From a547c6db4d2f16ba5ce8e7054bffad6acc248d40 Mon Sep 17 00:00:00 2001 From: Yang Zhang Date: Thu, 11 Apr 2013 19:25:10 +0800 Subject: KVM: VMX: Enable acknowledge interupt on vmexit The "acknowledge interrupt on exit" feature controls processor behavior for external interrupt acknowledgement. When this control is set, the processor acknowledges the interrupt controller to acquire the interrupt vector on VM exit. After enabling this feature, an interrupt which arrived when target cpu is running in vmx non-root mode will be handled by vmx handler instead of handler in idt. Currently, vmx handler only fakes an interrupt stack and jump to idt table to let real handler to handle it. Further, we will recognize the interrupt and only delivery the interrupt which not belong to current vcpu through idt table. The interrupt which belonged to current vcpu will be handled inside vmx handler. This will reduce the interrupt handle cost of KVM. Also, interrupt enable logic is changed if this feature is turnning on: Before this patch, hypervior call local_irq_enable() to enable it directly. Now IF bit is set on interrupt stack frame, and will be enabled on a return from interrupt handler if exterrupt interrupt exists. If no external interrupt, still call local_irq_enable() to enable it. Refer to Intel SDM volum 3, chapter 33.2. Signed-off-by: Yang Zhang Reviewed-by: Gleb Natapov Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/x86.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'arch/x86/kvm/x86.c') diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ae9744d03c83..1562671a8e18 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5820,7 +5820,9 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) vcpu->mode = OUTSIDE_GUEST_MODE; smp_wmb(); - local_irq_enable(); + + /* Interrupt is enabled by handle_external_intr() */ + kvm_x86_ops->handle_external_intr(vcpu); ++vcpu->stat.exits; -- cgit v1.2.3