/usr/share/qemu/keymaps/modifiers is in qemu-keymaps 2.0.0~rc1+dfsg-0ubuntu3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | Shift_R 0x36
Shift_L 0x2a
Alt_R 0xb8
Mode_switch 0xb8
ISO_Level3_Shift 0xb8
Alt_L 0x38
Control_R 0x9d
Control_L 0x1d
# Translate Super to Windows keys.
# This is hardcoded. See documentation for details.
Super_R 0xdc
Super_L 0xdb
# Translate Menu to the Windows Application key.
Menu 0xdd
|