Re: [PATCH 4/4] x86/cpu: Use SERIALIZE in sync_core() when available

From: peterz
Date: Mon Jul 27 2020 - 04:36:37 EST

On Sun, Jul 26, 2020 at 10:55:15PM -0700, hpa@xxxxxxxxx wrote:
> For a really overenginered solution, but which might perform
> unnecessary poorly on existing hardware:
> asm volatile("1: .byte 0xf, 0x1, 0xe8; 2:"
> _ASM_EXTABLE(1b,2b));

Ha! cute, you take an #UD ?

We could optimize the #UD exception handler for this I suppose, but that
makes it an even worse hack. The simple alternative() seems like a much
simpler approach.