v4.19.13 snapshot.
diff --git a/arch/x86/xen/pci-swiotlb-xen.c b/arch/x86/xen/pci-swiotlb-xen.c
new file mode 100644
index 0000000..37c6056
--- /dev/null
+++ b/arch/x86/xen/pci-swiotlb-xen.c
@@ -0,0 +1,94 @@
+/* Glue code to lib/swiotlb-xen.c */
+
+#include <linux/dma-mapping.h>
+#include <linux/pci.h>
+#include <xen/swiotlb-xen.h>
+
+#include <asm/xen/hypervisor.h>
+#include <xen/xen.h>
+#include <asm/iommu_table.h>
+
+
+#include <asm/xen/swiotlb-xen.h>
+#ifdef CONFIG_X86_64
+#include <asm/iommu.h>
+#include <asm/dma.h>
+#endif
+#include <linux/export.h>
+
+int xen_swiotlb __read_mostly;
+
+/*
+ * pci_xen_swiotlb_detect - set xen_swiotlb to 1 if necessary
+ *
+ * This returns non-zero if we are forced to use xen_swiotlb (by the boot
+ * option).
+ */
+int __init pci_xen_swiotlb_detect(void)
+{
+
+ if (!xen_pv_domain())
+ return 0;
+
+ /* If running as PV guest, either iommu=soft, or swiotlb=force will
+ * activate this IOMMU. If running as PV privileged, activate it
+ * irregardless.
+ */
+ if (xen_initial_domain() || swiotlb || swiotlb_force == SWIOTLB_FORCE)
+ xen_swiotlb = 1;
+
+ /* If we are running under Xen, we MUST disable the native SWIOTLB.
+ * Don't worry about swiotlb_force flag activating the native, as
+ * the 'swiotlb' flag is the only one turning it on. */
+ swiotlb = 0;
+
+#ifdef CONFIG_X86_64
+ /* pci_swiotlb_detect_4gb turns on native SWIOTLB if no_iommu == 0
+ * (so no iommu=X command line over-writes).
+ * Considering that PV guests do not want the *native SWIOTLB* but
+ * only Xen SWIOTLB it is not useful to us so set no_iommu=1 here.
+ */
+ if (max_pfn > MAX_DMA32_PFN)
+ no_iommu = 1;
+#endif
+ return xen_swiotlb;
+}
+
+void __init pci_xen_swiotlb_init(void)
+{
+ if (xen_swiotlb) {
+ xen_swiotlb_init(1, true /* early */);
+ dma_ops = &xen_swiotlb_dma_ops;
+
+#ifdef CONFIG_PCI
+ /* Make sure ACS will be enabled */
+ pci_request_acs();
+#endif
+ }
+}
+
+int pci_xen_swiotlb_init_late(void)
+{
+ int rc;
+
+ if (xen_swiotlb)
+ return 0;
+
+ rc = xen_swiotlb_init(1, false /* late */);
+ if (rc)
+ return rc;
+
+ dma_ops = &xen_swiotlb_dma_ops;
+#ifdef CONFIG_PCI
+ /* Make sure ACS will be enabled */
+ pci_request_acs();
+#endif
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(pci_xen_swiotlb_init_late);
+
+IOMMU_INIT_FINISH(pci_xen_swiotlb_detect,
+ NULL,
+ pci_xen_swiotlb_init,
+ NULL);