On Mon, Oct 08, 2018 at 10:02:40AM +0200, Christoph Hellwig wrote: > Like all other dma mapping drivers just return an error code instead > of an actual memory buffer. The reason for the overflow buffer was > that at the time swiotlb was invented there was no way to check for > dma mapping errors, but this has long been fixed.
RIP overflow buffer. Reviewed-by: Konrad Rzeszutek Wilk <[email protected]> Thank you! > > Signed-off-by: Christoph Hellwig <[email protected]> > --- > arch/arm64/mm/dma-mapping.c | 2 +- > arch/powerpc/kernel/dma-swiotlb.c | 4 +-- > include/linux/dma-direct.h | 2 ++ > include/linux/swiotlb.h | 3 -- > kernel/dma/direct.c | 2 -- > kernel/dma/swiotlb.c | 59 ++----------------------------- > 6 files changed, 8 insertions(+), 64 deletions(-) > > diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c > index 072c51fb07d7..8d91b927e09e 100644 > --- a/arch/arm64/mm/dma-mapping.c > +++ b/arch/arm64/mm/dma-mapping.c > @@ -324,7 +324,7 @@ static int __swiotlb_dma_supported(struct device *hwdev, > u64 mask) > static int __swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t addr) > { > if (swiotlb) > - return swiotlb_dma_mapping_error(hwdev, addr); > + return dma_direct_mapping_error(hwdev, addr); > return 0; > } > > diff --git a/arch/powerpc/kernel/dma-swiotlb.c > b/arch/powerpc/kernel/dma-swiotlb.c > index 88f3963ca30f..5fc335f4d9cd 100644 > --- a/arch/powerpc/kernel/dma-swiotlb.c > +++ b/arch/powerpc/kernel/dma-swiotlb.c > @@ -11,7 +11,7 @@ > * > */ > > -#include <linux/dma-mapping.h> > +#include <linux/dma-direct.h> > #include <linux/memblock.h> > #include <linux/pfn.h> > #include <linux/of_platform.h> > @@ -59,7 +59,7 @@ const struct dma_map_ops powerpc_swiotlb_dma_ops = { > .sync_single_for_device = swiotlb_sync_single_for_device, > .sync_sg_for_cpu = swiotlb_sync_sg_for_cpu, > .sync_sg_for_device = swiotlb_sync_sg_for_device, > - .mapping_error = swiotlb_dma_mapping_error, > + .mapping_error = dma_direct_mapping_error, > .get_required_mask = swiotlb_powerpc_get_required, > }; > > diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h > index fbca184ff5a0..bd73e7a91410 100644 > --- a/include/linux/dma-direct.h > +++ b/include/linux/dma-direct.h > @@ -5,6 +5,8 @@ > #include <linux/dma-mapping.h> > #include <linux/mem_encrypt.h> > > +#define DIRECT_MAPPING_ERROR 0 > + > #ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA > #include <asm/dma-direct.h> > #else > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h > index 7ef541ce8f34..f847c1b265c4 100644 > --- a/include/linux/swiotlb.h > +++ b/include/linux/swiotlb.h > @@ -106,9 +106,6 @@ extern void > swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg, > int nelems, enum dma_data_direction dir); > > -extern int > -swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr); > - > extern int > swiotlb_dma_supported(struct device *hwdev, u64 mask); > > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > index 674a8da22844..12798abba55e 100644 > --- a/kernel/dma/direct.c > +++ b/kernel/dma/direct.c > @@ -14,8 +14,6 @@ > #include <linux/pfn.h> > #include <linux/set_memory.h> > > -#define DIRECT_MAPPING_ERROR 0 > - > /* > * Most architectures use ZONE_DMA for the first 16 Megabytes, but > * some use it for entirely different regions: > diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c > index 69bf305ee5f8..11dbcd80b4a6 100644 > --- a/kernel/dma/swiotlb.c > +++ b/kernel/dma/swiotlb.c > @@ -72,13 +72,6 @@ static phys_addr_t io_tlb_start, io_tlb_end; > */ > static unsigned long io_tlb_nslabs; > > -/* > - * When the IOMMU overflows we return a fallback buffer. This sets the size. > - */ > -static unsigned long io_tlb_overflow = 32*1024; > - > -static phys_addr_t io_tlb_overflow_buffer; > - > /* > * This is a free list describing the number of free entries available from > * each index > @@ -126,7 +119,6 @@ setup_io_tlb_npages(char *str) > return 0; > } > early_param("swiotlb", setup_io_tlb_npages); > -/* make io_tlb_overflow tunable too? */ > > unsigned long swiotlb_nr_tbl(void) > { > @@ -194,16 +186,10 @@ void __init swiotlb_update_mem_attributes(void) > bytes = PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT); > set_memory_decrypted((unsigned long)vaddr, bytes >> PAGE_SHIFT); > memset(vaddr, 0, bytes); > - > - vaddr = phys_to_virt(io_tlb_overflow_buffer); > - bytes = PAGE_ALIGN(io_tlb_overflow); > - set_memory_decrypted((unsigned long)vaddr, bytes >> PAGE_SHIFT); > - memset(vaddr, 0, bytes); > } > > int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int > verbose) > { > - void *v_overflow_buffer; > unsigned long i, bytes; > > bytes = nslabs << IO_TLB_SHIFT; > @@ -212,17 +198,6 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned > long nslabs, int verbose) > io_tlb_start = __pa(tlb); > io_tlb_end = io_tlb_start + bytes; > > - /* > - * Get the overflow emergency buffer > - */ > - v_overflow_buffer = memblock_virt_alloc_low_nopanic( > - PAGE_ALIGN(io_tlb_overflow), > - PAGE_SIZE); > - if (!v_overflow_buffer) > - return -ENOMEM; > - > - io_tlb_overflow_buffer = __pa(v_overflow_buffer); > - > /* > * Allocate and initialize the free list array. This array is used > * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE > @@ -330,7 +305,6 @@ int > swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs) > { > unsigned long i, bytes; > - unsigned char *v_overflow_buffer; > > bytes = nslabs << IO_TLB_SHIFT; > > @@ -341,19 +315,6 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long > nslabs) > set_memory_decrypted((unsigned long)tlb, bytes >> PAGE_SHIFT); > memset(tlb, 0, bytes); > > - /* > - * Get the overflow emergency buffer > - */ > - v_overflow_buffer = (void *)__get_free_pages(GFP_DMA, > - > get_order(io_tlb_overflow)); > - if (!v_overflow_buffer) > - goto cleanup2; > - > - set_memory_decrypted((unsigned long)v_overflow_buffer, > - io_tlb_overflow >> PAGE_SHIFT); > - memset(v_overflow_buffer, 0, io_tlb_overflow); > - io_tlb_overflow_buffer = virt_to_phys(v_overflow_buffer); > - > /* > * Allocate and initialize the free list array. This array is used > * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE > @@ -390,10 +351,6 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long > nslabs) > sizeof(int))); > io_tlb_list = NULL; > cleanup3: > - free_pages((unsigned long)v_overflow_buffer, > - get_order(io_tlb_overflow)); > - io_tlb_overflow_buffer = 0; > -cleanup2: > io_tlb_end = 0; > io_tlb_start = 0; > io_tlb_nslabs = 0; > @@ -407,8 +364,6 @@ void __init swiotlb_exit(void) > return; > > if (late_alloc) { > - free_pages((unsigned long)phys_to_virt(io_tlb_overflow_buffer), > - get_order(io_tlb_overflow)); > free_pages((unsigned long)io_tlb_orig_addr, > get_order(io_tlb_nslabs * sizeof(phys_addr_t))); > free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs * > @@ -416,8 +371,6 @@ void __init swiotlb_exit(void) > free_pages((unsigned long)phys_to_virt(io_tlb_start), > get_order(io_tlb_nslabs << IO_TLB_SHIFT)); > } else { > - memblock_free_late(io_tlb_overflow_buffer, > - PAGE_ALIGN(io_tlb_overflow)); > memblock_free_late(__pa(io_tlb_orig_addr), > PAGE_ALIGN(io_tlb_nslabs * > sizeof(phys_addr_t))); > memblock_free_late(__pa(io_tlb_list), > @@ -790,7 +743,7 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct > page *page, > /* Oh well, have to allocate and map a bounce buffer. */ > map = map_single(dev, phys, size, dir, attrs); > if (map == SWIOTLB_MAP_ERROR) > - return __phys_to_dma(dev, io_tlb_overflow_buffer); > + return DIRECT_MAPPING_ERROR; > > dev_addr = __phys_to_dma(dev, map); > > @@ -801,7 +754,7 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct > page *page, > attrs |= DMA_ATTR_SKIP_CPU_SYNC; > swiotlb_tbl_unmap_single(dev, map, size, dir, attrs); > > - return __phys_to_dma(dev, io_tlb_overflow_buffer); > + return DIRECT_MAPPING_ERROR; > } > > /* > @@ -985,12 +938,6 @@ swiotlb_sync_sg_for_device(struct device *hwdev, struct > scatterlist *sg, > swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_DEVICE); > } > > -int > -swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr) > -{ > - return (dma_addr == __phys_to_dma(hwdev, io_tlb_overflow_buffer)); > -} > - > /* > * Return whether the given device DMA address mask can be supported > * properly. For example, if your device can only drive the low 24-bits > @@ -1033,7 +980,7 @@ void swiotlb_free(struct device *dev, size_t size, void > *vaddr, > } > > const struct dma_map_ops swiotlb_dma_ops = { > - .mapping_error = swiotlb_dma_mapping_error, > + .mapping_error = dma_direct_mapping_error, > .alloc = swiotlb_alloc, > .free = swiotlb_free, > .sync_single_for_cpu = swiotlb_sync_single_for_cpu, > -- > 2.19.0 > _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
