automatically using a memfd. However, there are some complications when migrating from different memory backends in qemu (mainly due to the internal object naming at this point, but there could be more). For now, it is simpler and safer to simply introduce a new source type "memfd". Eventually, the "anonymous" type could learn to use memfd transparently in a separate change. The main benefits are that it doesn't need to create filesystem files, and it also enforces sealing, providing a bit more safety. Signed-off-by: Marc-André Lureau <marcandre.lureau(a)redhat.com&gt; --- docs/formatdomain.html.in | 9 +-- docs/schemas/domaincommon.rng | 1 + src/conf/domain_conf.c | 3 +- src/conf/domain_conf.h | 1 + src/qemu/qemu_command.c | 69 +++++++++++++------ src/qemu/qemu_domain.c | 12 +++- .../memfd-memory-numa.x86_64-latest.args | 34 +++++++++ tests/qemuxml2argvdata/memfd-memory-numa.xml | 36 ++++++++++ tests/qemuxml2argvtest.c | 2 + 9 files changed, 140 insertions(+), 27 deletions(-) create mode 100644 tests/qemuxml2argvdata/memfd-memory-numa.x86_64-latest.args create mode 100644 tests/qemuxml2argvdata/memfd-memory-numa.xml diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index 295f9ff93e..e7f4ad4060 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -1126,7 +1126,7 @@ &lt;/hugepages&gt; &lt;nosharepages/&gt; &lt;locked/&gt; - &lt;source type="file|anonymous"/&gt; + &lt;source type="file|anonymous|memfd"/&gt; &lt;access mode="shared|private"/&gt; &lt;allocation mode="immediate|ondemand"/&gt; &lt;discard/&gt; @@ -1177,9 +1177,10 @@ suitable for the specific environment at the same time to mitigate the risks described above. <span class="since">Since 1.0.6</span></dd> <dt><code>source</code></dt> - <dd>Using the <code>type</code> attribute, it's possible to provide - "file" to utilize file memorybacking or keep the default - "anonymous".</dd> + <dd>Using the <code>type</code> attribute, it's possible to + provide "file" to utilize file memorybacking or keep the + default "anonymous". <span class="since">Since 4.10.0</span>, + you may choose "memfd" backing. (QEMU/KVM only)</dd> <dt><code>access</code></dt> <dd>Using the <code>mode</code> attribute, specify if the memory is to be "shared" or "private". This can be overridden per numa node by diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng index cad189513a..bfa76c4db3 100644 --- a/docs/schemas/domaincommon.rng +++ b/docs/schemas/domaincommon.rng @@ -655,6 +655,7 @@ <choice> <value>file</value> <value>anonymous</value> + <value>memfd</value> </choice> </attribute> </element> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index 6c15781dc0..bc82dc3504 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -898,7 +898,8 @@ VIR_ENUM_IMPL(virDomainDiskMirrorState, VIR_DOMAIN_DISK_MIRROR_STATE_LAST, VIR_ENUM_IMPL(virDomainMemorySource, VIR_DOMAIN_MEMORY_SOURCE_LAST, "none", "file", - "anonymous") + "anonymous", + "memfd")