On 7/18/2025 12:27 AM, Fuad Tabba wrote:
Add a new internal flag, KVM_MEMSLOT_GMEM_ONLY, to the top half of memslot->flags (which makes it strictly for KVM's internal use). This flag tracks when a guest_memfd-backed memory slot supports host userspace mmap operations, which implies that all memory, not just private memory for CoCo VMs, is consumed through guest_memfd: "gmem only". This optimization avoids repeatedly checking the underlying guest_memfd file for mmap support, which would otherwise require taking and releasing a reference on the file for each check. By caching this information directly in the memslot, we reduce overhead and simplify the logic involved in handling guest_memfd-backed pages for host mappings. Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx> Reviewed-by: Shivank Garg <shivankg@xxxxxxx> Acked-by: David Hildenbrand <david@xxxxxxxxxx> Suggested-by: David Hildenbrand <david@xxxxxxxxxx> Signed-off-by: Fuad Tabba <tabba@xxxxxxxxxx>
Reviewed-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
