E.g, why we cannot do:
static bool kvm_use_private_root(struct kvm *kvm)
{
return kvm->arch.vm_type == VM_TYPE_TDX;
}
Or,
static bool kvm_use_private_root(struct kvm *kvm)
{
return kvm->arch.use_private_root;
}
Or, assuming we would love to keep the kvm_gfn_shared_mask():
static bool kvm_use_private_root(struct kvm *kvm)
{
return !!kvm_gfn_shared_mask(kvm);
}
And then:
In fault handler:
if (fault->is_private && kvm_use_private_root(kvm))
// use private root
else
// use shared/normal root
When you zap:
bool private_gpa = kvm_mem_is_private(kvm, gfn);
if (private_gpa && kvm_use_private_root(kvm))
// zap private root
else
// zap shared/normal root.
I think you are trying to say not to abuse kvm_gfn_shared_mask() as is currently
done in this logic. But we already agreed on this. So not sure.
To be clear: We agreed on this in general, but not on this
kvm_on_private_root().
It's obvious that you still want to "use kvm_gfn_shared_mask() to
determine whether a GPA is private" for this helper but I don't like it.
In fact I don't see why we even need this helper.
I think I am just too obsessed on avoiding using kvm_gfn_shared_mask()
so I'll stop commenting/replying on this.
[...]
I don't think we can get rid of the shared mask. Even if we relied on
kvm_mem_is_private() to determine if a GPA is private or shared, at absolute
minimum we need to add the shared bit when we are zapping a GFN or mapping it.
No we cannot, but we can avoid using it here.
Let's table the discussion until we have some code to look again.
100% agreed.
