[PATCH v2 2/9] qemu: Introduced VIR_MIGRATE_TPM_SHARED_STORAGE for TPM migration

[Michal Prívozník]

On 10/6/22 15:47, Daniel P. Berrangé wrote:
> On Wed, Oct 05, 2022 at 10:02:00AM -0400, Stefan Berger wrote:
>> Introduced VIR_MIGRATE_TPM_SHARED_STORAGE for migrating a TPM across
>> shared storage.
>>
>> At this point do not support this flag in 'virsh', yet.
>>
>> Signed-off-by: Stefan Berger <stefanb at linux.ibm.com>
>> ---
>>  include/libvirt/libvirt-domain.h | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/include/libvirt/libvirt-domain.h b/include/libvirt/libvirt-domain.h
>> index 8357aea797..110929039d 100644
>> --- a/include/libvirt/libvirt-domain.h
>> +++ b/include/libvirt/libvirt-domain.h
>> @@ -1098,6 +1098,14 @@ typedef enum {
>>       * Since: 8.5.0
>>       */
>>      VIR_MIGRATE_ZEROCOPY = (1 << 20),
>> +
>> +    /* Support TPM migration across hosts that have shared storage setup for
>> +     * the directory structure holding the state of TPMs. Typically this would
>> +     * mean that the directory /var/lib/libvirt/swtpm is shared.
>> +     *
>> +     * Since: 8.9.0
>> +     */
>> +    VIR_MIGRATE_TPM_SHARED_STORAGE = (1 << 21),
> 
> Why do we need this flag at all.  We don't require users to set any flag
> when dealing with shared storage for disks, we just make sure we detect
> shared storage and "do the right thing" with it.

That could work. Until the state is stored on a shared FS but not shared
across migration hosts. But I guess our disk migration code would fail
then too, wouldn't it?

Michal