Add the external swtpm to the emulator cgroup so that upper limits of CPU
usage can be enforced on the emulated TPM.

To enable this we need to have the swtpm write its process id (pid) into a
file. We then read it from the file to configure the emulator cgroup.

The PID file is created in /var/run/libvirt/qemu/swtpm:

[root@localhost swtpm]# ls -lZ /var/run/libvirt/qemu/swtpm/
total 4
-rw-r--r--. 1 tss  tss  system_u:object_r:qemu_var_run_t:s0          5 Apr 10 12:26 1-testvm-swtpm.pid
srw-rw----. 1 qemu qemu system_u:object_r:svirt_image_t:s0:c597,c632 0 Apr 10 12:26 1-testvm-swtpm.sock

The swtpm command line now looks as follows:

root@localhost testvm]# ps auxZ | grep swtpm | grep socket | grep -v grep
system_u:system_r:virtd_t:s0:c597,c632 tss 18697 0.0  0.0 28172 3892 ?       Ss   16:46   0:00 /usr/bin/swtpm socket --daemon --ctrl type=unixio,path=/var/run/libvirt/qemu/swtpm/1-testvm-swtpm.sock,mode=0600 --tpmstate dir=/var/lib/libvirt/swtpm/485d0004-a48f-436a-8457-8a3b73e28568/tpm1.2/ --log file=/var/log/swtpm/libvirt/qemu/testvm-swtpm.log --pid file=/var/run/libvirt/qemu/swtpm/1-testvm-swtpm.pid
Signed-off-by: NStefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

Implement functions for managing the storage of the external swtpm as well
as starting and stopping it. Also implement functions to use swtpm_setup,
which simulates the manufacturing of a TPM, which includes creation of
certificates for the device.

Further, the external TPM needs storage on the host that we need to set
up before it can be run. We can clean up the host once the domain is
undefined.

This patch also implements a small layer for external device support that
calls into the TPM device layer if a domain has an attached TPM. This is
the layer we will wire up later on.
Signed-off-by: NStefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>