diff options
Diffstat (limited to 'arch/x86/kernel/apic')
| -rw-r--r-- | arch/x86/kernel/apic/Makefile | 3 | ||||
| -rw-r--r-- | arch/x86/kernel/apic/apic.c | 34 | ||||
| -rw-r--r-- | arch/x86/kernel/apic/bigsmp_32.c | 105 | ||||
| -rw-r--r-- | arch/x86/kernel/apic/io_apic.c | 13 | ||||
| -rw-r--r-- | arch/x86/kernel/apic/ipi.c | 33 | ||||
| -rw-r--r-- | arch/x86/kernel/apic/local.h | 13 | ||||
| -rw-r--r-- | arch/x86/kernel/apic/msi.c | 3 | ||||
| -rw-r--r-- | arch/x86/kernel/apic/probe_32.c | 29 | ||||
| -rw-r--r-- | arch/x86/kernel/apic/vector.c | 231 |
9 files changed, 128 insertions, 336 deletions
diff --git a/arch/x86/kernel/apic/Makefile b/arch/x86/kernel/apic/Makefile index 3bf0487cf3b7..52d1808ee360 100644 --- a/arch/x86/kernel/apic/Makefile +++ b/arch/x86/kernel/apic/Makefile @@ -23,8 +23,5 @@ obj-$(CONFIG_X86_X2APIC) += x2apic_cluster.o obj-y += apic_flat_64.o endif -# APIC probe will depend on the listing order here -obj-$(CONFIG_X86_BIGSMP) += bigsmp_32.o - # For 32bit, probe_32 need to be listed last obj-$(CONFIG_X86_LOCAL_APIC) += probe_$(BITS).o diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index c5fb28e6451a..62584a347931 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -509,19 +509,19 @@ static struct clock_event_device lapic_clockevent = { static DEFINE_PER_CPU(struct clock_event_device, lapic_events); static const struct x86_cpu_id deadline_match[] __initconst = { - X86_MATCH_VFM_STEPPINGS(INTEL_HASWELL_X, X86_STEPPINGS(0x2, 0x2), 0x3a), /* EP */ - X86_MATCH_VFM_STEPPINGS(INTEL_HASWELL_X, X86_STEPPINGS(0x4, 0x4), 0x0f), /* EX */ + X86_MATCH_VFM_STEPS(INTEL_HASWELL_X, 0x2, 0x2, 0x3a), /* EP */ + X86_MATCH_VFM_STEPS(INTEL_HASWELL_X, 0x4, 0x4, 0x0f), /* EX */ X86_MATCH_VFM(INTEL_BROADWELL_X, 0x0b000020), - X86_MATCH_VFM_STEPPINGS(INTEL_BROADWELL_D, X86_STEPPINGS(0x2, 0x2), 0x00000011), - X86_MATCH_VFM_STEPPINGS(INTEL_BROADWELL_D, X86_STEPPINGS(0x3, 0x3), 0x0700000e), - X86_MATCH_VFM_STEPPINGS(INTEL_BROADWELL_D, X86_STEPPINGS(0x4, 0x4), 0x0f00000c), - X86_MATCH_VFM_STEPPINGS(INTEL_BROADWELL_D, X86_STEPPINGS(0x5, 0x5), 0x0e000003), + X86_MATCH_VFM_STEPS(INTEL_BROADWELL_D, 0x2, 0x2, 0x00000011), + X86_MATCH_VFM_STEPS(INTEL_BROADWELL_D, 0x3, 0x3, 0x0700000e), + X86_MATCH_VFM_STEPS(INTEL_BROADWELL_D, 0x4, 0x4, 0x0f00000c), + X86_MATCH_VFM_STEPS(INTEL_BROADWELL_D, 0x5, 0x5, 0x0e000003), - X86_MATCH_VFM_STEPPINGS(INTEL_SKYLAKE_X, X86_STEPPINGS(0x3, 0x3), 0x01000136), - X86_MATCH_VFM_STEPPINGS(INTEL_SKYLAKE_X, X86_STEPPINGS(0x4, 0x4), 0x02000014), - X86_MATCH_VFM_STEPPINGS(INTEL_SKYLAKE_X, X86_STEPPINGS(0x5, 0xf), 0), + X86_MATCH_VFM_STEPS(INTEL_SKYLAKE_X, 0x3, 0x3, 0x01000136), + X86_MATCH_VFM_STEPS(INTEL_SKYLAKE_X, 0x4, 0x4, 0x02000014), + X86_MATCH_VFM_STEPS(INTEL_SKYLAKE_X, 0x5, 0xf, 0), X86_MATCH_VFM(INTEL_HASWELL, 0x22), X86_MATCH_VFM(INTEL_HASWELL_L, 0x20), @@ -1371,8 +1371,6 @@ void __init apic_intr_mode_init(void) x86_64_probe_apic(); - x86_32_install_bigsmp(); - if (x86_platform.apic_post_init) x86_platform.apic_post_init(); @@ -1674,7 +1672,6 @@ static __init void apic_read_boot_cpu_id(bool x2apic) boot_cpu_apic_version = GET_APIC_VERSION(apic_read(APIC_LVR)); } topology_register_boot_apic(boot_cpu_physical_apicid); - x86_32_probe_bigsmp_early(); } #ifdef CONFIG_X86_X2APIC @@ -2014,8 +2011,8 @@ static bool __init detect_init_APIC(void) case X86_VENDOR_HYGON: break; case X86_VENDOR_INTEL: - if (boot_cpu_data.x86 == 6 || boot_cpu_data.x86 == 15 || - (boot_cpu_data.x86 == 5 && boot_cpu_has(X86_FEATURE_APIC))) + if ((boot_cpu_data.x86 == 5 && boot_cpu_has(X86_FEATURE_APIC)) || + boot_cpu_data.x86_vfm >= INTEL_PENTIUM_PRO) break; goto no_apic; default: @@ -2582,19 +2579,12 @@ int apic_is_clustered_box(void) /* * APIC command line parameters */ -static int __init setup_disableapic(char *arg) +static int __init setup_nolapic(char *arg) { apic_is_disabled = true; setup_clear_cpu_cap(X86_FEATURE_APIC); return 0; } -early_param("disableapic", setup_disableapic); - -/* same as disableapic, for compatibility */ -static int __init setup_nolapic(char *arg) -{ - return setup_disableapic(arg); -} early_param("nolapic", setup_nolapic); static int __init parse_lapic_timer_c2_ok(char *arg) diff --git a/arch/x86/kernel/apic/bigsmp_32.c b/arch/x86/kernel/apic/bigsmp_32.c deleted file mode 100644 index 9285d500d5b4..000000000000 --- a/arch/x86/kernel/apic/bigsmp_32.c +++ /dev/null @@ -1,105 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* - * APIC driver for "bigsmp" xAPIC machines with more than 8 virtual CPUs. - * - * Drives the local APIC in "clustered mode". - */ -#include <linux/cpumask.h> -#include <linux/dmi.h> -#include <linux/smp.h> - -#include <asm/apic.h> -#include <asm/io_apic.h> - -#include "local.h" - -static u32 bigsmp_get_apic_id(u32 x) -{ - return (x >> 24) & 0xFF; -} - -static void bigsmp_send_IPI_allbutself(int vector) -{ - default_send_IPI_mask_allbutself_phys(cpu_online_mask, vector); -} - -static void bigsmp_send_IPI_all(int vector) -{ - default_send_IPI_mask_sequence_phys(cpu_online_mask, vector); -} - -static int dmi_bigsmp; /* can be set by dmi scanners */ - -static int hp_ht_bigsmp(const struct dmi_system_id *d) -{ - printk(KERN_NOTICE "%s detected: force use of apic=bigsmp\n", d->ident); - dmi_bigsmp = 1; - - return 0; -} - - -static const struct dmi_system_id bigsmp_dmi_table[] = { - { hp_ht_bigsmp, "HP ProLiant DL760 G2", - { DMI_MATCH(DMI_BIOS_VENDOR, "HP"), - DMI_MATCH(DMI_BIOS_VERSION, "P44-"), - } - }, - - { hp_ht_bigsmp, "HP ProLiant DL740", - { DMI_MATCH(DMI_BIOS_VENDOR, "HP"), - DMI_MATCH(DMI_BIOS_VERSION, "P47-"), - } - }, - { } /* NULL entry stops DMI scanning */ -}; - -static int probe_bigsmp(void) -{ - return dmi_check_system(bigsmp_dmi_table); -} - -static struct apic apic_bigsmp __ro_after_init = { - - .name = "bigsmp", - .probe = probe_bigsmp, - - .dest_mode_logical = false, - - .disable_esr = 1, - - .cpu_present_to_apicid = default_cpu_present_to_apicid, - - .max_apic_id = 0xFE, - .get_apic_id = bigsmp_get_apic_id, - - .calc_dest_apicid = apic_default_calc_apicid, - - .send_IPI = default_send_IPI_single_phys, - .send_IPI_mask = default_send_IPI_mask_sequence_phys, - .send_IPI_mask_allbutself = NULL, - .send_IPI_allbutself = bigsmp_send_IPI_allbutself, - .send_IPI_all = bigsmp_send_IPI_all, - .send_IPI_self = default_send_IPI_self, - - .read = native_apic_mem_read, - .write = native_apic_mem_write, - .eoi = native_apic_mem_eoi, - .icr_read = native_apic_icr_read, - .icr_write = native_apic_icr_write, - .wait_icr_idle = apic_mem_wait_icr_idle, - .safe_wait_icr_idle = apic_mem_wait_icr_idle_timeout, -}; - -bool __init apic_bigsmp_possible(bool cmdline_override) -{ - return apic == &apic_bigsmp || !cmdline_override; -} - -void __init apic_bigsmp_force(void) -{ - if (apic != &apic_bigsmp) - apic_install_driver(&apic_bigsmp); -} - -apic_driver(apic_bigsmp); diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c index 1029ea4ac8ba..eebc360ed1bb 100644 --- a/arch/x86/kernel/apic/io_apic.c +++ b/arch/x86/kernel/apic/io_apic.c @@ -1165,7 +1165,7 @@ static void io_apic_print_entries(unsigned int apic, unsigned int nr_entries) (entry.ir_index_15 << 15) | entry.ir_index_0_14, entry.ir_zero); } else { apic_dbg("%s, %s, D(%02X%02X), M(%1d)\n", buf, - entry.dest_mode_logical ? "logical " : "physic al", + entry.dest_mode_logical ? "logical " : "physical", entry.virt_destid_8_14, entry.destid_0_7, entry.delivery_mode); } } @@ -1861,7 +1861,7 @@ static struct irq_chip ioapic_chip __read_mostly = { .irq_set_affinity = ioapic_set_affinity, .irq_retrigger = irq_chip_retrigger_hierarchy, .irq_get_irqchip_state = ioapic_irq_get_chip_state, - .flags = IRQCHIP_SKIP_SET_WAKE | + .flags = IRQCHIP_SKIP_SET_WAKE | IRQCHIP_MOVE_DEFERRED | IRQCHIP_AFFINITY_PRE_STARTUP, }; @@ -2503,9 +2503,7 @@ static struct resource * __init ioapic_setup_resources(void) n = IOAPIC_RESOURCE_NAME_SIZE + sizeof(struct resource); n *= nr_ioapics; - mem = memblock_alloc(n, SMP_CACHE_BYTES); - if (!mem) - panic("%s: Failed to allocate %lu bytes\n", __func__, n); + mem = memblock_alloc_or_panic(n, SMP_CACHE_BYTES); res = (void *)mem; mem += sizeof(struct resource) * nr_ioapics; @@ -2564,11 +2562,8 @@ void __init io_apic_init_mappings(void) #ifdef CONFIG_X86_32 fake_ioapic_page: #endif - ioapic_phys = (unsigned long)memblock_alloc(PAGE_SIZE, + ioapic_phys = (unsigned long)memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE); - if (!ioapic_phys) - panic("%s: Failed to allocate %lu bytes align=0x%lx\n", - __func__, PAGE_SIZE, PAGE_SIZE); ioapic_phys = __pa(ioapic_phys); } io_apic_set_fixmap(idx, ioapic_phys); diff --git a/arch/x86/kernel/apic/ipi.c b/arch/x86/kernel/apic/ipi.c index 5da693d633b7..98a57cb4aa86 100644 --- a/arch/x86/kernel/apic/ipi.c +++ b/arch/x86/kernel/apic/ipi.c @@ -3,6 +3,7 @@ #include <linux/cpumask.h> #include <linux/delay.h> #include <linux/smp.h> +#include <linux/string_choices.h> #include <asm/io_apic.h> @@ -23,7 +24,7 @@ __setup("no_ipi_broadcast=", apic_ipi_shorthand); static int __init print_ipi_mode(void) { pr_info("IPI shorthand broadcast: %s\n", - apic_ipi_shorthand_off ? "disabled" : "enabled"); + str_disabled_enabled(apic_ipi_shorthand_off)); return 0; } late_initcall(print_ipi_mode); @@ -287,34 +288,4 @@ void default_send_IPI_mask_logical(const struct cpumask *cpumask, int vector) __default_send_IPI_dest_field(mask, vector, APIC_DEST_LOGICAL); local_irq_restore(flags); } - -#ifdef CONFIG_SMP -static int convert_apicid_to_cpu(u32 apic_id) -{ - int i; - - for_each_possible_cpu(i) { - if (per_cpu(x86_cpu_to_apicid, i) == apic_id) - return i; - } - return -1; -} - -int safe_smp_processor_id(void) -{ - u32 apicid; - int cpuid; - - if (!boot_cpu_has(X86_FEATURE_APIC)) - return 0; - - apicid = read_apic_id(); - if (apicid == BAD_APICID) - return 0; - - cpuid = convert_apicid_to_cpu(apicid); - - return cpuid >= 0 ? cpuid : 0; -} -#endif #endif diff --git a/arch/x86/kernel/apic/local.h b/arch/x86/kernel/apic/local.h index 842fe28496be..bdcf609eb283 100644 --- a/arch/x86/kernel/apic/local.h +++ b/arch/x86/kernel/apic/local.h @@ -65,17 +65,4 @@ void default_send_IPI_self(int vector); void default_send_IPI_mask_sequence_logical(const struct cpumask *mask, int vector); void default_send_IPI_mask_allbutself_logical(const struct cpumask *mask, int vector); void default_send_IPI_mask_logical(const struct cpumask *mask, int vector); -void x86_32_probe_bigsmp_early(void); -void x86_32_install_bigsmp(void); -#else -static inline void x86_32_probe_bigsmp_early(void) { } -static inline void x86_32_install_bigsmp(void) { } -#endif - -#ifdef CONFIG_X86_BIGSMP -bool apic_bigsmp_possible(bool cmdline_selected); -void apic_bigsmp_force(void); -#else -static inline bool apic_bigsmp_possible(bool cmdline_selected) { return false; }; -static inline void apic_bigsmp_force(void) { } #endif diff --git a/arch/x86/kernel/apic/msi.c b/arch/x86/kernel/apic/msi.c index 340769242dea..66bc5d3e79db 100644 --- a/arch/x86/kernel/apic/msi.c +++ b/arch/x86/kernel/apic/msi.c @@ -214,6 +214,7 @@ static bool x86_init_dev_msi_info(struct device *dev, struct irq_domain *domain, if (WARN_ON_ONCE(domain != real_parent)) return false; info->chip->irq_set_affinity = msi_set_affinity; + info->chip->flags |= IRQCHIP_MOVE_DEFERRED; break; case DOMAIN_BUS_DMAR: case DOMAIN_BUS_AMDVI: @@ -315,7 +316,7 @@ static struct irq_chip dmar_msi_controller = { .irq_retrigger = irq_chip_retrigger_hierarchy, .irq_compose_msi_msg = dmar_msi_compose_msg, .irq_write_msi_msg = dmar_msi_write_msg, - .flags = IRQCHIP_SKIP_SET_WAKE | + .flags = IRQCHIP_SKIP_SET_WAKE | IRQCHIP_MOVE_DEFERRED | IRQCHIP_AFFINITY_PRE_STARTUP, }; diff --git a/arch/x86/kernel/apic/probe_32.c b/arch/x86/kernel/apic/probe_32.c index f75ee345c02d..87bc9e7ca5d6 100644 --- a/arch/x86/kernel/apic/probe_32.c +++ b/arch/x86/kernel/apic/probe_32.c @@ -93,35 +93,6 @@ static int __init parse_apic(char *arg) } early_param("apic", parse_apic); -void __init x86_32_probe_bigsmp_early(void) -{ - if (nr_cpu_ids <= 8 || xen_pv_domain()) - return; - - if (IS_ENABLED(CONFIG_X86_BIGSMP)) { - switch (boot_cpu_data.x86_vendor) { - case X86_VENDOR_INTEL: - if (!APIC_XAPIC(boot_cpu_apic_version)) - break; - /* P4 and above */ - fallthrough; - case X86_VENDOR_HYGON: - case X86_VENDOR_AMD: - if (apic_bigsmp_possible(cmdline_apic)) - return; - break; - } - } - pr_info("Limiting to 8 possible CPUs\n"); - set_nr_cpu_ids(8); -} - -void __init x86_32_install_bigsmp(void) -{ - if (nr_cpu_ids > 8 && !xen_pv_domain()) - apic_bigsmp_force(); -} - void __init x86_32_probe_apic(void) { if (!cmdline_apic) { diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c index 736f62812f5c..72fa4bb78f0a 100644 --- a/arch/x86/kernel/apic/vector.c +++ b/arch/x86/kernel/apic/vector.c @@ -888,8 +888,109 @@ static int apic_set_affinity(struct irq_data *irqd, return err ? err : IRQ_SET_MASK_OK; } +static void free_moved_vector(struct apic_chip_data *apicd) +{ + unsigned int vector = apicd->prev_vector; + unsigned int cpu = apicd->prev_cpu; + bool managed = apicd->is_managed; + + /* + * Managed interrupts are usually not migrated away + * from an online CPU, but CPU isolation 'managed_irq' + * can make that happen. + * 1) Activation does not take the isolation into account + * to keep the code simple + * 2) Migration away from an isolated CPU can happen when + * a non-isolated CPU which is in the calculated + * affinity mask comes online. + */ + trace_vector_free_moved(apicd->irq, cpu, vector, managed); + irq_matrix_free(vector_matrix, cpu, vector, managed); + per_cpu(vector_irq, cpu)[vector] = VECTOR_UNUSED; + hlist_del_init(&apicd->clist); + apicd->prev_vector = 0; + apicd->move_in_progress = 0; +} + +/* + * Called from fixup_irqs() with @desc->lock held and interrupts disabled. + */ +static void apic_force_complete_move(struct irq_data *irqd) +{ + unsigned int cpu = smp_processor_id(); + struct apic_chip_data *apicd; + unsigned int vector; + + guard(raw_spinlock)(&vector_lock); + apicd = apic_chip_data(irqd); + if (!apicd) + return; + + /* + * If prev_vector is empty or the descriptor is neither currently + * nor previously on the outgoing CPU no action required. + */ + vector = apicd->prev_vector; + if (!vector || (apicd->cpu != cpu && apicd->prev_cpu != cpu)) + return; + + /* + * This is tricky. If the cleanup of the old vector has not been + * done yet, then the following setaffinity call will fail with + * -EBUSY. This can leave the interrupt in a stale state. + * + * All CPUs are stuck in stop machine with interrupts disabled so + * calling __irq_complete_move() would be completely pointless. + * + * 1) The interrupt is in move_in_progress state. That means that we + * have not seen an interrupt since the io_apic was reprogrammed to + * the new vector. + * + * 2) The interrupt has fired on the new vector, but the cleanup IPIs + * have not been processed yet. + */ + if (apicd->move_in_progress) { + /* + * In theory there is a race: + * + * set_ioapic(new_vector) <-- Interrupt is raised before update + * is effective, i.e. it's raised on + * the old vector. + * + * So if the target cpu cannot handle that interrupt before + * the old vector is cleaned up, we get a spurious interrupt + * and in the worst case the ioapic irq line becomes stale. + * + * But in case of cpu hotplug this should be a non issue + * because if the affinity update happens right before all + * cpus rendezvous in stop machine, there is no way that the + * interrupt can be blocked on the target cpu because all cpus + * loops first with interrupts enabled in stop machine, so the + * old vector is not yet cleaned up when the interrupt fires. + * + * So the only way to run into this issue is if the delivery + * of the interrupt on the apic/system bus would be delayed + * beyond the point where the target cpu disables interrupts + * in stop machine. I doubt that it can happen, but at least + * there is a theoretical chance. Virtualization might be + * able to expose this, but AFAICT the IOAPIC emulation is not + * as stupid as the real hardware. + * + * Anyway, there is nothing we can do about that at this point + * w/o refactoring the whole fixup_irq() business completely. + * We print at least the irq number and the old vector number, + * so we have the necessary information when a problem in that + * area arises. + */ + pr_warn("IRQ fixup: irq %d move in progress, old vector %d\n", + irqd->irq, vector); + } + free_moved_vector(apicd); +} + #else -# define apic_set_affinity NULL +# define apic_set_affinity NULL +# define apic_force_complete_move NULL #endif static int apic_retrigger_irq(struct irq_data *irqd) @@ -923,39 +1024,16 @@ static void x86_vector_msi_compose_msg(struct irq_data *data, } static struct irq_chip lapic_controller = { - .name = "APIC", - .irq_ack = apic_ack_edge, - .irq_set_affinity = apic_set_affinity, - .irq_compose_msi_msg = x86_vector_msi_compose_msg, - .irq_retrigger = apic_retrigger_irq, + .name = "APIC", + .irq_ack = apic_ack_edge, + .irq_set_affinity = apic_set_affinity, + .irq_compose_msi_msg = x86_vector_msi_compose_msg, + .irq_force_complete_move = apic_force_complete_move, + .irq_retrigger = apic_retrigger_irq, }; #ifdef CONFIG_SMP -static void free_moved_vector(struct apic_chip_data *apicd) -{ - unsigned int vector = apicd->prev_vector; - unsigned int cpu = apicd->prev_cpu; - bool managed = apicd->is_managed; - - /* - * Managed interrupts are usually not migrated away - * from an online CPU, but CPU isolation 'managed_irq' - * can make that happen. - * 1) Activation does not take the isolation into account - * to keep the code simple - * 2) Migration away from an isolated CPU can happen when - * a non-isolated CPU which is in the calculated - * affinity mask comes online. - */ - trace_vector_free_moved(apicd->irq, cpu, vector, managed); - irq_matrix_free(vector_matrix, cpu, vector, managed); - per_cpu(vector_irq, cpu)[vector] = VECTOR_UNUSED; - hlist_del_init(&apicd->clist); - apicd->prev_vector = 0; - apicd->move_in_progress = 0; -} - static void __vector_cleanup(struct vector_cleanup *cl, bool check_irr) { struct apic_chip_data *apicd; @@ -1068,99 +1146,6 @@ void irq_complete_move(struct irq_cfg *cfg) __vector_schedule_cleanup(apicd); } -/* - * Called from fixup_irqs() with @desc->lock held and interrupts disabled. - */ -void irq_force_complete_move(struct irq_desc *desc) -{ - unsigned int cpu = smp_processor_id(); - struct apic_chip_data *apicd; - struct irq_data *irqd; - unsigned int vector; - - /* - * The function is called for all descriptors regardless of which - * irqdomain they belong to. For example if an IRQ is provided by - * an irq_chip as part of a GPIO driver, the chip data for that - * descriptor is specific to the irq_chip in question. - * - * Check first that the chip_data is what we expect - * (apic_chip_data) before touching it any further. - */ - irqd = irq_domain_get_irq_data(x86_vector_domain, - irq_desc_get_irq(desc)); - if (!irqd) - return; - - raw_spin_lock(&vector_lock); - apicd = apic_chip_data(irqd); - if (!apicd) - goto unlock; - - /* - * If prev_vector is empty or the descriptor is neither currently - * nor previously on the outgoing CPU no action required. - */ - vector = apicd->prev_vector; - if (!vector || (apicd->cpu != cpu && apicd->prev_cpu != cpu)) - goto unlock; - - /* - * This is tricky. If the cleanup of the old vector has not been - * done yet, then the following setaffinity call will fail with - * -EBUSY. This can leave the interrupt in a stale state. - * - * All CPUs are stuck in stop machine with interrupts disabled so - * calling __irq_complete_move() would be completely pointless. - * - * 1) The interrupt is in move_in_progress state. That means that we - * have not seen an interrupt since the io_apic was reprogrammed to - * the new vector. - * - * 2) The interrupt has fired on the new vector, but the cleanup IPIs - * have not been processed yet. - */ - if (apicd->move_in_progress) { - /* - * In theory there is a race: - * - * set_ioapic(new_vector) <-- Interrupt is raised before update - * is effective, i.e. it's raised on - * the old vector. - * - * So if the target cpu cannot handle that interrupt before - * the old vector is cleaned up, we get a spurious interrupt - * and in the worst case the ioapic irq line becomes stale. - * - * But in case of cpu hotplug this should be a non issue - * because if the affinity update happens right before all - * cpus rendezvous in stop machine, there is no way that the - * interrupt can be blocked on the target cpu because all cpus - * loops first with interrupts enabled in stop machine, so the - * old vector is not yet cleaned up when the interrupt fires. - * - * So the only way to run into this issue is if the delivery - * of the interrupt on the apic/system bus would be delayed - * beyond the point where the target cpu disables interrupts - * in stop machine. I doubt that it can happen, but at least - * there is a theoretical chance. Virtualization might be - * able to expose this, but AFAICT the IOAPIC emulation is not - * as stupid as the real hardware. - * - * Anyway, there is nothing we can do about that at this point - * w/o refactoring the whole fixup_irq() business completely. - * We print at least the irq number and the old vector number, - * so we have the necessary information when a problem in that - * area arises. - */ - pr_warn("IRQ fixup: irq %d move in progress, old vector %d\n", - irqd->irq, vector); - } - free_moved_vector(apicd); -unlock: - raw_spin_unlock(&vector_lock); -} - #ifdef CONFIG_HOTPLUG_CPU /* * Note, this is not accurate accounting, but at least good enough to |