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@linutronix.de>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Juergen Gross <jgross@suse.com> # Xen PV (dom0 and unpriv. guest)

arch/x86/include/asm/mpspec.h

@@ -41,7 +41,6 @@ extern DECLARE_BITMAP(mp_bus_not_pci, MAX_MP_BUSSES);
 
 extern unsigned int boot_cpu_physical_apicid;
 extern u8 boot_cpu_apic_version;
-extern unsigned long mp_lapic_addr;
 
 #ifdef CONFIG_X86_LOCAL_APIC
 extern int smp_found_config;

arch/x86/kernel/apic/apic.c

@@ -172,7 +172,7 @@ static __init int setup_apicpmtimer(char *s)
 __setup("apicpmtimer", setup_apicpmtimer);
 #endif
 
-unsigned long mp_lapic_addr __ro_after_init;
+static unsigned long mp_lapic_addr __ro_after_init;
 bool apic_is_disabled __ro_after_init;
 /* Disable local APIC timer from the kernel commandline or via dmi quirk */
 static int disable_apic_timer __initdata;
@@ -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 long addr)
 			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;
 	}
 
@@ -2130,27 +2130,16 @@ 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);
 	}
 }
 
 static __init void apic_set_fixmap(void)
 {
 	set_fixmap_nocache(FIX_APIC_BASE, mp_lapic_addr);
-	apic_mmio_base = APIC_BASE;
+	apic_phys = apic_mmio_base = APIC_BASE;
 	apic_printk(APIC_VERBOSE, "mapped APIC to %16lx (%16lx)\n",
 		    apic_mmio_base, mp_lapic_addr);
 	apic_read_boot_cpu_id(false);
@@ -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)

arch/x86/kernel/mpparse.c

@@ -374,11 +374,6 @@ static inline void __init construct_default_ISA_mptable(int mpc_default_type)
 	int linttypes[2] = { mp_ExtINT, mp_NMI };
 	int i;
 
-	/*
-	 * local APIC has default address
-	 */
-	mp_lapic_addr = APIC_DEFAULT_PHYS_BASE;
-
 	/*
 	 * 2 CPUs, numbered 0 & 1.
 	 */
@@ -520,10 +515,8 @@ void __init default_get_smp_config(unsigned int early)
 	 */
 	if (mpf->feature1) {
 		if (early) {
-			/*
-			 * local APIC has default address
-			 */
-			mp_lapic_addr = APIC_DEFAULT_PHYS_BASE;
+			/* Local APIC has default address */
+			register_lapic_address(APIC_DEFAULT_PHYS_BASE);
 			goto out;
 		}