Re: [PATCH v2] hw/arm/virt: Fix gic-version=max when CONFIG_ARM_GIC_TCG is unset

[Peter Maydell]

On Fri, 4 Mar 2022 at 17:46, Eric Auger <eric.auger@redhat.com> wrote:
>
> In TCG mode, if gic-version=max we always select GICv3 even if
> CONFIG_ARM_GIC_TCG is unset. We shall rather select GICv2.
> This also brings the benefit of fixing qos tests errors for tests
> using gic-version=max with CONFIG_ARM_GIC_TCG unset.
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> Reviewed-by: Andrew Jones <drjones@redhat.com>
> Fixes: a8a5546798c3 ("hw/intc/arm_gicv3: Introduce CONFIG_ARM_GIC_TCG Kconfig 
> selector")
>
> ---
>
> v1 -> v2:
> - added Drew's R-b
> - dropped PATCH 2/2 for the time being (requires more discussions)
> ---
>  hw/arm/virt.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index 46bf7ceddf..f29779c951 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -1852,7 +1852,11 @@ static void finalize_gic_version(VirtMachineState *vms)
>          vms->gic_version = VIRT_GIC_VERSION_2;
>          break;
>      case VIRT_GIC_VERSION_MAX:
> +#ifdef CONFIG_ARM_GIC_TCG
>          vms->gic_version = VIRT_GIC_VERSION_3;
> +#else
> +        vms->gic_version = VIRT_GIC_VERSION_2;
> +#endif
>          break;
>      case VIRT_GIC_VERSION_HOST:
>          error_report("gic-version=host requires KVM");

This doesn't look right, because the correct condition for
"should 'max' be 2 or 3" is "do we have a GICv2 or a GICv3
compiled in", which is nothing to do with "is the GIC a TCG
GIC or the KVM GIC". Indeed at this point in the code we
know we're dealing with TCG, so the right response to
"we don't have a TCG GIC" is "give up entirely".

I think fundamentally CONFIG_ARM_GIC_TCG is either misnamed
or selecting the wrong files to compile.

thanks
-- PMM