v4.19.13 snapshot.
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
new file mode 100644
index 0000000..7ba73fe
--- /dev/null
+++ b/arch/x86/kernel/pci-dma.c
@@ -0,0 +1,196 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/dma-direct.h>
+#include <linux/dma-debug.h>
+#include <linux/dmar.h>
+#include <linux/export.h>
+#include <linux/bootmem.h>
+#include <linux/gfp.h>
+#include <linux/pci.h>
+
+#include <asm/proto.h>
+#include <asm/dma.h>
+#include <asm/iommu.h>
+#include <asm/gart.h>
+#include <asm/calgary.h>
+#include <asm/x86_init.h>
+#include <asm/iommu_table.h>
+
+static bool disable_dac_quirk __read_mostly;
+
+const struct dma_map_ops *dma_ops = &dma_direct_ops;
+EXPORT_SYMBOL(dma_ops);
+
+#ifdef CONFIG_IOMMU_DEBUG
+int panic_on_overflow __read_mostly = 1;
+int force_iommu __read_mostly = 1;
+#else
+int panic_on_overflow __read_mostly = 0;
+int force_iommu __read_mostly = 0;
+#endif
+
+int iommu_merge __read_mostly = 0;
+
+int no_iommu __read_mostly;
+/* Set this to 1 if there is a HW IOMMU in the system */
+int iommu_detected __read_mostly = 0;
+
+/*
+ * This variable becomes 1 if iommu=pt is passed on the kernel command line.
+ * If this variable is 1, IOMMU implementations do no DMA translation for
+ * devices and allow every device to access to whole physical memory. This is
+ * useful if a user wants to use an IOMMU only for KVM device assignment to
+ * guests and not for driver dma translation.
+ * It is also possible to disable by default in kernel config, and enable with
+ * iommu=nopt at boot time.
+ */
+#ifdef CONFIG_IOMMU_DEFAULT_PASSTHROUGH
+int iommu_pass_through __read_mostly = 1;
+#else
+int iommu_pass_through __read_mostly;
+#endif
+
+extern struct iommu_table_entry __iommu_table[], __iommu_table_end[];
+
+/* Dummy device used for NULL arguments (normally ISA). */
+struct device x86_dma_fallback_dev = {
+ .init_name = "fallback device",
+ .coherent_dma_mask = ISA_DMA_BIT_MASK,
+ .dma_mask = &x86_dma_fallback_dev.coherent_dma_mask,
+};
+EXPORT_SYMBOL(x86_dma_fallback_dev);
+
+void __init pci_iommu_alloc(void)
+{
+ struct iommu_table_entry *p;
+
+ sort_iommu_table(__iommu_table, __iommu_table_end);
+ check_iommu_entries(__iommu_table, __iommu_table_end);
+
+ for (p = __iommu_table; p < __iommu_table_end; p++) {
+ if (p && p->detect && p->detect() > 0) {
+ p->flags |= IOMMU_DETECTED;
+ if (p->early_init)
+ p->early_init();
+ if (p->flags & IOMMU_FINISH_IF_DETECTED)
+ break;
+ }
+ }
+}
+
+bool arch_dma_alloc_attrs(struct device **dev)
+{
+ if (!*dev)
+ *dev = &x86_dma_fallback_dev;
+
+ if (!is_device_dma_capable(*dev))
+ return false;
+ return true;
+
+}
+EXPORT_SYMBOL(arch_dma_alloc_attrs);
+
+/*
+ * See <Documentation/x86/x86_64/boot-options.txt> for the iommu kernel
+ * parameter documentation.
+ */
+static __init int iommu_setup(char *p)
+{
+ iommu_merge = 1;
+
+ if (!p)
+ return -EINVAL;
+
+ while (*p) {
+ if (!strncmp(p, "off", 3))
+ no_iommu = 1;
+ /* gart_parse_options has more force support */
+ if (!strncmp(p, "force", 5))
+ force_iommu = 1;
+ if (!strncmp(p, "noforce", 7)) {
+ iommu_merge = 0;
+ force_iommu = 0;
+ }
+
+ if (!strncmp(p, "biomerge", 8)) {
+ iommu_merge = 1;
+ force_iommu = 1;
+ }
+ if (!strncmp(p, "panic", 5))
+ panic_on_overflow = 1;
+ if (!strncmp(p, "nopanic", 7))
+ panic_on_overflow = 0;
+ if (!strncmp(p, "merge", 5)) {
+ iommu_merge = 1;
+ force_iommu = 1;
+ }
+ if (!strncmp(p, "nomerge", 7))
+ iommu_merge = 0;
+ if (!strncmp(p, "forcesac", 8))
+ pr_warn("forcesac option ignored.\n");
+ if (!strncmp(p, "allowdac", 8))
+ pr_warn("allowdac option ignored.\n");
+ if (!strncmp(p, "nodac", 5))
+ pr_warn("nodac option ignored.\n");
+ if (!strncmp(p, "usedac", 6)) {
+ disable_dac_quirk = true;
+ return 1;
+ }
+#ifdef CONFIG_SWIOTLB
+ if (!strncmp(p, "soft", 4))
+ swiotlb = 1;
+#endif
+ if (!strncmp(p, "pt", 2))
+ iommu_pass_through = 1;
+ if (!strncmp(p, "nopt", 4))
+ iommu_pass_through = 0;
+
+ gart_parse_options(p);
+
+#ifdef CONFIG_CALGARY_IOMMU
+ if (!strncmp(p, "calgary", 7))
+ use_calgary = 1;
+#endif /* CONFIG_CALGARY_IOMMU */
+
+ p += strcspn(p, ",");
+ if (*p == ',')
+ ++p;
+ }
+ return 0;
+}
+early_param("iommu", iommu_setup);
+
+static int __init pci_iommu_init(void)
+{
+ struct iommu_table_entry *p;
+
+ x86_init.iommu.iommu_init();
+
+ for (p = __iommu_table; p < __iommu_table_end; p++) {
+ if (p && (p->flags & IOMMU_DETECTED) && p->late_init)
+ p->late_init();
+ }
+
+ return 0;
+}
+/* Must execute after PCI subsystem */
+rootfs_initcall(pci_iommu_init);
+
+#ifdef CONFIG_PCI
+/* Many VIA bridges seem to corrupt data for DAC. Disable it here */
+
+static int via_no_dac_cb(struct pci_dev *pdev, void *data)
+{
+ pdev->dev.bus_dma_mask = DMA_BIT_MASK(32);
+ return 0;
+}
+
+static void via_no_dac(struct pci_dev *dev)
+{
+ if (!disable_dac_quirk) {
+ dev_info(&dev->dev, "disabling DAC on VIA PCI bridge\n");
+ pci_walk_bus(dev->subordinate, via_no_dac_cb, NULL);
+ }
+}
+DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_VIA, PCI_ANY_ID,
+ PCI_CLASS_BRIDGE_PCI, 8, via_no_dac);
+#endif