tpm: Pass migration key passphrase via fd to swtpm
tpm: Pass migration key passphrase via fd to swtpm

This patch now passes the passphrase as a migration key to swtpm.
This now encrypts the state of the TPM while a VM is migrated between
hosts or when suspended into a file. Since the migration key secret
is the same as the state encryption secret, this now requires that
the migration destination host has the same secret value.

Signed-off-by: Stefan Berger <5c96973112e540fb909b13997fcd087e5bfbee96@linux.ibm.com>
Reviewed-by: Daniel P. Berrangé <bb938cf255e055ff3507f2627d214e8e62118fcf@redhat.com>

olafhering/libvirt,crobinso/libvirt,olafhering/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,nertpinx/libvirt,nertpinx/libvirt,libvirt/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,jfehlig/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,libvirt/libvirt,jardasgit/libvirt,crobinso/libvirt,crobinso/libvirt,olafhering/libvirt,libvirt/libvirt,andreabolognani/libvirt,jardasgit/libvirt,nertpinx/libvirt,olafhering/libvirt,zippy2/libvirt,andreabolognani/libvirt,zippy2/libvirt,libvirt/libvirt,nertpinx/libvirt,zippy2/libvirt,crobinso/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,jardasgit/libvirt,jfehlig/libvirt,jardasgit/libvirt,zippy2/libvirt,jfehlig/libvirt,jardasgit/libvirt