Hi Joerg, On 14/11/2016 16:31, Joerg Roedel wrote: > Hi Eric, > > On Fri, Nov 11, 2016 at 05:45:19PM +0100, Auger Eric wrote: >> On 11/11/2016 17:22, Joerg Roedel wrote: >>> So I think we need a way to tell userspace about the reserved regions >>> (per iommu-group) so that userspace knows where it can not map anything, > >> Current plan is to expose that info through an iommu-group sysfs >> attribute, as you and Robin advised. > > Great. > >>> and VFIO can enforce that. But the right struct here is not an >>> iova-allocator rb-tree, a ordered linked list should be sufficient. >> I plan a linked list to store the reserved regions (P2P regions, MSI >> region, ...). get_dma_regions is called with a list local to a function >> for that. Might be needed to move that list head in the iommu_group to >> avoid calling the get_dm_regions again in the attribute show function? > > You can re-use the get_dm_regions() call-back available in the iommu-ops > already. Just rename it and add a flag to it which tells the iommu-core > whether that region needs to be mapped or not. > >> But to allocate the IOVAs within the MSI reserved region, I understand >> you don't want us to use the iova.c allocator, is that correct? We need >> an allocator though, even a very basic one based on bitmap or whatever. >> There potentially have several different physical MSI frame pages to map. > > I don't get this, what do you need and address-allocator for? There are potentially several MSI doorbell physical pages in the SOC that are accessed through the IOMMU (translated). Each of those must have a corresponding IOVA and IOVA/PA mapping programmed in the IOMMU. Else MSI will fault. - step 1 was to define a usable IOVA range for MSI mapping. So now we decided the base address and size would be hardcoded for ARM. The get_dm_region can be used to retrieve that hardcoded region. - Step2 is to allocate IOVAs within that range and map then for each of those MSI doorbells. This is done in the MSI controller compose() callback. I hope I succeeded in clarifying this time. Robin sent today a new version of its cookie think using a dummy allocator. I am currently integrating it. 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
