[PATCH v3 02/18] x86/msr/kvm: Remove vget_cycles()

Andy Lutomirski
2015-06-17T00:36:46Z

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's already checks
vclock_mode before calling that function, so the extra check is
unnecessary.

(Off-topic, but the whole KVM clock host implementation is gross.
IMO it should be rewritten.)

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
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;

--
2.4.2