QEMU uses British or American English in code and documentation. There are some typical spelling bugs which can be easily avoided by using tools like codespell.
codespell is a python script which detects (and optionally fixes) the most common spelling bugs.
If you installed codespell in your HOME directory, it can be called from the QEMU source directory like this:
~/bin/codespell.py -d -r -s -x scripts/codespell.exclude -q 2 ~/share/codespell/dictionary.txt .
-x scripts/codespell.exclude excludes some known lines from the check and needs a file which is not yet committed.