[PATCH v2 09/16] iommu/vt-d: Restore IOMMU state and reclaimed domain ids

[Samiullah Khawaja <skhawaja@google.com>]

During boot fetch the preserved state of IOMMU unit and if found then
restore the state.

- Reuse the root_table that was preserved in the previous kernel.
- Reclaim the domain ids of the preserved domains for each preserved
  devices so these are not acquired by another domain.

Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
---
 drivers/iommu/intel/iommu.c      | 55 ++++++++++++++++++++++--------
 drivers/iommu/intel/iommu.h      |  7 ++++
 drivers/iommu/intel/liveupdate.c | 57 ++++++++++++++++++++++++++++++++
 3 files changed, 105 insertions(+), 14 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 68fecd4e57fa..4118a0861f38 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -670,10 +670,17 @@ void dmar_fault_dump_ptes(struct intel_iommu *iommu, u16 source_id,
 #endif
 
 /* iommu handling */
-static int iommu_alloc_root_entry(struct intel_iommu *iommu)
+static int iommu_alloc_root_entry(struct intel_iommu *iommu,
+				  struct iommu_hw_ser *iommu_ser)
 {
 	struct root_entry *root;
 
+	if (iommu_ser) {
+		intel_iommu_liveupdate_restore_root_table(iommu, iommu_ser);
+		__iommu_flush_cache(iommu, iommu->root_entry, ROOT_SIZE);
+		return 0;
+	}
+
 	root = iommu_alloc_pages_node_sz(iommu->node, GFP_ATOMIC, SZ_4K);
 	if (!root) {
 		pr_err("Allocating root entry for %s failed\n",
@@ -992,15 +999,16 @@ static void disable_dmar_iommu(struct intel_iommu *iommu)
 		iommu_disable_translation(iommu);
 }
 
-static void free_dmar_iommu(struct intel_iommu *iommu)
+static void free_dmar_iommu(struct intel_iommu *iommu, struct iommu_hw_ser *iommu_ser)
 {
 	if (iommu->copied_tables) {
 		bitmap_free(iommu->copied_tables);
 		iommu->copied_tables = NULL;
 	}
 
-	/* free context mapping */
-	free_context_table(iommu);
+	/* free context mapping if there is no serialized state. */
+	if (!iommu_ser)
+		free_context_table(iommu);
 
 	if (ecap_prs(iommu->ecap))
 		intel_iommu_finish_prq(iommu);
@@ -1611,6 +1619,7 @@ static int copy_translation_tables(struct intel_iommu *iommu)
 
 static int __init init_dmars(void)
 {
+	struct iommu_hw_ser *iommu_ser = NULL;
 	struct dmar_drhd_unit *drhd;
 	struct intel_iommu *iommu;
 	int ret;
@@ -1633,8 +1642,12 @@ static int __init init_dmars(void)
 						   intel_pasid_max_id);
 		}
 
+		iommu_ser = iommu_get_preserved_data(iommu->reg_phys, IOMMU_INTEL);
+
 		intel_iommu_init_qi(iommu);
-		init_translation_status(iommu);
+
+		if (!iommu_ser)
+			init_translation_status(iommu);
 
 		if (translation_pre_enabled(iommu) && !is_kdump_kernel()) {
 			iommu_disable_translation(iommu);
@@ -1648,7 +1661,7 @@ static int __init init_dmars(void)
 		 * we could share the same root & context tables
 		 * among all IOMMU's. Need to Split it later.
 		 */
-		ret = iommu_alloc_root_entry(iommu);
+		ret = iommu_alloc_root_entry(iommu, iommu_ser);
 		if (ret)
 			goto free_iommu;
 
@@ -1732,8 +1745,12 @@ static int __init init_dmars(void)
 
 free_iommu:
 	for_each_active_iommu(iommu, drhd) {
-		disable_dmar_iommu(iommu);
-		free_dmar_iommu(iommu);
+		iommu_ser = iommu_get_preserved_data(iommu->reg_phys, IOMMU_INTEL);
+
+		if (!iommu_ser)
+			disable_dmar_iommu(iommu);
+
+		free_dmar_iommu(iommu, iommu_ser);
 	}
 
 	return ret;
@@ -2107,15 +2124,19 @@ int dmar_parse_one_satc(struct acpi_dmar_header *hdr, void *arg)
 static int intel_iommu_add(struct dmar_drhd_unit *dmaru)
 {
 	struct intel_iommu *iommu = dmaru->iommu;
+	struct iommu_hw_ser *iommu_ser = NULL;
 	int ret;
 
+	/* Use IOMMU HW unit MMIO base to identify the preserved state. */
+	iommu_ser = iommu_get_preserved_data(iommu->reg_phys, IOMMU_INTEL);
+
 	/*
 	 * Disable translation if already enabled prior to OS handover.
 	 */
-	if (iommu->gcmd & DMA_GCMD_TE)
+	if (!iommu_ser && iommu->gcmd & DMA_GCMD_TE)
 		iommu_disable_translation(iommu);
 
-	ret = iommu_alloc_root_entry(iommu);
+	ret = iommu_alloc_root_entry(iommu, iommu_ser);
 	if (ret)
 		goto out;
 
@@ -2150,9 +2171,10 @@ static int intel_iommu_add(struct dmar_drhd_unit *dmaru)
 	return 0;
 
 disable_iommu:
-	disable_dmar_iommu(iommu);
+	if (!iommu_ser)
+		disable_dmar_iommu(iommu);
 out:
-	free_dmar_iommu(iommu);
+	free_dmar_iommu(iommu, iommu_ser);
 	return ret;
 }
 
@@ -2160,6 +2182,7 @@ int dmar_iommu_hotplug(struct dmar_drhd_unit *dmaru, bool insert)
 {
 	int ret = 0;
 	struct intel_iommu *iommu = dmaru->iommu;
+	struct iommu_hw_ser *iommu_ser;
 
 	if (!intel_iommu_enabled)
 		return 0;
@@ -2169,8 +2192,12 @@ int dmar_iommu_hotplug(struct dmar_drhd_unit *dmaru, bool insert)
 	if (insert) {
 		ret = intel_iommu_add(dmaru);
 	} else {
-		disable_dmar_iommu(iommu);
-		free_dmar_iommu(iommu);
+		iommu_ser = iommu_get_preserved_data(iommu->reg_phys, IOMMU_INTEL);
+
+		if (!iommu_ser)
+			disable_dmar_iommu(iommu);
+
+		free_dmar_iommu(iommu, iommu_ser);
 	}
 
 	return ret;
diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index 5e0bc17e76bf..b0ec0b471a43 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -1293,6 +1293,8 @@ int intel_iommu_preserve(struct iommu_device *iommu,
 			 struct iommu_hw_ser *iommu_ser);
 void intel_iommu_unpreserve(struct iommu_device *iommu,
 			    struct iommu_hw_ser *iommu_ser);
+void intel_iommu_liveupdate_restore_root_table(struct intel_iommu *iommu,
+					       struct iommu_hw_ser *iommu_ser);
 #else
 static inline int intel_iommu_preserve_device(struct device *dev,
 					      struct iommu_device_ser *device_ser)
@@ -1310,6 +1312,11 @@ static inline void intel_iommu_unpreserve(struct iommu_device *iommu,
 					  struct iommu_hw_ser *iommu_ser)
 {
 }
+
+static inline void intel_iommu_liveupdate_restore_root_table(struct intel_iommu *iommu,
+							     struct iommu_hw_ser *iommu_ser)
+{
+}
 #endif
 
 #ifdef CONFIG_INTEL_IOMMU_SVM
diff --git a/drivers/iommu/intel/liveupdate.c b/drivers/iommu/intel/liveupdate.c
index 75fa68b701bf..50a63812533f 100644
--- a/drivers/iommu/intel/liveupdate.c
+++ b/drivers/iommu/intel/liveupdate.c
@@ -83,6 +83,63 @@ static int preserve_iommu_context_table(struct intel_iommu *iommu)
 	return ret;
 }
 
+static void restore_iommu_context(struct intel_iommu *iommu)
+{
+	struct context_entry *context;
+	int i;
+
+	for (i = 0; i < ROOT_ENTRY_NR; i++) {
+		context = iommu_context_addr(iommu, i, 0, 0);
+		if (context)
+			BUG_ON(!kho_restore_folio(virt_to_phys(context)));
+
+		if (!sm_supported(iommu))
+			continue;
+
+		context = iommu_context_addr(iommu, i, 0x80, 0);
+		if (context)
+			BUG_ON(!kho_restore_folio(virt_to_phys(context)));
+	}
+}
+
+static int _restore_used_domain_ids(struct iommu_device_ser *ser, void *arg)
+{
+	int id = ser->domain_iommu_ser.attachment_id;
+	struct iommu_hw_ser *iommu_hw_ser;
+	struct intel_iommu *iommu = arg;
+
+	iommu_hw_ser = phys_to_virt(ser->domain_iommu_ser.iommu_phys);
+	if (iommu_hw_ser->type != IOMMU_INTEL)
+		return 0;
+
+	/* Only allocate domain ID from associated IOMMU HW unit */
+	if (iommu_hw_ser->intel.phys_addr != iommu->reg_phys)
+		return 0;
+
+	/*
+	 * This can fail as multiple preserved devices can share the same domain
+	 * ID. Since this is done during DMAR init so these failures can be
+	 * ignored.
+	 */
+	ida_alloc_range(&iommu->domain_ida, id, id, GFP_ATOMIC);
+	return 0;
+}
+
+void intel_iommu_liveupdate_restore_root_table(struct intel_iommu *iommu,
+					       struct iommu_hw_ser *iommu_ser)
+{
+	if (!iommu_ser->intel.restored)
+		BUG_ON(!kho_restore_folio(iommu_ser->intel.root_table));
+
+	iommu->root_entry = __va(iommu_ser->intel.root_table);
+
+	if (!iommu_ser->intel.restored)
+		restore_iommu_context(iommu);
+
+	iommu_ser->intel.restored = 1;
+	iommu_for_each_preserved_device(_restore_used_domain_ids, iommu);
+}
+
 int intel_iommu_preserve_device(struct device *dev,
 				struct iommu_device_ser *device_ser)
 {
-- 
2.54.0.545.g6539524ca2-goog