Re: [RFC] virt/acpi: set PSCI flag even when psci_conduit is disabled

[Michael S. Tsirkin]

On Fri, Jul 03, 2020 at 11:37:02AM +0100, Peter Maydell wrote:
> On Fri, 3 Jul 2020 at 10:44, Heyi Guo <guoheyi@linux.alibaba.com> wrote:
> >
> > vms->psci_conduit being disabled only means PSCI is not implemented by
> > qemu; it doesn't mean PSCI is not supported on this virtual machine.
> > Actually vms->psci_conduit is set to disabled when vms->secure and
> > firmware_loaded are both set, which means we will run ARM trusted
> > firmware, which will definitely provide PSCI.
> >
> > The issue can be reproduced when running qemu in TCG mode with secure
> > enabled, while using ARM trusted firmware + qemu virt UEFI as firmware
> > binaries, and we can see secondary cores will not be waken up.
> 
> If you're using a real EL3 guest firmware then it's the job of
> the guest firmware to provide a DTB to the guest EL2/EL1 that says
> "and I support PSCI" if it supports PSCI, surely? QEMU can't tell
> whether the EL3 code does or doesn't do that...
> 
> thanks
> -- PMM

I guess this means qemu needs to find this out from firmware?
Perhaps through fwcfg ...
Don't really know about PSCI specifically, just a general
comment from ACPI POV.

-- 
MST