Date: Mon, 27 Oct 2025 14:34:34 GMT From: Justin Hibbits <jhibbits@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 190d0a96cf56 - main - amd64: Add cpu_stop() support to go UP after SMP Message-ID: <202510271434.59REYY0U063397@gitrepo.freebsd.org>
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The branch main has been updated by jhibbits: URL: https://cgit.FreeBSD.org/src/commit/?id=190d0a96cf5672c6cf0ce86eb91dd1f19d35baac commit 190d0a96cf5672c6cf0ce86eb91dd1f19d35baac Author: Justin Hibbits <jhibbits@FreeBSD.org> AuthorDate: 2025-10-26 02:45:08 +0000 Commit: Justin Hibbits <jhibbits@FreeBSD.org> CommitDate: 2025-10-27 14:33:49 +0000 amd64: Add cpu_stop() support to go UP after SMP Reviewed by: kib Sponsored by: Juniper Networks, Inc. Differential Revision: https://reviews.freebsd.org/D51622 --- sys/amd64/amd64/apic_vector.S | 11 +++++++++++ sys/amd64/amd64/mp_machdep.c | 13 +++++++++++++ sys/amd64/include/smp.h | 1 + sys/kern/subr_smp.c | 15 +++++++++++---- sys/sys/smp.h | 1 + sys/x86/include/apicvar.h | 3 ++- sys/x86/include/x86_smp.h | 2 ++ sys/x86/x86/mp_x86.c | 22 ++++++++++++++++++++++ 8 files changed, 63 insertions(+), 5 deletions(-) diff --git a/sys/amd64/amd64/apic_vector.S b/sys/amd64/amd64/apic_vector.S index e98bae9eb6c5..8691387a5a8e 100644 --- a/sys/amd64/amd64/apic_vector.S +++ b/sys/amd64/amd64/apic_vector.S @@ -203,6 +203,17 @@ IDTVEC(spuriousint) KMSAN_LEAVE jmp doreti +/* + * Executed by a CPU when it receives an IPI_OFF from another CPU. + * Should never return + */ + INTR_HANDLER cpuoff + KMSAN_ENTER + call cpuoff_handler + call as_lapic_eoi + KMSAN_LEAVE + jmp doreti + /* * Executed by a CPU when it receives an IPI_SWI. */ diff --git a/sys/amd64/amd64/mp_machdep.c b/sys/amd64/amd64/mp_machdep.c index 00e99f9df192..96ed0a2cc3ba 100644 --- a/sys/amd64/amd64/mp_machdep.c +++ b/sys/amd64/amd64/mp_machdep.c @@ -140,6 +140,10 @@ cpu_mp_start(void) setidt(IPI_STOP, pti ? IDTVEC(cpustop_pti) : IDTVEC(cpustop), SDT_SYSIGT, SEL_KPL, 0); + /* Install an inter-CPU IPI for CPU offline */ + setidt(IPI_OFF, pti ? IDTVEC(cpuoff_pti) : IDTVEC(cpuoff), + SDT_SYSIGT, SEL_KPL, 0); + /* Install an inter-CPU IPI for CPU suspend/resume */ setidt(IPI_SUSPEND, pti ? IDTVEC(cpususpend_pti) : IDTVEC(cpususpend), SDT_SYSIGT, SEL_KPL, 0); @@ -176,6 +180,15 @@ cpu_mp_start(void) #endif } +void +cpu_mp_stop(void) +{ + cpuset_t other_cpus = all_cpus; + + CPU_CLR(PCPU_GET(cpuid), &other_cpus); + offline_cpus(other_cpus); +} + /* * AP CPU's call this to initialize themselves. */ diff --git a/sys/amd64/include/smp.h b/sys/amd64/include/smp.h index bff92570ff82..28c372a2e556 100644 --- a/sys/amd64/include/smp.h +++ b/sys/amd64/include/smp.h @@ -30,6 +30,7 @@ inthand_t IDTVEC(ipi_intr_bitmap_handler_pti), IDTVEC(ipi_swi_pti), IDTVEC(cpustop_pti), + IDTVEC(cpuoff_pti), IDTVEC(cpususpend_pti), IDTVEC(rendezvous_pti); diff --git a/sys/kern/subr_smp.c b/sys/kern/subr_smp.c index 1f9577fddf9c..9f5106316018 100644 --- a/sys/kern/subr_smp.c +++ b/sys/kern/subr_smp.c @@ -242,7 +242,7 @@ generic_stop_cpus(cpuset_t map, u_int type) KASSERT( type == IPI_STOP || type == IPI_STOP_HARD #if X86 - || type == IPI_SUSPEND + || type == IPI_SUSPEND || type == IPI_OFF #endif , ("%s: invalid stop type", __func__)); @@ -260,7 +260,7 @@ generic_stop_cpus(cpuset_t map, u_int type) * will be lost, violating FreeBSD's assumption of reliable * IPI delivery. */ - if (type == IPI_SUSPEND) + if (type == IPI_SUSPEND || type == IPI_OFF) mtx_lock_spin(&smp_ipi_mtx); #endif @@ -280,7 +280,7 @@ generic_stop_cpus(cpuset_t map, u_int type) #endif #if X86 - if (type == IPI_SUSPEND) + if (type == IPI_SUSPEND || type == IPI_OFF) cpus = &suspended_cpus; else #endif @@ -298,7 +298,7 @@ generic_stop_cpus(cpuset_t map, u_int type) } #if X86 - if (type == IPI_SUSPEND) + if (type == IPI_SUSPEND || type == IPI_OFF) mtx_unlock_spin(&smp_ipi_mtx); #endif @@ -327,6 +327,13 @@ suspend_cpus(cpuset_t map) return (generic_stop_cpus(map, IPI_SUSPEND)); } + +int +offline_cpus(cpuset_t map) +{ + + return (generic_stop_cpus(map, IPI_OFF)); +} #endif /* diff --git a/sys/sys/smp.h b/sys/sys/smp.h index 252dc9dc1cae..5b968aa69791 100644 --- a/sys/sys/smp.h +++ b/sys/sys/smp.h @@ -259,6 +259,7 @@ int stop_cpus_hard(cpuset_t); #if defined(__amd64__) || defined(__i386__) int suspend_cpus(cpuset_t); int resume_cpus(cpuset_t); +int offline_cpus(cpuset_t); #endif void smp_rendezvous_action(void); diff --git a/sys/x86/include/apicvar.h b/sys/x86/include/apicvar.h index c537d0ee0cdd..551f5527ac00 100644 --- a/sys/x86/include/apicvar.h +++ b/sys/x86/include/apicvar.h @@ -134,7 +134,8 @@ #define IPI_STOP (APIC_IPI_INTS + 6) /* Stop CPU until restarted. */ #define IPI_SUSPEND (APIC_IPI_INTS + 7) /* Suspend CPU until restarted. */ #define IPI_SWI (APIC_IPI_INTS + 8) /* Run clk_intr_event. */ -#define IPI_DYN_FIRST (APIC_IPI_INTS + 9) +#define IPI_OFF (APIC_IPI_INTS + 9) /* Stop CPU forever */ +#define IPI_DYN_FIRST (APIC_IPI_INTS + 10) #define IPI_DYN_LAST (254) /* IPIs allocated at runtime */ /* diff --git a/sys/x86/include/x86_smp.h b/sys/x86/include/x86_smp.h index 8b9eb2ec9b66..f5015e9d8a24 100644 --- a/sys/x86/include/x86_smp.h +++ b/sys/x86/include/x86_smp.h @@ -77,6 +77,7 @@ extern u_long *ipi_rendezvous_counts[MAXCPU]; inthand_t IDTVEC(ipi_intr_bitmap_handler), /* Bitmap based IPIs */ IDTVEC(ipi_swi), /* Runs delayed SWI */ + IDTVEC(cpuoff), /* CPU goes offline until hard reset */ IDTVEC(cpustop), /* CPU stops & waits to be restarted */ IDTVEC(cpususpend), /* CPU suspends & waits to be resumed */ IDTVEC(rendezvous); /* handle CPU rendezvous */ @@ -93,6 +94,7 @@ void assign_cpu_ids(void); void cpu_add(u_int apic_id, char boot_cpu); void cpustop_handler(void); void cpususpend_handler(void); +void cpuoff_handler(void); void init_secondary_tail(void); void init_secondary(void); void ipi_startup(int apic_id, int vector); diff --git a/sys/x86/x86/mp_x86.c b/sys/x86/x86/mp_x86.c index c0da41a4d222..6b1715853763 100644 --- a/sys/x86/x86/mp_x86.c +++ b/sys/x86/x86/mp_x86.c @@ -1696,6 +1696,28 @@ cpususpend_handler(void) CPU_CLR_ATOMIC(cpu, &toresume_cpus); } +void +cpuoff_handler(void) +{ + u_int cpu; + + cpu = PCPU_GET(cpuid); + + /* Time to go catatonic. A reset will be required to leave. */ + disable_intr(); + lapic_disable(); + CPU_SET_ATOMIC(cpu, &suspended_cpus); + + /* + * There technically should be no need for the `while` here, since it + * cannot be interrupted (interrupts are disabled). Be safe anyway. + * Any interrupt at this point will likely be fatal, as the page tables + * are likely going away shortly. + */ + while (1) + halt(); +} + /* * Handle an IPI_SWI by waking delayed SWI thread. */home | help
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