Re: [PATCH v6 10/16] irqchip/riscv-imsic: Add MSI address list

["Nutty.Liu" <nutty.liu@hotmail.com>]

On 9/25/2026 11:16 PM, Andrew Jones wrote:
> Upcoming RISC-V IOMMU interrupt remapping needs to map every possible
> host IMSIC target into one contiguous MSI IOVA range. MSI message
> composition then uses the target CPU's position within that range.
>
> Build an IMSIC physical address array indexed by logical CPU.
> Require every possible CPU to have an initialized IMSIC page before
> publishing the array. This preserves physical address zero as a valid
> target and guarantees the array has num_possible_cpus() entries.
>
> The array size and each target's index can therefore be derived
> directly, without storing duplicate count or per-CPU index metadata.
>
> Signed-off-by: Andrew Jones <andrew.jones@oss.qualcomm.com>
> Tested-by: Fangyu Yu <fangyu.yu@linux.alibaba.com>
Reviewed-by: Nutty Liu <nutty.liu@hotmail.com>

Thanks,
Nutty
> ---
>   drivers/irqchip/irq-riscv-imsic-state.c | 32 +++++++++++++++++++++++++
>   drivers/irqchip/irq-riscv-imsic-state.h |  3 +++
>   2 files changed, 35 insertions(+)
>
> diff --git a/drivers/irqchip/irq-riscv-imsic-state.c b/drivers/irqchip/irq-riscv-imsic-state.c
> index df38a7670a89..abd1cdb640ea 100644
> --- a/drivers/irqchip/irq-riscv-imsic-state.c
> +++ b/drivers/irqchip/irq-riscv-imsic-state.c
> @@ -709,6 +709,31 @@ static int __init imsic_get_mmio_resource(struct fwnode_handle *fwnode,
>   	return of_address_to_resource(to_of_node(fwnode), index, res);
>   }
>   
> +static int __init imsic_init_msi_pa_list(void)
> +{
> +	struct imsic_global_config *global = &imsic->global;
> +	phys_addr_t *msi_pa_list;
> +	unsigned int cpu;
> +
> +	msi_pa_list = kcalloc(num_possible_cpus(), sizeof(*msi_pa_list), GFP_KERNEL);
> +	if (!msi_pa_list)
> +		return -ENOMEM;
> +
> +	for_each_possible_cpu(cpu) {
> +		struct imsic_local_config *local = per_cpu_ptr(global->local, cpu);
> +
> +		if (!local->msi_va) {
> +			kfree(msi_pa_list);
> +			return -ENODEV;
> +		}
> +
> +		msi_pa_list[cpu] = local->msi_pa;
> +	}
> +
> +	imsic->msi_pa_list = msi_pa_list;
> +	return 0;
> +}
> +
>   static int __init imsic_parse_fwnode(struct fwnode_handle *fwnode,
>   				     struct imsic_global_config *global,
>   				     u32 *nr_parent_irqs,
> @@ -959,6 +984,12 @@ int __init imsic_setup_state(struct fwnode_handle *fwnode, void *opaque)
>   		goto out_local_cleanup;
>   	}
>   
> +	rc = imsic_init_msi_pa_list();
> +	if (rc) {
> +		pr_err("%pfwP: failed to initialize MSI address list\n", fwnode);
> +		goto out_local_cleanup;
> +	}
> +
>   	/* Initialize matrix allocator */
>   	rc = imsic_matrix_init();
>   	if (rc) {
> @@ -984,6 +1015,7 @@ int __init imsic_setup_state(struct fwnode_handle *fwnode, void *opaque)
>   out_free_local:
>   	free_percpu(imsic->global.local);
>   out_free_priv:
> +	kfree(imsic->msi_pa_list);
>   	kfree(imsic);
>   	imsic = NULL;
>   	return rc;
> diff --git a/drivers/irqchip/irq-riscv-imsic-state.h b/drivers/irqchip/irq-riscv-imsic-state.h
> index c42ee180b305..e51c61dcced3 100644
> --- a/drivers/irqchip/irq-riscv-imsic-state.h
> +++ b/drivers/irqchip/irq-riscv-imsic-state.h
> @@ -50,6 +50,9 @@ struct imsic_priv {
>   	/* Global configuration common for all HARTs */
>   	struct imsic_global_config		global;
>   
> +	/* MSI target physical addresses indexed by logical CPU for IOMMU mapping */
> +	phys_addr_t				*msi_pa_list;
> +
>   	/* Per-CPU state */
>   	struct imsic_local_priv __percpu	*lpriv;
>