From aaacfc9ae225e88695e610a35627d2256dc08633 Mon Sep 17 00:00:00 2001 From: Joerg Roedel Date: Wed, 16 Apr 2008 16:51:18 +0200 Subject: [PATCH] KVM: SVM: disable CR8 intercept when tpr is not masking interrupts This patch disables the intercept of CR8 writes if the TPR is not masking interrupts. This reduces the total number CR8 intercepts to below 1 percent of what we have without this patch using Windows 64 bit guests. Signed-off-by: Joerg Roedel Signed-off-by: Avi Kivity --- arch/x86/kvm/svm.c | 31 +++++++++++++++++++++++++++---- 1 file changed, 27 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index ee2ee83f3c..61bb2cb512 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1502,6 +1502,27 @@ static void svm_set_irq(struct kvm_vcpu *vcpu, int irq) svm_inject_irq(svm, irq); } +static void update_cr8_intercept(struct kvm_vcpu *vcpu) +{ + struct vcpu_svm *svm = to_svm(vcpu); + struct vmcb *vmcb = svm->vmcb; + int max_irr, tpr; + + if (!irqchip_in_kernel(vcpu->kvm) || vcpu->arch.apic->vapic_addr) + return; + + vmcb->control.intercept_cr_write &= ~INTERCEPT_CR8_MASK; + + max_irr = kvm_lapic_find_highest_irr(vcpu); + if (max_irr == -1) + return; + + tpr = kvm_lapic_get_cr8(vcpu) << 4; + + if (tpr >= (max_irr & 0xf0)) + vmcb->control.intercept_cr_write |= INTERCEPT_CR8_MASK; +} + static void svm_intr_assist(struct kvm_vcpu *vcpu) { struct vcpu_svm *svm = to_svm(vcpu); @@ -1514,14 +1535,14 @@ static void svm_intr_assist(struct kvm_vcpu *vcpu) SVM_EVTINJ_VEC_MASK; vmcb->control.exit_int_info = 0; svm_inject_irq(svm, intr_vector); - return; + goto out; } if (vmcb->control.int_ctl & V_IRQ_MASK) - return; + goto out; if (!kvm_cpu_has_interrupt(vcpu)) - return; + goto out; if (!(vmcb->save.rflags & X86_EFLAGS_IF) || (vmcb->control.int_state & SVM_INTERRUPT_SHADOW_MASK) || @@ -1529,12 +1550,14 @@ static void svm_intr_assist(struct kvm_vcpu *vcpu) /* unable to deliver irq, set pending irq */ vmcb->control.intercept |= (1ULL << INTERCEPT_VINTR); svm_inject_irq(svm, 0x0); - return; + goto out; } /* Okay, we can deliver the interrupt: grab it and update PIC state. */ intr_vector = kvm_cpu_get_interrupt(vcpu); svm_inject_irq(svm, intr_vector); kvm_timer_intr_post(vcpu, intr_vector); +out: + update_cr8_intercept(vcpu); } static void kvm_reput_irq(struct vcpu_svm *svm) -- 2.39.5