Re: [RFC v2 PATCH 04/13] KVM: Add fd-based memslot data structure and utils

[Paolo Bonzini]

On 11/19/21 14:47, Chao Peng wrote:
> For fd-based memslot store the file references for shared fd and the
> private fd (if any) in the memslot structure. Since there is no 'hva'
> concept we cannot call hva_to_pfn() to get a pfn, instead kvm_memfd_ops
> is added to get_pfn/put_pfn from the memory backing stores that provide
> these fds.
>
> Signed-off-by: Yu Zhang<yu.c.zhang@linux.intel.com>
> Signed-off-by: Chao Peng<chao.p.peng@linux.intel.com>
> ---

What about kvm_read/write_guest?  Maybe the proposal which kept 
userspace_addr for the shared fd is more doable (it would be great to 
ultimately remove the mandatory userspace mapping for the shared fd, but 
I think KVM is not quite ready for that).

Paolo