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

[Alexander Graf]

On 15.06.21 13:02, Peter Maydell wrote:
> 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.


Let's move the conversation to 19/19 then. My take on this is that TCG
is misinterpreting the SMCCC spec.


Alex