Re: [RFC v2-fix 1/1] x86/traps: Add #VE support for TDX guest

[Dan Williams]

On Tue, May 18, 2021 at 8:45 AM Andi Kleen <ak@xxxxxxxxxxxxxxx> wrote:
>
>
> On 5/18/2021 8:11 AM, Dave Hansen wrote:
> > On 5/17/21 5:09 PM, Kuppuswamy Sathyanarayanan wrote:
> >> After TDGETVEINFO #VE could happen in theory (e.g. through an NMI),
> >> although we don't expect it to happen because we don't expect NMIs to
> >> trigger #VEs. Another case where they could happen is if the #VE
> >> exception panics, but in this case there are no guarantees on anything
> >> anyways.
> > This implies: "we do not expect any NMI to do MMIO".  Is that true?  Why?
>
> Only drivers that are not supported in TDX anyways could do it (mainly
> watchdog drivers)

What about apei_{read,write}() for ACPI error handling? Those are
called in NMI to do MMIO accesses. It's not just watchdog drivers.