From: Rahul Singh <rahul.singh@arm.com>

XEN will create an IOMMU device tree node in the device tree
to enable the dom0 to discover the virtual SMMUv3 during dom0 boot.
IOMMU device tree node will only be created when cmdline option viommu
is enabled.

Signed-off-by: Rahul Singh <rahul.singh@arm.com>
Signed-off-by: Milan Djokic <milan_djokic@epam.com>
---
 xen/arch/arm/domain_build.c       | 94 +++++++++++++++++++++++++++++++
 xen/arch/arm/include/asm/viommu.h |  1 +
 2 files changed, 95 insertions(+)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 30a4f1fd09..57072686f9 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -1440,6 +1440,95 @@ int __init make_timer_node(const struct kernel_info *kinfo)
     return res;
 }
 
+#ifdef CONFIG_VIRTUAL_IOMMU
+static int make_hwdom_viommu_node(const struct kernel_info *kinfo)
+{
+    uint32_t len;
+    int res;
+    char buf[24];
+    void *fdt = kinfo->fdt;
+    const void *prop = NULL;
+    const struct dt_device_node *iommu = NULL;
+    struct host_iommu *iommu_data;
+    gic_interrupt_t intr;
+
+    if ( list_empty(&host_iommu_list) )
+        return 0;
+
+    list_for_each_entry( iommu_data, &host_iommu_list, entry )
+    {
+        if ( iommu_data->hwdom_node_created )
+            return 0;
+
+        iommu = iommu_data->dt_node;
+
+        snprintf(buf, sizeof(buf), "iommu@%"PRIx64, iommu_data->addr);
+
+        res = fdt_begin_node(fdt, buf);
+        if ( res )
+            return res;
+
+        prop = dt_get_property(iommu, "compatible", &len);
+        if ( !prop )
+        {
+            res = -FDT_ERR_XEN(ENOENT);
+            return res;
+        }
+
+        res = fdt_property(fdt, "compatible", prop, len);
+        if ( res )
+            return res;
+
+        if ( iommu->phandle )
+        {
+            res = fdt_property_cell(fdt, "phandle", iommu->phandle);
+            if ( res )
+                return res;
+        }
+
+        /* Use the same reg regions as the IOMMU node in host DTB. */
+        prop = dt_get_property(iommu, "reg", &len);
+        if ( !prop )
+        {
+            printk(XENLOG_ERR "vIOMMU: Can't find IOMMU reg property.\n");
+            res = -FDT_ERR_XEN(ENOENT);
+            return res;
+        }
+
+        res = fdt_property(fdt, "reg", prop, len);
+        if ( res )
+            return res;
+
+        prop = dt_get_property(iommu, "#iommu-cells", &len);
+        if ( !prop )
+        {
+            res = -FDT_ERR_XEN(ENOENT);
+            return res;
+        }
+
+        res = fdt_property(fdt, "#iommu-cells", prop, len);
+        if ( res )
+            return res;
+
+        res = fdt_property_string(fdt, "interrupt-names", "combined");
+        if ( res )
+            return res;
+
+        set_interrupt(intr, iommu_data->irq, 0xf, DT_IRQ_TYPE_LEVEL_HIGH);
+
+        res = fdt_property_interrupts(kinfo, &intr, 1);
+        if ( res )
+            return res;
+
+        iommu_data->hwdom_node_created = true;
+
+        fdt_end_node(fdt);
+    }
+
+    return res;
+}
+#endif
+
 static int __init handle_node(struct domain *d, struct kernel_info *kinfo,
                               struct dt_device_node *node,
                               p2m_type_t p2mt)
@@ -1508,6 +1597,11 @@ static int __init handle_node(struct domain *d, struct kernel_info *kinfo,
     if ( dt_match_node(timer_matches, node) )
         return make_timer_node(kinfo);
 
+#ifdef CONFIG_VIRTUAL_IOMMU
+    if ( device_get_class(node) == DEVICE_IOMMU && is_viommu_enabled() )
+        return make_hwdom_viommu_node(kinfo);
+#endif
+
     /* Skip nodes used by Xen */
     if ( dt_device_used_by(node) == DOMID_XEN )
     {
diff --git a/xen/arch/arm/include/asm/viommu.h b/xen/arch/arm/include/asm/viommu.h
index 811e9312d5..b519a73d4d 100644
--- a/xen/arch/arm/include/asm/viommu.h
+++ b/xen/arch/arm/include/asm/viommu.h
@@ -19,6 +19,7 @@ struct host_iommu {
     paddr_t addr;
     paddr_t size;
     uint32_t irq;
+    bool hwdom_node_created;
 };
 
 struct viommu_ops {
-- 
2.43.0