[PATCH] x86/apic: Get rid of apic_version[] array. Save up to 128k
From: Denys Vlasenko
Date: Tue Sep 13 2016 - 14:12:50 EST
This array is [MAX_LOCAL_APIC], and MAX_LOCAL_APIC can easily be up to 32k.
The "APIC version mismatch" message, which should trigger when two different
APIC versions in different CPUs are seen, is in kernel since 2009 and no one
is hitting it.
Replace the array with a single variable, u8 boot_cpu_apic_version.
(Why u8?
APIC version values as of year 2016 are no larger than 0x1f on all known CPUs.
Version field in the APIC register is 8 bit wide - not likely
to overflow byte range in foreseeable future.)
"APIC version mismatch" check is not removed.
Signed-off-by: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
CC: Ingo Molnar <mingo@xxxxxxxxxx>
CC: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
CC: "H. Peter Anvin" <hpa@xxxxxxxxx>
CC: Borislav Petkov <bp@xxxxxxxxx>
CC: Brian Gerst <brgerst@xxxxxxxxx>
CC: Mike Travis <travis@xxxxxxx>
CC: x86@xxxxxxxxxx
CC: linux-kernel@xxxxxxxxxxxxxxx
---
This is the alternative patch for
"x86/apic: Use byte array apic_version[], not int array" one.
arch/x86/include/asm/mpspec.h | 2 +-
arch/x86/kernel/acpi/boot.c | 2 +-
arch/x86/kernel/apic/apic.c | 19 ++++++++-----------
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, 18 insertions(+), 21 deletions(-)
diff --git a/arch/x86/include/asm/mpspec.h b/arch/x86/include/asm/mpspec.h
index b07233b..c2f94dc 100644
--- 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_BUSSES];
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
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 90d84c3..fbd1944 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -182,7 +182,7 @@ static int acpi_register_lapic(int id, u32 acpiid, u8 enabled)
}
if (boot_cpu_physical_apicid != -1U)
- ver = apic_version[boot_cpu_physical_apicid];
+ ver = boot_cpu_apic_version;
cpu = generic_processor_info(id, ver);
if (cpu >= 0)
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 50c95af..8f9be74 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -63,6 +63,8 @@ unsigned disabled_cpus;
/* Processor that is doing the boot up */
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.
@@ -1816,8 +1818,7 @@ 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));
}
}
@@ -1831,14 +1832,11 @@ void __init register_lapic_address(unsigned long address)
APIC_BASE, mp_lapic_addr);
}
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_physical_apicid = read_apic_id();
+ boot_cpu_apic_version = GET_APIC_VERSION(apic_read(APIC_LVR));
}
}
-int apic_version[MAX_LOCAL_APIC];
-
/*
* Local APIC interrupts
*/
@@ -2128,11 +2126,10 @@ 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);
@@ -2275,7 +2272,7 @@ 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 7491f41..48e6d84 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 7c43e71..5630962 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) {
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 4296beb..75a0454 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -690,7 +690,7 @@ wakeup_secondary_cpu_via_nmi(int apicid, unsigned long start_eip)
* 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);
@@ -717,7 +717,7 @@ wakeup_secondary_cpu_via_init(int phys_apicid, unsigned long start_eip)
/*
* 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);
@@ -756,7 +756,7 @@ wakeup_secondary_cpu_via_init(int phys_apicid, unsigned long start_eip)
* 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;
@@ -994,7 +994,7 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle)
/*
* 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);
}
@@ -1249,7 +1249,7 @@ static int __init smp_sanity_check(unsigned max_cpus)
/*
* 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",
--
2.9.2