[PATCH v3 10/18] iommu/vt-d: Restore IOMMU state and reclaimed domain ids

[Samiullah Khawaja]

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@xxxxxxxxxx>
---
 drivers/iommu/intel/iommu.c      | 87 +++++++++++++++++++++++---------
 drivers/iommu/intel/iommu.h      |  7 +++
 drivers/iommu/intel/liveupdate.c | 60 ++++++++++++++++++++++
 3 files changed, 130 insertions(+), 24 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 26258861e3bf..cd40e274482b 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -990,15 +990,16 @@ 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);
@@ -1609,6 +1610,7 @@ 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;
@@ -1631,8 +1633,16 @@ static int __init init_dmars(void)
 						   intel_pasid_max_id);
 		}
 
+		iommu_ser = iommu_get_preserved_data(iommu->reg_phys, IOMMU_INTEL);
+		if (iommu_ser && IS_ERR(iommu_ser)) {
+			ret = PTR_ERR(iommu_ser);
+			goto free_iommu;
+		}
+
 		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);
@@ -1641,14 +1651,18 @@ static int __init init_dmars(void)
 				iommu->name);
 		}
 
-		/*
-		 * TBD:
-		 * we could share the same root & context tables
-		 * among all IOMMU's. Need to Split it later.
-		 */
-		ret = iommu_alloc_root_entry(iommu);
-		if (ret)
-			goto free_iommu;
+		if (iommu_ser) {
+			intel_iommu_liveupdate_restore_root_table(iommu, iommu_ser);
+		} else {
+			/*
+			 * TBD:
+			 * we could share the same root & context tables
+			 * among all IOMMU's. Need to Split it later.
+			 */
+			ret = iommu_alloc_root_entry(iommu);
+			if (ret)
+				goto free_iommu;
+		}
 
 		if (translation_pre_enabled(iommu)) {
 			pr_info("Translation already enabled - trying to copy translation structures\n");
@@ -1684,7 +1698,10 @@ static int __init init_dmars(void)
 	 */
 	for_each_active_iommu(iommu, drhd) {
 		iommu_flush_write_buffer(iommu);
-		iommu_set_root_entry(iommu);
+
+		iommu_ser = iommu_get_preserved_data(iommu->reg_phys, IOMMU_INTEL);
+		if (!iommu_ser)
+			iommu_set_root_entry(iommu);
 	}
 
 	check_tylersburg_isoch();
@@ -1730,8 +1747,11 @@ 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;
@@ -2105,17 +2125,29 @@ 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);
+	if (iommu_ser && IS_ERR(iommu_ser)) {
+		ret = PTR_ERR(iommu_ser);
+		goto out;
+	}
+
 	/*
 	 * 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);
-	if (ret)
-		goto out;
+	if (iommu_ser) {
+		intel_iommu_liveupdate_restore_root_table(iommu, iommu_ser);
+	} else {
+		ret = iommu_alloc_root_entry(iommu);
+		if (ret)
+			goto out;
+	}
 
 	intel_svm_check(iommu);
 
@@ -2141,16 +2173,19 @@ static int intel_iommu_add(struct dmar_drhd_unit *dmaru)
 	if (ret)
 		goto disable_iommu;
 
-	iommu_set_root_entry(iommu);
+	if (!iommu_ser)
+		iommu_set_root_entry(iommu);
+
 	iommu_enable_translation(iommu);
 
 	iommu_disable_protect_mem_regions(iommu);
 	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;
 }
 
@@ -2158,6 +2193,7 @@ 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;
@@ -2167,8 +2203,11 @@ 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 561cc4d14912..a2c2cb86a7fc 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -1295,6 +1295,8 @@ int intel_iommu_preserve(struct iommu_device *iommu,
 void intel_iommu_unpreserve(struct iommu_device *iommu,
 			    struct iommu_hw_ser *iommu_ser);
 void clear_unpreserved_context_entries(struct intel_iommu *iommu);
+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)
@@ -1316,6 +1318,11 @@ static inline void intel_iommu_unpreserve(struct iommu_device *iommu,
 static inline void clear_unpreserved_context_entries(struct intel_iommu *iommu)
 {
 }
+
+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 aac7aa89a182..1a1868e6cc59 100644
--- a/drivers/iommu/intel/liveupdate.c
+++ b/drivers/iommu/intel/liveupdate.c
@@ -194,6 +194,66 @@ static int preserve_iommu_context_tables(struct device_domain_info *info)
 	return 0;
 }
 
+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)
+			iommu_restore_pages(virt_to_phys(context));
+
+		if (!sm_supported(iommu))
+			continue;
+
+		context = iommu_context_addr(iommu, i, 0x80, 0);
+		if (context)
+			iommu_restore_pages(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;
+
+	if (WARN_ON(!ser->domain_iommu_ser.iommu_phys))
+		return -ENOENT;
+
+	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)
+		iommu_restore_pages(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)
 {
-- 
2.54.0.1136.gdb2ca164c4-goog