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| author |   Andy Lutomirski <luto@kernel.org> | 2015-06-25 18:44:11 +0200 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2015-07-06 15:23:30 +0200 |
| commit | 502dfeff239e8313bfbe906ca0a1a6827ac8481b (patch) | |
| tree | 00e069166b5fb7e115b52d1b9d5d9e9d3c8b3e20 /arch/x86/include/asm/pvclock.h | |
| parent | x86/asm/tsc: Use rdtsc_ordered() in read_tsc() instead of get_cycles() (diff) | |
| download | linux-dev-502dfeff239e8313bfbe906ca0a1a6827ac8481b.tar.xz linux-dev-502dfeff239e8313bfbe906ca0a1a6827ac8481b.zip | |
x86/asm/tsc, x86/kvm: Drop open-coded barrier and use rdtsc_ordered() in kvmclock
__pvclock_read_cycles() used to have two barriers, one of which was unnecessary,
which got removed after an initial version of this patch was sent.
But the barrier is still open-coded unnecessarily - get rid of
that barrier and clean up the code by just using rdtsc_ordered().
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Huang Rui <ray.huang@amd.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krcmar <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm ML <kvm@vger.kernel.org>
Link: http://lkml.kernel.org/r/678981cc4761fb38a793c217c9cac42503cf3719.1434501121.git.luto@kernel.org
[ Ported it to v4.2-rc1. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/pvclock.h')
| -rw-r--r-- | arch/x86/include/asm/pvclock.h | 10 |
1 files changed, 2 insertions, 8 deletions
diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h index 5c490db62e32..7a6bed5c08bc 100644 --- a/arch/x86/include/asm/pvclock.h +++ b/arch/x86/include/asm/pvclock.h @@ -62,7 +62,7 @@ static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift) static __always_inline u64 pvclock_get_nsec_offset(const struct pvclock_vcpu_time_info *src) { - u64 delta = rdtsc() - src->tsc_timestamp; + u64 delta = rdtsc_ordered() - src->tsc_timestamp; return pvclock_scale_delta(delta, src->tsc_to_system_mul, src->tsc_shift); } @@ -76,13 +76,7 @@ unsigned __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src, u8 ret_flags; version = src->version; - /* Note: emulated platforms which do not advertise SSE2 support - * result in kvmclock not using the necessary RDTSC barriers. - * Without barriers, it is possible that RDTSC instruction reads from - * the time stamp counter outside rdtsc_barrier protected section - * below, resulting in violation of monotonicity. - */ - rdtsc_barrier(); + offset = pvclock_get_nsec_offset(src); ret = src->system_time + offset; ret_flags = src->flags; |