On 6/19/2026 8:31 AM, Ackerley Tng via B4 Relay wrote:

From: Ackerley Tng <redacted>

All-shared guest_memfd used to be only supported for non-CoCo VMs where
preparation doesn't apply. INIT_SHARED is about to be supported for CoCo
VMs in a later patch in this series.

In addition, KVM_SET_MEMORY_ATTRIBUTES2 is about to be supported in
guest_memfd in a later patch in this series.

This means that the kvm fault handler may now call kvm_gmem_get_pfn() on a
shared folio for a CoCo VM where preparation applies.

Add a check to make sure that preparation is only performed for private
folios.

Preparation will be undone on freeing (see kvm_gmem_free_folio()) and on
conversion to shared.

Suggested-by: Michael Roth <redacted>
Reviewed-by: Fuad Tabba <redacted>
Signed-off-by: Ackerley Tng <redacted>

Reviewed-by: Binbin Wu <redacted>