x86/mm: Allow temporary MMs when IRQs are on

x86/mm: Allow temporary MMs when IRQs are on

EFI runtime services should use temporary MMs, but EFI runtime services
want IRQs on.  Preemption must still be disabled in a temporary MM context.

At some point, the entirely temporary MM mechanism should be moved out of
arch code.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250402094540.3586683-6-mingo@kernel.org