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

From: Peter Maydell
Subject: Re: [RFC] virt/acpi: set PSCI flag even when psci_conduit is disabled
Date: Fri, 3 Jul 2020 15:41:05 +0100

On Fri, 3 Jul 2020 at 15:36, Heyi Guo <guoheyi@linux.alibaba.com> wrote:
> 在 2020/7/3 下午6:37, Peter Maydell 写道:
> > 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, Peter. Does that mean the ACPI tables generated in qemu are only
> templates and firmware should update them if necessary?

I don't really know enough about ACPI to say. I hadn't noticed
that this patch only updated the ACPI tables, sorry. Perhaps it
is correct; Andrew will probably know better than me.

-- PMM

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