On 05/27/2013 08:23 PM, Paolo Bonzini wrote:
> Il 25/05/2013 04:45, David Gibson ha scritto:
>>>> + case KVM_CREATE_SPAPR_TCE_IOMMU: {
>>>> + struct kvm_create_spapr_tce_iommu create_tce_iommu;
>>>> + struct kvm *kvm = filp->private_data;
>>>> +
>>>> + r = -EFAULT;
>>>> + if (copy_from_user(&create_tce_iommu, argp,
>>>> + sizeof(create_tce_iommu)))
>>>> + goto out;
>>>> + r = kvm_vm_ioctl_create_spapr_tce_iommu(kvm,
>>>> &create_tce_iommu);
>>>> + goto out;
>>>> + }
>
> Would it make sense to make this the only interface for creating TCEs?
> That is, pass both a window_size and an IOMMU group id (or e.g. -1 for
> no hardware IOMMU usage), and have a single ioctl for both cases?
> There's some duplicated code between kvm_vm_ioctl_create_spapr_tce and
> kvm_vm_ioctl_create_spapr_tce_iommu.
Just few bits. Is there really much sense in making one function from those
two? I tried, looked a bit messy.
> KVM_CREATE_SPAPR_TCE could stay for backwards-compatibility, or you
> could just use a new capability and drop the old ioctl.
The old capability+ioctl already exist for quite a while and few QEMU
versions supporting it were released so we do not want just drop it. So
then what is the benefit of having a new interface with support of both types?
> I'm not sure
> whether you're already considering the ABI to be stable for kvmppc.
Is any bit of KVM using it? Cannot see from Documentation/ABI.
--
Alexey
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