Re: [PATCH v12 13/23] hw/intc/arm_gicv3: Add has-nmi property to GICv3 device

[Peter Maydell]

On Wed, 3 Apr 2024 at 11:18, Jinjie Ruan <ruanjinjie@huawei.com> wrote:
>
> Add a property has-nmi to the GICv3 device, and use this to set
> the NMI bit in the GICD_TYPER register. This isn't visible to
> guests yet because the property defaults to false and we won't
> set it in the board code until we've landed all of the changes
> needed to implement FEAT_GICV3_NMI.
>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>


> diff --git a/hw/intc/arm_gicv3_common.c b/hw/intc/arm_gicv3_common.c
> index c52f060026..2d2cea6858 100644
> --- a/hw/intc/arm_gicv3_common.c
> +++ b/hw/intc/arm_gicv3_common.c
> @@ -569,6 +569,7 @@ static Property arm_gicv3_common_properties[] = {
>      DEFINE_PROP_UINT32("num-irq", GICv3State, num_irq, 32),
>      DEFINE_PROP_UINT32("revision", GICv3State, revision, 3),
>      DEFINE_PROP_BOOL("has-lpi", GICv3State, lpi_enable, 0),
> +    DEFINE_PROP_BOOL("has-nmi", GICv3State, nmi_support, 0),
>      DEFINE_PROP_BOOL("has-security-extensions", GICv3State, security_extn, 
> 0),
>      /*
>       * Compatibility property: force 8 bits of physical priority, even

I was thinking about how we'll (eventually) want to handle NMI
for non-TCG cases (KVM, hvf), and I realised there's a missing
piece here: we want to make it an error to try to set has-nmi=true
for the KVM GICv3, because it doesn't support NMIs yet.

So in hw/intc/arm_gicv3_kvm.c:kvm_arm_gicv3_realize(), we want
to add a check similar to the existing "fail if s->revision != 3"
and "fail if s->security_extn" that does

    if (s->nmi_support) {
        error_setg(errp, "NMI is not supported with the in-kernel GIC");
        return;
    }

(There are some work-in-progress kernel patches for NMI support
in the in-kernel GIC, but nothing has landed yet. When it does
we'll then be able to add the support in the QEMU code.)

thanks
-- PMM