diff options
| -rw-r--r-- | Documentation/admin-guide/kdump/kdump.rst | 7 | ||||
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 9 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/topology.c | 97 |
3 files changed, 61 insertions, 52 deletions
diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst index 5762e7477a0c..0302a93b1d40 100644 --- a/Documentation/admin-guide/kdump/kdump.rst +++ b/Documentation/admin-guide/kdump/kdump.rst @@ -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 diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 31b3a25680d0..4b9b4d662e31 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -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. diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c index fc47f5216f9a..d55533170ba0 100644 --- a/arch/x86/kernel/cpu/topology.c +++ b/arch/x86/kernel/cpu/topology.c @@ -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); |