From 02daab21d94dc4cf01b2fd09863d59a436900322 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Wed, 30 Dec 2009 12:40:26 +0200 Subject: KVM: Lazify fpu activation and deactivation Defer fpu deactivation as much as possible - if the guest fpu is loaded, keep it loaded until the next heavyweight exit (where we are forced to unload it). This reduces unnecessary exits. We also defer fpu activation on clts; while clts signals the intent to use the fpu, we can't be sure the guest will actually use it. Signed-off-by: Avi Kivity --- arch/x86/kvm/x86.c | 7 ++++++- 1 file changed, 6 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 748b15d8e46d..1de2ad7a004d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1509,8 +1509,8 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) { - kvm_x86_ops->vcpu_put(vcpu); kvm_put_guest_fpu(vcpu); + kvm_x86_ops->vcpu_put(vcpu); } static int is_efer_nx(void) @@ -4006,6 +4006,10 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) r = 0; goto out; } + if (test_and_clear_bit(KVM_REQ_DEACTIVATE_FPU, &vcpu->requests)) { + vcpu->fpu_active = 0; + kvm_x86_ops->fpu_deactivate(vcpu); + } } preempt_disable(); @@ -5075,6 +5079,7 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu) kvm_fx_save(&vcpu->arch.guest_fx_image); kvm_fx_restore(&vcpu->arch.host_fx_image); ++vcpu->stat.fpu_reload; + set_bit(KVM_REQ_DEACTIVATE_FPU, &vcpu->requests); } EXPORT_SYMBOL_GPL(kvm_put_guest_fpu); -- cgit v1.2.2