Re: [PATCH] x86 efi: bugfix interrupt disabling sequence

[Matt Fleming <matt-HNK1S37rvNbeXh+fF434Mdi2O/JbrIOy@public.gmane.org>]

On Mon, 23 Sep, at 11:45:28AM, Bart Kuivenhoven wrote:
> The problem in efi_main was that the idt was cleared before the
> interrupts were disabled.
> 
> The UEFI spec states that interrupts aren't used so this shouldn't be
> too much of a problem. Peripherals however don't necessarily know about
> this and thus might cause interrupts to happen anyway. Even if
> ExitBootServices() has been called.
> 
> This means there is a risk of an interrupt being triggered while the IDT
> register is nullified and the interrupt bit hasn't been cleared,
> allowing for a triple fault.
> 
> This patch disables the interrupt flag, while leaving the existing IDT
> in place. The CPU won't care about the IDT at all as long as the
> interrupt bit is off, so it's safe to leave it in place as nothing will
> ever happen to it.
> 
> Signed-off-by: Bart Kuivenhoven <bemk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> ---
>  arch/x86/boot/compressed/eboot.c | 15 +--------------
>  1 file changed, 1 insertion(+), 14 deletions(-)

Applied, thanks Bart!

-- 
Matt Fleming, Intel Open Source Technology Center