diff options
Diffstat (limited to 'arch/arm/xen')
| -rw-r--r-- | arch/arm/xen/mm.c | 38 |
1 files changed, 27 insertions, 11 deletions
diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c index 7b517e913762..7c34f7126b04 100644 --- a/arch/arm/xen/mm.c +++ b/arch/arm/xen/mm.c @@ -48,22 +48,22 @@ static void dma_cache_maint(dma_addr_t handle, unsigned long offset, size_t size, enum dma_data_direction dir, enum dma_cache_op op) { struct gnttab_cache_flush cflush; - unsigned long pfn; + unsigned long xen_pfn; size_t left = size; - pfn = (handle >> PAGE_SHIFT) + offset / PAGE_SIZE; - offset %= PAGE_SIZE; + xen_pfn = (handle >> XEN_PAGE_SHIFT) + offset / XEN_PAGE_SIZE; + offset %= XEN_PAGE_SIZE; do { size_t len = left; /* buffers in highmem or foreign pages cannot cross page * boundaries */ - if (len + offset > PAGE_SIZE) - len = PAGE_SIZE - offset; + if (len + offset > XEN_PAGE_SIZE) + len = XEN_PAGE_SIZE - offset; cflush.op = 0; - cflush.a.dev_bus_addr = pfn << PAGE_SHIFT; + cflush.a.dev_bus_addr = xen_pfn << XEN_PAGE_SHIFT; cflush.offset = offset; cflush.length = len; @@ -79,7 +79,7 @@ static void dma_cache_maint(dma_addr_t handle, unsigned long offset, HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1); offset = 0; - pfn++; + xen_pfn++; left -= len; } while (left); } @@ -141,10 +141,26 @@ bool xen_arch_need_swiotlb(struct device *dev, phys_addr_t phys, dma_addr_t dev_addr) { - unsigned long pfn = PFN_DOWN(phys); - unsigned long bfn = PFN_DOWN(dev_addr); - - return (!hypercall_cflush && (pfn != bfn) && !is_device_dma_coherent(dev)); + unsigned int xen_pfn = XEN_PFN_DOWN(phys); + unsigned int bfn = XEN_PFN_DOWN(dev_addr); + + /* + * The swiotlb buffer should be used if + * - Xen doesn't have the cache flush hypercall + * - The Linux page refers to foreign memory + * - The device doesn't support coherent DMA request + * + * The Linux page may be spanned acrros multiple Xen page, although + * it's not possible to have a mix of local and foreign Xen page. + * Furthermore, range_straddles_page_boundary is already checking + * if buffer is physically contiguous in the host RAM. + * + * Therefore we only need to check the first Xen page to know if we + * require a bounce buffer because the device doesn't support coherent + * memory and we are not able to flush the cache. + */ + return (!hypercall_cflush && (xen_pfn != bfn) && + !is_device_dma_coherent(dev)); } int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order, |