KVM: guest_memfd: Add helpers to query SHARED vs. PRIVATE for a given page

Add helpers to check if a given page in a guest_memfd instance is PRIVATE
versus SHARED, and use the "is shared" helper instead of an open-coded
equivalent in the user pagefault handler.  In addition to the immediate
usage, providing an "is private" helper will allow cleaning up the so
called prepare() code, and eventually will be heavily used once in-place
conversion support comes along.

No functional change intended.

Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Ackerley Tng <ackerleytng@google.com>
Reviewed-by: Fuad Tabba <fuad.tabba@linux.dev>
Link: https://patch.msgid.link/20260723210811.72720-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

0 files changed, 0 insertions, 0 deletions