[PATCH v3 0/6] qemu: tpm: Add support for migration across shared storage

[Stefan Berger]

On 10/21/22 06:55, Michal Prívozník wrote:
> On 10/18/22 19:04, Stefan Berger wrote:
>> This series of patches adds support for migrating vTPMs across hosts whose
>> storage has been set up to share the directory structure holding the state
>> of the TPM (swtpm). The existence of share storage influences the
>> management of the directory structure holding the TPM state, which for
>> example is only removed when a domain is undefined and not when a VM is
>> removed on the migration source host. Further, when shared storage is used
>> then security labeling on the destination side is skipped assuming that the
>> labeling was already done on the source side.
>>
>> I have tested this with an NFS setup where I had to turn SELinux off on
>> the hosts since the SELinux MLS range labeling is not supported by NFS.
>>
>> For shared storage support to work properly both sides of the migration
>> need to be clients of the shared storage setup, meaning that they both have
>> to have /var/lib/libvirt/swtpm mounted as shared storage, because other-
>> wise the virFileIsSharedFS() may not detect shared storage and in the
>> worst case may cause the TPM emulator (swtpm) to malfunction if for
>> example the source side removed the TPM state directory structure.
>>
>> Shared storage migration requires (upcoming) swtpm v0.8.
>>
>>     Stefan
>>
>> v3:
>>    - Relying entirely on virFileIsSharedFS() on migration source and
>>      destination sides to detect whether shared storage is set up between
>>      hosts; no more hint about shared storage from user via flag
>>    - Added support for virDomainTPMPrivate structure to store and persist
>>      TPM-related private data
>>
>> Stefan Berger (6):
>>    util: Add parsing support for swtpm's cmdarg-migration capability
>>    qemu: tpm: Conditionally create storage on incoming migration
>>    qemu: tpm: Add support for storing private TPM-related data
>>    qemu: tpm: Pass --migration option to swtpm if supported and needed
>>    qemu: tpm: Avoid security labels on incoming migration with shared
>>      storage
>>    qemu: tpm: Never remove state on outgoing migration and shared storage
>>
>>   src/conf/domain_conf.c    |  63 ++++++++++++++++++++--
>>   src/conf/domain_conf.h    |   9 ++++
>>   src/qemu/qemu_domain.c    |  85 +++++++++++++++++++++++++++--
>>   src/qemu/qemu_domain.h    |  17 +++++-
>>   src/qemu/qemu_driver.c    |  20 +++----
>>   src/qemu/qemu_extdevice.c |  10 ++--
>>   src/qemu/qemu_extdevice.h |   6 ++-
>>   src/qemu/qemu_migration.c |  20 ++++---
>>   src/qemu/qemu_process.c   |   9 ++--
>>   src/qemu/qemu_snapshot.c  |   4 +-
>>   src/qemu/qemu_tpm.c       | 111 ++++++++++++++++++++++++++++++++++----
>>   src/qemu/qemu_tpm.h       |  12 ++++-
>>   src/util/virtpm.c         |   1 +
>>   src/util/virtpm.h         |   1 +
>>   14 files changed, 318 insertions(+), 50 deletions(-)
>>
> 
> Patches look good. I did an experiment and tried to rework the code that
> patch 3/6 is not needed. You can find it here:
> 
> https://gitlab.com/MichalPrivoznik/libvirt/-/commits/tpm_migration_rework
> 
> If you don't like it, I can merge your patches as they are. Or, let me
> know if you're okay with my changes. No need to resend either way.


I think we need a v4. I have mine here: https://github.com/stefanberger/libvirt-tpm/tree/swtpm_shared_storage.v4

> 
> Michal
>