Re: [PATCH v8 18/19] arm: Enable Windows 10 trusted SMCCC boot call

[Peter Maydell]

On Wed, 19 May 2021 at 21:23, Alexander Graf <agraf@csgraf.de> wrote:
>
> Windows 10 calls an SMCCC call via SMC unconditionally on boot. It lives
> in the trusted application call number space, but its purpose is unknown.
>
> In our current SMC implementation, we inject a UDEF for unknown SMC calls,
> including this one. However, Windows breaks on boot when we do this. Instead,
> let's return an error code.
>
> With this and -M virt,virtualization=on I can successfully boot the current
> Windows 10 Insider Preview in TCG.


Same comments apply here and for patch 19.

Either we can:
 * find a spec for whatever this SMC ABI is and implement it
   consistently across TCG, KVM and HVF
 * find whether we're misimplementing whatever the SMCCC spec says
   should happen for unknown SMC calls, and fix that bug

But we're not adding random hacky workarounds for specific guest OSes.

-- PMM