You can test, if you are affected, by running cat /proc/mtrr on the command line. If you can’t see a line, which ends in write-combining you are most certainly affected by this. You can further check with lspci -vv and check the Region 0 memory range of your VGA adaptor. If you cant find that memory range in your mtrr file, you are probably affected.

Until the fix is released, one solution is to run this shell script as root after every restart of your X.org server. Warning: Audit any external file before you run it as root on your computer! The script should update the MTRR configuration of the Kernel with the correct settings. If you are affected by the bug, you will notice a slight improvement in overall graphics performance and the full-screen Flash videos should now play as originally intended.