linux-kernel - [RFC][PATCH 34/34] x86/cpu: Mark new boot CPU and config structures appropriately

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Date: Thu, 22 Feb 2024 10:40:11 -0800
From: Dave Hansen <dave.hansen@...ux.intel.com>
To: linux-kernel@...r.kernel.org
Cc: kirill.shutemov@...ux.intel.com,pbonzini@...hat.com,tglx@...utronix.de,x86@...nel.org,bp@...en8.de,Dave Hansen <dave.hansen@...ux.intel.com>
Subject: [RFC][PATCH 34/34] x86/cpu: Mark new boot CPU and config structures appropriately


From: Dave Hansen <dave.hansen@...ux.intel.com>

Just to recap the rules:

 1. 'bsp_addr_config' is only used in early boot by the BSP.
 2. 'x86_config' is only written once by the BSP and can be
    used read-only during normal system operation

Mark 'bsp_addr_config' so it goes away after boot *and* non-init
references to it can be detected and warned about.

Mark 'x86_config' as __ro_after_init so it does not turn into the same
mess that 'boot_cpu_data' is.

Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
---

 b/arch/x86/kernel/setup.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff -puN arch/x86/kernel/setup.c~mark-new-structs arch/x86/kernel/setup.c
--- a/arch/x86/kernel/setup.c~mark-new-structs	2024-02-22 10:09:05.173109438 -0800
+++ b/arch/x86/kernel/setup.c	2024-02-22 10:09:05.177109595 -0800
@@ -131,8 +131,8 @@ struct ist_info ist_info;
 struct cpuinfo_x86 boot_cpu_data __read_mostly;
 EXPORT_SYMBOL(boot_cpu_data);
 
-struct x86_addr_config bsp_addr_config;
-struct x86_sys_config x86_config __read_mostly;
+struct x86_addr_config bsp_addr_config __initdata;
+struct x86_sys_config x86_config __ro_after_init;
 
 #if !defined(CONFIG_X86_PAE) || defined(CONFIG_X86_64)
 __visible unsigned long mmu_cr4_features __ro_after_init;
_