KVM: selftests: Set up page size and alignment independently for guest_memfd

Currently, vm_mem_add derives the backing source page size, alignment
padding, and mmap size from the backing source type upfront before checking
if guest_memfd is being mmapped.

With shared memory also mmap()-ed from guest_memfd, the alignment of the
mmap-ed address needs to respect guest_memfd's backing page size.

Refactor the backing store setup to configure the backing source page
size, alignment, mmap flags, and mmap offset directly for guest_memfd
when it is mmapped, ignoring the backing source type.

Skip hugepage validation and anonymous memory madvise calls when mmapping
from guest_memfd, since those are not applicable when mmapping guest_memfd.

Signed-off-by: Ackerley Tng <ackerleytng@google.com>
Reviewed-by: Fuad Tabba <fuad.tabba@linux.dev>
Tested-by: Yan Zhao <yan.y.zhao@intel.com>
Link: https://patch.msgid.link/20260910-gmem-inplace-conversion-v13-42-dd6fbf94f4e1@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

0 files changed, 0 insertions, 0 deletions