[PATCH RFC V3 3/6] KVM: LAPIC: introduce set_target_expiration() to set target expiration time

[Wanpeng Li]

From: Wanpeng Li 

Introduce set_target_expiration() to set target expiration time which is 
when LVTT current-count register counts down to zero and a timer interrupt 
is generated.

Cc: Paolo Bonzini 
Cc: Radim Krčmář 
Cc: Yunhong Jiang 
Signed-off-by: Wanpeng Li 
---
 arch/x86/kvm/lapic.c | 47 +++
 arch/x86/kvm/lapic.h |  1 +
 2 files changed, 48 insertions(+)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index dce6c0b..09dad85 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1391,6 +1391,53 @@ static void start_sw_period(struct kvm_lapic *apic)
apic->lapic_timer.period)));
 }
 
+static bool set_target_expiration(struct kvm_lapic *apic)
+{
+   ktime_t now;
+   u64 tscl = rdtsc();
+
+   now = apic->lapic_timer.timer.base->get_time();
+   apic->lapic_timer.period = (u64)kvm_lapic_get_reg(apic, APIC_TMICT)
+   * APIC_BUS_CYCLE_NS * apic->divide_count;
+
+   if (!apic->lapic_timer.period)
+   return false;
+
+   /*
+* Do not allow the guest to program periodic timers with small
+* interval, since the hrtimers are not throttled by the host
+* scheduler.
+*/
+   if (apic_lvtt_period(apic)) {
+   s64 min_period = min_timer_period_us * 1000LL;
+
+   if (apic->lapic_timer.period < min_period) {
+   pr_info_ratelimited(
+   "kvm: vcpu %i: requested %lld ns "
+   "lapic timer period limited to %lld ns\n",
+   apic->vcpu->vcpu_id,
+   apic->lapic_timer.period, min_period);
+   apic->lapic_timer.period = min_period;
+   }
+   }
+
+   apic_debug("%s: bus cycle is %" PRId64 "ns, now 0x%016"
+  PRIx64 ", "
+  "timer initial count 0x%x, period %lldns, "
+  "expire @ 0x%016" PRIx64 ".\n", __func__,
+  APIC_BUS_CYCLE_NS, ktime_to_ns(now),
+  kvm_lapic_get_reg(apic, APIC_TMICT),
+  apic->lapic_timer.period,
+  ktime_to_ns(ktime_add_ns(now,
+   apic->lapic_timer.period)));
+
+   apic->lapic_timer.tscdeadline = kvm_read_l1_tsc(apic->vcpu, tscl) +
+   nsec_to_cycles(apic->vcpu, apic->lapic_timer.period);
+   apic->lapic_timer.target_expiration = ktime_add_ns(now, 
apic->lapic_timer.period);
+
+   return true;
+}
+
 bool kvm_lapic_hv_timer_in_use(struct kvm_vcpu *vcpu)
 {
if (!lapic_in_kernel(vcpu))
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index f60d01c..889b504 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -15,6 +15,7 @@
 struct kvm_timer {
struct hrtimer timer;
s64 period; /* unit: ns */
+   ktime_t target_expiration;
u32 timer_mode;
u32 timer_mode_mask;
u64 tscdeadline;
-- 
1.9.1

[PATCH RFC V3 3/6] KVM: LAPIC: introduce set_target_expiration() to set target expiration time

[Wanpeng Li]

From: Wanpeng Li 

Introduce set_target_expiration() to set target expiration time which is 
when LVTT current-count register counts down to zero and a timer interrupt 
is generated.

Cc: Paolo Bonzini 
Cc: Radim Krčmář 
Cc: Yunhong Jiang 
Signed-off-by: Wanpeng Li 
---
 arch/x86/kvm/lapic.c | 47 +++
 arch/x86/kvm/lapic.h |  1 +
 2 files changed, 48 insertions(+)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index dce6c0b..09dad85 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1391,6 +1391,53 @@ static void start_sw_period(struct kvm_lapic *apic)
apic->lapic_timer.period)));
 }
 
+static bool set_target_expiration(struct kvm_lapic *apic)
+{
+   ktime_t now;
+   u64 tscl = rdtsc();
+
+   now = apic->lapic_timer.timer.base->get_time();
+   apic->lapic_timer.period = (u64)kvm_lapic_get_reg(apic, APIC_TMICT)
+   * APIC_BUS_CYCLE_NS * apic->divide_count;
+
+   if (!apic->lapic_timer.period)
+   return false;
+
+   /*
+* Do not allow the guest to program periodic timers with small
+* interval, since the hrtimers are not throttled by the host
+* scheduler.
+*/
+   if (apic_lvtt_period(apic)) {
+   s64 min_period = min_timer_period_us * 1000LL;
+
+   if (apic->lapic_timer.period < min_period) {
+   pr_info_ratelimited(
+   "kvm: vcpu %i: requested %lld ns "
+   "lapic timer period limited to %lld ns\n",
+   apic->vcpu->vcpu_id,
+   apic->lapic_timer.period, min_period);
+   apic->lapic_timer.period = min_period;
+   }
+   }
+
+   apic_debug("%s: bus cycle is %" PRId64 "ns, now 0x%016"
+  PRIx64 ", "
+  "timer initial count 0x%x, period %lldns, "
+  "expire @ 0x%016" PRIx64 ".\n", __func__,
+  APIC_BUS_CYCLE_NS, ktime_to_ns(now),
+  kvm_lapic_get_reg(apic, APIC_TMICT),
+  apic->lapic_timer.period,
+  ktime_to_ns(ktime_add_ns(now,
+   apic->lapic_timer.period)));
+
+   apic->lapic_timer.tscdeadline = kvm_read_l1_tsc(apic->vcpu, tscl) +
+   nsec_to_cycles(apic->vcpu, apic->lapic_timer.period);
+   apic->lapic_timer.target_expiration = ktime_add_ns(now, 
apic->lapic_timer.period);
+
+   return true;
+}
+
 bool kvm_lapic_hv_timer_in_use(struct kvm_vcpu *vcpu)
 {
if (!lapic_in_kernel(vcpu))
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index f60d01c..889b504 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -15,6 +15,7 @@
 struct kvm_timer {
struct hrtimer timer;
s64 period; /* unit: ns */
+   ktime_t target_expiration;
u32 timer_mode;
u32 timer_mode_mask;
u64 tscdeadline;
-- 
1.9.1