Andrew Jones [off-list ref] writes:

On Tue, Nov 25, 2014 at 04:10:01PM +0000, Alex Benn?e wrote:

quoted

This commit adds a stub function to support the KVM_SET_GUEST_DEBUG
ioctl. Currently any operation flag will return EINVAL. Actual
functionality will be added with further patches.

Technically the stub is already there, and you're extending it to
start looking at control flags, but still not doing anything yet.

Sure we do:

quoted

 int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
 					struct kvm_guest_debug *dbg)
 {
-	return -EINVAL;
+	/* If it's not enabled clear all flags */
+	if (!(dbg->control & KVM_GUESTDBG_ENABLE)) {
+		vcpu->guest_debug = 0;
+		return 0;
+	}

That's some class non-functionality right there ;-)

quoted

+	vcpu->guest_debug = dbg->control;
+	kvm_info("%s: guest_debug is 0x%lx\n", __func__, vcpu->guest_debug);
+
+	/* Single Step */
+	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) {
+		kvm_info("SS requested, not yet implemented\n");
+		return -EINVAL;
+	}
+
+	/* Software Break Points */
+	if (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP) {
+		kvm_info("SW BP support requested, not yet implemented\n");
+		return -EINVAL;
+	}
+
+	/* Hardware assisted Break and Watch points */
+	if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) {
+		kvm_info("HW BP support requested, not yet implemented\n");
+		return -EINVAL;
+	}
+
+	return 0;
 }

I guess all the kvm_info's were useful for developing this patch series,
but do we still need them?

They also served the very useful roll of stopping checkpatch.pl bitching
about my reluctance to remove braces from the if () { } clauses. However
I take your point. I can certainly remove the kvm_info() statements as
each bit of functionality is added while leaving this one to help when
someone is bisecting and confused.

-- 
Alex Benn?e