From 67f9d3c5e58f1a958a2b1b7a102a71e3ce252fc4 Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Wed, 10 Jul 2024 20:59:37 -0400
Subject: kernel/amd64: reboot: Halt all with REBOOT_HALT

This commit changes how reboot() handles REBOOT_HALT. Now instead of one
core being halted, all cores will be halted through an IPI to a halt
vector.

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/arch/amd64/amd64/machdep.c | 24 ++++++++++++++++++++++++
 sys/arch/amd64/amd64/reboot.c  |  9 ++-------
 2 files changed, 26 insertions(+), 7 deletions(-)

(limited to 'sys/arch/amd64')

diff --git a/sys/arch/amd64/amd64/machdep.c b/sys/arch/amd64/amd64/machdep.c
index 03b10f0..2185028 100644
--- a/sys/arch/amd64/amd64/machdep.c
+++ b/sys/arch/amd64/amd64/machdep.c
@@ -38,6 +38,7 @@
 #include <machine/cpuid.h>
 #include <machine/lapic.h>
 #include <machine/uart.h>
+#include <machine/intr.h>
 
 #if defined(__SPECTRE_IBRS)
 #define SPECTRE_IBRS  __SPECTRE_IBRS
@@ -45,6 +46,8 @@
 #define SPECTRE_IBRS 0
 #endif
 
+static uint8_t halt_vector = 0;
+
 int ibrs_enable(void);
 void syscall_isr(void);
 
@@ -54,9 +57,21 @@ static struct gdtr bsp_gdtr = {
     .offset = (uintptr_t)&g_gdt_data[0]
 };
 
+__attribute__((__interrupt__))
+static void
+cpu_halt_isr(void *p)
+{
+    __ASMV("cli; hlt");
+    __builtin_unreachable();
+}
+
 static void
 setup_vectors(void)
 {
+    if (halt_vector == 0) {
+        halt_vector = intr_alloc_vector("cpu-halt", IPL_HIGH);
+    }
+
     idt_set_desc(0x0, IDT_TRAP_GATE, ISR(arith_err), 0);
     idt_set_desc(0x2, IDT_TRAP_GATE, ISR(nmi), 0);
     idt_set_desc(0x3, IDT_TRAP_GATE, ISR(breakpoint_handler), 0);
@@ -70,6 +85,7 @@ setup_vectors(void)
     idt_set_desc(0xD, IDT_TRAP_GATE, ISR(general_prot), 0);
     idt_set_desc(0xE, IDT_TRAP_GATE, ISR(page_fault), 0);
     idt_set_desc(0x80, IDT_USER_INT_GATE, ISR(syscall_isr), 0);
+    idt_set_desc(halt_vector, IDT_INT_GATE, ISR(cpu_halt_isr), 0);
 }
 
 static inline void
@@ -92,6 +108,14 @@ try_mitigate_spectre(void)
     ibrs_enable();
 }
 
+void
+cpu_halt_all(void)
+{
+    /* Send IPI to all cores */
+    lapic_send_ipi(0, IPI_SHORTHAND_ALL, halt_vector);
+    for (;;);
+}
+
 void
 serial_init(void)
 {
diff --git a/sys/arch/amd64/amd64/reboot.c b/sys/arch/amd64/amd64/reboot.c
index da1b46a..02126d3 100644
--- a/sys/arch/amd64/amd64/reboot.c
+++ b/sys/arch/amd64/amd64/reboot.c
@@ -31,18 +31,13 @@
 #include <sys/param.h>
 #include <sys/cdefs.h>
 #include <machine/pio.h>
-
-__always_inline static inline void
-cpu_halt(void)
-{
-    __ASMV("cli; hlt");
-}
+#include <machine/cpu.h>
 
 void
 cpu_reboot(int method)
 {
     if (ISSET(method, REBOOT_HALT)) {
-        cpu_halt();
+        cpu_halt_all();
     }
 
     /* Pulse the reset line until the machine goes down */
-- 
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