1 files changed, 78 insertions, 0 deletions
diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
new file mode 100644
index 000000000..c2cfa5e7c
--- /dev/null
+++ b/arch/x86/kernel/pci-swiotlb.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/pci.h>
+#include <linux/cache.h>
+#include <linux/init.h>
+#include <linux/swiotlb.h>
+#include <linux/memblock.h>
+#include <linux/dma-direct.h>
+#include <linux/mem_encrypt.h>
+
+#include <asm/iommu.h>
+#include <asm/swiotlb.h>
+#include <asm/dma.h>
+#include <asm/xen/swiotlb-xen.h>
+#include <asm/iommu_table.h>
+
+int swiotlb __read_mostly;
+
+/*
+ * pci_swiotlb_detect_override - set swiotlb to 1 if necessary
+ *
+ * This returns non-zero if we are forced to use swiotlb (by the boot
+ * option).
+ */
+int __init pci_swiotlb_detect_override(void)
+{
+	if (swiotlb_force == SWIOTLB_FORCE)
+		swiotlb = 1;
+
+	return swiotlb;
+}
+IOMMU_INIT_FINISH(pci_swiotlb_detect_override,
+		  pci_xen_swiotlb_detect,
+		  pci_swiotlb_init,
+		  pci_swiotlb_late_init);
+
+/*
+ * If 4GB or more detected (and iommu=off not set) or if SME is active
+ * then set swiotlb to 1 and return 1.
+ */
+int __init pci_swiotlb_detect_4gb(void)
+{
+	/* don't initialize swiotlb if iommu=off (no_iommu=1) */
+	if (!no_iommu && max_possible_pfn > MAX_DMA32_PFN)
+		swiotlb = 1;
+
+	/*
+	 * If SME is active then swiotlb will be set to 1 so that bounce
+	 * buffers are allocated and used for devices that do not support
+	 * the addressing range required for the encryption mask.
+	 */
+	if (sme_active())
+		swiotlb = 1;
+
+	return swiotlb;
+}
+IOMMU_INIT(pci_swiotlb_detect_4gb,
+	   pci_swiotlb_detect_override,
+	   pci_swiotlb_init,
+	   pci_swiotlb_late_init);
+
+void __init pci_swiotlb_init(void)
+{
+	if (swiotlb)
+		swiotlb_init(0);
+}
+
+void __init pci_swiotlb_late_init(void)
+{
+	/* An IOMMU turned us off. */
+	if (!swiotlb)
+		swiotlb_exit();
+	else {
+		printk(KERN_INFO "PCI-DMA: "
+		       "Using software bounce buffering for IO (SWIOTLB)\n");
+		swiotlb_print_info();
+	}
+}