x86/apic: Get rid of apic_version[] array

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>

3 files changed, 10 insertions, 13 deletions

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 1cbae30af51c..779dae5a852f 100644
--- 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.
  */
@@ -1812,8 +1814,7 @@ 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));
 	}
 }
 
@@ -1828,13 +1829,10 @@ void __init register_lapic_address(unsigned long address)
 	}
 	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
  */
@@ -2124,11 +2122,10 @@ int generic_processor_info(int apicid, int version)
 			   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);
@@ -2271,7 +2268,7 @@ 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;
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 7491f417a8e4..48e6d84f173e 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1593,7 +1593,7 @@ void __init setup_ioapic_ids_from_mpc(void)
 	 * 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();
 }
@@ -2423,7 +2423,7 @@ static int io_apic_get_unique_id(int ioapic, int apic_id)
 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;
diff --git a/arch/x86/kernel/apic/probe_32.c b/arch/x86/kernel/apic/probe_32.c
index 7c43e716c158..563096267ca2 100644
--- a/arch/x86/kernel/apic/probe_32.c
+++ b/arch/x86/kernel/apic/probe_32.c
@@ -152,7 +152,7 @@ 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) {