On Tue, Oct 31, 2023 at 2:36 PM Sean Christopherson <seanjc@xxxxxxxxxx> wrote: > On Tue, Oct 31, 2023, David Matlack wrote: > > On 2023-10-27 11:21 AM, Sean Christopherson wrote: > > > Introduce an ioctl(), KVM_CREATE_GUEST_MEMFD, to allow creating file-based > > > memory that is tied to a specific KVM virtual machine and whose primary > > > purpose is to serve guest memory. > > > Maybe can you sketch out how you see this proposal being extensible to > > using guest_memfd for shared mappings? > > For in-place conversions, e.g. pKVM, no additional guest_memfd is needed. What's > missing there is the ability to (safely) mmap() guest_memfd, e.g. KVM needs to > ensure there are no outstanding references when converting back to private. > > For TDX/SNP, assuming we don't find a performant and robust way to do in-place > conversions, a second fd+offset pair would be needed. Is there a way to support non-in-place conversions within a single guest_memfd?
