Re: [PATCH v1 09/17] xen/riscv: add helper to check APLIC MSI mode

On 20.07.2026 18:02, Oleksii Kurochko wrote:
> This helper can be used outside aplic.c to determine whether MSI mode
> is enabled. A follow-up patch uses it to decide whether the guest
> IMSIC state should be saved/restored.

How would this work, when ...

> --- a/xen/arch/riscv/aplic.c
> +++ b/xen/arch/riscv/aplic.c
> @@ -93,6 +93,11 @@ void aplic_hw_write_reg(unsigned int offset, uint32_t value)
>      spin_unlock_irqrestore(&aplic.lock, flags);
>  }
>  
> +bool has_msi_support(void)
> +{
> +    return readl(&aplic.regs->domaincfg) & APLIC_DOMAINCFG_DM;

... you read a global here? To know what state a guest's vAPLIC is in, you'd
need to read its (virtual) register, wouldn't you?

> +}

I think the name is overly ambiguous, the more that there's also no parameter
the type of which would help disambiguation. Judging from title and description,
maybe aplic_msi_mode_enabled() or simpler aplic_msi_mode() could be more to the
point. (Note that neither "has" nor "available" would really express things
correctly, as the DM field can [aiui] in principle be changed.)

Jan