6 files changed, 46 insertions, 2 deletions
diff --git a/sys/arch/amd64/amd64/machdep.c b/sys/arch/amd64/amd64/machdep.c
index efd1af8..19dcf44 100644
--- a/sys/arch/amd64/amd64/machdep.c
+++ b/sys/arch/amd64/amd64/machdep.c
@@ -418,6 +418,7 @@ cpu_startup(struct cpu_info *ci)
     setup_vectors(ci);
 
     try_mitigate_spectre();
+    ci->online = 1;
 
     cpu_get_info(ci);
     cpu_enable_smep();
diff --git a/sys/include/arch/amd64/cdefs.h b/sys/include/arch/amd64/cdefs.h
index 0a20324..d038a15 100644
--- a/sys/include/arch/amd64/cdefs.h
+++ b/sys/include/arch/amd64/cdefs.h
@@ -31,7 +31,7 @@
 #define _AMD64_CDEFS_H_
 
 #include <sys/cdefs.h>
-#include <machine/sync.h>
+#include <machine/cpu.h>
 
 /*
  * Please use CLI wisely, it is a good idea to use
@@ -41,7 +41,7 @@
 #define md_pause()  __ASMV("rep; nop")      /* (F3 90) PAUSE */
 #define md_intoff() __ASMV("cli")           /* Clear interrupts */
 #define md_inton()  __ASMV("sti")           /* Enable interrupts */
-#define md_hlt()    __ASMV("hlt")           /* Halt the processor */
+#define md_hlt() cpu_halt()                 /* Halt the processor */
 
 /*
  * AMD64 specific defines
diff --git a/sys/include/arch/amd64/cpu.h b/sys/include/arch/amd64/cpu.h
index 046b621..116661b 100644
--- a/sys/include/arch/amd64/cpu.h
+++ b/sys/include/arch/amd64/cpu.h
@@ -36,6 +36,7 @@
 #include <sys/sched.h>
 #include <sys/spinlock.h>
 #include <machine/tss.h>
+#include <machine/cdefs.h>
 
 #define CPU_IRQ(IRQ_N) (BIT((IRQ_N)) & 0xFF)
 
@@ -51,6 +52,7 @@ struct cpu_info {
     uint8_t family : 4;         /* CPU family ID */
     uint8_t has_x2apic : 1;
     uint8_t tlb_shootdown : 1;
+    uint8_t online : 1;         /* CPU online */
     uint8_t ipl;
     size_t lapic_tmr_freq;
     uint8_t irq_mask;
@@ -80,4 +82,18 @@ void mp_bootstrap_aps(struct cpu_info *ci);
 
 extern struct cpu_info g_bsp_ci;
 
+__always_inline static inline void
+cpu_halt(void)
+{
+    struct cpu_info *ci = this_cpu();
+
+    if (ci != NULL)
+        ci->online = 0;
+
+    __ASMV("hlt");
+
+    if (ci != NULL)
+        ci->online = 1;
+}
+
 #endif  /* !_MACHINE_CPU_H_ */
diff --git a/sys/include/sys/queue.h b/sys/include/sys/queue.h
index e5d607d..92c1ff2 100644
--- a/sys/include/sys/queue.h
+++ b/sys/include/sys/queue.h
@@ -27,7 +27,12 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
+#if !defined(_KERNEL)
+#include <stdint.h>
+#include <stddef.h>
+#else
 #include <sys/types.h>
+#endif  /* !_KERNEL */
 
 #ifndef _QUEUE_H_
 #define _QUEUE_H_
diff --git a/sys/include/sys/sched.h b/sys/include/sys/sched.h
index abc2718..7a859b2 100644
--- a/sys/include/sys/sched.h
+++ b/sys/include/sys/sched.h
@@ -49,11 +49,13 @@ struct sched_cpu {
  *
  * @nproc: Number processes running
  * @ncpu: Number of CPU cores
+ * @nhlt: Number of halted CPU cores
  * @quantum_usec: Scheduler quantum (microseconds)
  */
 struct sched_stat {
     size_t nproc;
     uint16_t ncpu;
+    uint16_t nhlt;
     uint32_t quantum_usec;
     struct sched_cpu cpus[CPU_MAX];
 };
diff --git a/sys/kern/kern_accnt.c b/sys/kern/kern_accnt.c
index cd15863..51905e7 100644
--- a/sys/kern/kern_accnt.c
+++ b/sys/kern/kern_accnt.c
@@ -58,6 +58,25 @@ ctl_stat_read(struct ctlfs_dev *cdp, struct sio_txn *sio)
     return sio->len;
 }
 
+static uint16_t
+cpu_nhlt(void)
+{
+    uint16_t nhlt = 0;
+    struct cpu_info *ci;
+
+    for (size_t i = 0; i < CPU_MAX; ++i) {
+        ci = cpu_get(i);
+        if (ci == NULL) {
+            continue;
+        }
+        if (!ci->online) {
+            ++nhlt;
+        }
+    }
+
+    return nhlt;
+}
+
 /*
  * Get scheduler accounting information
  *
@@ -71,6 +90,7 @@ sched_stat(struct sched_stat *statp)
     statp->nproc = atomic_load_64(&g_nthreads);
     statp->ncpu = cpu_count();
     statp->quantum_usec = DEFAULT_TIMESLICE_USEC;
+    statp->nhlt = cpu_nhlt();
 
     /*
      * Setup the per-cpu info/statistics