These patches aim to prevent the FPU being left enabled across a task context switch due to full kernel preemption. This could result in returning to a KVM guest with FPU enabled. Patch 1 fixes a more theoretical case that I spotted where TIF_USEDFPU is cleared without disabling the FPU in the execve path. Patch 2 fixes a much easier to hit case (multiple WARNs before reaching login prompt if only the WARN part of patch is applied) due to saved Status in interrupt context not being updated when FPU is disabled. In doing so it also allows an orphaned enabled FPU to remain enabled through to user mode, hence the new WARN on context switch to catch future cases of it. James Hogan (2): MIPS: Properly disable FPU in start_thread() MIPS: Fix FPU disable with preemption arch/mips/include/asm/fpu.h | 4 ++++ arch/mips/include/asm/stackframe.h | 4 ++-- arch/mips/kernel/process.c | 6 ++---- 3 files changed, 8 insertions(+), 6 deletions(-) -- 2.4.10
