Re: [Xen-devel] [PATCH v2] x86/boot: enable NMIs after traps init

[Jason Andryuk <jandryuk@xxxxxxxxx>]

On Tue, Oct 23, 2018 at 7:15 AM Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
>
> On 23/10/18 11:59, Sergey Dyasli wrote:
> > In certain scenarios, NMIs might be disabled during Xen boot process.
> > Such situation will cause alternative_instructions() to:
> >
> >     panic("Timed out waiting for alternatives self-NMI to hit");
> >
> > This bug was originally seen when using Tboot to boot Xen.
> >
> > To prevent this from happening, enable NMIs during cpu_init() and
> > during __start_xen() for BSP.
> >
> > Signed-off-by: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>
>
> Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

FYI, Ross and Eric came up with a tboot patch recently added to OpenXT:
https://github.com/OpenXT/xenclient-oe/blob/master/recipes-openxt/tboot/tboot-1.9.6/0023-tboot-Unmask-NMI-potentially-masked-during-SENTER.patch

Using this Xen patch with the tboot one reverted works too.

Tested-by: Jason Andryuk <jandryuk@xxxxxxxxx>

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