Re: [PATCH V2 16/32] x86/sgx: Support restricting of enclave page permissions

[Jarkko Sakkinen]

Sorry, I missed this.

On Thu, Mar 03, 2022 at 01:44:14PM -0800, Dave Hansen wrote:
> On 3/3/22 13:23, Reinette Chatre wrote:
> > Unfortunately MAP_POPULATE is not supported by SGX VMAs because of their
> > VM_IO and VM_PFNMAP flags. When VMAs with such flags obtain this capability
> > then I believe that SGX would benefit.
> 
> Some Intel folks asked for this quite a while ago.  I think it's
> entirely doable: add a new vm_ops->populate() function that will allow
> ignoring VM_IO|VM_PFNMAP if present.

I'm sorry what I don't understand what you mean by ignoring here,
i.e. cannot fully comprehend the last sentece.

And would the vm_ops->populate() be called right after the existing ones
involved with the VMA creation process?

> Or, if nobody wants to waste all of the vm_ops space, just add an
> arch_vma_populate() or something which can call over into SGX.
> 
> I'll happily review the patches if anyone can put such a beast together.

I'll start with vm_ops->populate() and check the feedback first for
that.

BR, Jarkko