releases/4.7.8/x86-apic-get-rid-of-apic_version-array.patch

From cff9ab2b291e64259d97add48fe073c081afe4e2 Mon Sep 17 00:00:00 2001
From: Denys Vlasenko <dvlasenk@redhat.com>
Date: Tue, 13 Sep 2016 20:12:32 +0200
Subject: x86/apic: Get rid of apic_version[] array

From: Denys Vlasenko <dvlasenk@redhat.com>

commit cff9ab2b291e64259d97add48fe073c081afe4e2 upstream.

The array has a size of MAX_LOCAL_APIC, which can be as large as 32k, so it
can consume up to 128k.

The array has been there forever and was never used for anything useful
other than a version mismatch check which was introduced in 2009.

There is no reason to store the version in an array. The kernel is not
prepared to handle different APIC versions anyway, so the real important
part is to detect a version mismatch and warn about it, which can be done
with a single variable as well.

[ tglx: Massaged changelog ]

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
CC: Andy Lutomirski <luto@amacapital.net>
CC: Borislav Petkov <bp@alien8.de>
CC: Brian Gerst <brgerst@gmail.com>
CC: Mike Travis <travis@sgi.com>
Link: http://lkml.kernel.org/r/20160913181232.30815-1-dvlasenk@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/include/asm/mpspec.h   |    2 +-
 arch/x86/kernel/acpi/boot.c     |    2 +-
 arch/x86/kernel/apic/apic.c     |   17 +++++++----------
 arch/x86/kernel/apic/io_apic.c  |    4 ++--
 arch/x86/kernel/apic/probe_32.c |    2 +-
 arch/x86/kernel/smpboot.c       |   10 +++++-----
 6 files changed, 17 insertions(+), 20 deletions(-)

--- a/arch/x86/include/asm/mpspec.h
+++ b/arch/x86/include/asm/mpspec.h
@@ -6,7 +6,6 @@
 #include <asm/x86_init.h>
 #include <asm/apicdef.h>
 
-extern int apic_version[];
 extern int pic_mode;
 
 #ifdef CONFIG_X86_32
@@ -40,6 +39,7 @@ extern int mp_bus_id_to_type[MAX_MP_BUSS
 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
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -180,7 +180,7 @@ static int acpi_register_lapic(int id, u
 	}
 
 	if (boot_cpu_physical_apicid != -1U)
-		ver = apic_version[boot_cpu_physical_apicid];
+		ver = boot_cpu_apic_version;
 
 	return generic_processor_info(id, ver);
 }
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -64,6 +64,8 @@ unsigned disabled_cpus;
 unsigned int boot_cpu_physical_apicid = -1U;
 EXPORT_SYMBOL_GPL(boot_cpu_physical_apicid);
 
+u8 boot_cpu_apic_version;
+
 /*
  * The highest APIC ID seen during enumeration.
  */
@@ -1790,8 +1792,7 @@ void __init init_apic_mappings(void)
 		 * since smp_sanity_check is prepared for such a case
 		 * and disable smp mode
 		 */
-		apic_version[new_apicid] =
-			 GET_APIC_VERSION(apic_read(APIC_LVR));
+		boot_cpu_apic_version = GET_APIC_VERSION(apic_read(APIC_LVR));
 	}
 }
 
@@ -1806,13 +1807,10 @@ void __init register_lapic_address(unsig
 	}
 	if (boot_cpu_physical_apicid == -1U) {
 		boot_cpu_physical_apicid  = read_apic_id();
-		apic_version[boot_cpu_physical_apicid] =
-			 GET_APIC_VERSION(apic_read(APIC_LVR));
+		boot_cpu_apic_version = GET_APIC_VERSION(apic_read(APIC_LVR));
 	}
 }
 
-int apic_version[MAX_LOCAL_APIC];
-
 /*
  * Local APIC interrupts
  */
@@ -2102,11 +2100,10 @@ int generic_processor_info(int apicid, i
 			   cpu, apicid);
 		version = 0x10;
 	}
-	apic_version[apicid] = version;
 
-	if (version != apic_version[boot_cpu_physical_apicid]) {
+	if (version != boot_cpu_apic_version) {
 		pr_warning("BIOS bug: APIC version mismatch, boot CPU: %x, CPU %d: version %x\n",
-			apic_version[boot_cpu_physical_apicid], cpu, version);
+			boot_cpu_apic_version, cpu, version);
 	}
 
 	physid_set(apicid, phys_cpu_present_map);
@@ -2249,7 +2246,7 @@ int __init APIC_init_uniprocessor(void)
 	 * Complain if the BIOS pretends there is one.
 	 */
 	if (!boot_cpu_has(X86_FEATURE_APIC) &&
-	    APIC_INTEGRATED(apic_version[boot_cpu_physical_apicid])) {
+	    APIC_INTEGRATED(boot_cpu_apic_version)) {
 		pr_err("BIOS bug, local APIC 0x%x not detected!...\n",
 			boot_cpu_physical_apicid);
 		return -1;
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1592,7 +1592,7 @@ void __init setup_ioapic_ids_from_mpc(vo
 	 * no meaning without the serial APIC bus.
 	 */
 	if (!(boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
-		|| APIC_XAPIC(apic_version[boot_cpu_physical_apicid]))
+		|| APIC_XAPIC(boot_cpu_apic_version))
 		return;
 	setup_ioapic_ids_from_mpc_nocheck();
 }
@@ -2422,7 +2422,7 @@ static int io_apic_get_unique_id(int ioa
 static u8 io_apic_unique_id(int idx, u8 id)
 {
 	if ((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) &&
-	    !APIC_XAPIC(apic_version[boot_cpu_physical_apicid]))
+	    !APIC_XAPIC(boot_cpu_apic_version))
 		return io_apic_get_unique_id(idx, id);
 	else
 		return id;
--- a/arch/x86/kernel/apic/probe_32.c
+++ b/arch/x86/kernel/apic/probe_32.c
@@ -153,7 +153,7 @@ early_param("apic", parse_apic);
 
 void __init default_setup_apic_routing(void)
 {
-	int version = apic_version[boot_cpu_physical_apicid];
+	int version = boot_cpu_apic_version;
 
 	if (num_possible_cpus() > 8) {
 		switch (boot_cpu_data.x86_vendor) {
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -676,7 +676,7 @@ wakeup_secondary_cpu_via_nmi(int apicid,
 	 * Give the other CPU some time to accept the IPI.
 	 */
 	udelay(200);
-	if (APIC_INTEGRATED(apic_version[boot_cpu_physical_apicid])) {
+	if (APIC_INTEGRATED(boot_cpu_apic_version)) {
 		maxlvt = lapic_get_maxlvt();
 		if (maxlvt > 3)			/* Due to the Pentium erratum 3AP.  */
 			apic_write(APIC_ESR, 0);
@@ -703,7 +703,7 @@ wakeup_secondary_cpu_via_init(int phys_a
 	/*
 	 * Be paranoid about clearing APIC errors.
 	 */
-	if (APIC_INTEGRATED(apic_version[phys_apicid])) {
+	if (APIC_INTEGRATED(boot_cpu_apic_version)) {
 		if (maxlvt > 3)		/* Due to the Pentium erratum 3AP.  */
 			apic_write(APIC_ESR, 0);
 		apic_read(APIC_ESR);
@@ -742,7 +742,7 @@ wakeup_secondary_cpu_via_init(int phys_a
 	 * Determine this based on the APIC version.
 	 * If we don't have an integrated APIC, don't send the STARTUP IPIs.
 	 */
-	if (APIC_INTEGRATED(apic_version[phys_apicid]))
+	if (APIC_INTEGRATED(boot_cpu_apic_version))
 		num_starts = 2;
 	else
 		num_starts = 0;
@@ -980,7 +980,7 @@ static int do_boot_cpu(int apicid, int c
 		/*
 		 * Be paranoid about clearing APIC errors.
 		*/
-		if (APIC_INTEGRATED(apic_version[boot_cpu_physical_apicid])) {
+		if (APIC_INTEGRATED(boot_cpu_apic_version)) {
 			apic_write(APIC_ESR, 0);
 			apic_read(APIC_ESR);
 		}
@@ -1235,7 +1235,7 @@ static int __init smp_sanity_check(unsig
 	/*
 	 * If we couldn't find a local APIC, then get out of here now!
 	 */
-	if (APIC_INTEGRATED(apic_version[boot_cpu_physical_apicid]) &&
+	if (APIC_INTEGRATED(boot_cpu_apic_version) &&
 	    !boot_cpu_has(X86_FEATURE_APIC)) {
 		if (!disable_apic) {
 			pr_err("BIOS bug, local APIC #%d not detected!...\n",