Re: [RFC] x86_64: A real proposal for iret-less return to kernel

[Andy Lutomirski]

On May 21, 2014 5:51 AM, "Jiri Kosina" <jkosina@xxxxxxx> wrote:
>
> On Tue, 20 May 2014, Andy Lutomirski wrote:
>
> > So the issue here is that we can have an NMI followed immediately by
> > an MCE.  The MCE code can call force_sig
>
> This is interesting by itself. force_sig() takes siglock spinlock. This
> really looks like a deadlock sitting there waiting to happen.

ISTM the do_machine_check code ought to consider any kill-worthy MCE
from kernel space to be non-recoverable, but I want to keep the scope
of these patches under control.

That being said, if an MCE that came from CPL0 never tried to return,
this would be simpler.  I don't know enough about the machine check
architecture to know whether that's a reasonable thing to do.

--Andy

>
> --
> Jiri Kosina
> SUSE Labs
>
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