KVM: emulate lapic tsc deadline timer for guest
This patch emulate lapic tsc deadline timer for guest:
Enumerate tsc deadline timer capability by CPUID;
Enable tsc deadline timer mode by lapic MMIO;
Start tsc deadline timer by WRMSR;
[jan: use do_div()]
[avi: fix for !irqchip_in_kernel()]
[marcelo: another fix for !irqchip_in_kernel()]
Signed-off-by: Liu, Jinsong <jinsong.liu@intel.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 2fb20ca..54abb40 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -138,9 +138,23 @@
return apic_get_reg(apic, lvt_type) & APIC_VECTOR_MASK;
}
+static inline int apic_lvtt_oneshot(struct kvm_lapic *apic)
+{
+ return ((apic_get_reg(apic, APIC_LVTT) &
+ apic->lapic_timer.timer_mode_mask) == APIC_LVT_TIMER_ONESHOT);
+}
+
static inline int apic_lvtt_period(struct kvm_lapic *apic)
{
- return apic_get_reg(apic, APIC_LVTT) & APIC_LVT_TIMER_PERIODIC;
+ return ((apic_get_reg(apic, APIC_LVTT) &
+ apic->lapic_timer.timer_mode_mask) == APIC_LVT_TIMER_PERIODIC);
+}
+
+static inline int apic_lvtt_tscdeadline(struct kvm_lapic *apic)
+{
+ return ((apic_get_reg(apic, APIC_LVTT) &
+ apic->lapic_timer.timer_mode_mask) ==
+ APIC_LVT_TIMER_TSCDEADLINE);
}
static inline int apic_lvt_nmi_mode(u32 lvt_val)
@@ -169,7 +183,7 @@
}
static unsigned int apic_lvt_mask[APIC_LVT_NUM] = {
- LVT_MASK | APIC_LVT_TIMER_PERIODIC, /* LVTT */
+ LVT_MASK , /* part LVTT mask, timer mode mask added at runtime */
LVT_MASK | APIC_MODE_MASK, /* LVTTHMR */
LVT_MASK | APIC_MODE_MASK, /* LVTPC */
LINT_MASK, LINT_MASK, /* LVT0-1 */
@@ -572,6 +586,9 @@
break;
case APIC_TMCCT: /* Timer CCR */
+ if (apic_lvtt_tscdeadline(apic))
+ return 0;
+
val = apic_get_tmcct(apic);
break;
@@ -666,37 +683,40 @@
static void start_apic_timer(struct kvm_lapic *apic)
{
- ktime_t now = apic->lapic_timer.timer.base->get_time();
-
- apic->lapic_timer.period = (u64)apic_get_reg(apic, APIC_TMICT) *
- APIC_BUS_CYCLE_NS * apic->divide_count;
+ ktime_t now;
atomic_set(&apic->lapic_timer.pending, 0);
- if (!apic->lapic_timer.period)
- return;
- /*
- * 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_lvtt_period(apic) || apic_lvtt_oneshot(apic)) {
+ /* lapic timer in oneshot or peroidic mode */
+ now = apic->lapic_timer.timer.base->get_time();
+ apic->lapic_timer.period = (u64)apic_get_reg(apic, APIC_TMICT)
+ * APIC_BUS_CYCLE_NS * apic->divide_count;
- 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;
+ if (!apic->lapic_timer.period)
+ return;
+ /*
+ * 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;
+ }
}
- }
- hrtimer_start(&apic->lapic_timer.timer,
- ktime_add_ns(now, apic->lapic_timer.period),
- HRTIMER_MODE_ABS);
+ hrtimer_start(&apic->lapic_timer.timer,
+ ktime_add_ns(now, apic->lapic_timer.period),
+ HRTIMER_MODE_ABS);
- apic_debug("%s: bus cycle is %" PRId64 "ns, now 0x%016"
+ 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__,
@@ -705,6 +725,30 @@
apic->lapic_timer.period,
ktime_to_ns(ktime_add_ns(now,
apic->lapic_timer.period)));
+ } else if (apic_lvtt_tscdeadline(apic)) {
+ /* lapic timer in tsc deadline mode */
+ u64 guest_tsc, tscdeadline = apic->lapic_timer.tscdeadline;
+ u64 ns = 0;
+ struct kvm_vcpu *vcpu = apic->vcpu;
+ unsigned long this_tsc_khz = vcpu_tsc_khz(vcpu);
+ unsigned long flags;
+
+ if (unlikely(!tscdeadline || !this_tsc_khz))
+ return;
+
+ local_irq_save(flags);
+
+ now = apic->lapic_timer.timer.base->get_time();
+ guest_tsc = kvm_x86_ops->read_l1_tsc(vcpu);
+ if (likely(tscdeadline > guest_tsc)) {
+ ns = (tscdeadline - guest_tsc) * 1000000ULL;
+ do_div(ns, this_tsc_khz);
+ }
+ hrtimer_start(&apic->lapic_timer.timer,
+ ktime_add_ns(now, ns), HRTIMER_MODE_ABS);
+
+ local_irq_restore(flags);
+ }
}
static void apic_manage_nmi_watchdog(struct kvm_lapic *apic, u32 lvt0_val)
@@ -792,7 +836,6 @@
case APIC_LVT0:
apic_manage_nmi_watchdog(apic, val);
- case APIC_LVTT:
case APIC_LVTTHMR:
case APIC_LVTPC:
case APIC_LVT1:
@@ -806,7 +849,22 @@
break;
+ case APIC_LVTT:
+ if ((apic_get_reg(apic, APIC_LVTT) &
+ apic->lapic_timer.timer_mode_mask) !=
+ (val & apic->lapic_timer.timer_mode_mask))
+ hrtimer_cancel(&apic->lapic_timer.timer);
+
+ if (!apic_sw_enabled(apic))
+ val |= APIC_LVT_MASKED;
+ val &= (apic_lvt_mask[0] | apic->lapic_timer.timer_mode_mask);
+ apic_set_reg(apic, APIC_LVTT, val);
+ break;
+
case APIC_TMICT:
+ if (apic_lvtt_tscdeadline(apic))
+ break;
+
hrtimer_cancel(&apic->lapic_timer.timer);
apic_set_reg(apic, APIC_TMICT, val);
start_apic_timer(apic);
@@ -902,6 +960,32 @@
*----------------------------------------------------------------------
*/
+u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu)
+{
+ struct kvm_lapic *apic = vcpu->arch.apic;
+ if (!apic)
+ return 0;
+
+ if (apic_lvtt_oneshot(apic) || apic_lvtt_period(apic))
+ return 0;
+
+ return apic->lapic_timer.tscdeadline;
+}
+
+void kvm_set_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu, u64 data)
+{
+ struct kvm_lapic *apic = vcpu->arch.apic;
+ if (!apic)
+ return;
+
+ if (apic_lvtt_oneshot(apic) || apic_lvtt_period(apic))
+ return;
+
+ hrtimer_cancel(&apic->lapic_timer.timer);
+ apic->lapic_timer.tscdeadline = data;
+ start_apic_timer(apic);
+}
+
void kvm_lapic_set_tpr(struct kvm_vcpu *vcpu, unsigned long cr8)
{
struct kvm_lapic *apic = vcpu->arch.apic;