Re: [PATCH 4/7] x86/idle: Disable IBRS entering idle and enable it on wakeup

Thomas Gleixner
2018-01-04T23:46:19Z

On Fri, 5 Jan 2018, Andrea Arcangeli wrote:

> On Thu, Jan 04, 2018 at 03:22:09PM -0800, Tim Chen wrote:
> > No one should be calling this with IRQs enabled. This check is probably
> > just paranoid. I can get rid of it.
>
> Yes, confirmed.
>
> > It probably doesn't matter as we will be switching the check
> > to the spec_ctrl_ibrs a couple of patches later.
>
> The other problem with static_cpu_has is later the code intends to
> support the cpuid rescan post late microcode update which will set
> bits in boot_cpu_data (and transfer them to each cpu_has). If we'd
> only support early microcode update static_cpu_has should have been ok
> too.

What's the problem to make the early update mandatory for this?

Thanks,

tglx