On Tue, Sep 07, 2021 at 02:05:12PM +0200, Jan Beulich wrote: > Generic swiotlb code makes sure to keep the slab count a multiple of the > number of slabs per segment. Yet even without checking whether any such > assumption is made elsewhere, it is easy to see that xen_swiotlb_fixup() > might alter unrelated memory when calling xen_create_contiguous_region() > for the last segment, when that's not a full one - the function acts on > full order-N regions, not individual pages. > > Align the slab count suitably when halving it for a retry. Add a build > time check and a runtime one. Replace the no longer useful local > variable "slabs" by an "order" one calculated just once, outside of the > loop. Re-use "order" for calculating "dma_bits", and change the type of > the latter as well as the one of "i" while touching this anyway. > > Signed-off-by: Jan Beulich <[email protected]>
Looks good, Reviewed-by: Christoph Hellwig <[email protected]>
