From 0a5fff192388d2a74aa9ab5e0d394b745df9f225 Mon Sep 17 00:00:00 2001 From: Gleb Natapov Date: Tue, 21 Apr 2009 17:45:06 +0300 Subject: KVM: Do not report TPR write to userspace if new value bigger or equal to a previous one. Saves many exits to userspace in a case of IRQ chip in userspace. Signed-off-by: Gleb Natapov Signed-off-by: Avi Kivity --- arch/x86/kvm/vmx.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) (limited to 'arch/x86/kvm/vmx.c') diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 9162b4cd3410..51f804c8fe79 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2724,13 +2724,18 @@ static int handle_cr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) kvm_set_cr4(vcpu, kvm_register_read(vcpu, reg)); skip_emulated_instruction(vcpu); return 1; - case 8: - kvm_set_cr8(vcpu, kvm_register_read(vcpu, reg)); - skip_emulated_instruction(vcpu); - if (irqchip_in_kernel(vcpu->kvm)) - return 1; - kvm_run->exit_reason = KVM_EXIT_SET_TPR; - return 0; + case 8: { + u8 cr8_prev = kvm_get_cr8(vcpu); + u8 cr8 = kvm_register_read(vcpu, reg); + kvm_set_cr8(vcpu, cr8); + skip_emulated_instruction(vcpu); + if (irqchip_in_kernel(vcpu->kvm)) + return 1; + if (cr8_prev <= cr8) + return 1; + kvm_run->exit_reason = KVM_EXIT_SET_TPR; + return 0; + } }; break; case 2: /* clts */ -- cgit v1.2.3