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[ Upstream commite93ec87286] Today a PV guest (including dom0) can create 2MB contiguous memory regions for DMA buffers at max. This has led to problems at least with the megaraid_sas driver, which wants to allocate a 2.3MB DMA buffer. The limiting factor is the frame array used to do the hypercall for making the memory contiguous, which has 512 entries and is just a static array in mmu_pv.c. In order to not waste memory for non-PV guests, put the initial frame array into .init.data section and dynamically allocate an array from the .init_after_bootmem hook of PV guests. In case a contiguous memory area larger than the initially supported 2MB is requested, allocate a larger buffer for the frame list. Note that such an allocation is tried only after memory management has been initialized properly, which is tested via a flag being set in the .init_after_bootmem hook. Fixes:9f40ec84a7("xen/swiotlb: add alignment check for dma buffers") Signed-off-by: Juergen Gross <jgross@suse.com> Tested-by: Alan Robinson <Alan.Robinson@fujitsu.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Sasha Levin <sashal@kernel.org>