Re: [PATCH 00/10] Introduce Virtual IRQ (VIRQ) framework

On Fri, May 15, 2026 at 4:28 AM Raymond Mao <[email protected]> wrote:
>
> From: Raymond Mao <[email protected]>
>
> This series introduces a Virtual IRQ (VIRQ) framework for OpenSBI to
> support domain-aware wired interrupt couriering.
>
> The main use case is to let OpenSBI receive a host HWIRQ in M-mode,
> map it into a per-channel VIRQ number space, route it to a target
> domain, notify the target S-mode payload, and let that payload
> pop/complete the pending VIRQ through an SBI ecall interface.
>
> The implementation is organized as follows:
>
>   - add irqchip helpers for S-mode pending notification
>   - extend domain context switching to support VIRQ-driven
>     cross-domain couriering and return-to-previous-domain flow
>   - add the core VIRQ mapping, routing, and per-(domain,hart)
>     pending queue framework
>   - add a VIRQ vendor ecall extension for POP and COMPLETE
>   - parse sysirq routing rules from DT under /chosen/opensbi-domains
>   - derive APLIC target hart routing from sysirq nodes
>   - update the irqchip/APLIC path to support deferred completion and
>     per-HWIRQ APLIC targets
>   - document the DT binding and routing rules
>
> The DT routing model is based on "opensbi,mpxy-sysirq" nodes.
> Each interrupts-extended entry contributes one routed physical source,
> its entry index becomes the VIRQ number within the selected
> opensbi,mpxy-channel-id, and opensbi,domain selects the destination
> OpenSBI domain.
>
> This series depends on a previous patch set:
> [PATCH v2 1/3] lib: utils: irqchip: implement APLIC hwirq operation hooks
> https://lore.kernel.org/opensbi/[email protected]/#t
>
> Raymond Mao (10):
>   lib: irqchip: add S-mode notification helpers
>   lib: sbi: domain: adaptation for supporting VIRQ couriering domain
>     context switch
>   lib: sbi: Add Virtual IRQ (VIRQ) subsystem
>   lib: sbi: Add VIRQ ecall extension
>   lib: sbi: domain: add domain lookup by name
>   lib: utils: fdt: parse sysirq routing from DT
>   lib: utils: irqchip: derive APLIC targets from sysirq nodes
>   lib: irqchip: support deferred completion and per-HWIRQ APLIC targets
>   lib: sbi: domain: ensure boot_hartid is assigned
>   docs: domain: document sysirq VIRQ mapping and routing rules

This VIRQ abstraction is not needed with the improved SBI irqchip
where each external interrupt (wired / MSI) can be uniquely identified
by a tuple which SBI irqchip instance and hwirq number in the instance.

Also, the VIRQ ecall is ad-hoc and does not correspond to any
SBI extension.

All-in-all the whole interrupt routing for supervisor domains must
be re-written using SBI MPXY + RPMI system irq service group
as the interface for supervisor domains.

The SBI MPXY is already a ratified SBI extension and OpenSBI
already has an extensible MPXY framework with a number of MPXY
drivers under lib/utils/mpxy. The RPMI system irq draft specifcation
was already shared few months back.

Regards,
Anup

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