Installed virtuabox on fedora 28 workstation following this blog, but throws error:
http://danniel-lara.blogspot.com/2018/05/virtualbox-no-fedora-28.html


[root@localhost ~]# akmods --kernels 4.16.6-302.fc28.x86_64
Checking kmods exist for 4.16.6-302.fc28.x86_64            [  OK  ]

[root@localhost ~]# systemctl restart systemd-modules-load.service
Job for systemd-modules-load.service failed because the control process exited with error code.
See "systemctl status systemd-modules-load.service" and "journalctl -xe" for details.

[root@localhost ~]# journalctl -xe
-- 
-- The start-up result is RESULT.
May 07 11:56:46 localhost.localdomain audit[1]: SERVICE_START pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='unit=dnf-makecache comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=?>
May 07 11:56:46 localhost.localdomain audit[1]: SERVICE_STOP pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='unit=dnf-makecache comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? >
May 07 11:57:31 localhost.localdomain sudo[4370]:   user : problem with defaults entries ; TTY=pts/1 ; PWD=/home/user ; USER=root ;
May 07 11:57:31 localhost.localdomain dbus-daemon[1354]: [system] Activating via systemd: service name='net.reactivated.Fprint' unit='fprintd.service' requested by ':1.98' (uid=0 pid=4370 comm="sudo -i " label="unconfined_u:unconfined_r>
May 07 11:57:31 localhost.localdomain systemd[1]: Starting Fingerprint Authentication Daemon...
-- Subject: Unit fprintd.service has begun start-up
-- Defined-By: systemd
-- Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit fprintd.service has begun starting up.
May 07 11:57:31 localhost.localdomain dbus-daemon[1354]: [system] Successfully activated service 'net.reactivated.Fprint'
May 07 11:57:31 localhost.localdomain systemd[1]: Started Fingerprint Authentication Daemon.
-- Subject: Unit fprintd.service has finished start-up
-- Defined-By: systemd
-- Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit fprintd.service has finished starting up.
-- 
-- The start-up result is RESULT.
May 07 11:57:31 localhost.localdomain audit[1]: SERVICE_START pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='unit=fprintd comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=s>
May 07 11:57:32 localhost.localdomain audit[4370]: USER_AUTH pid=4370 uid=1000 auid=1000 ses=2 subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 msg='op=PAM:authentication grantors=pam_succeed_if,pam_localuser,pam_unix acct="da>
May 07 11:57:32 localhost.localdomain audit[4370]: USER_ACCT pid=4370 uid=1000 auid=1000 ses=2 subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 msg='op=PAM:accounting grantors=pam_unix,pam_localuser acct="user" exe="/usr/bin>
May 07 11:57:32 localhost.localdomain sudo[4370]:   user : TTY=pts/1 ; PWD=/home/user ; USER=root ; COMMAND=/bin/bash
May 07 11:57:32 localhost.localdomain audit[4370]: USER_CMD pid=4370 uid=1000 auid=1000 ses=2 subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 msg='cwd="/home/user" cmd="-bash" terminal=pts/1 res=success'
May 07 11:57:32 localhost.localdomain audit[4370]: CRED_REFR pid=4370 uid=0 auid=1000 ses=2 subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 msg='op=PAM:setcred grantors=pam_localuser,pam_unix acct="root" exe="/usr/bin/sudo" h>
May 07 11:57:32 localhost.localdomain sudo[4370]: pam_systemd(sudo-i:session): Cannot create session: Already running in a session
May 07 11:57:32 localhost.localdomain audit[4370]: USER_START pid=4370 uid=0 auid=1000 ses=2 subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 msg='op=PAM:session_open grantors=pam_keyinit,pam_keyinit,pam_limits,pam_keyinit,pam>
May 07 11:57:32 localhost.localdomain sudo[4370]: pam_unix(sudo-i:session): session opened for user root by user(uid=0)
May 07 11:58:01 localhost.localdomain audit[1]: SERVICE_STOP pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='unit=fprintd comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=su>
May 07 11:58:32 localhost.localdomain packagekitd[3100]: Skipping refresh of phracek-PyCharm: cannot update repo 'phracek-PyCharm': Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors were tried; Last error: Sta>
May 07 11:58:33 localhost.localdomain PackageKit[3100]: search-file transaction /215_dcadaaee from uid 0 finished with success after 2107ms
May 07 11:58:38 localhost.localdomain systemd[1]: Starting Load Kernel Modules...
-- Subject: Unit systemd-modules-load.service has begun start-up
-- Defined-By: systemd
-- Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit systemd-modules-load.service has begun starting up.
May 07 11:58:38 localhost.localdomain systemd-modules-load[4664]: Failed to insert 'vboxdrv': Operation not permitted
May 07 11:58:38 localhost.localdomain systemd-modules-load[4664]: Failed to insert 'vboxnetflt': Operation not permitted
May 07 11:58:38 localhost.localdomain systemd-modules-load[4664]: Failed to insert 'vboxnetadp': Operation not permitted
May 07 11:58:38 localhost.localdomain systemd-modules-load[4664]: Failed to insert 'vboxpci': Operation not permitted
May 07 11:58:38 localhost.localdomain systemd[1]: systemd-modules-load.service: Main process exited, code=exited, status=1/FAILURE
May 07 11:58:38 localhost.localdomain systemd[1]: systemd-modules-load.service: Failed with result 'exit-code'.
May 07 11:58:38 localhost.localdomain systemd[1]: Failed to start Load Kernel Modules.
-- Subject: Unit systemd-modules-load.service has failed
-- Defined-By: systemd
-- Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit systemd-modules-load.service has failed.
-- 
-- The result is RESULT.
May 07 11:58:38 localhost.localdomain audit[1]: SERVICE_START pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='unit=systemd-modules-load comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? ter>
[root@localhost ~]#

(In reply to Matt Daveson from comment #0)
> Add virtualbox repositories by default, so I can install VirtualBox with dnf
> without having to add any custom .repo

You don't need _ANY_ third party repositories, all that's needed is integrated into Fedora already and shipped in live images OOTB:

https://fedoraproject.org/wiki/Changes/VirtualBox_Guest_Integration

https://blogs.gnome.org/uraeus/2018/04/24/warming-up-for-fedora-workstation-28/

You DO NOT need to compile any third party kernel modules or use any third party repositories at all any more.