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It doesn't >> clear everything. > > ?? It starts out with a 0 DTE table? There is no inherited DTE table > except for kdump. > >> May be we should just remove ignore_device() completely? as >> - normal boot, its not yet configured, so no DMA is allowed >> - kdump boot, old DTE is still valid and let it continue? > > Yes, that makes alot more sense to me. Ack. @Pranjal, Can you fixup and send v4? > > But this comment is also wrong: Yeah. One of the cleanup patch missed to update below comment. > > /* > * Order is important here to make sure any unity map requirements are > * fulfilled. The unity mappings are created and written to the device > * table during the iommu_init_pci() call. > * > * After that we call init_device_table_dma() to make sure any > * uninitialized DTE will block DMA, and in the end we flush the caches > * of all IOMMUs to make sure the changes to the device table are > * active. > */ > for_each_pci_segment(pci_seg) > init_device_table_dma(pci_seg); > > The DTE starts out with blocking because it starts out as 0. This > isn't making the DTE blocking, it is doing something else. And it is > very suspicious and racey looking to me. IIRC there were some requirement to keep V bit ON. Otherwise I don't see why we should set and flush the dte here. Let me dig the details. -Vasant