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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? >> > > Ack. I'll remove ignore_device entirely and drop patch 3 for v4. Thanks. > >>> >>> 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. >> > > Should I also update the comment in this series? (It seems less relevant > to the ATS stuff) I'd say lets do that as separate patch. For now lets get this series finalized. -Vasant