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SubjectRe: [PATCH 62/62] x86/sev-es: Add NMI state tracking
On Tue, Feb 11, 2020 at 02:50:29PM -0800, Andy Lutomirski wrote:
> On Tue, Feb 11, 2020 at 5:53 AM Joerg Roedel <joro@8bytes.org> wrote:
> This patch is overcomplicated IMO. Just do the magic incantation in C
> from do_nmi or from here:
>
> /*
> * For ease of testing, unmask NMIs right away. Disabled by
> * default because IRET is very expensive.
>
> If you do the latter, you'll need to handle the case where the NMI
> came from user mode.
>
> The ideal solution is do_nmi, I think.
>
> if (static_cpu_has(X86_BUG_AMD_FORGOT_ABOUT_NMI))
> sev_es_unmask_nmi();
>
> Feel free to use X86_FEATURE_SEV_ES instead :)

Yeah, I also had that implemented once, but then changed it because I
thought that nested NMIs do not necessarily call into do_nmi(), which
would cause NMIs to stay blocked forever. I need to read through the NMI
entry code again to check if that can really happen.

Regards,

Joerg

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