Merge git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6

[cascardo/linux.git] / include / asm-i386 / tsc.h

diff --git a/include/asm-i386/tsc.h b/include/asm-i386/tsc.h
index 84016ff..3f3c1fa 100644 (file)
--- a/include/asm-i386/tsc.h
+++ b/include/asm-i386/tsc.h
@@ -35,25 +35,30 @@ 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;
 
+       /*
+        * 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,
+                                "=A" (ret), "0" (0ULL) : "ecx", "memory");
+       if (ret)
+               return ret;
+
        /*
         * Don't do an additional sync on CPUs where we know
         * RDTSC is already synchronous:
         */
        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);