Re: [PATCH v6 14/23] xen/riscv: introduce minimal virtual APLIC (vAPLIC) infrastructure

[Jan Beulich <jbeulich@xxxxxxxx>]

On 20.07.2026 17:59, Oleksii Kurochko wrote:
> At the current development stage, only domain vINTC init and deinit
> operations are required, so implement those first.
> 
> Initialize vAPLIC's domaincfg to with the interrupt-enable bit set and
> MSI delivery mode selected as the current solution is exepcted to have
> always IMSIC, and initialize vintc->ops.
> 
> Other operations such as emulate_load(), emulate_store(), and is_access()
> will be needed once guests are running and MMIO accesses to APLIC MMIO
> range must be handled. These will be introduced separately later.
> 
> Introduce a structure to describe a virtual interrupt controller (vINTC)
> and a vintc_ops structure, which provides operations to emulate load and
> store accesses to interrupt controller MMIOs and to check whether a given
> address falls within the MMIO range of a specific virtual interrupt
> controller.
> Note that already existed init_ops field in struct vintc will be init-ed
> for APLIC in the follow up patch.
> 
> The vAPLIC implementation of these operations will be provided later
> once guests can be run and these operations are actually needed.
> 
> Introduce these structures here as they are required for the implementation
> of domain_vaplic_init() and domain_vaplic_alloc(). Also, introduce
> vaplic_init() and init vintc_ops->vcpu_init() with it.
> 
> Co-developed-by: Romain Caritey <Romain.Caritey@xxxxxxxxxxxxx>
> Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>

Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
albeit I (continue to) think that ...

> --- a/xen/arch/riscv/include/asm/intc.h
> +++ b/xen/arch/riscv/include/asm/intc.h
> @@ -17,6 +17,7 @@ enum intc_variant {
>  struct cpu_user_regs;
>  struct irq_desc;
>  struct kernel_info;
> +struct vcpu;
>  
>  struct intc_info {
>      enum intc_variant hw_variant;
> @@ -53,8 +54,19 @@ struct vintc_init_ops {
>      int (*make_domu_dt_node)(struct kernel_info *kinfo);
>  };
>  
> +struct vintc_ops {
> +    /* Initialize some vINTC-related stuff for a vCPU */
> +    int (*vcpu_init)(struct vcpu *v);
> +
> +    /* Deinitialize some vINTC-related stuff for a vCPU */
> +    void (*vcpu_deinit)(struct vcpu *v);
> +};
> +
>  struct vintc {
> +    /* Used during domain build only; dropped afterwards. */
>      const struct vintc_init_ops *init_ops;

... "dropped" in the comment is misleading - there's nothing being dropped
here, as that's technically impossible. Iirc you don't even poison the
field once domain build is finished.

Jan