On 12/16/2025 4:51 AM, Peter Xu wrote:
Host backends supports guest-memfd now by detecting whether it's a
confidential VM. There's no way to choose it yet from the memory level to
use it fully shared. If we use guest-memfd, it so far always implies we
need two layers of memory backends, while the guest-memfd only provides the
private set of pages.
This patch introduces a way so that QEMU can consume guest memfd as the
only source of memory to back the object (aka, fully shared).
To use the fully shared guest-memfd, one can add a memfd object with:
-object memory-backend-memfd,guest-memfd=on,share=on
Note that share=on is required with fully shared guest_memfd.
PS: there's a trivial touch-up on fd<0 check, because the stub to create
guest-memfd may return negative but not -1.
Signed-off-by: Peter Xu <[email protected]>
Reviewed-by: Xiaoyao Li <[email protected]>
