Commit "fd3c136 vga: make sure vga register setup for vbe stays intact
(CVE-2016-3712)." causes a regression. The win7 installer is unhappy
because it can't freely modify vga registers any more while in vbe mode.
This patch introduces a new sr_vbe register set. The vbe_update_vgaregs
will fill sr_vbe[] instead of sr[]. Normal vga register reads and
writes go to sr[]. Any sr register read access happens through a new
sr() helper function which will read from sr_vbe[] with vbe active and
from sr[] otherwise.
This way we can allow guests update sr[] registers as they want, without
allowing them disrupt vbe video modes that way.
Cc: qemu-stable@nongnu.org
Reported-by: Thomas Lamprecht <thomas@lamprecht.org>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 1463475294-14119-1-git-send-email-kraxel@redhat.com
94ef4f337f