KVM: Fix guest register corruption on paravirt hypercall

The hypercall code mixes up the ->cache_regs() and ->decache_regs()
callbacks, resulting in guest register corruption.
Signed-off-by: Dor Laor <dor.laor@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

drivers/kvm/kvm_main.c

@@ -1177,7 +1177,7 @@ int kvm_hypercall(struct kvm_vcpu *vcpu, struct kvm_run *run)
 {
 	unsigned long nr, a0, a1, a2, a3, a4, a5, ret;
 
-	kvm_arch_ops->decache_regs(vcpu);
+	kvm_arch_ops->cache_regs(vcpu);
 	ret = -KVM_EINVAL;
 #ifdef CONFIG_X86_64
 	if (is_long_mode(vcpu)) {
@@ -1204,7 +1204,7 @@ int kvm_hypercall(struct kvm_vcpu *vcpu, struct kvm_run *run)
 		;
 	}
 	vcpu->regs[VCPU_REGS_RAX] = ret;
-	kvm_arch_ops->cache_regs(vcpu);
+	kvm_arch_ops->decache_regs(vcpu);
 	return 1;
 }
 EXPORT_SYMBOL_GPL(kvm_hypercall);