v4.19.13 snapshot.
diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c
new file mode 100644
index 0000000..7d0f307
--- /dev/null
+++ b/drivers/iommu/irq_remapping.c
@@ -0,0 +1,192 @@
+#include <linux/seq_file.h>
+#include <linux/cpumask.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/msi.h>
+#include <linux/irq.h>
+#include <linux/pci.h>
+#include <linux/irqdomain.h>
+
+#include <asm/hw_irq.h>
+#include <asm/irq_remapping.h>
+#include <asm/processor.h>
+#include <asm/x86_init.h>
+#include <asm/apic.h>
+#include <asm/hpet.h>
+
+#include "irq_remapping.h"
+
+int irq_remapping_enabled;
+int irq_remap_broken;
+int disable_sourceid_checking;
+int no_x2apic_optout;
+
+int disable_irq_post = 0;
+
+static int disable_irq_remap;
+static struct irq_remap_ops *remap_ops;
+
+static void irq_remapping_restore_boot_irq_mode(void)
+{
+ /*
+ * With interrupt-remapping, for now we will use virtual wire A
+ * mode, as virtual wire B is little complex (need to configure
+ * both IOAPIC RTE as well as interrupt-remapping table entry).
+ * As this gets called during crash dump, keep this simple for
+ * now.
+ */
+ if (boot_cpu_has(X86_FEATURE_APIC) || apic_from_smp_config())
+ disconnect_bsp_APIC(0);
+}
+
+static void __init irq_remapping_modify_x86_ops(void)
+{
+ x86_apic_ops.restore = irq_remapping_restore_boot_irq_mode;
+}
+
+static __init int setup_nointremap(char *str)
+{
+ disable_irq_remap = 1;
+ return 0;
+}
+early_param("nointremap", setup_nointremap);
+
+static __init int setup_irqremap(char *str)
+{
+ if (!str)
+ return -EINVAL;
+
+ while (*str) {
+ if (!strncmp(str, "on", 2)) {
+ disable_irq_remap = 0;
+ disable_irq_post = 0;
+ } else if (!strncmp(str, "off", 3)) {
+ disable_irq_remap = 1;
+ disable_irq_post = 1;
+ } else if (!strncmp(str, "nosid", 5))
+ disable_sourceid_checking = 1;
+ else if (!strncmp(str, "no_x2apic_optout", 16))
+ no_x2apic_optout = 1;
+ else if (!strncmp(str, "nopost", 6))
+ disable_irq_post = 1;
+
+ str += strcspn(str, ",");
+ while (*str == ',')
+ str++;
+ }
+
+ return 0;
+}
+early_param("intremap", setup_irqremap);
+
+void set_irq_remapping_broken(void)
+{
+ irq_remap_broken = 1;
+}
+
+bool irq_remapping_cap(enum irq_remap_cap cap)
+{
+ if (!remap_ops || disable_irq_post)
+ return false;
+
+ return (remap_ops->capability & (1 << cap));
+}
+EXPORT_SYMBOL_GPL(irq_remapping_cap);
+
+int __init irq_remapping_prepare(void)
+{
+ if (disable_irq_remap)
+ return -ENOSYS;
+
+ if (intel_irq_remap_ops.prepare() == 0)
+ remap_ops = &intel_irq_remap_ops;
+ else if (IS_ENABLED(CONFIG_AMD_IOMMU) &&
+ amd_iommu_irq_ops.prepare() == 0)
+ remap_ops = &amd_iommu_irq_ops;
+ else
+ return -ENOSYS;
+
+ return 0;
+}
+
+int __init irq_remapping_enable(void)
+{
+ int ret;
+
+ if (!remap_ops->enable)
+ return -ENODEV;
+
+ ret = remap_ops->enable();
+
+ if (irq_remapping_enabled)
+ irq_remapping_modify_x86_ops();
+
+ return ret;
+}
+
+void irq_remapping_disable(void)
+{
+ if (irq_remapping_enabled && remap_ops->disable)
+ remap_ops->disable();
+}
+
+int irq_remapping_reenable(int mode)
+{
+ if (irq_remapping_enabled && remap_ops->reenable)
+ return remap_ops->reenable(mode);
+
+ return 0;
+}
+
+int __init irq_remap_enable_fault_handling(void)
+{
+ if (!irq_remapping_enabled)
+ return 0;
+
+ if (!remap_ops->enable_faulting)
+ return -ENODEV;
+
+ return remap_ops->enable_faulting();
+}
+
+void panic_if_irq_remap(const char *msg)
+{
+ if (irq_remapping_enabled)
+ panic(msg);
+}
+
+/**
+ * irq_remapping_get_ir_irq_domain - Get the irqdomain associated with the IOMMU
+ * device serving request @info
+ * @info: interrupt allocation information, used to identify the IOMMU device
+ *
+ * It's used to get parent irqdomain for HPET and IOAPIC irqdomains.
+ * Returns pointer to IRQ domain, or NULL on failure.
+ */
+struct irq_domain *
+irq_remapping_get_ir_irq_domain(struct irq_alloc_info *info)
+{
+ if (!remap_ops || !remap_ops->get_ir_irq_domain)
+ return NULL;
+
+ return remap_ops->get_ir_irq_domain(info);
+}
+
+/**
+ * irq_remapping_get_irq_domain - Get the irqdomain serving the request @info
+ * @info: interrupt allocation information, used to identify the IOMMU device
+ *
+ * There will be one PCI MSI/MSIX irqdomain associated with each interrupt
+ * remapping device, so this interface is used to retrieve the PCI MSI/MSIX
+ * irqdomain serving request @info.
+ * Returns pointer to IRQ domain, or NULL on failure.
+ */
+struct irq_domain *
+irq_remapping_get_irq_domain(struct irq_alloc_info *info)
+{
+ if (!remap_ops || !remap_ops->get_irq_domain)
+ return NULL;
+
+ return remap_ops->get_irq_domain(info);
+}