Some extra information, I have selinux set to Permissive mode, so this is *not* a selinux issue.
The journal does not contain any other useful info.

> Could not create EK certificate locally
> Could not import signing key : The requested data were not available.

The signing key for signing the certificate is not readable or missing. It could be a permission problem accessing the key.

You need to check ~/.config/swtpm_setup.conf  if this files exists, /etc/swtpm_setup.conf otherwise.


My ~/.config/swtpm_setup.conf looks like this:

create_certs_tool = /usr/bin/swtpm_localca
create_certs_tool_config = /home/stefanb/.config/swtpm-localca.conf
create_certs_tool_options = /home/stefanb/.config/swtpm-localca.options
[...]

Now you have to look into what create_certs_tool_config points to -- my '/home/stefanb/.config/swtpm-localca.conf' looks like this:

statedir = /home/stefanb/.config/var/lib/swtpm-localca
signingkey = /home/stefanb/.config/var/lib/swtpm-localca/signkey.pem
issuercert = /home/stefanb/.config/var/lib/swtpm-localca/issuercert.pem
certserial = /home/stefanb/.config/var/lib/swtpm-localca/certserial


The signing key and all the other files must available:

$ ls -lZ /home/stefanb/.config/var/lib/swtpm-localca/*
-rw-r--r--. 1 stefanb stefanb unconfined_u:object_r:config_home_t:s0    3 Oct 14 17:22 /home/stefanb/.config/var/lib/swtpm-localca/certserial
-rw-rw-r--. 1 stefanb stefanb unconfined_u:object_r:config_home_t:s0 1505 May 25  2022 /home/stefanb/.config/var/lib/swtpm-localca/issuercert.pem
-rw-r-----. 1 stefanb stefanb unconfined_u:object_r:config_home_t:s0 8170 May 25  2022 /home/stefanb/.config/var/lib/swtpm-localca/signkey.pem
-rw-rw-r--. 1 stefanb stefanb unconfined_u:object_r:config_home_t:s0 1468 May 25  2022 /home/stefanb/.config/var/lib/swtpm-localca/swtpm-localca-rootca-cert.pem
-rw-r-----. 1 stefanb stefanb unconfined_u:object_r:config_home_t:s0 8177 May 25  2022 /home/stefanb/.config/var/lib/swtpm-localca/swtpm-localca-rootca-privkey.pem


The path for /etc/swtpm_setup.conf leads to these files here:

$ sudo ls -l /var/lib/swtpm-localca/
[sudo] password for stefanb:
total 36
-rw-r--r--. 1 tss root 2973 Oct 15  2023 bundle.pem
-rw-r--r--. 1 tss root   27 Nov 12 15:20 certserial
-rw-r--r--. 1 tss root 1505 May 28  2021 issuercert.pem
-rw-r-----. 1 tss root 8170 May 28  2021 signkey.pem
-rw-r--r--. 1 tss root 1468 May 28  2021 swtpm-localca-rootca-cert.pem
-rw-r-----. 1 tss root 8170 May 28  2021 swtpm-localca-rootca-privkey.pem

If all these files are available and have their permissions set properly (as should be by default) the certificate should be created. 

Another configuration that may play a role is that of libvirt /etc/libvirt/qemu.conf:

It shows this here by default:
# User for the swtpm TPM Emulator
#
# Default is 'tss'; this is the same user that tcsd (TrouSerS) installs
# and uses; alternative is 'root'
#
#swtpm_user = "tss"
#swtpm_group = "tss"

> Could not create EK certificate locally
> Could not import signing key : The requested data were not available.

Actually above is not correct. The signing key can be read but something is wrong with the format of the key that does not allow gnutls to read it:

        if (sigkeypass) {
            err = gnutls_x509_privkey_import2(sigkey, &datum, GNUTLS_X509_FMT_PEM,
                                              sigkeypass, 0);
        } else {
            err = gnutls_x509_privkey_import(sigkey, &datum, GNUTLS_X509_FMT_PEM);
        }
    }
    gnutls_free(datum.data);
    datum.data = NULL;
    CHECK_GNUTLS_ERROR(err, "Could not import signing key : %s\n",
                       gnutls_strerror(err));


So this here should work for the private key:

certtool --infile ~/.config/var/lib/swtpm-localca/signkey.pem  -k

Looks like that was some incorrect permissions I had in the swtpm files in the ~/.config directory.
I recently copied the ~/.config folder from another system and I probably messed up with the permissions in that directory. Anyway, did a `sudo chown -R kkoukiou:kkoukiou ~/.config/` and now it works. 

Sorry for the noise.