Patch "x86/of: Unconditionally call unflatten_and_copy_device_tree()" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    x86/of: Unconditionally call unflatten_and_copy_device_tree()

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     x86-of-unconditionally-call-unflatten_and_copy_devic.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 09bf4fd081a502dd7c3ddb4473deaf92b5faccd9
Author: Stephen Boyd <sboyd@xxxxxxxxxx>
Date:   Fri Feb 16 17:05:53 2024 -0800

    x86/of: Unconditionally call unflatten_and_copy_device_tree()
    
    [ Upstream commit 40f18dbbb42c56019b889b5b1fdce3da89e354da ]
    
    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@xxxxxxxxxx>
    Cc: Frank Rowand <frowand.list@xxxxxxxxx>
    Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
    Cc: Ingo Molnar <mingo@xxxxxxxxxx>
    Cc: Borislav Petkov <bp@xxxxxxxxx>
    Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
    Cc: x86@xxxxxxxxxx
    Cc: H. Peter Anvin <hpa@xxxxxxxxx>
    Tested-by: Saurabh Sengar <ssengar@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20240217010557.2381548-5-sboyd@xxxxxxxxxx
    Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
    Stable-dep-of: b2473a359763 ("of/fdt: add dt_phys arg to early_init_dt_scan and early_init_dt_verify")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/x86/kernel/devicetree.c b/arch/x86/kernel/devicetree.c
index c13c9cb40b9b4..47fe7de1575dd 100644
--- a/arch/x86/kernel/devicetree.c
+++ b/arch/x86/kernel/devicetree.c
@@ -283,22 +283,24 @@ static 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);
 }
 #else
 static inline void x86_flattree_get_config(void) { }