Similar to how iommufd got serialise and deserialise hooks, now add this
to the platform iommu driver, in this case intel-iommu. Once again this
will be fleshed out in the next commits to actually serialise the struct
dmar_domain before kexec and restore them after kexec.
---
 drivers/iommu/intel/Makefile    |  1 +
 drivers/iommu/intel/iommu.c     | 18 +++++++++++++++
 drivers/iommu/intel/iommu.h     | 18 +++++++++++++++
 drivers/iommu/intel/serialise.c | 40 +++++++++++++++++++++++++++++++++
 4 files changed, 77 insertions(+)
 create mode 100644 drivers/iommu/intel/serialise.c

diff --git a/drivers/iommu/intel/Makefile b/drivers/iommu/intel/Makefile
index c8beb0281559..ca9f73992620 100644
--- a/drivers/iommu/intel/Makefile
+++ b/drivers/iommu/intel/Makefile
@@ -9,3 +9,4 @@ ifdef CONFIG_INTEL_IOMMU
 obj-$(CONFIG_IRQ_REMAP) += irq_remapping.o
 endif
 obj-$(CONFIG_INTEL_IOMMU_PERF_EVENTS) += perfmon.o
+obj-$(CONFIG_KEXEC_KHO) += serialise.o
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index f473a8c008a7..7e77b787148a 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -65,6 +65,7 @@ static int rwbf_quirk;
 static int force_on = 0;
 static int intel_iommu_tboot_noforce;
 static int no_platform_optin;
+DEFINE_XARRAY(persistent_domains);
 
 #define ROOT_ENTRY_NR (VTD_PAGE_SIZE/sizeof(struct root_entry))
 
@@ -3393,6 +3394,10 @@ static __init int tboot_force_iommu(void)
 	return 1;
 }
 
+static struct notifier_block serialise_kho_nb = {
+	.notifier_call = intel_iommu_serialise_kho,
+};
+
 int __init intel_iommu_init(void)
 {
 	int ret = -ENODEV;
@@ -3432,6 +3437,12 @@ int __init intel_iommu_init(void)
 	if (!no_iommu)
 		intel_iommu_debugfs_init();
 
+	if (IS_ENABLED(CONFIG_KEXEC_KHO)) {
+		ret = register_kho_notifier(&serialise_kho_nb);
+		if (ret)
+			goto out_free_dmar;
+	}
+
 	if (no_iommu || dmar_disabled) {
 		/*
 		 * We exit the function here to ensure IOMMU's remapping and
@@ -3738,6 +3749,7 @@ intel_iommu_domain_alloc_user(struct device *dev, u32 flags,
 	struct intel_iommu *iommu = info->iommu;
 	struct dmar_domain *dmar_domain;
 	struct iommu_domain *domain;
+	int rc;
 
 	/* Must be NESTING domain */
 	if (parent) {
@@ -3778,6 +3790,12 @@ intel_iommu_domain_alloc_user(struct device *dev, u32 flags,
 		domain->dirty_ops = &intel_dirty_ops;
 	}
 
+	if (persistent_id) {
+		rc = xa_insert(&persistent_domains, persistent_id, domain, GFP_KERNEL_ACCOUNT);
+		if (rc)
+			pr_warn("Unable to track persistent domain %lu\n", persistent_id);
+	}
+
 	return domain;
 }
 
diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index cfd006588824..7866342f0909 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -11,6 +11,7 @@
 #define _INTEL_IOMMU_H_
 
 #include <linux/types.h>
+#include <linux/kexec.h>
 #include <linux/iova.h>
 #include <linux/io.h>
 #include <linux/idr.h>
@@ -496,6 +497,7 @@ struct q_inval {
 #define PRQ_DEPTH	((0x1000 << PRQ_ORDER) >> 5)
 
 struct dmar_pci_notify_info;
+extern struct xarray persistent_domains;
 
 #ifdef CONFIG_IRQ_REMAP
 /* 1MB - maximum possible interrupt remapping table size */
@@ -1225,6 +1227,22 @@ static inline int iommu_calculate_max_sagaw(struct intel_iommu *iommu)
 #define intel_iommu_sm (0)
 #endif
 
+#ifdef CONFIG_KEXEC_KHO
+int intel_iommu_serialise_kho(struct notifier_block *self, unsigned long cmd,
+			  void *fdt);
+int __init intel_iommu_deserialise_kho(void);
+#else
+int intel_iommu_serialise_kho(struct notifier_block *self, unsigned long cmd,
+			  void *fdt)
+{
+	return 0;
+}
+int __init intel_iommu_deserialise_kho(void)
+{
+	return 0;
+}
+#endif /* CONFIG_KEXEC_KHO */
+
 static inline const char *decode_prq_descriptor(char *str, size_t size,
 		u64 dw0, u64 dw1, u64 dw2, u64 dw3)
 {
diff --git a/drivers/iommu/intel/serialise.c b/drivers/iommu/intel/serialise.c
new file mode 100644
index 000000000000..08a548b33703
--- /dev/null
+++ b/drivers/iommu/intel/serialise.c
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include "iommu.h"
+
+static int serialise_domain(void *fdt, struct iommu_domain *domain)
+{
+	return 0;
+}
+
+int intel_iommu_serialise_kho(struct notifier_block *self, unsigned long cmd,
+			  void *fdt)
+{
+	static const char compatible[] = "intel-iommu-v0";
+	struct iommu_domain *domain;
+	unsigned long xa_idx;
+	int err = 0;
+
+	switch (cmd) {
+	case KEXEC_KHO_ABORT:
+		/* Would do serialise rollback here. */
+		return NOTIFY_DONE;
+	case KEXEC_KHO_DUMP:
+		err |= fdt_begin_node(fdt, "intel-iommu");
+		fdt_property(fdt, "compatible", compatible, sizeof(compatible));
+		err |= fdt_begin_node(fdt, "domains");
+		xa_for_each(&persistent_domains, xa_idx, domain) {
+			err |= serialise_domain(fdt, domain);
+		}
+		err |= fdt_end_node(fdt); /* domains */
+		err |= fdt_end_node(fdt); /* intel-iommu*/
+		return err? NOTIFY_BAD : NOTIFY_DONE;
+	default:
+		return NOTIFY_BAD;
+	}
+}
+
+int __init intel_iommu_deserialise_kho(void)
+{
+	return 0;
+}
-- 
2.34.1