linux-kernel - [PATCH v2 1/2] x86/of: split x86_dtb_init for early x86_flattree_get

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Message-Id: <1692949657-16446-1-git-send-email-ssengar@linux.microsoft.com>
Date:   Fri, 25 Aug 2023 00:47:36 -0700
From:   Saurabh Sengar <ssengar@...ux.microsoft.com>
To:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
        luto@...nel.org, peterz@...radead.org, mikelley@...rosoft.com,
        linux-kernel@...r.kernel.org
Cc:     ssengar@...ux.microsoft.com
Subject: [PATCH v2 1/2] x86/of: split x86_dtb_init for early x86_flattree_get_config call

Fetching the device tree configuration before initmem_init is necessary
to allow the parsing of NUMA node information. However moving entire
x86_dtb_init before initmem_init is not correct as APIC/IO-APIC enumeration
has to be after initmem_init. Thus, split the x86_dtb_init function to
incorporate a call to x86_flattree_get_config before initmem_init, and
leaving the ACPI/IOAPIC registration sequence as is.

Signed-off-by: Saurabh Sengar <ssengar@...ux.microsoft.com>
---
[V2]
 - split the x86_dtb_init to call x86_flattree_get_config early

 arch/x86/include/asm/prom.h  | 5 +++++
 arch/x86/kernel/devicetree.c | 6 +-----
 arch/x86/kernel/setup.c      | 2 ++
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/prom.h b/arch/x86/include/asm/prom.h
index b716d291d0d4..65dee2420624 100644
--- a/arch/x86/include/asm/prom.h
+++ b/arch/x86/include/asm/prom.h
@@ -31,6 +31,11 @@ static inline void x86_dtb_init(void) { }
 #define of_ioapic 0
 #endif
 
+#ifdef CONFIG_OF_EARLY_FLATTREE
+void x86_flattree_get_config(void);
+#else
+static inline void x86_flattree_get_config(void) { }
+#endif
 extern char cmd_line[COMMAND_LINE_SIZE];
 
 #endif /* __ASSEMBLY__ */
diff --git a/arch/x86/kernel/devicetree.c b/arch/x86/kernel/devicetree.c
index 87d38f17ff5c..afd09924094e 100644
--- a/arch/x86/kernel/devicetree.c
+++ b/arch/x86/kernel/devicetree.c
@@ -278,7 +278,7 @@ static void __init dtb_apic_setup(void)
 }
 
 #ifdef CONFIG_OF_EARLY_FLATTREE
-static void __init x86_flattree_get_config(void)
+void __init x86_flattree_get_config(void)
 {
 	u32 size, map_len;
 	void *dt;
@@ -300,14 +300,10 @@ static void __init x86_flattree_get_config(void)
 	unflatten_and_copy_device_tree();
 	early_memunmap(dt, map_len);
 }
-#else
-static inline void x86_flattree_get_config(void) { }
 #endif
 
 void __init x86_dtb_init(void)
 {
-	x86_flattree_get_config();
-
 	if (!of_have_populated_dt())
 		return;
 
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index b9145a63da77..ef73704fa27f 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1221,6 +1221,8 @@ void __init setup_arch(char **cmdline_p)
 
 	early_acpi_boot_init();
 
+	x86_flattree_get_config();
+
 	initmem_init();
 	dma_contiguous_reserve(max_pfn_mapped << PAGE_SHIFT);
 
-- 
2.34.1