Re: [PATCH v4 2/5] x86, traps: Track entry into and exit from IST context

Andy Lutomirski
2015-01-05T21:55:04Z

On Mon, Jan 5, 2015 at 1:46 PM, Tony Luck <tony.luck@gmail.com> wrote:
> On Wed, Dec 10, 2014 at 4:24 PM, Andy Lutomirski <luto@amacapital.net> wrote:
>> I think you need ist_begin_non_atomic() before local_irq_enable() and
>> ist_end_non_atomic() after local_irq_disable(). Otherwise it should
>> be good.
>
> In your x86/paranoid branch you added:
>
> prev_state = ist_enter(regs);
> .... body of do_machine_check() here ...
> ist_exit(regs, prev_state);
>
> Does that override the previous advice? Or do I still need something before
> I call local_irq_enable() and after local_irq_disable()?

I think I was just being vague. It would be:

prev_state = ist_enter(regs);
.... beginning of do_machine_check() here ...

if (whatever condition) {
ist_begin_non_atomic();
local_irq_enable();

...

local_irq_disable();
ist_end_non_atomic();
ist_exit(regs, prev_state);

--Andy

>
> -Tony

--
Andy Lutomirski
AMA Capital Management, LLC