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diff --git a/sys/amd64/amd64/apic_vector.S b/sys/amd64/amd64/apic_vector.S
--- a/sys/amd64/amd64/apic_vector.S
+++ b/sys/amd64/amd64/apic_vector.S
@@ -203,6 +203,17 @@
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
--- a/sys/amd64/amd64/mp_machdep.c
+++ b/sys/amd64/amd64/mp_machdep.c
@@ -140,6 +140,10 @@
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 @@
#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
--- a/sys/amd64/include/smp.h
+++ b/sys/amd64/include/smp.h
@@ -30,6 +30,7 @@
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
--- a/sys/kern/subr_smp.c
+++ b/sys/kern/subr_smp.c
@@ -242,7 +242,7 @@
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 @@
* 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 @@
#endif
#if X86
- if (type == IPI_SUSPEND)
+ if (type == IPI_SUSPEND || type == IPI_OFF)
cpus = &suspended_cpus;
else
#endif
@@ -298,7 +298,7 @@
}
#if X86
- if (type == IPI_SUSPEND)
+ if (type == IPI_SUSPEND || type == IPI_OFF)
mtx_unlock_spin(&smp_ipi_mtx);
#endif
@@ -327,6 +327,13 @@
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
--- a/sys/sys/smp.h
+++ b/sys/sys/smp.h
@@ -259,6 +259,7 @@
#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
--- 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
--- a/sys/x86/include/x86_smp.h
+++ b/sys/x86/include/x86_smp.h
@@ -77,6 +77,7 @@
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 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
--- a/sys/x86/x86/mp_x86.c
+++ b/sys/x86/x86/mp_x86.c
@@ -1696,6 +1696,28 @@
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.
*/

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