KVM: PPC: Preload FPU when possible

There are some situations when we're pretty sure the guest will use the
FPU soon. So we can save the churn of going into the guest, finding out
it does want to use the FPU and going out again.

This patch adds preloading of the FPU when it's reasonable.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

arch/powerpc/kvm/book3s.c

@@ -138,6 +138,10 @@ void kvmppc_set_msr(struct kvm_vcpu *vcpu, u64 msr)
 		kvmppc_mmu_flush_segments(vcpu);
 		kvmppc_mmu_map_segment(vcpu, vcpu->arch.pc);
 	}
+
+	/* Preload FPU if it's enabled */
+	if (vcpu->arch.msr & MSR_FP)
+		kvmppc_handle_ext(vcpu, BOOK3S_INTERRUPT_FP_UNAVAIL, MSR_FP);
 }
 
 void kvmppc_inject_interrupt(struct kvm_vcpu *vcpu, int vec, u64 flags)
@@ -1196,6 +1200,10 @@ int __kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 	/* XXX we get called with irq disabled - change that! */
 	local_irq_enable();
 
+	/* Preload FPU if it's enabled */
+	if (vcpu->arch.msr & MSR_FP)
+		kvmppc_handle_ext(vcpu, BOOK3S_INTERRUPT_FP_UNAVAIL, MSR_FP);
+
 	ret = __kvmppc_vcpu_entry(kvm_run, vcpu);
 
 	local_irq_disable();