Add a knob for disabling/enabling HTT, "machdep.hyperthreading_allowed".

Default off due to information disclosure on multi-user systems.

Submitted by:	cperciva
Reviewed by:	jhb

1 files changed, 8 insertions, 0 deletions

diff --git a/sys/i386/include/cpufunc.h b/sys/i386/include/cpufunc.h
index ecb84cd..9a646f6 100644
--- a/sys/i386/include/cpufunc.h
+++ b/sys/i386/include/cpufunc.h
@@ -93,6 +93,14 @@ do_cpuid(u_int ax, u_int *p)
 }
 
 static __inline void
+cpuid_count(u_int ax, u_int cx, u_int *p)
+{
+	__asm __volatile("cpuid"
+			 : "=a" (p[0]), "=b" (p[1]), "=c" (p[2]), "=d" (p[3])
+			 :  "0" (ax), "c" (cx));
+}
+
+static __inline void
 enable_intr(void)
 {
 	__asm __volatile("sti");