KVM: x86: Remove support for reporting coalesced APIC IRQs
Since the arrival of posted interrupt support we can no longer guarantee
that coalesced IRQs are always reported to the IRQ source. Moreover,
accumulated APIC timer events could cause a busy loop when a VCPU should
rather be halted. The consensus is to remove coalesced tracking from the
LAPIC.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Acked-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index e1adbb4..9d75193 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -405,17 +405,17 @@
return highest_irr;
}
-static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
- int vector, int level, int trig_mode,
- unsigned long *dest_map);
+static void __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
+ int vector, int level, int trig_mode,
+ unsigned long *dest_map);
-int kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq,
- unsigned long *dest_map)
+void kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq,
+ unsigned long *dest_map)
{
struct kvm_lapic *apic = vcpu->arch.apic;
- return __apic_accept_irq(apic, irq->delivery_mode, irq->vector,
- irq->level, irq->trig_mode, dest_map);
+ __apic_accept_irq(apic, irq->delivery_mode, irq->vector,
+ irq->level, irq->trig_mode, dest_map);
}
static int pv_eoi_put_user(struct kvm_vcpu *vcpu, u8 val)
@@ -608,7 +608,8 @@
*r = -1;
if (irq->shorthand == APIC_DEST_SELF) {
- *r = kvm_apic_set_irq(src->vcpu, irq, dest_map);
+ kvm_apic_set_irq(src->vcpu, irq, dest_map);
+ *r = 1;
return true;
}
@@ -653,7 +654,8 @@
continue;
if (*r < 0)
*r = 0;
- *r += kvm_apic_set_irq(dst[i]->vcpu, irq, dest_map);
+ kvm_apic_set_irq(dst[i]->vcpu, irq, dest_map);
+ *r += 1;
}
ret = true;
@@ -662,15 +664,11 @@
return ret;
}
-/*
- * Add a pending IRQ into lapic.
- * Return 1 if successfully added and 0 if discarded.
- */
-static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
- int vector, int level, int trig_mode,
- unsigned long *dest_map)
+/* Set an IRQ pending in the lapic. */
+static void __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
+ int vector, int level, int trig_mode,
+ unsigned long *dest_map)
{
- int result = 0;
struct kvm_vcpu *vcpu = apic->vcpu;
switch (delivery_mode) {
@@ -684,13 +682,10 @@
if (dest_map)
__set_bit(vcpu->vcpu_id, dest_map);
- if (kvm_x86_ops->deliver_posted_interrupt) {
- result = 1;
+ if (kvm_x86_ops->deliver_posted_interrupt)
kvm_x86_ops->deliver_posted_interrupt(vcpu, vector);
- } else {
- result = !apic_test_and_set_irr(vector, apic);
-
- if (!result) {
+ else {
+ if (apic_test_and_set_irr(vector, apic)) {
if (trig_mode)
apic_debug("level trig mode repeatedly "
"for vector %d", vector);
@@ -702,7 +697,7 @@
}
out:
trace_kvm_apic_accept_irq(vcpu->vcpu_id, delivery_mode,
- trig_mode, vector, !result);
+ trig_mode, vector, false);
break;
case APIC_DM_REMRD:
@@ -714,14 +709,12 @@
break;
case APIC_DM_NMI:
- result = 1;
kvm_inject_nmi(vcpu);
kvm_vcpu_kick(vcpu);
break;
case APIC_DM_INIT:
if (!trig_mode || level) {
- result = 1;
/* assumes that there are only KVM_APIC_INIT/SIPI */
apic->pending_events = (1UL << KVM_APIC_INIT);
/* make sure pending_events is visible before sending
@@ -738,7 +731,6 @@
case APIC_DM_STARTUP:
apic_debug("SIPI to vcpu %d vector 0x%02x\n",
vcpu->vcpu_id, vector);
- result = 1;
apic->sipi_vector = vector;
/* make sure sipi_vector is visible for the receiver */
smp_wmb();
@@ -760,7 +752,6 @@
delivery_mode);
break;
}
- return result;
}
int kvm_apic_compare_prio(struct kvm_vcpu *vcpu1, struct kvm_vcpu *vcpu2)
@@ -1470,7 +1461,7 @@
return 0;
}
-int kvm_apic_local_deliver(struct kvm_lapic *apic, int lvt_type)
+void kvm_apic_local_deliver(struct kvm_lapic *apic, int lvt_type)
{
u32 reg = kvm_apic_get_reg(apic, lvt_type);
int vector, mode, trig_mode;
@@ -1479,10 +1470,8 @@
vector = reg & APIC_VECTOR_MASK;
mode = reg & APIC_MODE_MASK;
trig_mode = reg & APIC_LVT_LEVEL_TRIGGER;
- return __apic_accept_irq(apic, mode, vector, 1, trig_mode,
- NULL);
+ __apic_accept_irq(apic, mode, vector, 1, trig_mode, NULL);
}
- return 0;
}
void kvm_apic_nmi_wd_deliver(struct kvm_vcpu *vcpu)
@@ -1608,8 +1597,8 @@
return;
if (atomic_read(&apic->lapic_timer.pending) > 0) {
- if (kvm_apic_local_deliver(apic, APIC_LVTT))
- atomic_dec(&apic->lapic_timer.pending);
+ kvm_apic_local_deliver(apic, APIC_LVTT);
+ atomic_set(&apic->lapic_timer.pending, 0);
}
}