x86/of: Unconditionally call unflatten_and_copy_device_tree()

Call this function unconditionally so that we can populate an empty DTB
on platforms that don't boot with a firmware provided or builtin DTB.
There's no harm in calling unflatten_device_tree() unconditionally here.
If there isn't a non-NULL 'initial_boot_params' pointer then
unflatten_device_tree() returns early.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org
Cc: H. Peter Anvin <hpa@zytor.com>
Tested-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/20240217010557.2381548-5-sboyd@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>

diff --git a/arch/x86/kernel/devicetree.c b/arch/x86/kernel/devicetree.c
index afd09924094eca5e444fd1beaf20c7e02f888e85..650752d112a64969c29563db9fd91ff4ea013afd 100644 (file)
--- a/arch/x86/kernel/devicetree.c
+++ b/arch/x86/kernel/devicetree.c
@@ -283,22 +283,24 @@ void __init x86_flattree_get_config(void)
        u32 size, map_len;
        void *dt;
 
-       if (!initial_dtb)
-               return;
-
-       map_len = max(PAGE_SIZE - (initial_dtb & ~PAGE_MASK), (u64)128);
+       if (initial_dtb) {
+               map_len = max(PAGE_SIZE - (initial_dtb & ~PAGE_MASK), (u64)128);
+
+               dt = early_memremap(initial_dtb, map_len);
+               size = fdt_totalsize(dt);
+               if (map_len < size) {
+                       early_memunmap(dt, map_len);
+                       dt = early_memremap(initial_dtb, size);
+                       map_len = size;
+               }
 
-       dt = early_memremap(initial_dtb, map_len);
-       size = fdt_totalsize(dt);
-       if (map_len < size) {
-               early_memunmap(dt, map_len);
-               dt = early_memremap(initial_dtb, size);
-               map_len = size;
+               early_init_dt_verify(dt);
        }
 
-       early_init_dt_verify(dt);
        unflatten_and_copy_device_tree();
-       early_memunmap(dt, map_len);
+
+       if (initial_dtb)
+               early_memunmap(dt, map_len);
 }
 #endif