@@ -191,9 +191,7 @@ Dump-capture kernel config options (Arch Dependent, i386 and x86_64)
CPU is enough for kdump kernel to dump vmcore on most of systems.
However, you can also specify nr_cpus=X to enable multiple processors
- in kdump kernel. In this case, "disable_cpu_apicid=" is needed to
- tell kdump kernel which cpu is 1st kernel's BSP. Please refer to
- admin-guide/kernel-parameters.txt for more details.
+ in kdump kernel.
With CONFIG_SMP=n, the above things are not related.
@@ -454,8 +452,7 @@ Notes on loading the dump-capture kernel:
to use multi-thread programs with it, such as parallel dump feature of
makedumpfile. Otherwise, the multi-thread program may have a great
performance degradation. To enable multi-cpu support, you should bring up an
- SMP dump-capture kernel and specify maxcpus/nr_cpus, disable_cpu_apicid=[X]
- options while loading it.
+ SMP dump-capture kernel and specify maxcpus/nr_cpus options while loading it.
* For s390x there are two kdump modes: If a ELF header is specified with
the elfcorehdr= kernel parameter, it is used by the kdump kernel as it
@@ -1100,15 +1100,6 @@
Disable TLBIE instruction. Currently does not work
with KVM, with HASH MMU, or with coherent accelerators.
- 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
to workaround buggy firmware.
@@ -32,18 +32,13 @@ static struct {
unsigned int nr_disabled_cpus;
unsigned int nr_rejected_cpus;
u32 boot_cpu_apic_id;
+ u32 real_bsp_apic_id;
} topo_info __read_mostly = {
.nr_assigned_cpus = 1,
.boot_cpu_apic_id = BAD_APICID,
+ .real_bsp_apic_id = BAD_APICID,
};
-/*
- * 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 u32 disabled_cpu_apicid __ro_after_init = BAD_APICID;
-
bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
{
return phys_id == (u64)cpuid_to_apicid[cpu];
@@ -123,6 +118,60 @@ static void topo_set_cpuids(unsigned int cpu, u32 apic_id, u32 acpi_id)
cpu_mark_primary_thread(cpu, apic_id);
}
+static __init bool check_for_real_bsp(u32 apic_id)
+{
+ /*
+ * There is no real good way to detect whether this a kdump()
+ * kernel, but except on the Voyager SMP monstrosity which is not
+ * longer supported, the real BSP APIC ID is the first one which is
+ * enumerated by firmware. That allows to detect whether the boot
+ * CPU is the real BSP. If it is not, then do not register the APIC
+ * because sending INIT to the real BSP would reset the whole
+ * system.
+ *
+ * The first APIC ID which is enumerated by firmware is detectable
+ * because the boot CPU APIC ID is registered before that without
+ * invoking this code.
+ */
+ if (topo_info.real_bsp_apic_id != BAD_APICID)
+ return false;
+
+ if (apic_id == topo_info.boot_cpu_apic_id) {
+ topo_info.real_bsp_apic_id = apic_id;
+ return false;
+ }
+
+ pr_warn("Boot CPU APIC ID not the first enumerated APIC ID: %x > %x\n",
+ topo_info.boot_cpu_apic_id, apic_id);
+ pr_warn("Crash kernel detected. Disabling real BSP to prevent machine INIT\n");
+
+ topo_info.real_bsp_apic_id = apic_id;
+ return true;
+}
+
+static __init void topo_register_apic(u32 apic_id, u32 acpi_id, bool present)
+{
+ int cpu;
+
+ if (present) {
+ set_bit(apic_id, phys_cpu_present_map);
+
+ /*
+ * Double registration is valid in case of the boot CPU
+ * APIC because that is registered before the enumeration
+ * of the APICs via firmware parsers or VM guest
+ * mechanisms.
+ */
+ if (apic_id == topo_info.boot_cpu_apic_id)
+ cpu = 0;
+ else
+ cpu = topo_get_cpunr(apic_id);
+ topo_set_cpuids(cpu, apic_id, acpi_id);
+ } else {
+ topo_info.nr_disabled_cpus++;
+ }
+}
+
/**
* topology_register_apic - Register an APIC in early topology maps
* @apic_id: The APIC ID to set up
@@ -131,16 +180,13 @@ static void topo_set_cpuids(unsigned int cpu, u32 apic_id, u32 acpi_id)
*/
void __init topology_register_apic(u32 apic_id, u32 acpi_id, bool present)
{
- int cpu;
-
if (apic_id >= MAX_LOCAL_APIC) {
pr_err_once("APIC ID %x exceeds kernel limit of: %x\n", apic_id, MAX_LOCAL_APIC - 1);
topo_info.nr_rejected_cpus++;
return;
}
- if (disabled_cpu_apicid == apic_id) {
- pr_info("Disabling CPU as requested via 'disable_cpu_apicid=0x%x'.\n", apic_id);
+ if (check_for_real_bsp(apic_id)) {
topo_info.nr_rejected_cpus++;
return;
}
@@ -152,23 +198,7 @@ void __init topology_register_apic(u32 apic_id, u32 acpi_id, bool present)
return;
}
- if (present) {
- set_bit(apic_id, phys_cpu_present_map);
-
- /*
- * Double registration is valid in case of the boot CPU
- * APIC because that is registered before the enumeration
- * of the APICs via firmware parsers or VM guest
- * mechanisms.
- */
- if (apic_id == topo_info.boot_cpu_apic_id)
- cpu = 0;
- else
- cpu = topo_get_cpunr(apic_id);
- topo_set_cpuids(cpu, apic_id, acpi_id);
- } else {
- topo_info.nr_disabled_cpus++;
- }
+ topo_register_apic(apic_id, acpi_id, present);
}
/**
@@ -182,7 +212,7 @@ void __init topology_register_boot_apic(u32 apic_id)
WARN_ON_ONCE(topo_info.boot_cpu_apic_id != BAD_APICID);
topo_info.boot_cpu_apic_id = apic_id;
- topology_register_apic(apic_id, CPU_ACPIID_INVALID, true);
+ topo_register_apic(apic_id, CPU_ACPIID_INVALID, true);
}
#ifdef CONFIG_ACPI_HOTPLUG_CPU
@@ -335,12 +365,3 @@ static int __init setup_possible_cpus(char *str)
}
early_param("possible_cpus", setup_possible_cpus);
#endif
-
-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);