linux/kernel/dma/direct.c, branch v5.6

dma-direct: improve DMA mask overflow reporting

2020-02-05T17:53:41Z

Remove the unset dma_mask case as that won't get into mapping calls anymore, and also report the other errors unconditonally and with a slightly improved message. Remove the now pointless report_addr helper. Signed-off-by: Christoph Hellwig Reviewed-by: Konrad Rzeszutek Wilk

dma-direct: improve swiotlb error reporting

2020-02-05T17:53:05Z

Untangle the way how dma_direct_map_page calls into swiotlb to be able to properly report errors where the swiotlb DMA address overflows the mask separately from overflows in the !swiotlb case. This means that siotlb_map now has to do a little more work that duplicates dma_direct_map_page, but doing so greatly simplifies the calling convention. Signed-off-by: Christoph Hellwig Reviewed-by: Konrad Rzeszutek Wilk

dma-direct: relax addressability checks in dma_direct_supported

2020-02-05T17:50:55Z

dma_direct_supported tries to find the minimum addressable bitmask based on the end pfn and optional magic that architectures can use to communicate the size of the magic ZONE_DMA that can be used for bounce buffering. But between the DMA offsets that can change per device (or sometimes even region), the fact the ZONE_DMA isn't even guaranteed to be the lowest addresses and failure of having proper interfaces to the MM code this fails at least for one arm subarchitecture. As all the legacy DMA implementations have supported 32-bit DMA masks, and 32-bit masks are guranteed to always work by the API contract (using bounce buffers if needed), we can short cut the complicated check and always return true without breaking existing assumptions. Hopefully we can properly clean up the interaction with the arch defined zones and the bootmem allocator eventually. Fixes: ad3c7b18c5b3 ("arm: use swiotlb for bounce buffering on LPAE configs") Reported-by: Peter Ujfalusi Signed-off-by: Christoph Hellwig Tested-by: Peter Ujfalusi

dma-mapping: treat dev->bus_dma_mask as a DMA limit

2019-11-21T17:14:35Z

Using a mask to represent bus DMA constraints has a set of limitations. The biggest one being it can only hold a power of two (minus one). The DMA mapping code is already aware of this and treats dev->bus_dma_mask as a limit. This quirk is already used by some architectures although still rare. With the introduction of the Raspberry Pi 4 we've found a new contender for the use of bus DMA limits, as its PCIe bus can only address the lower 3GB of memory (of a total of 4GB). This is impossible to represent with a mask. To make things worse the device-tree code rounds non power of two bus DMA limits to the next power of two, which is unacceptable in this case. In the light of this, rename dev->bus_dma_mask to dev->bus_dma_limit all over the tree and treat it as such. Note that dev->bus_dma_limit should contain the higher accessible DMA address. Signed-off-by: Nicolas Saenz Julienne Reviewed-by: Robin Murphy Signed-off-by: Christoph Hellwig

Merge branch 'for-next/zone-dma' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux into dma-mapping-for-next

2019-11-21T17:13:03Z

Pull in a stable branch from the arm64 tree that adds the zone_dma_bits variable to avoid creating hard to resolve conflicts with that addition.

dma-direct: exclude dma_direct_map_resource from the min_low_pfn check

2019-11-20T19:31:41Z

The valid memory address check in dma_capable only makes sense when mapping normal memory, not when using dma_map_resource to map a device resource. Add a new boolean argument to dma_capable to exclude that check for the dma_map_resource case. Fixes: b12d66278dd6 ("dma-direct: check for overflows on 32 bit DMA addresses") Reported-by: Marek Szyprowski Signed-off-by: Christoph Hellwig Acked-by: Marek Szyprowski Tested-by: Marek Szyprowski

dma-direct: don't check swiotlb=force in dma_direct_map_resource

2019-11-20T19:31:41Z

When mapping resources we can't just use swiotlb ram for bounce buffering. Switch to a direct dma_capable check instead. Fixes: cfced786969c ("dma-mapping: remove the default map_resource implementation") Reported-by: Robin Murphy Signed-off-by: Christoph Hellwig Acked-by: Marek Szyprowski Tested-by: Marek Szyprowski

dma-mapping: drop the dev argument to arch_sync_dma_for_*

2019-11-20T19:31:38Z

These are pure cache maintainance routines, so drop the unused struct device argument. Signed-off-by: Christoph Hellwig Suggested-by: Daniel Vetter

dma-mapping: merge the generic remapping helpers into dma-direct

2019-11-11T09:52:18Z

Integrate the generic dma remapping implementation into the main flow. This prepares for architectures like xtensa that use an uncached segment for pages in the kernel mapping, but can also remap highmem from CMA. To simplify that implementation we now always deduct the page from the physical address via the DMA address instead of the virtual address. Signed-off-by: Christoph Hellwig Reviewed-by: Max Filippov

dma-direct: provide mmap and get_sgtable method overrides

2019-11-11T09:52:15Z

For dma-direct we know that the DMA address is an encoding of the physical address that we can trivially decode. Use that fact to provide implementations that do not need the arch_dma_coherent_to_pfn architecture hook. Note that we still can only support mmap of non-coherent memory only if the architecture provides a way to set an uncached bit in the page tables. This must be true for architectures that use the generic remap helpers, but other architectures can also manually select it. Signed-off-by: Christoph Hellwig Reviewed-by: Max Filippov