linux-kernel - [PATCH v2 2/6] x86/boot: Remove extra call to copy

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Message-Id: <20230412184502.145289-3-brgerst@gmail.com>
Date:   Wed, 12 Apr 2023 14:44:58 -0400
From:   Brian Gerst <brgerst@...il.com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>, Brian Gerst <brgerst@...il.com>
Subject: [PATCH v2 2/6] x86/boot: Remove extra call to copy_bootdata()

The call to copy_bootdata() in x86_64_start_reservations() is only
applicable to Xen, since native has already call it.  Xen on the other
hand, has already filled in boot_params and just passes its address in,
so the copy ends up being a no-op and can be removed.

Signed-off-by: Brian Gerst <brgerst@...il.com>
---
 arch/x86/include/asm/setup.h | 2 +-
 arch/x86/kernel/head64.c     | 8 ++------
 arch/x86/xen/enlighten_pv.c  | 2 +-
 3 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
index f37cbff7354c..fd409b7dda74 100644
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -129,7 +129,7 @@ asmlinkage void __init i386_start_kernel(void);
 
 #else
 asmlinkage void __init x86_64_start_kernel(char *real_mode);
-asmlinkage void __init x86_64_start_reservations(char *real_mode_data);
+asmlinkage void __init x86_64_start_reservations(void);
 
 #endif /* __i386__ */
 #endif /* _SETUP */
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 4a3b195c9002..6e0f53a66678 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -533,15 +533,11 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
 	/* set init_top_pgt kernel high mapping*/
 	init_top_pgt[511] = early_top_pgt[511];
 
-	x86_64_start_reservations(real_mode_data);
+	x86_64_start_reservations();
 }
 
-void __init x86_64_start_reservations(char *real_mode_data)
+void __init x86_64_start_reservations(void)
 {
-	/* version is always not zero if it is copied */
-	if (!boot_params.hdr.version)
-		copy_bootdata(__va(real_mode_data));
-
 	sanitize_boot_params(&boot_params);
 
 	x86_early_init_platform_quirks();
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 5a034a994682..a4db5c28af57 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -1430,7 +1430,7 @@ asmlinkage __visible void __init xen_start_kernel(struct start_info *si)
 
 	/* Start the world */
 	cr4_init_shadow(); /* 32b kernel does this in i386_start_kernel() */
-	x86_64_start_reservations((char *)__pa_symbol(&boot_params));
+	x86_64_start_reservations();
 }
 
 static int xen_cpu_up_prepare_pv(unsigned int cpu)
-- 
2.39.2