On 2014-06-27 07:46, Le Tan wrote: > 2014-06-27 12:55 GMT+08:00 Paolo Bonzini <pbonz...@redhat.com>: >> Il 27/06/2014 04:08, Le Tan ha scritto: >> >>> 1. In struct IOMMUTLBEntry, I think the addr_mask field should be the >>> mask of the page offset, right? But I see different usages of this >>> field. In spapr_tce_translate_iommu(), the addr_mask field is assigned >>> with the mask of the page offset. However, in pbm_translate_iommu(), >>> in the passthrough case, the addr_mask field seems to be assigned the >>> mask of the page number. Is there any problem here? >> >> >> The intended usage is the one of spapr_tce_translate_iommu(). In practice >> it doesn't matter, both work. >> >> >>> 2. For q35, how to identify origination of DMA requests? The VT-d >>> manual says we should use source-id(for PCI-Express devices, it is >>> requester identifier) to map devices to domains. What is the related >>> part in QEMU? Where can I get the source-id of a DMA request? >> >> >> You need to create a different AddressSpace for each PCI bus or device. > > How to create a different AddressSpace for each device? I thought a > AddressSpace just belongs to a PCI bus before. The paging structures > for different functions of the same device can also be different, too. > So maybe we should create a different AddressSpace for each function? > How to achieve it? Could you give me some more hints or is there any > existing example in QEMU?
I would suggest to study the apb IOMMU implementation Paolo referenced and the PCI layer functions used by that code. Specifically, pci_setup_iommu takes a callback that is supposed to return an address space to be used for a particular device. For apb, it's the same for all devices on a bus, but that's not required... Jan
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