From: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
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@xxxxxxxxxxx>
---
Changes in v2:
- preserve return values where we need to count to how many VCPUs an
IRQ was delivered
arch/x86/kvm/lapic.c | 57 ++++++++++++++++++++-----------------------------
arch/x86/kvm/lapic.h | 6 ++--
virt/kvm/irq_comm.c | 9 +++++--
3 files changed, 32 insertions(+), 40 deletions(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index e29883c..3bc58cd 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -405,17 +405,17 @@ int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu)
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 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
*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 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
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 @@ out:
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 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
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 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
}
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 @@ out:
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 @@ out:
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 @@ out:
delivery_mode);
break;
}
- return result;
}
int kvm_apic_compare_prio(struct kvm_vcpu *vcpu1, struct kvm_vcpu *vcpu2)
@@ -1470,7 +1461,7 @@ int apic_has_pending_timer(struct kvm_vcpu *vcpu)
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 @@ int kvm_apic_local_deliver(struct kvm_lapic *apic, int lvt_type)
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 @@ void kvm_inject_apic_timer_irqs(struct kvm_vcpu *vcpu)
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);
}
}
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index c730ac9..61a73a0 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -57,9 +57,9 @@ void kvm_apic_update_tmr(struct kvm_vcpu *vcpu, u32 *tmr);
void kvm_apic_update_irr(struct kvm_vcpu *vcpu, u32 *pir);
int kvm_apic_match_physical_addr(struct kvm_lapic *apic, u16 dest);
int kvm_apic_match_logical_addr(struct kvm_lapic *apic, u8 mda);
-int kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq,
- unsigned long *dest_map);
-int kvm_apic_local_deliver(struct kvm_lapic *apic, int lvt_type);
+void kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq,
+ unsigned long *dest_map);
+void kvm_apic_local_deliver(struct kvm_lapic *apic, int lvt_type);
bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
struct kvm_lapic_irq *irq, int *r, unsigned long *dest_map);
diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index 25ab480..d60e1f1 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -91,7 +91,8 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
if (!kvm_is_dm_lowest_prio(irq)) {
if (r < 0)
r = 0;
- r += kvm_apic_set_irq(vcpu, irq, dest_map);
+ kvm_apic_set_irq(vcpu, irq, dest_map);
+ r++;
} else if (kvm_lapic_enabled(vcpu)) {
if (!lowest)
lowest = vcpu;
@@ -100,8 +101,10 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
}
}
- if (lowest)
- r = kvm_apic_set_irq(lowest, irq, dest_map);
+ if (lowest) {
+ kvm_apic_set_irq(lowest, irq, dest_map);
+ r = 1;
+ }
return r;
}
--
1.7.3.4
--
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