[PATCH 4/4] docs: add s390-pv documentation
Add documentation for launch security type s390-pv.
Signed-off-by: Boris Fiuczynski <fiuczy(a)linux.ibm.com>
---
docs/formatdomain.rst | 7 ++++
docs/kbase/s390_protected_virt.rst | 55 +++++++++++++++++++++++++-----
2 files changed, 54 insertions(+), 8 deletions(-)
diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
index fa5c14febc..635fd5a55f 100644
--- a/docs/formatdomain.rst
+++ b/docs/formatdomain.rst
@@ -8044,6 +8044,13 @@ Note: DEA/TDEA is synonymous with DES/TDES.
Launch Security
---------------
+Specifying ``<launchSecurity type='s390-pv'\>`` in an s390 VM prepares for
+running the guest in protected virtualization secure mode, also known as
+IBM Secure Execution. For more required host and guest preparation steps, see
+`Protected Virtualization on s390 <kbase/s390_protected_virt.html>`__
+:since:`Since 7.4.0`
+
+
The contents of the ``<launchSecurity type='sev'>`` element is used to
provide
the guest owners input used for creating an encrypted VM using the AMD SEV
feature (Secure Encrypted Virtualization). SEV is an extension to the AMD-V
diff --git a/docs/kbase/s390_protected_virt.rst b/docs/kbase/s390_protected_virt.rst
index 1718a556d4..5c9ce0e21c 100644
--- a/docs/kbase/s390_protected_virt.rst
+++ b/docs/kbase/s390_protected_virt.rst
@@ -127,10 +127,13 @@ Protected virtualization guests support I/O using virtio devices.
As the virtio data structures of secure guests are not accessible
by the host, it is necessary to use shared memory ('bounce buffers').
-To enable virtio devices to use shared buffers, it is necessary
-to configure them with platform_iommu enabled. This can done by adding
-``iommu='on'`` to the driver element of a virtio device definition in the
-guest's XML, e.g.
+Since libvirt 7.4.0 the
+`<launchSecurity> <https://libvirt.org/formatdomain.html#launchSecurity>`__
+element with type ``s390-pv`` should be used on protected virtualization guests.
+Without ``launchSecurity`` you must enable all virtio devices to use shared
+buffers by configuring them with platform_iommu enabled.
+This can done by adding ``iommu='on'`` to the driver element of a virtio
+device definition in the guest's XML, e.g.
::
@@ -140,8 +143,10 @@ guest's XML, e.g.
<driver name='vhost' iommu='on'/>
</interface>
-It is mandatory to define all virtio bus devices in this way to
-prevent the host from attempting to access protected memory.
+Unless you are using ``launchSecurity`` you must define all virtio bus
+devices in this way to prevent the host from attempting to access
+protected memory.
+
Ballooning will not work and is fenced by QEMU. It should be
disabled by specifying
@@ -158,8 +163,42 @@ allocated 2K entries. A commonly used value for swiotlb is 262144.
Example guest definition
========================
-Minimal domain XML for a protected virtualization guest, essentially
-it's mostly about the ``iommu`` property
+Minimal domain XML for a protected virtualization guest with
+the ``launchSecurity`` element of type ``s390-pv``
+
+::
+
+ <domain type='kvm'>
+ <name>protected</name>
+ <memory unit='KiB'>2048000</memory>
+ <currentMemory unit='KiB'>2048000</currentMemory>
+ <vcpu>1</vcpu>
+ <os>
+ <type arch='s390x'>hvm</type>
+ </os>
+ <cpu mode='host-model'/>
+ <devices>
+ <disk type='file' device='disk'>
+ <driver name='qemu' type='qcow2' cache='none'
io='native'>
+ <source file='/var/lib/libvirt/images/protected.qcow2'/>
+ <target dev='vda' bus='virtio'/>
+ </disk>
+ <interface type='network'>
+ <source network='default'/>
+ <model type='virtio'/>
+ </interface>
+ <console type='pty'/>
+ <memballoon model='none'/>
+ </devices>
+ <launchSecurity type='s390-pv'/>
+ </domain>
+
+
+Example guest definition without launchSecurity
+===============================================
+
+Minimal domain XML for a protected virtualization guest using the
+``iommu='on'`` setting for each virtio device.
::
--
2.30.2