diff options
Diffstat (limited to 'arch/x86/kernel/cpu/topology.c')
| -rw-r--r-- | arch/x86/kernel/cpu/topology.c | 78 |
1 files changed, 70 insertions, 8 deletions
diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c index 3259b1d4fefe..e35ccdc84910 100644 --- a/arch/x86/kernel/cpu/topology.c +++ b/arch/x86/kernel/cpu/topology.c @@ -30,6 +30,7 @@ #include <asm/hypervisor.h> #include <asm/io_apic.h> #include <asm/mpspec.h> +#include <asm/msr.h> #include <asm/smp.h> #include "cpu.h" @@ -123,12 +124,14 @@ static void topo_set_cpuids(unsigned int cpu, u32 apic_id, u32 acpi_id) early_per_cpu(x86_cpu_to_apicid, cpu) = apic_id; early_per_cpu(x86_cpu_to_acpiid, cpu) = acpi_id; #endif - set_cpu_possible(cpu, true); set_cpu_present(cpu, true); } static __init bool check_for_real_bsp(u32 apic_id) { + bool is_bsp = false, has_apic_base = boot_cpu_data.x86 >= 6; + u64 msr; + /* * There is no real good way to detect whether this a kdump() * kernel, but except on the Voyager SMP monstrosity which is not @@ -145,17 +148,61 @@ static __init bool check_for_real_bsp(u32 apic_id) if (topo_info.real_bsp_apic_id != BAD_APICID) return false; + /* + * Check whether the enumeration order is broken by evaluating the + * BSP bit in the APICBASE MSR. If the CPU does not have the + * APICBASE MSR then the BSP detection is not possible and the + * kernel must rely on the firmware enumeration order. + */ + if (has_apic_base) { + rdmsrq(MSR_IA32_APICBASE, msr); + is_bsp = !!(msr & MSR_IA32_APICBASE_BSP); + } + if (apic_id == topo_info.boot_cpu_apic_id) { - topo_info.real_bsp_apic_id = apic_id; - return false; + /* + * If the boot CPU has the APIC BSP bit set then the + * firmware enumeration is agreeing. If the CPU does not + * have the APICBASE MSR then the only choice is to trust + * the enumeration order. + */ + if (is_bsp || !has_apic_base) { + topo_info.real_bsp_apic_id = apic_id; + return false; + } + /* + * If the boot APIC is enumerated first, but the APICBASE + * MSR does not have the BSP bit set, then there is no way + * to discover the real BSP here. Assume a crash kernel and + * limit the number of CPUs to 1 as an INIT to the real BSP + * would reset the machine. + */ + pr_warn("Enumerated BSP APIC %x is not marked in APICBASE MSR\n", apic_id); + pr_warn("Assuming crash kernel. Limiting to one CPU to prevent machine INIT\n"); + set_nr_cpu_ids(1); + goto fwbug; } - pr_warn("Boot CPU APIC ID not the first enumerated APIC ID: %x > %x\n", + pr_warn("Boot CPU APIC ID not the first enumerated APIC ID: %x != %x\n", topo_info.boot_cpu_apic_id, apic_id); + + if (is_bsp) { + /* + * The boot CPU has the APIC BSP bit set. Use it and complain + * about the broken firmware enumeration. + */ + topo_info.real_bsp_apic_id = topo_info.boot_cpu_apic_id; + goto fwbug; + } + pr_warn("Crash kernel detected. Disabling real BSP to prevent machine INIT\n"); topo_info.real_bsp_apic_id = apic_id; return true; + +fwbug: + pr_warn(FW_BUG "APIC enumeration order not specification compliant\n"); + return false; } static unsigned int topo_unit_count(u32 lvlid, enum x86_topology_domains at_level, @@ -210,7 +257,11 @@ static __init void topo_register_apic(u32 apic_id, u32 acpi_id, bool present) topo_info.nr_disabled_cpus++; } - /* Register present and possible CPUs in the domain maps */ + /* + * Register present and possible CPUs in the domain + * maps. cpu_possible_map will be updated in + * topology_init_possible_cpus() after enumeration is done. + */ for (dom = TOPO_SMT_DOMAIN; dom < TOPO_MAX_DOMAIN; dom++) set_bit(topo_apicid(apic_id, dom), apic_maps[dom].map); } @@ -378,8 +429,8 @@ void __init topology_apply_cmdline_limits_early(void) { unsigned int possible = nr_cpu_ids; - /* 'maxcpus=0' 'nosmp' 'nolapic' 'disableapic' 'noapic' */ - if (!setup_max_cpus || ioapic_is_disabled || apic_is_disabled) + /* 'maxcpus=0' 'nosmp' 'nolapic' */ + if (!setup_max_cpus || apic_is_disabled) possible = 1; /* 'possible_cpus=N' */ @@ -393,7 +444,7 @@ void __init topology_apply_cmdline_limits_early(void) static __init bool restrict_to_up(void) { - if (!smp_found_config || ioapic_is_disabled) + if (!smp_found_config) return true; /* * XEN PV is special as it does not advertise the local APIC @@ -415,6 +466,17 @@ void __init topology_init_possible_cpus(void) unsigned int total = assigned + disabled; u32 apicid, firstid; + /* + * If there was no APIC registered, then fake one so that the + * topology bitmap is populated. That ensures that the code below + * is valid and the various query interfaces can be used + * unconditionally. This does not affect the actual APIC code in + * any way because either the local APIC address has not been + * registered or the local APIC was disabled on the command line. + */ + if (topo_info.boot_cpu_apic_id == BAD_APICID) + topology_register_boot_apic(0); + if (!restrict_to_up()) { if (WARN_ON_ONCE(assigned > nr_cpu_ids)) { disabled += assigned - nr_cpu_ids; |