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torvaldstorvalds
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Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86/apic changes from Ingo Molnar: "Two main changes: - improve local APIC Error Status Register reporting robustness - add the 'disable_cpu_apicid=x' boot parameter for kexec booting" * 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86, apic: Make disabled_cpu_apicid static read_mostly, fix typos x86, apic, kexec: Add disable_cpu_apicid kernel parameter x86/apic: Read Error Status Register correctly
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‎Documentation/kernel-parameters.txt

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@@ -774,6 +774,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
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disable= [IPV6]
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See Documentation/networking/ipv6.txt.
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disable_cpu_apicid= [X86,APIC,SMP]
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Format: <int>
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The number of initial APIC ID for the
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corresponding CPU to be disabled at boot,
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mostly used for the kdump 2nd kernel to
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disable BSP to wake up multiple CPUs without
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causing system reset or hang due to sending
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INIT from AP to BSP.
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disable_ddw [PPC/PSERIES]
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Disable Dynamic DMA Window support. Use this if
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to workaround buggy firmware.

‎arch/x86/kernel/apic/apic.c

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Original file line numberDiff line numberDiff line change
@@ -74,6 +74,13 @@ unsigned int max_physical_apicid;
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*/
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physid_mask_t phys_cpu_present_map;
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/*
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* Processor to be disabled specified by kernel parameter
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* disable_cpu_apicid=<int>, mostly used for the kdump 2nd kernel to
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* avoid undefined behaviour caused by sending INIT from AP to BSP.
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*/
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static unsigned int disabled_cpu_apicid __read_mostly = BAD_APICID;
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/*
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* Map cpu index to physical APIC ID
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*/
@@ -1968,7 +1975,7 @@ __visible void smp_trace_spurious_interrupt(struct pt_regs *regs)
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*/
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static inline void __smp_error_interrupt(struct pt_regs *regs)
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{
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u32 v0, v1;
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u32 v;
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u32 i = 0;
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static const char * const error_interrupt_reason[] = {
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"Send CS error", /* APIC Error Bit 0 */
@@ -1982,21 +1989,20 @@ static inline void __smp_error_interrupt(struct pt_regs *regs)
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};
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/* First tickle the hardware, only then report what went on. -- REW */
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v0 = apic_read(APIC_ESR);
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apic_write(APIC_ESR, 0);
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v1 = apic_read(APIC_ESR);
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v = apic_read(APIC_ESR);
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ack_APIC_irq();
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atomic_inc(&irq_err_count);
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apic_printk(APIC_DEBUG, KERN_DEBUG "APIC error on CPU%d: %02x(%02x)",
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smp_processor_id(), v0 , v1);
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apic_printk(APIC_DEBUG, KERN_DEBUG "APIC error on CPU%d: %02x",
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smp_processor_id(), v);
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v1 = v1 & 0xff;
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while (v1) {
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if (v1 & 0x1)
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v &= 0xff;
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while (v) {
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if (v & 0x1)
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apic_printk(APIC_DEBUG, KERN_CONT " : %s", error_interrupt_reason[i]);
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i++;
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v1 >>= 1;
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v >>= 1;
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}
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apic_printk(APIC_DEBUG, KERN_CONT "\n");
@@ -2114,6 +2120,39 @@ int generic_processor_info(int apicid, int version)
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bool boot_cpu_detected = physid_isset(boot_cpu_physical_apicid,
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phys_cpu_present_map);
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/*
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* boot_cpu_physical_apicid is designed to have the apicid
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* returned by read_apic_id(), i.e, the apicid of the
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* currently booting-up processor. However, on some platforms,
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* it is temporarily modified by the apicid reported as BSP
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* through MP table. Concretely:
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*
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* - arch/x86/kernel/mpparse.c: MP_processor_info()
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* - arch/x86/mm/amdtopology.c: amd_numa_init()
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* - arch/x86/platform/visws/visws_quirks.c: MP_processor_info()
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*
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* This function is executed with the modified
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* boot_cpu_physical_apicid. So, disabled_cpu_apicid kernel
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* parameter doesn't work to disable APs on kdump 2nd kernel.
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*
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* Since fixing handling of boot_cpu_physical_apicid requires
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* another discussion and tests on each platform, we leave it
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* for now and here we use read_apic_id() directly in this
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* function, generic_processor_info().
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*/
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if (disabled_cpu_apicid != BAD_APICID &&
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disabled_cpu_apicid != read_apic_id() &&
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disabled_cpu_apicid == apicid) {
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int thiscpu = num_processors + disabled_cpus;
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pr_warning("APIC: Disabling requested cpu."
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" Processor %d/0x%x ignored.\n",
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thiscpu, apicid);
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disabled_cpus++;
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return -ENODEV;
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}
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/*
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* If boot cpu has not been detected yet, then only allow upto
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* nr_cpu_ids - 1 processors and keep one slot free for boot cpu
@@ -2592,3 +2631,12 @@ static int __init lapic_insert_resource(void)
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* that is using request_resource
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*/
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late_initcall(lapic_insert_resource);
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static int __init apic_set_disabled_cpu_apicid(char *arg)
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{
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if (!arg || !get_option(&arg, &disabled_cpu_apicid))
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return -EINVAL;
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return 0;
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}
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early_param("disable_cpu_apicid", apic_set_disabled_cpu_apicid);

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