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
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 0940078..3b8e262 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -774,6 +774,15 @@
disable= [IPV6]
See Documentation/networking/ipv6.txt.
+ disable_cpu_apicid= [X86,APIC,SMP]
+ Format: <int>
+ The number of initial APIC ID for the
+ corresponding CPU to be disabled at boot,
+ mostly used for the kdump 2nd kernel to
+ disable BSP to wake up multiple CPUs without
+ causing system reset or hang due to sending
+ INIT from AP to BSP.
+
disable_ddw [PPC/PSERIES]
Disable Dynamic DMA Window support. Use this if
to workaround buggy firmware.
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index d278736..7f26c9a 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -75,6 +75,13 @@
physid_mask_t phys_cpu_present_map;
/*
+ * Processor to be disabled specified by kernel parameter
+ * disable_cpu_apicid=<int>, mostly used for the kdump 2nd kernel to
+ * avoid undefined behaviour caused by sending INIT from AP to BSP.
+ */
+static unsigned int disabled_cpu_apicid __read_mostly = BAD_APICID;
+
+/*
* Map cpu index to physical APIC ID
*/
DEFINE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_cpu_to_apicid, BAD_APICID);
@@ -1968,7 +1975,7 @@
*/
static inline void __smp_error_interrupt(struct pt_regs *regs)
{
- u32 v0, v1;
+ u32 v;
u32 i = 0;
static const char * const error_interrupt_reason[] = {
"Send CS error", /* APIC Error Bit 0 */
@@ -1982,21 +1989,20 @@
};
/* First tickle the hardware, only then report what went on. -- REW */
- v0 = apic_read(APIC_ESR);
apic_write(APIC_ESR, 0);
- v1 = apic_read(APIC_ESR);
+ v = apic_read(APIC_ESR);
ack_APIC_irq();
atomic_inc(&irq_err_count);
- apic_printk(APIC_DEBUG, KERN_DEBUG "APIC error on CPU%d: %02x(%02x)",
- smp_processor_id(), v0 , v1);
+ apic_printk(APIC_DEBUG, KERN_DEBUG "APIC error on CPU%d: %02x",
+ smp_processor_id(), v);
- v1 = v1 & 0xff;
- while (v1) {
- if (v1 & 0x1)
+ v &= 0xff;
+ while (v) {
+ if (v & 0x1)
apic_printk(APIC_DEBUG, KERN_CONT " : %s", error_interrupt_reason[i]);
i++;
- v1 >>= 1;
+ v >>= 1;
}
apic_printk(APIC_DEBUG, KERN_CONT "\n");
@@ -2115,6 +2121,39 @@
phys_cpu_present_map);
/*
+ * boot_cpu_physical_apicid is designed to have the apicid
+ * returned by read_apic_id(), i.e, the apicid of the
+ * currently booting-up processor. However, on some platforms,
+ * it is temporarily modified by the apicid reported as BSP
+ * through MP table. Concretely:
+ *
+ * - arch/x86/kernel/mpparse.c: MP_processor_info()
+ * - arch/x86/mm/amdtopology.c: amd_numa_init()
+ * - arch/x86/platform/visws/visws_quirks.c: MP_processor_info()
+ *
+ * This function is executed with the modified
+ * boot_cpu_physical_apicid. So, disabled_cpu_apicid kernel
+ * parameter doesn't work to disable APs on kdump 2nd kernel.
+ *
+ * Since fixing handling of boot_cpu_physical_apicid requires
+ * another discussion and tests on each platform, we leave it
+ * for now and here we use read_apic_id() directly in this
+ * function, generic_processor_info().
+ */
+ if (disabled_cpu_apicid != BAD_APICID &&
+ disabled_cpu_apicid != read_apic_id() &&
+ disabled_cpu_apicid == apicid) {
+ int thiscpu = num_processors + disabled_cpus;
+
+ pr_warning("APIC: Disabling requested cpu."
+ " Processor %d/0x%x ignored.\n",
+ thiscpu, apicid);
+
+ disabled_cpus++;
+ return -ENODEV;
+ }
+
+ /*
* If boot cpu has not been detected yet, then only allow upto
* nr_cpu_ids - 1 processors and keep one slot free for boot cpu
*/
@@ -2592,3 +2631,12 @@
* that is using request_resource
*/
late_initcall(lapic_insert_resource);
+
+static int __init apic_set_disabled_cpu_apicid(char *arg)
+{
+ if (!arg || !get_option(&arg, &disabled_cpu_apicid))
+ return -EINVAL;
+
+ return 0;
+}
+early_param("disable_cpu_apicid", apic_set_disabled_cpu_apicid);