Re: [PATCH v3 08/40] KVM: arm64: gic-v5: Add VPE doorbell domain

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Missing NULL check for fwnode allocation allows unintended fallback to nameless domains.
--

commit 6a3e1b90ffc14235d7c9484abe0167a310e9d6ca
Author: Sascha Bischoff <Sascha.Bischoff@arm.com>

KVM: arm64: gic-v5: Add VPE doorbell domain

This commit adds support for a per-VM VPE doorbell irq domain to handle
GICv5 hardware notifications for non-resident VPEs. It allocates a doorbell
per VPE under the GICv5 LPI domain and stores the base in the VM's GICv5
state. The per-VPE doorbell state is also added to the CPU interface state.

> diff --git a/arch/arm64/kvm/vgic/vgic-v5.c b/arch/arm64/kvm/vgic/vgic-v5.c
> index 3f7b132110114..1baec8e97ac28 100644
> --- a/arch/arm64/kvm/vgic/vgic-v5.c
> +++ b/arch/arm64/kvm/vgic/vgic-v5.c

[ ... ]

> @@ -152,6 +153,132 @@ int vgic_v5_probe(const struct gic_kvm_info *info)
>  	return 0;
>  }

[ ... ]

> +static int vgic_v5_create_per_vm_domain(struct kvm *kvm)
> +{
> +	struct vgic_v5_vm *vm = &kvm->arch.vgic.gicv5_vm;
> +	int nr_vcpus = atomic_read(&kvm->online_vcpus);
> +	int id = task_pid_nr(current);
> +	int ret, db_virq = 0;
> +
> +	if (!gicv5_global_data.lpi_domain) {
> +		kvm_err("LPI domain uninitialized, can't set up KVM Doorbells\n");
> +		return -ENODEV;
> +	}
> +
> +	vm->fwnode = irq_domain_alloc_named_id_fwnode("GICv5-vpe-db", id);

[Severity: Medium]
Is it possible for irq_domain_alloc_named_id_fwnode() to fail and return NULL
here under memory pressure?

If it does, passing a NULL fwnode into irq_domain_create_hierarchy() below
will cause it to silently fall back to a nameless domain, degrading the
diagnostic state. Should there be a check here to return -ENOMEM if
vm->fwnode fails to allocate?

> +
> +	/*
> +	 * KVM per-VM VPE DB domain; child of LPI domain; only ever handles
> +	 * doorbells. We know how many doorbells we have, and therefore we
> +	 * create a linear domain.
> +	 */
> +	vm->domain = irq_domain_create_hierarchy(gicv5_global_data.lpi_domain,
> +						 0, nr_vcpus, vm->fwnode,
> +						 &vgic_v5_irq_db_domain_ops, vm);

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260703154811.3355680-1-sascha.bischoff@arm.com?part=8