pc-bios/s390-ccw: Handle true secure IPL mode
When secure boot is enabled (-secure-boot on) and certificate(s) are provided, the boot operates in True Secure IPL mode. Any verification error during True Secure IPL mode will cause the entire boot process to terminate. Secure IPL in audit mode requires at least one certificate provided in the key store along with necessary facilities. If secure boot is enabled but no certificate is provided, the boot process will also terminate, as this is not a valid secure boot configuration. Note: True Secure IPL mode is implemented for the SCSI scheme of virtio-blk/virtio-scsi devices. Signed-off-by: Zhuoying Cai <zycai@linux.ibm.com> Reviewed-by: Collin Walling <walling@linux.ibm.com> Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com> Link: https://lore.kernel.org/qemu-devel/20260730214624.2328883-30-zycai@linux.ibm.com Signed-off-by: Eric Farman <farman@linux.ibm.com>