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-rw-r--r--arch/x86/include/asm/kvm_host.h1
-rw-r--r--arch/x86/kvm/trace.h39
-rw-r--r--arch/x86/kvm/x86.c57
3 files changed, 89 insertions, 8 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 32f0e4a063b..9fb6d8da7a4 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -561,6 +561,7 @@ struct kvm_arch {
u64 cur_tsc_write;
u64 cur_tsc_offset;
u8 cur_tsc_generation;
+ int nr_vcpus_matched_tsc;
spinlock_t pvclock_gtod_sync_lock;
bool use_master_clock;
diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index 1d652685608..fe5e00ed703 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -764,21 +764,54 @@ TRACE_EVENT(
{VCLOCK_HPET, "hpet"} \
TRACE_EVENT(kvm_update_master_clock,
- TP_PROTO(bool use_master_clock, unsigned int host_clock),
- TP_ARGS(use_master_clock, host_clock),
+ TP_PROTO(bool use_master_clock, unsigned int host_clock, bool offset_matched),
+ TP_ARGS(use_master_clock, host_clock, offset_matched),
TP_STRUCT__entry(
__field( bool, use_master_clock )
__field( unsigned int, host_clock )
+ __field( bool, offset_matched )
),
TP_fast_assign(
__entry->use_master_clock = use_master_clock;
__entry->host_clock = host_clock;
+ __entry->offset_matched = offset_matched;
),
- TP_printk("masterclock %d hostclock %s",
+ TP_printk("masterclock %d hostclock %s offsetmatched %u",
__entry->use_master_clock,
+ __print_symbolic(__entry->host_clock, host_clocks),
+ __entry->offset_matched)
+);
+
+TRACE_EVENT(kvm_track_tsc,
+ TP_PROTO(unsigned int vcpu_id, unsigned int nr_matched,
+ unsigned int online_vcpus, bool use_master_clock,
+ unsigned int host_clock),
+ TP_ARGS(vcpu_id, nr_matched, online_vcpus, use_master_clock,
+ host_clock),
+
+ TP_STRUCT__entry(
+ __field( unsigned int, vcpu_id )
+ __field( unsigned int, nr_vcpus_matched_tsc )
+ __field( unsigned int, online_vcpus )
+ __field( bool, use_master_clock )
+ __field( unsigned int, host_clock )
+ ),
+
+ TP_fast_assign(
+ __entry->vcpu_id = vcpu_id;
+ __entry->nr_vcpus_matched_tsc = nr_matched;
+ __entry->online_vcpus = online_vcpus;
+ __entry->use_master_clock = use_master_clock;
+ __entry->host_clock = host_clock;
+ ),
+
+ TP_printk("vcpu_id %u masterclock %u offsetmatched %u nr_online %u"
+ " hostclock %s",
+ __entry->vcpu_id, __entry->use_master_clock,
+ __entry->nr_vcpus_matched_tsc, __entry->online_vcpus,
__print_symbolic(__entry->host_clock, host_clocks))
);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f3c069efc72..422ef5ed219 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1103,12 +1103,40 @@ static u64 compute_guest_tsc(struct kvm_vcpu *vcpu, s64 kernel_ns)
return tsc;
}
+void kvm_track_tsc_matching(struct kvm_vcpu *vcpu)
+{
+#ifdef CONFIG_X86_64
+ bool vcpus_matched;
+ bool do_request = false;
+ struct kvm_arch *ka = &vcpu->kvm->arch;
+ struct pvclock_gtod_data *gtod = &pvclock_gtod_data;
+
+ vcpus_matched = (ka->nr_vcpus_matched_tsc + 1 ==
+ atomic_read(&vcpu->kvm->online_vcpus));
+
+ if (vcpus_matched && gtod->clock.vclock_mode == VCLOCK_TSC)
+ if (!ka->use_master_clock)
+ do_request = 1;
+
+ if (!vcpus_matched && ka->use_master_clock)
+ do_request = 1;
+
+ if (do_request)
+ kvm_make_request(KVM_REQ_MASTERCLOCK_UPDATE, vcpu);
+
+ trace_kvm_track_tsc(vcpu->vcpu_id, ka->nr_vcpus_matched_tsc,
+ atomic_read(&vcpu->kvm->online_vcpus),
+ ka->use_master_clock, gtod->clock.vclock_mode);
+#endif
+}
+
void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data)
{
struct kvm *kvm = vcpu->kvm;
u64 offset, ns, elapsed;
unsigned long flags;
s64 usdiff;
+ bool matched;
raw_spin_lock_irqsave(&kvm->arch.tsc_write_lock, flags);
offset = kvm_x86_ops->compute_tsc_offset(vcpu, data);
@@ -1151,6 +1179,7 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data)
offset = kvm_x86_ops->compute_tsc_offset(vcpu, data);
pr_debug("kvm: adjusted tsc offset by %llu\n", delta);
}
+ matched = true;
} else {
/*
* We split periods of matched TSC writes into generations.
@@ -1165,6 +1194,7 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data)
kvm->arch.cur_tsc_nsec = ns;
kvm->arch.cur_tsc_write = data;
kvm->arch.cur_tsc_offset = offset;
+ matched = false;
pr_debug("kvm: new tsc generation %u, clock %llu\n",
kvm->arch.cur_tsc_generation, data);
}
@@ -1188,6 +1218,15 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data)
kvm_x86_ops->write_tsc_offset(vcpu, offset);
raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags);
+
+ spin_lock(&kvm->arch.pvclock_gtod_sync_lock);
+ if (matched)
+ kvm->arch.nr_vcpus_matched_tsc++;
+ else
+ kvm->arch.nr_vcpus_matched_tsc = 0;
+
+ kvm_track_tsc_matching(vcpu);
+ spin_unlock(&kvm->arch.pvclock_gtod_sync_lock);
}
EXPORT_SYMBOL_GPL(kvm_write_tsc);
@@ -1279,8 +1318,9 @@ static bool kvm_get_time_and_clockread(s64 *kernel_ns, cycle_t *cycle_now)
/*
*
- * Assuming a stable TSC across physical CPUS, the following condition
- * is possible. Each numbered line represents an event visible to both
+ * Assuming a stable TSC across physical CPUS, and a stable TSC
+ * across virtual CPUs, the following condition is possible.
+ * Each numbered line represents an event visible to both
* CPUs at the next numbered event.
*
* "timespecX" represents host monotonic time. "tscX" represents
@@ -1313,7 +1353,7 @@ static bool kvm_get_time_and_clockread(s64 *kernel_ns, cycle_t *cycle_now)
* copy of host monotonic time values. Update that master copy
* in lockstep.
*
- * Rely on synchronization of host TSCs for monotonicity.
+ * Rely on synchronization of host TSCs and guest TSCs for monotonicity.
*
*/
@@ -1322,20 +1362,27 @@ static void pvclock_update_vm_gtod_copy(struct kvm *kvm)
#ifdef CONFIG_X86_64
struct kvm_arch *ka = &kvm->arch;
int vclock_mode;
+ bool host_tsc_clocksource, vcpus_matched;
+
+ vcpus_matched = (ka->nr_vcpus_matched_tsc + 1 ==
+ atomic_read(&kvm->online_vcpus));
/*
* If the host uses TSC clock, then passthrough TSC as stable
* to the guest.
*/
- ka->use_master_clock = kvm_get_time_and_clockread(
+ host_tsc_clocksource = kvm_get_time_and_clockread(
&ka->master_kernel_ns,
&ka->master_cycle_now);
+ ka->use_master_clock = host_tsc_clocksource & vcpus_matched;
+
if (ka->use_master_clock)
atomic_set(&kvm_guest_has_master_clock, 1);
vclock_mode = pvclock_gtod_data.clock.vclock_mode;
- trace_kvm_update_master_clock(ka->use_master_clock, vclock_mode);
+ trace_kvm_update_master_clock(ka->use_master_clock, vclock_mode,
+ vcpus_matched);
#endif
}
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-12-18 07:34:50 +0000