From: Zachary Amsden <zamsden@redhat.com>
To: kvm@vger.kernel.org
Cc: Zachary Amsden <zamsden@redhat.com>, Avi Kivity <avi@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
Glauber Costa <glommer@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
John Stultz <johnstul@us.ibm.com>,
linux-kernel@vger.kernel.org
Subject: [KVM timekeeping 33/35] Indicate reliable TSC in kvmclock
Date: Thu, 19 Aug 2010 22:07:47 -1000 [thread overview]
Message-ID: <1282291669-25709-34-git-send-email-zamsden@redhat.com> (raw)
In-Reply-To: <1282291669-25709-1-git-send-email-zamsden@redhat.com>
When no platform bugs have been detected, no TSC warps have been
detected, and the hardware guarantees to us TSC does not change
rate or stop with P-state or C-state changes, we can consider it reliable.
Signed-off-by: Zachary Amsden <zamsden@redhat.com>
---
arch/x86/kvm/x86.c | 10 +++++++++-
1 files changed, 9 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 86f182a..a7fa24e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -55,6 +55,7 @@
#include <asm/mce.h>
#include <asm/i387.h>
#include <asm/xcr.h>
+#include <asm/pvclock-abi.h>
#define MAX_IO_MSRS 256
#define CR0_RESERVED_BITS \
@@ -900,6 +901,13 @@ static void kvm_get_time_scale(uint32_t scaled_khz, uint32_t base_khz,
static DEFINE_PER_CPU(unsigned long, cpu_tsc_khz);
unsigned long max_tsc_khz;
+static inline int kvm_tsc_reliable(void)
+{
+ return (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) &&
+ boot_cpu_has(X86_FEATURE_NONSTOP_TSC) &&
+ !check_tsc_unstable());
+}
+
static inline u64 nsec_to_cycles(struct kvm *kvm, u64 nsec)
{
return pvclock_scale_delta(nsec, kvm->arch.virtual_tsc_mult,
@@ -1151,7 +1159,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
vcpu->hv_clock.tsc_timestamp = tsc_timestamp;
vcpu->hv_clock.system_time = kernel_ns + v->kvm->arch.kvmclock_offset;
vcpu->last_kernel_ns = kernel_ns;
- vcpu->hv_clock.flags = 0;
+ vcpu->hv_clock.flags = kvm_tsc_reliable() ? PVCLOCK_TSC_STABLE_BIT : 0;
/*
* The interface expects us to write an even number signaling that the
--
1.7.1
next prev parent reply other threads:[~2010-08-20 8:07 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-20 8:07 KVM timekeeping and TSC virtualization Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 01/35] Drop vm_init_tsc Zachary Amsden
2010-08-20 16:54 ` Glauber Costa
2010-08-20 8:07 ` [KVM timekeeping 02/35] Convert TSC writes to TSC offset writes Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 03/35] Move TSC offset writes to common code Zachary Amsden
2010-08-20 17:06 ` Glauber Costa
2010-08-24 0:51 ` Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 04/35] Fix SVM VMCB reset Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 05/35] Move TSC reset out of vmcb_init Zachary Amsden
2010-08-20 17:08 ` Glauber Costa
2010-08-24 0:52 ` Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 06/35] TSC reset compensation Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 07/35] Make cpu_tsc_khz updates use local CPU Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 08/35] Warn about unstable TSC Zachary Amsden
2010-08-20 17:28 ` Glauber Costa
2010-08-24 0:56 ` Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 09/35] Unify TSC logic Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 10/35] Fix deep C-state TSC desynchronization Zachary Amsden
2010-08-20 17:30 ` Glauber Costa
2010-09-14 9:10 ` Jan Kiszka
2010-09-14 9:27 ` Avi Kivity
2010-09-14 10:40 ` Jan Kiszka
2010-09-14 10:47 ` Avi Kivity
2010-09-14 19:32 ` Zachary Amsden
2010-09-14 22:26 ` Jan Kiszka
2010-09-14 23:40 ` Zachary Amsden
2010-09-15 5:34 ` Jan Kiszka
2010-09-15 7:55 ` Avi Kivity
2010-09-15 8:04 ` Jan Kiszka
2010-09-15 12:29 ` Glauber Costa
2010-09-15 4:07 ` Zachary Amsden
2010-09-15 8:09 ` Jan Kiszka
2010-09-15 12:32 ` Glauber Costa
2010-09-15 18:27 ` Jan Kiszka
2010-09-17 22:09 ` Zachary Amsden
2010-09-17 22:31 ` Zachary Amsden
2010-09-18 23:53 ` Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 11/35] Add helper functions for time computation Zachary Amsden
2010-08-20 17:34 ` Glauber Costa
2010-08-24 0:58 ` Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 12/35] Robust TSC compensation Zachary Amsden
2010-08-20 17:40 ` Glauber Costa
2010-08-24 1:01 ` Zachary Amsden
2010-08-24 21:33 ` Daniel Verkamp
2010-08-20 8:07 ` [KVM timekeeping 13/35] Perform hardware_enable in CPU_STARTING callback Zachary Amsden
2010-08-27 16:32 ` Jan Kiszka
2010-08-27 23:43 ` Zachary Amsden
2010-08-30 9:10 ` Jan Kiszka
2010-08-20 8:07 ` [KVM timekeeping 14/35] Add clock sync request to hardware enable Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 15/35] Move scale_delta into common header Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 16/35] Fix a possible backwards warp of kvmclock Zachary Amsden
2011-09-02 18:34 ` Philipp Hahn
2011-09-05 14:06 ` [BUG, PATCH-2.6.32] " Philipp Hahn
2011-09-12 11:32 ` Marcelo Tosatti
2010-08-20 8:07 ` [KVM timekeeping 17/35] Implement getnsboottime kernel API Zachary Amsden
2010-08-20 18:39 ` john stultz
2010-08-20 23:37 ` Zachary Amsden
2010-08-21 0:02 ` john stultz
2010-08-21 0:52 ` Zachary Amsden
2010-08-21 1:04 ` john stultz
2010-08-21 1:22 ` Zachary Amsden
2010-08-27 18:05 ` Jan Kiszka
2010-08-27 23:48 ` Zachary Amsden
2010-08-30 18:07 ` Jan Kiszka
2010-08-20 8:07 ` [KVM timekeeping 18/35] Use getnsboottime in KVM Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 19/35] Add timekeeping documentation Zachary Amsden
2010-08-20 17:50 ` Glauber Costa
2010-08-20 8:07 ` [KVM timekeeping 20/35] Make math work for other scales Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 21/35] Track max tsc_khz Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 22/35] Track tsc last write in vcpu Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 23/35] Set initial TSC rate conversion factors Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 24/35] Timer request function renaming Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 25/35] Add clock catchup mode Zachary Amsden
2010-08-25 17:27 ` Marcelo Tosatti
2010-08-25 20:48 ` Zachary Amsden
2010-08-25 22:01 ` Marcelo Tosatti
2010-08-25 23:38 ` Glauber Costa
2010-08-26 0:17 ` Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 26/35] Catchup slower TSC to guest rate Zachary Amsden
2010-09-07 3:44 ` Dong, Eddie
2010-09-07 22:14 ` Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 27/35] Add TSC trapping Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 28/35] Unstable TSC write compensation Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 29/35] TSC overrun protection Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 30/35] IOCTL for setting TSC rate Zachary Amsden
2010-08-20 17:56 ` Glauber Costa
2010-08-21 16:11 ` Arnd Bergmann
2010-08-20 8:07 ` [KVM timekeeping 31/35] Exit conditions for TSC trapping Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 32/35] Entry " Zachary Amsden
2010-08-20 8:07 ` Zachary Amsden [this message]
2010-08-20 17:45 ` [KVM timekeeping 33/35] Indicate reliable TSC in kvmclock Glauber Costa
2010-08-24 1:14 ` Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 34/35] Remove dead code Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 35/35] Add some debug stuff Zachary Amsden
2010-08-20 13:26 ` KVM timekeeping and TSC virtualization David S. Ahern
2010-08-20 23:24 ` Zachary Amsden
2010-08-22 1:32 ` David S. Ahern
2010-08-24 1:44 ` Zachary Amsden
2010-08-24 3:04 ` David S. Ahern
2010-08-24 5:47 ` Zachary Amsden
2010-08-24 13:32 ` David S. Ahern
2010-08-24 23:01 ` Zachary Amsden
2010-08-25 16:55 ` Marcelo Tosatti
2010-08-25 20:32 ` Zachary Amsden
2010-08-24 22:13 ` Marcelo Tosatti
2010-08-25 4:04 ` Zachary Amsden
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