X-Git-Url: http://pileus.org/git/?a=blobdiff_plain;f=include%2Fasm-i386%2Ftsc.h;h=a4d806610b7ff5c56dc51a628ca8f20ad73d1c89;hb=d7e28ffe6c74416b54345d6004fd0964c115b12c;hp=84016ff481b9d2e5df72a2e8bb7411088d971d53;hpb=e0cc09e295f346b7921e921f385fe5213472316a;p=~andy%2Flinux

diff --git a/include/asm-i386/tsc.h b/include/asm-i386/tsc.h
index 84016ff481b..a4d806610b7 100644
--- a/include/asm-i386/tsc.h
+++ b/include/asm-i386/tsc.h
@@ -35,8 +35,18 @@ static inline cycles_t get_cycles(void)
 static __always_inline cycles_t get_cycles_sync(void)
 {
 	unsigned long long ret;
-#ifdef X86_FEATURE_SYNC_RDTSC
-	unsigned eax;
+	unsigned eax, edx;
+
+	/*
+  	 * Use RDTSCP if possible; it is guaranteed to be synchronous
+ 	 * and doesn't cause a VMEXIT on Hypervisors
+	 */
+	alternative_io(ASM_NOP3, ".byte 0x0f,0x01,0xf9", X86_FEATURE_RDTSCP,
+		       ASM_OUTPUT2("=a" (eax), "=d" (edx)),
+		       "a" (0U), "d" (0U) : "ecx", "memory");
+	ret = (((unsigned long long)edx) << 32) | ((unsigned long long)eax);
+	if (ret)
+		return ret;
 
 	/*
 	 * Don't do an additional sync on CPUs where we know
@@ -44,18 +54,16 @@ static __always_inline cycles_t get_cycles_sync(void)
 	 */
 	alternative_io("cpuid", ASM_NOP2, X86_FEATURE_SYNC_RDTSC,
 			  "=a" (eax), "0" (1) : "ebx","ecx","edx","memory");
-#else
-	sync_core();
-#endif
 	rdtscll(ret);
 
 	return ret;
 }
 
 extern void tsc_init(void);
-extern void mark_tsc_unstable(void);
+extern void mark_tsc_unstable(char *reason);
 extern int unsynchronized_tsc(void);
 extern void init_tsc_clocksource(void);
+int check_tsc_unstable(void);
 
 /*
  * Boot-time check whether the TSCs are synchronized across