[PATCH v4 0/7] qemu: tpm: Add support for migration across shared storage

[Michal Prívozník]

On 11/8/22 15:10, Stefan Berger wrote:
> 
> 
> On 11/7/22 03:31, Michal Prívozník wrote:
>> On 10/24/22 12:28, 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
>>>
>>> v4:
>>>    - Fixed long-standing bug regarding offline migration that now
>>> blocks if
>>>      no shared storage is set up
>>>    - Addressed Michal's concerns
>>>
>>> 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 (7):
>>>    util: Add parsing support for swtpm's cmdarg-migration capability
>>>    qemu: tpm: Allow offline migration with TPM_EMULATOR only with shared
>>>      storage
>>>    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 |  28 +++++++--
>>>   src/qemu/qemu_process.c   |   9 ++-
>>>   src/qemu/qemu_snapshot.c  |   4 +-
>>>   src/qemu/qemu_tpm.c       | 122 ++++++++++++++++++++++++++++++++++----
>>>   src/qemu/qemu_tpm.h       |  14 ++++-
>>>   src/util/virtpm.c         |   1 +
>>>   src/util/virtpm.h         |   1 +
>>>   14 files changed, 339 insertions(+), 50 deletions(-)
>>>
>>
>> Hey, sorry for late review. I just have to small nits. I surely want to
>> avoid making you send another version. My suggestions are trivial
> 
> How is it going to work without another version. I am fine with you
> making the changes but I can also send another version...

I'll do the changes just before pushing. Fortunately, we are not doing
merge requests where this would be more complicated.

Reviewed-by: Michal Privoznik <mprivozn at redhat.com>

and pushed. Thank you for your patience.

BTW: do you have any plans of making a release of swtpm in near future?
I think it may be worth it so that distros can pick up this new feature.

Michal