Re: [PATCH v4 03/48] irqchip/gic-v5: Set up gic_kvm_info on ACPI hosts

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Failed ACPI GSI registration for maintenance IRQ due to missing GICv5 hardware IRQ type encoding.
--

--- Patch [3]: [PATCH v4 03/48] irqchip/gic-v5: Set up gic_kvm_info on ACPI hosts ---
commit 6d138977b1bc438c493851b44358f453400237da
Author: Sascha Bischoff <Sascha.Bischoff@arm.com>

irqchip/gic-v5: Set up gic_kvm_info on ACPI hosts

This commit adds ACPI support for setting up KVM host information on GICv5
systems. It parses MADT GICC entries to retrieve the maintenance interrupt and
registers it as a GSI to be passed to KVM.

> diff --git a/drivers/irqchip/irq-gic-v5.c b/drivers/irqchip/irq-gic-v5.c
> --- a/drivers/irqchip/irq-gic-v5.c
> +++ b/drivers/irqchip/irq-gic-v5.c
[ ... ]
> @@ -1162,11 +1164,100 @@ static void __init gic_of_setup_kvm_info(struct device_node *node)
[ ... ]
> +static void __init gic_acpi_setup_kvm_info(void)
> +{
> +	unsigned int maint_irq = 0;
> +	int irq;
> +
> +	if (!gic_acpi_collect_virt_info()) {
> +		pr_warn("Unable to get hardware information used for virtualization\n");
> +		return;
> +	}
> +
> +	if (acpi_v5_kvm_info.maint_irq) {
> +		irq = acpi_register_gsi(NULL, acpi_v5_kvm_info.maint_irq,
> +					acpi_v5_kvm_info.maint_irq_mode,
> +					ACPI_ACTIVE_HIGH);

[Severity: High]
Does this fail to register the maintenance IRQ?

acpi_register_gsi() passes the raw maint_irq directly into fwspec.param[0].
However, the GICv5 PPI domain select function expects the hardware IRQ type to
be encoded in the upper bits:

drivers/irqchip/irq-gic-v5.c:gicv5_irq_ppi_domain_select() {
    ...
    if (is_fwnode_irqchip(fwspec->fwnode))
        hwirq_type = FIELD_GET(GICV5_HWIRQ_TYPE, fwspec->param[0]);

    if (hwirq_type != GICV5_HWIRQ_TYPE_PPI)
        return 0;
    ...
}

Because the raw MADT value doesn't have the GICV5_HWIRQ_TYPE_PPI bits set, the
mapping will be rejected. Should the GSI be encoded with the PPI type before
calling acpi_register_gsi()?

> +		if (irq > 0)
> +			maint_irq = irq;
> +		else
> +			pr_warn("Failed to register GSI for GICv5 maintenance IRQ\n");
> +	}
> +
> +	gic_setup_kvm_info(maint_irq);
>  }

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260724104819.1296803-1-sascha.bischoff@arm.com?part=3