On 5/13/20 10:10 AM, Daniel Henrique Barboza wrote:
QEMU 4.1.0 introduced a new device type called TPM Proxy, currently
implemented by PPC64 guests via a new virtual device called
'spapr-tpm-proxy' (see QEMU 0fb6bd073230 for more info).
The TPM Proxy device interacts with a TPM Resource Manager, a host
device capable of multiplexing the host TPM with multiple processes.
This allows multiple guests to access some TPM features at the
same time. Note that this mode of operation does not provide
full TPM features to be available for the guest - for that case
the guest still needs to assign a vTPM device (tpm-spapr for
PPC64 guests). Although redundant, there is currently no technical
limitation for a guest to assign both a vTPM and a TPM Proxy at the
same time.
This patch adds documentation and schema for a new TPM model
type called 'spapr-tpm-proxy' that creates this new TPM Proxy
device. This model is valid only for the 'passthrough' backend.
An example of a TPM Proxy device connected to a TPM Resource Manager
'/dev/tpmrm0' will look like this:
<tpm model='spapr-tpm-proxy'>
<backend type='passthrough'>
<device path='/dev/tpmrm0'/>
</backend>
</tpm>
Signed-off-by: Daniel Henrique Barboza <danielhb413@xxxxxxxxx>
---
docs/formatdomain.html.in | 16 +++++++++++++++-
docs/schemas/domaincommon.rng | 1 +
2 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index 23eb029234..ccbb696058 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -8792,6 +8792,15 @@ qemu-kvm -net nic,model=? /dev/null
backend device is a TPM 2.0. <span class="since">Since 6.1.0</span>,
pSeries guests on PPC64 are supported and the default is
<code>tpm-spapr</code>.
+
+ <span class="since">Since 6.4.0</span>, a new model called
+ <code>spapr-tpm-proxy</code> was added for pSeries guests. This model
I think you should mention its application is restricted to 'secure VM'
here since this seems to be what it is used for. A normal 'pSeries
guest' won't make use of it, or would it?
+ only works with the 'passthrough' backend. It creates a TPM Proxy
+ device that allows a QEMU guest to interact with an existing TPM Resource
+ Manager in the host, for example /dev/tpmrm0. A TPM Resource Manager
+ enables the host TPM device to be securely multiplexed across
+ several guests. Only one TPM Proxy device is allowed per guest, but
+ a TPM Proxy device can be added together with other TPM devices.
</p>
</dd>
<dt><code>backend</code></dt>
@@ -8804,7 +8813,7 @@ qemu-kvm -net nic,model=? /dev/null
<dt><code>passthrough</code></dt>
<dd>
<p>
- Use the host's TPM device.
+ Use the host's TPM or TPM Resource Manager device.
</p>
<p>
This backend type requires exclusive access to a TPM device on
@@ -8812,6 +8821,11 @@ qemu-kvm -net nic,model=? /dev/null
qualified file name is specified by path attribute of the
<code>source</code> element. If no file name is specified then
/dev/tpm0 is automatically used.
+
+ <span class="since">Since 6.4.0</span>, when choosing the
+ <code>spapr-tpm-proxy</code> model, the file name specified is
+ expected to be a TPM Resource Manager device, e.g.
+ /dev/tpmrm0.
</p>
</dd>
</dl>
diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
index 9d60b090f3..50860419c3 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -4610,6 +4610,7 @@
<value>tpm-tis</value>
<value>tpm-crb</value>
<value>tpm-spapr</value>
+ <value>spapr-tpm-proxy</value>
</choice>
</attribute>
</optional>
