1 files changed, 19 insertions, 0 deletions
diff --git a/sys/arch/amd64/amd64/machdep.c b/sys/arch/amd64/amd64/machdep.c
index 19ba28a..275c23e 100644
--- a/sys/arch/amd64/amd64/machdep.c
+++ b/sys/arch/amd64/amd64/machdep.c
@@ -35,6 +35,14 @@
 #include <machine/asm.h>
 #include <machine/cpuid.h>
 
+#if defined(__SPECTRE_IBRS)
+#define SPECTRE_IBRS  __SPECTRE_IBRS
+#else
+#define SPECTRE_IBRS 0
+#endif
+
+int ibrs_enable(void);
+
 static struct cpu_info g_bsp_ci = {0};
 static struct gdtr bsp_gdtr = {
     .limit = sizeof(struct gdt_entry) * 256 - 1,
@@ -58,6 +66,16 @@ setup_vectors(void)
     idt_set_desc(0xE, IDT_TRAP_GATE, ISR(page_fault), 0);
 }
 
+static void
+try_mitigate_spectre(void)
+{
+    if (!SPECTRE_IBRS) {
+        return;
+    }
+
+    ibrs_enable();
+}
+
 void
 cpu_startup(void)
 {
@@ -66,4 +84,5 @@ cpu_startup(void)
 
     setup_vectors();
     amd64_write_gs_base((uintptr_t)&g_bsp_ci);
+    try_mitigate_spectre();
 }