On Wed, Feb 19 2025 at 17:31, Nicolin Chen wrote:

From: Jason Gunthorpe <jgg@nvidia.com>

Currently, IRQ_MSI_IOMMU is selected if DMA_IOMMU is available to provide
an implementation for iommu_dma_prepare/compose_msi_msg(). However, it'll
make more sense for irqchips that call prepare/compose to select it, and
that will trigger all the additional code and data to be compiled into
the kernel.

If IRQ_MSI_IOMMU is selected with no IOMMU side implementation, then the
prepare/compose() will be NOP stubs.

If IRQ_MSI_IOMMU is not selected by an irqchip, then the related code on
the iommu side is compiled out.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <redacted>

Reviewed-by: Thomas Gleixner <redacted>

I don't think I have conflicting changes here, so the MSI/IRQ related
changes can be routed through the IOMMU tree along with the rest.

Thanks,

        tglx