| Message ID | 20615df14ae2eb713ea7a5f5123c1dc4c7ca993d.1434501121.git.luto@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Jun 16, 2015 at 05:35:50PM -0700, Andy Lutomirski wrote: > 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(-) Acked-by: Borislav Petkov <bp@suse.de>
On 17/06/2015 02:35, Andy Lutomirski wrote: > 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. Or more simply, KVM (host-side) requires the TSC to exist. Acked-by: Paolo Bonzini <pbonzini@redhat.com> > (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; > > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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;
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(-)