iommu/vt-d: Add helper for nested domain allocation

This adds helper for accepting user parameters and allocate a nested
domain.

Link: https://lore.kernel.org/r/20231026044216.64964-4-yi.l.liu@intel.comReviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/iommu/intel/Makefile

 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_DMAR_TABLE) += dmar.o
-obj-$(CONFIG_INTEL_IOMMU) += iommu.o pasid.o
+obj-$(CONFIG_INTEL_IOMMU) += iommu.o pasid.o nested.o
 obj-$(CONFIG_DMAR_TABLE) += trace.o cap_audit.o
 obj-$(CONFIG_DMAR_PERF) += perf.o
 obj-$(CONFIG_INTEL_IOMMU_DEBUGFS) += debugfs.o

drivers/iommu/intel/iommu.h

@@ -884,6 +884,8 @@ void *alloc_pgtable_page(int node, gfp_t gfp);
 void free_pgtable_page(void *vaddr);
 void iommu_flush_write_buffer(struct intel_iommu *iommu);
 struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devfn);
+struct iommu_domain *intel_nested_domain_alloc(struct iommu_domain *parent,
+					       const struct iommu_user_data *user_data);
 
 #ifdef CONFIG_INTEL_IOMMU_SVM
 void intel_svm_check(struct intel_iommu *iommu);

drivers/iommu/intel/nested.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * nested.c - nested mode translation support
+ *
+ * Copyright (C) 2023 Intel Corporation
+ *
+ * Author: Lu Baolu <baolu.lu@linux.intel.com>
+ *         Jacob Pan <jacob.jun.pan@linux.intel.com>
+ *         Yi Liu <yi.l.liu@intel.com>
+ */
+
+#define pr_fmt(fmt)	"DMAR: " fmt
+
+#include <linux/iommu.h>
+
+#include "iommu.h"
+
+static void intel_nested_domain_free(struct iommu_domain *domain)
+{
+	kfree(to_dmar_domain(domain));
+}
+
+static const struct iommu_domain_ops intel_nested_domain_ops = {
+	.free			= intel_nested_domain_free,
+};
+
+struct iommu_domain *intel_nested_domain_alloc(struct iommu_domain *parent,
+					       const struct iommu_user_data *user_data)
+{
+	struct dmar_domain *s2_domain = to_dmar_domain(parent);
+	struct iommu_hwpt_vtd_s1 vtd;
+	struct dmar_domain *domain;
+	int ret;
+
+	/* Must be nested domain */
+	if (user_data->type != IOMMU_HWPT_DATA_VTD_S1)
+		return ERR_PTR(-EOPNOTSUPP);
+	if (parent->ops != intel_iommu_ops.default_domain_ops)
+		return ERR_PTR(-EINVAL);
+
+	ret = iommu_copy_struct_from_user(&vtd, user_data,
+					  IOMMU_HWPT_DATA_VTD_S1, __reserved);
+	if (ret)
+		return ERR_PTR(ret);
+
+	domain = kzalloc(sizeof(*domain), GFP_KERNEL_ACCOUNT);
+	if (!domain)
+		return ERR_PTR(-ENOMEM);
+
+	domain->use_first_level = true;
+	domain->s2_domain = s2_domain;
+	domain->s1_pgtbl = vtd.pgtbl_addr;
+	domain->s1_cfg = vtd;
+	domain->domain.ops = &intel_nested_domain_ops;
+	domain->domain.type = IOMMU_DOMAIN_NESTED;
+	INIT_LIST_HEAD(&domain->devices);
+	INIT_LIST_HEAD(&domain->dev_pasids);
+	spin_lock_init(&domain->lock);
+	xa_init(&domain->iommu_array);
+
+	return &domain->domain;
+}