Introduce relocate_fdt() and call it to relocate FDT to Xen heap
instead of using early mapping as it is expected that discard_initial_modules()
( is supposed to call in the future ) discards the FDT boot module and
remove_early_mappings() destroys the early mapping.

Unflatten a device tree, creating the tree of struct device_node.
It also fills the "name" and "type" pointers of the nodes so the normal
device-tree walking functions can be used.

Set device_tree_flattened to NULL in the case when acpi_disabled is
equal to false.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
---
Changes in V3:
 - Add Acked-by: Jan Beulich <jbeulich@suse.com>.
---
Changes in V2:
 - Move introduction of relocate_fdt() to the current patch with the following
   change:
    - use xvmalloc() instead of xmalloc_bytes() in relocate_fdt();
 - Drop the check of returned fdt_size from boot_fdt_info() to be in sync
   with Arm and boot_fdt_info() will panic anyway if something wrong with
   DTB.
 - Update the commit message.
---
 xen/arch/riscv/setup.c | 31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/xen/arch/riscv/setup.c b/xen/arch/riscv/setup.c
index bea3f27c4d..fb6bbba684 100644
--- a/xen/arch/riscv/setup.c
+++ b/xen/arch/riscv/setup.c
@@ -1,5 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
+#include <xen/acpi.h>
 #include <xen/bug.h>
 #include <xen/bootfdt.h>
 #include <xen/compile.h>
@@ -8,6 +9,7 @@
 #include <xen/mm.h>
 #include <xen/shutdown.h>
 #include <xen/vmap.h>
+#include <xen/xvmalloc.h>
 
 #include <public/version.h>
 
@@ -52,10 +54,24 @@ void __init copy_from_paddr(void *dst, paddr_t paddr, unsigned long len)
     }
 }
 
+/* Relocate the FDT in Xen heap */
+static void * __init relocate_fdt(paddr_t dtb_paddr, size_t dtb_size)
+{
+    void *fdt = xvmalloc_array(uint8_t, dtb_size);
+
+    if ( !fdt )
+        panic("Unable to allocate memory for relocating the Device-Tree.\n");
+
+    copy_from_paddr(fdt, dtb_paddr, dtb_size);
+
+    return fdt;
+}
+
 void __init noreturn start_xen(unsigned long bootcpu_id,
                                paddr_t dtb_addr)
 {
     const char *cmdline;
+    size_t fdt_size;
 
     remove_identity_mapping();
 
@@ -80,8 +96,7 @@ void __init noreturn start_xen(unsigned long bootcpu_id,
                           _end - _start, false) )
         panic("Failed to add BOOTMOD_XEN\n");
 
-    if ( !boot_fdt_info(device_tree_flattened, dtb_addr) )
-        BUG();
+    fdt_size = boot_fdt_info(device_tree_flattened, dtb_addr);
 
     cmdline = boot_fdt_cmdline(device_tree_flattened);
     printk("Command line: %s\n", cmdline);
@@ -99,6 +114,18 @@ void __init noreturn start_xen(unsigned long bootcpu_id,
      */
     system_state = SYS_STATE_boot;
 
+    if ( acpi_disabled )
+    {
+        printk("Booting using Device Tree\n");
+        device_tree_flattened = relocate_fdt(dtb_addr, fdt_size);
+        dt_unflatten_host_device_tree();
+    }
+    else
+    {
+        device_tree_flattened = NULL;
+        panic("Booting using ACPI isn't supported\n");
+    }
+
     printk("All set up\n");
 
     machine_halt();
-- 
2.47.1