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

[Michal Prívozník]

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
(moving a few lines of code into a different function or dropping it)
and as such I can squash them in before pushing.

Tentatively-ACKed-by: me

Michal