[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCHv5 0/4] dma, x86, xen: reduce SWIOTLB usage in Xen guests
On systems where DMA addresses and physical addresses are not 1:1 (such as Xen PV guests), the generic dma_get_required_mask() will not return the correct mask (since it uses max_pfn). Some device drivers (such as mptsas, mpt2sas) use dma_get_required_mask() to set the device's DMA mask to allow them to use only 32-bit DMA addresses in hardware structures. This results in unnecessary use of the SWIOTLB if DMA addresses are more than 32-bits, impacting performance significantly. This series allows Xen PV guests to override the default dma_get_required_mask() with a more suitable one. Changes in v5: - xen_swiotlb_get_required_mask() is x86 only. Changes in v4: - Assume 64-bit mask is required. Changes in v3: - fix off-by-one in xen_dma_get_required_mask() - split ia64 changes into separate patch. Changes in v2: - split x86 and xen changes into separate patches David _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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