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SubjectRe: [PATCH 3/7] KVM: arm: guest debug, add stub KVM_SET_GUEST_DEBUG ioctl
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Andrew Jones <drjones@redhat.com> writes:

> On Tue, Nov 25, 2014 at 04:10:01PM +0000, Alex Bennée wrote:
>> 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:

>> 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 ;-)

>> + 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 Bennée


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