Re: [RFC PATCH v4 01/16] iommu/arm-smmu-v3: Discover RME support and realm IRQ topology

[Nicolin Chen <nicolinc@nvidia.com>]

On Mon, Apr 27, 2026 at 02:23:29PM +0530, Aneesh Kumar K.V (Arm) wrote:
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-realm.c
> @@ -0,0 +1,124 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2026 ARM Ltd.
> + */
> +
> +#include <linux/interrupt.h>
> +#include <asm/rmi_smc.h>
> +#include <asm/rmi_cmds.h>
> +
> +#include "arm-smmu-v3.h"
> +
> +#define	RMI_PSMMU_IRQ_GERROR	BIT(0)
> +#define	RMI_PSMMU_IRQ_EVENTQ	BIT(1)
> +#define	RMI_PSMMU_IRQ_PRIQ	BIT(2)
> +#define	RMI_PSMMU_IRQ_CMDQ	BIT(3)
[...]
> +	if (irq == smmu->realm_evtq_irq)
> +		notify_flags =  RMI_PSMMU_IRQ_EVENTQ;
> +	else if (irq == smmu->realm_gerr_irq)
> +		notify_flags =  RMI_PSMMU_IRQ_GERROR;
> +	else if (irq == smmu->realm_pri_irq)
> +		notify_flags =  RMI_PSMMU_IRQ_PRIQ;

These are defined as BIT(x)...

> +		if (rmi_psmmu_irq_notify(smmu->base_phys,
> +					 notify_flags, &event)) {
[...]
> +			rmi_psmmu_event_consume(smmu->base_phys, notify_flags);

.. and passed to RMI_PSMMU_IRQ_NOTIFY and RMI_PSMMU_EVENT_CONSUME.

RMI_PSMMU_IRQ_NOTIFY takes RmiPsmmuIrqSet type, which is a 4-bit
field that has a range of [BIT(0), BIT(3)]. So this is correct.

However, RMI_PSMMU_EVENT_CONSUME takes RmiPsmmuIrq type, which is
a 2-bit field that has a range of [0x0, 0x3]. So this seems wrong.

> +void arm_smmu_setup_realm_irqs(struct arm_smmu_device *smmu)
> +{
> +	int irq, ret;
> +
> +	irq = smmu->realm_evtq_irq;
> +	if (irq) {
> +		ret = devm_request_threaded_irq(smmu->dev, irq, NULL,
> +						arm_smmu_realm_notify_thread,
> +						IRQF_ONESHOT,
> +						"arm-smmu-v3-realm-evtq",
> +						smmu);

These IRQ numbers are raw numbers forwarded by firmware and then
returned by RMI_PSMMU_INFO:

+		if ((psmmu_info->flags & RMI_PSMMU_IRQCFG_MASK) ==
+		    RMI_PSMMU_IRQCFG_IRQ_WIRED) {
+			smmu->realm_gerr_irq = psmmu_info->gerror_intr_num;
+			smmu->realm_evtq_irq = psmmu_info->eventq_intr_num;
+			smmu->realm_pri_irq = psmmu_info->priq_intr_num;

Should they be converted to Linux IRQ numbers before forwarded to
devm_request_threaded_irq?

> @@ -782,6 +787,9 @@ struct arm_smmu_device {
>  
>  	int				gerr_irq;
>  	int				combined_irq;
> +	int				realm_gerr_irq;
> +	int				realm_evtq_irq;
> +	int				realm_pri_irq;

Nit: this series adds a few realm-specific things in the top SMMU
structure. Maybe a "struct arm_realm_psmmu" can make them clearer.

Thanks
Nicolin