Description of problem:
plymouthd needs access to determine if the OS is booted in UEFI mode.
SELinux is preventing plymouthd from 'getattr' accesses on the directory /sys/firmware/efi/efivars.

*****  Plugin restorecon (99.5 confidence) suggests   ************************

If you want to fix the label. 
/sys/firmware/efi/efivars default label should be sysfs_t.
Then you can run restorecon. The access attempt may have been stopped due to insufficient permissions to access a parent directory in which case try to change the following command accordingly.
Do
# /sbin/restorecon -v /sys/firmware/efi/efivars

*****  Plugin catchall (1.49 confidence) suggests   **************************

If you believe that plymouthd should be allowed getattr access on the efivars directory by default.
Then you should report this as a bug.
You can generate a local policy module to allow this access.
Do
allow this access for now by executing:
# ausearch -c 'plymouthd' --raw | audit2allow -M my-plymouthd
# semodule -X 300 -i my-plymouthd.pp

Additional Information:
Source Context                system_u:system_r:plymouthd_t:s0
Target Context                system_u:object_r:efivarfs_t:s0
Target Objects                /sys/firmware/efi/efivars [ dir ]
Source                        plymouthd
Source Path                   plymouthd
Port                          <Unknown>
Host                          (removed)
Source RPM Packages           
Target RPM Packages           
Policy RPM                    selinux-policy-3.14.3-15.fc30.noarch
Selinux Enabled               True
Policy Type                   targeted
Enforcing Mode                Permissive
Host Name                     (removed)
Platform                      Linux (removed) 4.21.0-0.rc0.git1.1.fc30.x86_64 #1
                              SMP Thu Dec 27 04:40:43 UTC 2018 x86_64 x86_64
Alert Count                   4
First Seen                    2018-12-29 08:26:48 CET
Last Seen                     2018-12-30 15:08:34 CET
Local ID                      56ad95c7-ebf3-461a-bcbf-7e308456527c

Raw Audit Messages
type=AVC msg=audit(1546178914.26:146): avc:  denied  { getattr } for  pid=882 comm="plymouthd" path="/sys/firmware/efi/efivars" dev="efivarfs" ino=11707 scontext=system_u:system_r:plymouthd_t:s0 tcontext=system_u:object_r:efivarfs_t:s0 tclass=dir permissive=1


Hash: plymouthd,plymouthd_t,efivarfs_t,dir,getattr

Version-Release number of selected component:
selinux-policy-3.14.3-15.fc30.noarch

Additional info:
component:      selinux-policy
reporter:       libreport-2.9.7
hashmarkername: setroubleshoot
kernel:         4.21.0-0.rc0.git1.1.fc30.x86_64
type:           libreport

Potential duplicate: bug 1648978