Re: [RFC PATCH v2.1] x86/sev-es: Handle NMI State

[Dave Hansen]

On 3/20/20 6:17 AM, Joerg Roedel wrote:
> On Thu, Mar 19, 2020 at 08:35:59AM -0700, Andy Lutomirski wrote:
>> 1. Just put the NMI unmask in do_nmi().  The kernel *already* knows
>> how to handle running do_nmi() with NMIs unmasked.  This is much, much
>> simpler than your code.
> Okay, attached is the updated patch which implements this approach. I
> tested it in an SEV-ES guest with 'perf top' running for a little more
> than 30 minutes and all looked good. I also removed the dead code from
> the patch.

FWIW, perf plus the x86 selftests run in a big loop was my best way of
stressing the NMI path when we mucked with it for PTI.  The selftests
make sure to hit some of the more rare entry/exit paths.