[libvirt] [PATCH v3 0/9] x86: Secure Encrypted Virtualization (AMD)

Brijesh Singh brijesh.singh at amd.com
Wed Mar 14 15:44:26 UTC 2018

The patch series is test with QEMU recent pull which includes SEV support:


This patch series provides support for launching an encrypted guest using
AMD's new Secure Encrypted  Virtualization (SEV) feature.

SEV is an extension to the AMD-V architecture which supports running
multiple VMs under the control of a hypervisor. When enabled, SEV feature
allows the memory contents of a virtual machine (VM) to be transparently
encrypted with a key unique to the guest VM.

At very high level the flow looks this:

1. mgmt tool calls virConnectGetDomainCapabilities. This returns an XML document
that includes the following

  <sev supported='yes'>
  <cbitpos> </cbitpos>
  <reduced-phys-bits> </reduced-phys-bits>
  <pdh> </pdh>
  <cert-chain> </cert-chain>

If <sev> is provided then we indicate that hypervisor is capable of launching
SEV guest. 

2. (optional) mgmt tool can provide the PDH and Cert-chain to guest owner in case
if guest owner wish to establish a secure connection with SEV firmware to
negotiate a key used for validating the measurement.

3. mgmt tool requests to start a guest calling virCreateXML(), passing VIR_DOMAIN_START_PAUSED.
The xml would include

<launch-security type='sev'>
<cbitpos> </cbitpos>  /* the value is same as what is obtained via virConnectGetDomainCapabilities()
<reduced-phys-bits> </reduced-phys-bits>  /* the value is same as what is obtained via virConnectGetDomainCapabilities()
<dh-cert> .. </dh> /* guest owners diffie-hellman key */ (optional)
<session> ..</session> /* guest owners session blob */ (optional)
   <policy> ..</policy> /* guest policy */ (optional)

4. Libvirt generate the QEMU cli arg to enable the SEV feature, a typical
args looks like this:

# $QEMU ..
-machine memory-encryption=sev0 \
-object sev-guest,id=sev0,dh-cert-file=<file>....

5. Libvirt generates lifecycle VIR_DOMAIN_EVENT_SUSPENDED_PAUSED event

6. mgmt tool gets the VIR_DOMAIN_EVENT_SUSPENDED_PAUSED and calls virDomainGetLaunchSecretInfo()
to retrieve the measurement of encrypted memory.

7. (optional) mgmt tool can provide the measurement value to guest owner, which can
validate the measurement and gives GO/NO-GO answer. If mgmt tool gets GO then
it resumes the guest otherwise it calls destroy() to kill the guest.

8. mgmt tool resumes the guest

* SEV guest require to use DMA apis for the virtio devices. In order to use the DMA
apis the virtio devices must have this tag

<driver iommu=on ats=on>

It is a bit unclear to me where these changes need to go. Do we need to
modify the libvirt to automatically add these when SEV is enabled or
we ask mgmt tool to make sure that it creates XML with right tag to enable
the DMA APIs for virtio devices. I am looking for some suggestions.

Using these patches we have succesfully booted and tested a guest both with and
without SEV enabled.

SEV Firmware API spec is available at:

Changes since v2:
 * make cbitpos, policy and reduced-phys-bits as unsigned int
 * update virDomainGetLaunchSecurityInfo to accept virTypedParameterPtr *params
   instead of virTypedParameterPtr params.

Changes since v1:
 * rename <sev> -> <launch-security> for domain
 * add more information about policy and other fields in domaincaps.html
 * split the domain_conf support in two patches
 * add virDomainGetLaunchInfo() to retrieve the SEV measurement
 * extend virsh command to show the domain's launch security information
 * add test cases to validate newly added <launch-security> element
 * fix issues reported with 'make check' and 'make syntax-check'

The complete git tree is available at:

Brijesh Singh (8):
  qemu: provide support to query the SEV capability
  qemu: introduce SEV feature in hypervisor capabilities
  conf: introduce launch-security element in domain
  qemu: add support to launch SEV guest
  libvirt: add new public API to get launch security info
  remote: implement the remote protocol for launch security
  qemu_driver: add support to launch security info
  virsh: implement new command for launch security

Xiaogang Chen (1):
  tests: extend tests to include sev specific tag parsing

 docs/formatdomain.html.in           | 120 ++++++++++++++++++++++++++++++++++++
 docs/formatdomaincaps.html.in       |  40 ++++++++++++
 docs/schemas/domaincaps.rng         |  20 ++++++
 docs/schemas/domaincommon.rng       |  39 ++++++++++++
 include/libvirt/libvirt-domain.h    |  17 +++++
 src/conf/domain_capabilities.c      |  20 ++++++
 src/conf/domain_capabilities.h      |  14 +++++
 src/conf/domain_conf.c              | 110 +++++++++++++++++++++++++++++++++
 src/conf/domain_conf.h              |  26 ++++++++
 src/driver-hypervisor.h             |   7 +++
 src/libvirt-domain.c                |  48 +++++++++++++++
 src/libvirt_public.syms             |   5 ++
 src/qemu/qemu_capabilities.c        |  40 ++++++++++++
 src/qemu/qemu_capabilities.h        |   1 +
 src/qemu/qemu_capspriv.h            |   4 ++
 src/qemu/qemu_command.c             |  35 +++++++++++
 src/qemu/qemu_driver.c              |  66 ++++++++++++++++++++
 src/qemu/qemu_monitor.c             |  17 +++++
 src/qemu/qemu_monitor.h             |   6 ++
 src/qemu/qemu_monitor_json.c        | 105 +++++++++++++++++++++++++++++++
 src/qemu/qemu_monitor_json.h        |   5 ++
 src/qemu/qemu_process.c             |  58 +++++++++++++++++
 src/remote/remote_daemon_dispatch.c |  47 ++++++++++++++
 src/remote/remote_driver.c          |  42 ++++++++++++-
 src/remote/remote_protocol.x        |  20 +++++-
 src/remote_protocol-structs         |  11 ++++
 tests/genericxml2xmlindata/sev.xml  |  20 ++++++
 tests/genericxml2xmloutdata/sev.xml |  22 +++++++
 tests/genericxml2xmltest.c          |   2 +
 tests/qemuxml2argvdata/sev.args     |  24 ++++++++
 tests/qemuxml2argvdata/sev.xml      |  35 +++++++++++
 tests/qemuxml2argvtest.c            |   2 +
 tests/qemuxml2xmloutdata/sev.xml    |  39 ++++++++++++
 tests/qemuxml2xmltest.c             |   2 +
 tools/virsh-domain.c                |  84 +++++++++++++++++++++++++
 35 files changed, 1151 insertions(+), 2 deletions(-)
 create mode 100644 tests/genericxml2xmlindata/sev.xml
 create mode 100644 tests/genericxml2xmloutdata/sev.xml
 create mode 100644 tests/qemuxml2argvdata/sev.args
 create mode 100644 tests/qemuxml2argvdata/sev.xml
 create mode 100644 tests/qemuxml2xmloutdata/sev.xml


More information about the libvir-list mailing list