Hi Joerg, On 10/11/2016 17:13, Joerg Roedel wrote: > On Thu, Nov 10, 2016 at 04:57:51PM +0100, Auger Eric wrote: >> It does not only serve the purpose to register the MSI IOVA region. We >> also need to allocate an iova_domain where MSI IOVAs will be allocated >> upon the request of the relevant MSI controllers. Do you mean you don't >> like to use the iova allocator for this purpose? > > Yes, it looks like the only purpose of iommu_get_dma_msi_region_cookie() > is to get the msi-region information into into the reserved-list. > > Why do you need to 'allocate' the MSI region after all? Except for > IOMMU_DOMAIN_DMA domains the iommu-core code does not care about address > allocation. This is up to the users of the domain, which includes that > the user has to take care of the MSI region. The purpose is to reuse the transparent MSI IOVA allocation scheme introduced by Robin in [PATCH v7 00/22] Generic DT bindings for PCI IOMMUs and ARM SMMU (commit 44bb7e243bd4b4e5c79de2452cd9762582f58925). GICv2m and GICV3 ITS use dma-mapping iommu_dma_map_msi_msg to allocate an MSI IOVA on-demand. This relies on the existence of an allocated iova_domain whose handle is stored in domain->iova_cookie. the iommu_dma_init_domain could be done in VFIO instead of in the IOMMU-code, on the basis of dm region info. But we would need to differentiate the MSI window from P2P windows. msi-region start/length are arbitrarily chosen and the setup of the reserved region list does not depend on iommu_get_dma_msi_region_cookie; but maybe I completely misunderstand your question. > Besides that, 'iommu_get_dma_msi_region_cookie' is a terrible function > name and does not describe at all what the function does or is supposed > to do. Yes this was discussed with Alex& Robin already (https://patchwork.kernel.org/patch/9363989/). I proposed to rename into iommu_setup_dma_msi_region but this was not validated. Thanks Eric > > > Joerg > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
