Run some memfd-related checks before registering hostmem-memfd &
various properties. This will help libvirt to figure out what the host
is supposed to be capable of.
qemu_memfd_check() is changed to a less optimized version, since it is
used with various flags, it no longer caches the result.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180906161415.8543-1-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a new memory backend, similar to hostmem-file, except that it
doesn't need to create files. It also enforces memory sealing.
This backend is mainly useful for sharing the memory with other
processes.
Note that Linux supports transparent huge-pages of shmem/memfd memory
since 4.8. It is relatively easier to set up THP than a dedicate
hugepage mount point by using "madvise" in
/sys/kernel/mm/transparent_hugepage/shmem_enabled.
Since 4.14, memfd allows to set hugetlb requirement explicitly.
Pending for merge in 4.16 is memfd sealing support for hugetlb backed
memory.
Usage:
-object memory-backend-memfd,id=mem1,size=1G
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180201132757.23063-5-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
