linux-kernel - [patch 15/58] x86/apic: Sanitize APIC address setup

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Message-ID: <20230717223223.971994770@linutronix.de>
Date:   Tue, 18 Jul 2023 01:14:57 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Wei Liu <wei.liu@...nel.org>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        Juergen Gross <jgross@...e.com>
Subject: [patch 15/58] x86/apic: Sanitize APIC address setup

Convert places which just write mp_lapic_addr and let them register the
local APIC address directly instead of relying on magic other code to do
so.

Add a WARN_ON() into register_lapic_address() which is raised when
register_lapic_address() is invoked more than once during boot.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/kernel/apic/apic.c |   25 ++++++++-----------------
 1 file changed, 8 insertions(+), 17 deletions(-)

--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -2009,12 +2009,12 @@ static bool __init detect_init_APIC(void
 		return false;
 	}
 
-	mp_lapic_addr = APIC_DEFAULT_PHYS_BASE;
+	register_lapic_address(APIC_DEFAULT_PHYS_BASE);
 	return true;
 }
 #else
 
-static bool __init apic_verify(void)
+static bool __init apic_verify(unsigned long addr)
 {
 	u32 features, h, l;
 
@@ -2028,15 +2028,15 @@ static bool __init apic_verify(void)
 		return false;
 	}
 	set_cpu_cap(&boot_cpu_data, X86_FEATURE_APIC);
-	mp_lapic_addr = APIC_DEFAULT_PHYS_BASE;
 
 	/* The BIOS may have set up the APIC at some other address */
 	if (boot_cpu_data.x86 >= 6) {
 		rdmsr(MSR_IA32_APICBASE, l, h);
 		if (l & MSR_IA32_APICBASE_ENABLE)
-			mp_lapic_addr = l & MSR_IA32_APICBASE_BASE;
+			addr = l & MSR_IA32_APICBASE_BASE;
 	}
 
+	register_lapic_address(addr);
 	pr_info("Found and enabled local APIC!\n");
 	return true;
 }
@@ -2063,7 +2063,7 @@ bool __init apic_force_enable(unsigned l
 			enabled_via_apicbase = 1;
 		}
 	}
-	return apic_verify();
+	return apic_verify(addr);
 }
 
 /*
@@ -2105,7 +2105,7 @@ static bool __init detect_init_APIC(void
 		if (!apic_force_enable(APIC_DEFAULT_PHYS_BASE))
 			return false;
 	} else {
-		if (!apic_verify())
+		if (!apic_verify(APIC_DEFAULT_PHYS_BASE))
 			return false;
 	}
 
@@ -2130,20 +2130,9 @@ void __init init_apic_mappings(void)
 	if (x2apic_mode)
 		return;
 
-	/* If no local APIC can be found return early */
 	if (!smp_found_config && !detect_init_APIC()) {
-		/* lets NOP'ify apic operations */
 		pr_info("APIC: disable apic facility\n");
 		apic_disable();
-	} else {
-		apic_phys = mp_lapic_addr;
-
-		/*
-		 * If the system has ACPI MADT tables or MP info, the LAPIC
-		 * address is already registered.
-		 */
-		if (!acpi_lapic && !smp_found_config)
-			register_lapic_address(apic_phys);
 	}
 }
 
@@ -2158,6 +2147,8 @@ static __init void apic_set_fixmap(void)
 
 void __init register_lapic_address(unsigned long address)
 {
+	/* This should only happen once */
+	WARN_ON_ONCE(mp_lapic_addr);
 	mp_lapic_addr = address;
 
 	if (!x2apic_mode)