linux-kernel - [tip: x86/apic] x86/of: Fix the APIC address registration

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Date:   Wed, 09 Aug 2023 15:34:15 -0000
From:   "tip-bot2 for Thomas Gleixner" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/apic] x86/of: Fix the APIC address registration

The following commit has been merged into the x86/apic branch of tip:

Commit-ID:     b735dd86b7c75df0863065ae5ab154be2dcf2a9d
Gitweb:        https://git.kernel.org/tip/b735dd86b7c75df0863065ae5ab154be2dcf2a9d
Author:        Thomas Gleixner <tglx@...utronix.de>
AuthorDate:    Tue, 08 Aug 2023 15:03:47 -07:00
Committer:     Dave Hansen <dave.hansen@...ux.intel.com>
CommitterDate: Wed, 09 Aug 2023 08:10:11 -07:00

x86/of: Fix the APIC address registration

The device tree APIC parser tries to force-enable the local APIC when it is
not set in CPUID. apic_force_enable() registers the boot CPU apic on
success.

If that succeeds then dtb_lapic_setup() registers the local APIC again
eventually with a different address.

Rewrite the code so that it only registers it once.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/x86/kernel/devicetree.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kernel/devicetree.c b/arch/x86/kernel/devicetree.c
index 56f6d59..8f94eb6 100644
--- a/arch/x86/kernel/devicetree.c
+++ b/arch/x86/kernel/devicetree.c
@@ -157,19 +157,15 @@ static void __init dtb_lapic_setup(void)
 
 	/* Did the boot loader setup the local APIC ? */
 	if (!boot_cpu_has(X86_FEATURE_APIC)) {
+		/* Try force enabling, which registers the APIC address */
 		if (apic_force_enable(lapic_addr))
 			return;
-	}
-	smp_found_config = 1;
-	if (of_property_read_bool(dn, "intel,virtual-wire-mode")) {
-		pr_info("Virtual Wire compatibility mode.\n");
-		pic_mode = 0;
 	} else {
-		pr_info("IMCR and PIC compatibility mode.\n");
-		pic_mode = 1;
+		register_lapic_address(lapic_addr);
 	}
-
-	register_lapic_address(lapic_addr);
+	smp_found_config = 1;
+	pic_mode = !of_property_read_bool(dn, "intel,virtual-wire-mode");
+	pr_info("%s compatibility mode.\n", pic_mode ? "IMCR and PIC" : "Virtual Wire");
 }
 
 #endif /* CONFIG_X86_LOCAL_APIC */