Re: [PATCH RFC v7 07/64] KVM: SEV: Handle KVM_HC_MAP_GPA_RANGE hypercall

[Sean Christopherson]

On Fri, Jan 13, 2023, Borislav Petkov wrote:
> On Wed, Dec 14, 2022 at 01:39:59PM -0600, Michael Roth wrote:
> > From: Nikunj A Dadhania <nikunj@xxxxxxx>
> > 
> > KVM_HC_MAP_GPA_RANGE hypercall is used by the SEV guest to notify a
> > change in the page encryption status to the hypervisor.
> > 
> > The hypercall exits to userspace with KVM_EXIT_HYPERCALL exit code,
> > currently this is used for explicit memory conversion between
> > shared/private for memfd based private memory.
> 
> So Tom and I spent a while to figure out what this is doing...
> 
> Please explain in more detail what that is. Like the hypercall gets ignored for
> memslots which cannot be private...?

Don't bother, just drop the patch.  It's perfectly legal for userspace to create
the private memslot in response to a guest request.