[PATCH v4 5/6] KVM: Non-atomic interrupt injection

Avi Kivity
2010-08-30T11:37:05Z

Change the interrupt injection code to work from preemptible, interrupts
enabled context. This works by adding a ->cancel_injection() operation
that undoes an injection in case we were not able to actually enter the guest
(this condition could never happen with atomic injection).

Signed-off-by: Avi Kivity <avi@redhat.com>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/svm.c | 12 ++++++++++++
arch/x86/kvm/vmx.c | 11 +++++++++++
arch/x86/kvm/x86.c | 31 ++++++++++++++++---------------
4 files changed, 40 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 9b30285..8004b34 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -510,6 +510,7 @@ struct kvm_x86_ops {
void (*queue_exception)(struct kvm_vcpu *vcpu, unsigned nr,
bool has_error_code, u32 error_code,
bool reinject);
+ void (*cancel_injection)(struct kvm_vcpu *vcpu);
int (*interrupt_allowed)(struct kvm_vcpu *vcpu);
int (*nmi_allowed)(struct kvm_vcpu *vcpu);
bool (*get_nmi_mask)(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 8884e51..e64a5b1 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3160,6 +3160,17 @@ static void svm_complete_interrupts(struct vcpu_svm *svm)
}
}

+static void svm_cancel_injection(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_svm *svm = to_svm(vcpu);
+ struct vmcb_control_area *control = &svm->vmcb->control;
+
+ control->exit_int_info = control->event_inj;
+ control->exit_int_info_err = control->event_inj_err;
+ control->event_inj = 0;
+ svm_complete_interrupts(svm);
+}
+
#ifdef CONFIG_X86_64
#define R "r"
#else
@@ -3523,6 +3534,7 @@ static struct kvm_x86_ops svm_x86_ops = {
.set_irq = svm_set_irq,
.set_nmi = svm_inject_nmi,
.queue_exception = svm_queue_exception,
+ .cancel_injection = svm_cancel_injection,
.interrupt_allowed = svm_interrupt_allowed,
.nmi_allowed = svm_nmi_allowed,
.get_nmi_mask = svm_get_nmi_mask,
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c6d37df..41b1ff6 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3901,6 +3901,16 @@ static void vmx_complete_interrupts(struct vcpu_vmx *vmx)
IDT_VECTORING_ERROR_CODE);
}

+static void vmx_cancel_injection(struct kvm_vcpu *vcpu)
+{
+ __vmx_complete_interrupts(to_vmx(vcpu),
+ vmcs_read32(VM_ENTRY_INTR_INFO_FIELD),
+ VM_ENTRY_INSTRUCTION_LEN,
+ VM_ENTRY_EXCEPTION_ERROR_CODE);
+
+ vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, 0);
+}
+
/*
* Failure to inject an interrupt should give us the information
* in IDT_VECTORING_INFO_FIELD. However, if the failure occurs
@@ -4354,6 +4364,7 @@ static struct kvm_x86_ops vmx_x86_ops = {
.set_irq = vmx_inject_irq,
.set_nmi = vmx_inject_nmi,
.queue_exception = vmx_queue_exception,
+ .cancel_injection = vmx_cancel_injection,
.interrupt_allowed = vmx_interrupt_allowed,
.nmi_allowed = vmx_nmi_allowed,
.get_nmi_mask = vmx_get_nmi_mask,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 907ea7f..bb447f5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4911,6 +4911,21 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
if (unlikely(r))
goto out;

+ if (kvm_check_request(KVM_REQ_EVENT, vcpu)) {
+ inject_pending_event(vcpu);
+
+ /* enable NMI/IRQ window open exits if needed */
+ if (vcpu->arch.nmi_pending)
+ kvm_x86_ops->enable_nmi_window(vcpu);
+ else if (kvm_cpu_has_interrupt(vcpu) || req_int_win)
+ kvm_x86_ops->enable_irq_window(vcpu);
+
+ if (kvm_lapic_enabled(vcpu)) {
+ update_cr8_intercept(vcpu);
+ kvm_lapic_sync_to_vapic(vcpu);
+ }
+ }
+
preempt_disable();

kvm_x86_ops->prepare_guest_switch(vcpu);
@@ -4929,25 +4944,11 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
smp_wmb();
local_irq_enable();
preempt_enable();
+ kvm_x86_ops->cancel_injection(vcpu);
r = 1;
goto out;
}

- if (kvm_check_request(KVM_REQ_EVENT, vcpu)) {
- inject_pending_event(vcpu);
-
- /* enable NMI/IRQ window open exits if needed */
- if (vcpu->arch.nmi_pending)
- kvm_x86_ops->enable_nmi_window(vcpu);
- else if (kvm_cpu_has_interrupt(vcpu) || req_int_win)
- kvm_x86_ops->enable_irq_window(vcpu);
-
- if (kvm_lapic_enabled(vcpu)) {
- update_cr8_intercept(vcpu);
- kvm_lapic_sync_to_vapic(vcpu);
- }
- }
-
srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);

kvm_guest_enter();
--
1.7.1