From: Andy Lutomirski <[email protected]>

The only caller was KVM's read_tsc(). The only difference between
vget_cycles() and native_read_tsc() was that vget_cycles() returned
zero instead of crashing on TSC-less systems. KVM already checks
vclock_mode() before calling that function, so the extra check is
unnecessary. Also, KVM (host-side) requires the TSC to exist.

Signed-off-by: Andy Lutomirski <[email protected]>
Acked-by: Paolo Bonzini <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: Huang Rui <[email protected]>
Cc: John Stultz <[email protected]>
Cc: Len Brown <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: kvm ML <[email protected]>
Cc: x86-ml <[email protected]>
Link: 
http://lkml.kernel.org/r/20615df14ae2eb713ea7a5f5123c1dc4c7ca993d.1434501121.git.l...@kernel.org
Signed-off-by: Borislav Petkov <[email protected]>
---
 arch/x86/include/asm/tsc.h | 13 -------------
 arch/x86/kvm/x86.c         |  2 +-
 2 files changed, 1 insertion(+), 14 deletions(-)

diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h
index fd11128faf25..3da1cc1218ac 100644
--- a/arch/x86/include/asm/tsc.h
+++ b/arch/x86/include/asm/tsc.h
@@ -32,19 +32,6 @@ static inline cycles_t get_cycles(void)
        return ret;
 }
 
-static __always_inline cycles_t vget_cycles(void)
-{
-       /*
-        * We only do VDSOs on TSC capable CPUs, so this shouldn't
-        * access boot_cpu_data (which is not VDSO-safe):
-        */
-#ifndef CONFIG_X86_TSC
-       if (!cpu_has_tsc)
-               return 0;
-#endif
-       return (cycles_t)native_read_tsc();
-}
-
 extern void tsc_init(void);
 extern void mark_tsc_unstable(char *reason);
 extern int unsynchronized_tsc(void);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 26eaeb522cab..c26faf408bce 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1430,7 +1430,7 @@ static cycle_t read_tsc(void)
         * but no one has ever seen it happen.
         */
        rdtsc_barrier();
-       ret = (cycle_t)vget_cycles();
+       ret = (cycle_t)native_read_tsc();
 
        last = pvclock_gtod_data.clock.cycle_last;
 
-- 
2.3.5

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