v4.19.13 snapshot.
diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
new file mode 100644
index 0000000..785d2a5
--- /dev/null
+++ b/arch/arm/xen/mm.c
@@ -0,0 +1,204 @@
+#include <linux/cpu.h>
+#include <linux/dma-mapping.h>
+#include <linux/bootmem.h>
+#include <linux/gfp.h>
+#include <linux/highmem.h>
+#include <linux/export.h>
+#include <linux/memblock.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/dma-mapping.h>
+#include <linux/vmalloc.h>
+#include <linux/swiotlb.h>
+
+#include <xen/xen.h>
+#include <xen/interface/grant_table.h>
+#include <xen/interface/memory.h>
+#include <xen/page.h>
+#include <xen/swiotlb-xen.h>
+
+#include <asm/cacheflush.h>
+#include <asm/xen/hypercall.h>
+#include <asm/xen/interface.h>
+
+unsigned long xen_get_swiotlb_free_pages(unsigned int order)
+{
+ struct memblock_region *reg;
+ gfp_t flags = __GFP_NOWARN|__GFP_KSWAPD_RECLAIM;
+
+ for_each_memblock(memory, reg) {
+ if (reg->base < (phys_addr_t)0xffffffff) {
+ flags |= __GFP_DMA;
+ break;
+ }
+ }
+ return __get_free_pages(flags, order);
+}
+
+enum dma_cache_op {
+ DMA_UNMAP,
+ DMA_MAP,
+};
+static bool hypercall_cflush = false;
+
+/* functions called by SWIOTLB */
+
+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 xen_pfn;
+ size_t left = 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 > XEN_PAGE_SIZE)
+ len = XEN_PAGE_SIZE - offset;
+
+ cflush.op = 0;
+ cflush.a.dev_bus_addr = xen_pfn << XEN_PAGE_SHIFT;
+ cflush.offset = offset;
+ cflush.length = len;
+
+ if (op == DMA_UNMAP && dir != DMA_TO_DEVICE)
+ cflush.op = GNTTAB_CACHE_INVAL;
+ if (op == DMA_MAP) {
+ if (dir == DMA_FROM_DEVICE)
+ cflush.op = GNTTAB_CACHE_INVAL;
+ else
+ cflush.op = GNTTAB_CACHE_CLEAN;
+ }
+ if (cflush.op)
+ HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1);
+
+ offset = 0;
+ xen_pfn++;
+ left -= len;
+ } while (left);
+}
+
+static void __xen_dma_page_dev_to_cpu(struct device *hwdev, dma_addr_t handle,
+ size_t size, enum dma_data_direction dir)
+{
+ dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_UNMAP);
+}
+
+static void __xen_dma_page_cpu_to_dev(struct device *hwdev, dma_addr_t handle,
+ size_t size, enum dma_data_direction dir)
+{
+ dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_MAP);
+}
+
+void __xen_dma_map_page(struct device *hwdev, struct page *page,
+ dma_addr_t dev_addr, unsigned long offset, size_t size,
+ enum dma_data_direction dir, unsigned long attrs)
+{
+ if (is_device_dma_coherent(hwdev))
+ return;
+ if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
+ return;
+
+ __xen_dma_page_cpu_to_dev(hwdev, dev_addr, size, dir);
+}
+
+void __xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
+ size_t size, enum dma_data_direction dir,
+ unsigned long attrs)
+
+{
+ if (is_device_dma_coherent(hwdev))
+ return;
+ if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
+ return;
+
+ __xen_dma_page_dev_to_cpu(hwdev, handle, size, dir);
+}
+
+void __xen_dma_sync_single_for_cpu(struct device *hwdev,
+ dma_addr_t handle, size_t size, enum dma_data_direction dir)
+{
+ if (is_device_dma_coherent(hwdev))
+ return;
+ __xen_dma_page_dev_to_cpu(hwdev, handle, size, dir);
+}
+
+void __xen_dma_sync_single_for_device(struct device *hwdev,
+ dma_addr_t handle, size_t size, enum dma_data_direction dir)
+{
+ if (is_device_dma_coherent(hwdev))
+ return;
+ __xen_dma_page_cpu_to_dev(hwdev, handle, size, dir);
+}
+
+bool xen_arch_need_swiotlb(struct device *dev,
+ phys_addr_t phys,
+ dma_addr_t dev_addr)
+{
+ 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,
+ unsigned int address_bits,
+ dma_addr_t *dma_handle)
+{
+ if (!xen_initial_domain())
+ return -EINVAL;
+
+ /* we assume that dom0 is mapped 1:1 for now */
+ *dma_handle = pstart;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(xen_create_contiguous_region);
+
+void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
+{
+ return;
+}
+EXPORT_SYMBOL_GPL(xen_destroy_contiguous_region);
+
+const struct dma_map_ops *xen_dma_ops;
+EXPORT_SYMBOL(xen_dma_ops);
+
+int __init xen_mm_init(void)
+{
+ struct gnttab_cache_flush cflush;
+ if (!xen_initial_domain())
+ return 0;
+ xen_swiotlb_init(1, false);
+ xen_dma_ops = &xen_swiotlb_dma_ops;
+
+ cflush.op = 0;
+ cflush.a.dev_bus_addr = 0;
+ cflush.offset = 0;
+ cflush.length = 0;
+ if (HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1) != -ENOSYS)
+ hypercall_cflush = true;
+ return 0;
+}
+arch_initcall(xen_mm_init);