Messages in this thread | | | Date | Tue, 6 Jul 2021 06:48:48 +0200 | From | Christoph Hellwig <> | Subject | Re: [PATCH v15 06/12] swiotlb: Use is_swiotlb_force_bounce for swiotlb data bouncing |
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On Mon, Jul 05, 2021 at 08:03:52PM +0100, Will Deacon wrote: > So at this point, the AMD IOMMU driver does: > > swiotlb = (iommu_default_passthrough() || sme_me_mask) ? 1 : 0; > > where 'swiotlb' is a global variable indicating whether or not swiotlb > is in use. It's picked up a bit later on by pci_swiotlb_late_init(), which > will call swiotlb_exit() if 'swiotlb' is false. > > Now, that used to work fine, because swiotlb_exit() clears > 'io_tlb_default_mem' to NULL, but now with the restricted DMA changes, I > think that all the devices which have successfully probed beforehand will > have stale pointers to the freed structure in their 'dev->dma_io_tlb_mem' > field.
Yeah. I don't think we can do that anymore, and I also think it is a bad idea to start with.
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