On Thu, Jan 10, 2019 at 02:44:31PM +0100, Joerg Roedel wrote: > From: Joerg Roedel <[email protected]> > > The SWIOTLB implementation has a maximum size it can > allocate dma-handles for. This needs to be exported so that > device drivers don't try to allocate larger chunks. > > This is especially important for block device drivers like > virtio-blk, that might do DMA through SWIOTLB.
Why not use swiotlb_nr_tbl ? That is how drivers/gpu/drm use to figure if they need to limit the size of pages. > > Signed-off-by: Joerg Roedel <[email protected]> > --- > include/linux/swiotlb.h | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h > index 7c007ed7505f..0bcc80a97036 100644 > --- a/include/linux/swiotlb.h > +++ b/include/linux/swiotlb.h > @@ -72,6 +72,11 @@ static inline bool is_swiotlb_buffer(phys_addr_t paddr) > return paddr >= io_tlb_start && paddr < io_tlb_end; > } > > +static inline size_t swiotlb_max_alloc_size(void) > +{ > + return ((1UL << IO_TLB_SHIFT) * IO_TLB_SEGSIZE); > +} > + > bool swiotlb_map(struct device *dev, phys_addr_t *phys, dma_addr_t *dma_addr, > size_t size, enum dma_data_direction dir, unsigned long attrs); > void __init swiotlb_exit(void); > @@ -95,6 +100,13 @@ static inline unsigned int swiotlb_max_segment(void) > { > return 0; > } > + > +static inline size_t swiotlb_max_alloc_size(void) > +{ > + /* There is no limit when SWIOTLB isn't used */ > + return ~0UL; > +} > + > #endif /* CONFIG_SWIOTLB */ > > extern void swiotlb_print_info(void); > -- > 2.17.1 >
