Regression: QEMU 2.4 on Linux 4.2 fails to init display with SMM enabled

[Alex]

QEMU version: 2.4, also tested b37686f (2015-10-09 12:18:13 +0100) not working. Requires KVM and SDL, possibly others.
Kernel version: 4.1 working, 4.2 not working.
Architecture: x86_64
Target: x86_64, also tested i386 not working.

Step 0: Install versions listed above.
Step 1: Run "qemu-system-$TARGET -enable-kvm"
Step 2: Run "qemu-system-$TARGET -enable-kvm -nodefaults -vga std -machine pc-i440fx-2.3"
Step 3: Run "qemu-system-$TARGET -enable-kvm -nodefaults -vga std -machine pc-i440fx-2.4"
Step 4: Run "qemu-system-$TARGET -enable-kvm -nodefaults -vga std -machine pc-i440fx-2.3,smm=on"
Step 5: Run "qemu-system-$TARGET -enable-kvm -nodefaults -vga std -machine pc-i440fx-2.4,smm=off"
Step 6: Run "qemu-system-$TARGET -enable-kvm -nodefaults -vga std -machine pc-q35-2.3"
Step 7: Run "qemu-system-$TARGET -enable-kvm -nodefaults -vga std -machine pc-q35-2.4"
Step 8: Run "qemu-system-$TARGET -enable-kvm -nodefaults -vga std -machine pc-q35-2.3,smm=on"
Step 9: Run "qemu-system-$TARGET -enable-kvm -nodefaults -vga std -machine pc-q35-2.4,smm=off"

Expected behavior: All 8 invocations result in an rectangular SDL window showing a framebuffer showing failure to locate a boot device.

Actual behavior: Invocations corresponding to steps 2, 4, 5, 6, 8, and 9 (i.e. those using 2.4 and *not* smm=off) behave as expected, however those in steps 1, 3, and 7 result in a square black SDL window with no text. Note that step 1 is more or less the "default configuration" for QEMU with KVM.

[Alex (hello71)]

fixed in linux