[PATCH v2 1/5] KVM: LAPIC: Introduce interrupt delivery fastpath
From: Wanpeng Li
Date: Thu Apr 23 2020 - 05:02:03 EST
From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
Introduce interrupt delivery fastpath, I observe kvm_x86_ops.deliver_posted_interrupt()
has more latency then vmx_sync_pir_to_irr in my case, since it needs to wait
vmentry, after that it can handle external interrupt, ack the notification
vector, read posted-interrupt desciptor etc, it is slower than evaluate and
delivery during vmentry method. For non-APICv, inject directly since we will
not go though inject_pending_event().
Tested-by: Haiwei Li <lihaiwei@xxxxxxxxxxx>
Cc: Haiwei Li <lihaiwei@xxxxxxxxxxx>
Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/lapic.c | 32 ++++++++++++++++++++++++++++++++
arch/x86/kvm/svm/avic.c | 5 +++++
arch/x86/kvm/svm/svm.c | 1 +
arch/x86/kvm/svm/svm.h | 1 +
arch/x86/kvm/vmx/vmx.c | 23 +++++++++++++++++------
6 files changed, 57 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index f26df2c..f809763 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1157,6 +1157,7 @@ struct kvm_x86_ops {
void (*set_apic_access_page_addr)(struct kvm_vcpu *vcpu);
int (*deliver_posted_interrupt)(struct kvm_vcpu *vcpu, int vector);
int (*sync_pir_to_irr)(struct kvm_vcpu *vcpu);
+ bool (*pi_test_and_set_pir_on)(struct kvm_vcpu *vcpu, int vector);
int (*set_tss_addr)(struct kvm *kvm, unsigned int addr);
int (*set_identity_map_addr)(struct kvm *kvm, u64 ident_addr);
int (*get_tdp_level)(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 38f7dc9..7703142 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1259,6 +1259,30 @@ void kvm_apic_send_ipi(struct kvm_lapic *apic, u32 icr_low, u32 icr_high)
kvm_irq_delivery_to_apic(apic->vcpu->kvm, apic, &irq, NULL);
}
+static void fast_deliver_interrupt(struct kvm_lapic *apic, int vector)
+{
+ struct kvm_vcpu *vcpu = apic->vcpu;
+
+ kvm_lapic_clear_vector(vector, apic->regs + APIC_TMR);
+
+ if (vcpu->arch.apicv_active) {
+ if (kvm_x86_ops.pi_test_and_set_pir_on(vcpu, vector))
+ return;
+
+ kvm_x86_ops.sync_pir_to_irr(vcpu);
+ } else {
+ kvm_lapic_set_irr(vector, apic);
+ if (kvm_cpu_has_injectable_intr(vcpu)) {
+ if (kvm_x86_ops.interrupt_allowed(vcpu)) {
+ kvm_queue_interrupt(vcpu,
+ kvm_cpu_get_interrupt(vcpu), false);
+ kvm_x86_ops.set_irq(vcpu);
+ } else
+ kvm_x86_ops.enable_irq_window(vcpu);
+ }
+ }
+}
+
static u32 apic_get_tmcct(struct kvm_lapic *apic)
{
ktime_t remaining, now;
@@ -2351,6 +2375,14 @@ int kvm_apic_local_deliver(struct kvm_lapic *apic, int lvt_type)
return 0;
}
+static void kvm_apic_local_deliver_fast(struct kvm_lapic *apic, int lvt_type)
+{
+ u32 reg = kvm_lapic_get_reg(apic, lvt_type);
+
+ if (kvm_apic_hw_enabled(apic) && !(reg & APIC_LVT_MASKED))
+ fast_deliver_interrupt(apic, reg & APIC_VECTOR_MASK);
+}
+
void kvm_apic_nmi_wd_deliver(struct kvm_vcpu *vcpu)
{
struct kvm_lapic *apic = vcpu->arch.apic;
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index e80daa9..ab9e0fd 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -905,6 +905,11 @@ int svm_update_pi_irte(struct kvm *kvm, unsigned int host_irq,
return ret;
}
+bool svm_pi_test_and_set_pir_on(struct kvm_vcpu *vcpu, int vector)
+{
+ return false;
+}
+
bool svm_check_apicv_inhibit_reasons(ulong bit)
{
ulong supported = BIT(APICV_INHIBIT_REASON_DISABLE) |
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index eb95283..fd0cab3 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4035,6 +4035,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
.deliver_posted_interrupt = svm_deliver_avic_intr,
.dy_apicv_has_pending_interrupt = svm_dy_apicv_has_pending_interrupt,
.update_pi_irte = svm_update_pi_irte,
+ .pi_test_and_set_pir_on = svm_pi_test_and_set_pir_on,
.setup_mce = svm_setup_mce,
.smi_allowed = svm_smi_allowed,
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index ca95204..8a62a8b 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -457,6 +457,7 @@ int svm_update_pi_irte(struct kvm *kvm, unsigned int host_irq,
uint32_t guest_irq, bool set);
void svm_vcpu_blocking(struct kvm_vcpu *vcpu);
void svm_vcpu_unblocking(struct kvm_vcpu *vcpu);
+bool svm_pi_test_and_set_pir_on(struct kvm_vcpu *vcpu, int vector);
/* sev.c */
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 766303b..fd20cb3 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -3883,6 +3883,21 @@ static int vmx_deliver_nested_posted_interrupt(struct kvm_vcpu *vcpu,
}
return -1;
}
+
+static bool vmx_pi_test_and_set_pir_on(struct kvm_vcpu *vcpu, int vector)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+
+ if (pi_test_and_set_pir(vector, &vmx->pi_desc))
+ return true;
+
+ /* If a previous notification has sent the IPI, nothing to do. */
+ if (pi_test_and_set_on(&vmx->pi_desc))
+ return true;
+
+ return false;
+}
+
/*
* Send interrupt to vcpu via posted interrupt way.
* 1. If target vcpu is running(non-root mode), send posted interrupt
@@ -3892,7 +3907,6 @@ static int vmx_deliver_nested_posted_interrupt(struct kvm_vcpu *vcpu,
*/
static int vmx_deliver_posted_interrupt(struct kvm_vcpu *vcpu, int vector)
{
- struct vcpu_vmx *vmx = to_vmx(vcpu);
int r;
r = vmx_deliver_nested_posted_interrupt(vcpu, vector);
@@ -3902,11 +3916,7 @@ static int vmx_deliver_posted_interrupt(struct kvm_vcpu *vcpu, int vector)
if (!vcpu->arch.apicv_active)
return -1;
- if (pi_test_and_set_pir(vector, &vmx->pi_desc))
- return 0;
-
- /* If a previous notification has sent the IPI, nothing to do. */
- if (pi_test_and_set_on(&vmx->pi_desc))
+ if (vmx_pi_test_and_set_pir_on(vcpu, vector))
return 0;
if (!kvm_vcpu_trigger_posted_interrupt(vcpu, false))
@@ -7826,6 +7836,7 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
.hwapic_isr_update = vmx_hwapic_isr_update,
.guest_apic_has_interrupt = vmx_guest_apic_has_interrupt,
.sync_pir_to_irr = vmx_sync_pir_to_irr,
+ .pi_test_and_set_pir_on = vmx_pi_test_and_set_pir_on,
.deliver_posted_interrupt = vmx_deliver_posted_interrupt,
.dy_apicv_has_pending_interrupt = vmx_dy_apicv_has_pending_interrupt,
--
2.7.4