Re: [Qemu-devel] [PATCH] hostmem-memfd: honour share=on/off property

[Igor Mammedov <imammedo@redhat.com>]

On Tue, 28 Aug 2018 17:38:40 +0200
Marc-André Lureau <marcandre.lureau@redhat.com> wrote:

> The share=on/off property is used to modified mmap() MAP_SHARED
> setting. Make it on by default for convenience and compatibility
> reasons.
> 
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  backends/hostmem-memfd.c | 4 +++-
>  qemu-options.hx          | 4 +++-
>  2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/backends/hostmem-memfd.c b/backends/hostmem-memfd.c
> index 1e20fe0ba8..abd52364db 100644
> --- a/backends/hostmem-memfd.c
> +++ b/backends/hostmem-memfd.c
> @@ -59,7 +59,8 @@ memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
>  
>      name = object_get_canonical_path(OBJECT(backend));
>      memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend),
> -                                   name, backend->size, true, fd, errp);
> +                                   name, backend->size,
> +                                   backend->share, fd, errp);
>      g_free(name);
>  }
>  
> @@ -131,6 +132,7 @@ memfd_backend_instance_init(Object *obj)
>  
>      /* default to sealed file */
>      m->seal = true;
> +    MEMORY_BACKEND(m)->share = true;
>  }
>  
>  static void
> diff --git a/qemu-options.hx b/qemu-options.hx
> index f14e423b7c..25c02d72b8 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -4029,7 +4029,7 @@ Memory backend objects offer more control than the @option{-m} option that is
>  traditionally used to define guest RAM. Please refer to
>  @option{memory-backend-file} for a description of the options.
>  
> -@item -object memory-backend-memfd,id=@var{id},merge=@var{on|off},dump=@var{on|off},prealloc=@var{on|off},size=@var{size},host-nodes=@var{host-nodes},policy=@var{default|preferred|bind|interleave},seal=@var{on|off},hugetlb=@var{on|off},hugetlbsize=@var{size}
> +@item -object memory-backend-memfd,id=@var{id},merge=@var{on|off},dump=@var{on|off},share=@var{on|off},prealloc=@var{on|off},size=@var{size},host-nodes=@var{host-nodes},policy=@var{default|preferred|bind|interleave},seal=@var{on|off},hugetlb=@var{on|off},hugetlbsize=@var{size}
>  
>  Creates an anonymous memory file backend object, which allows QEMU to
>  share the memory with an external process (e.g. when using
> @@ -4051,6 +4051,8 @@ with the @option{seal} option (requires at least Linux 4.16).
>  Please refer to @option{memory-backend-file} for a description of the
>  other options.
>  
> +The @option{share} boolean option is @var{on} by default with memfd.
> +
>  @item -object rng-random,id=@var{id},filename=@var{/dev/random}
>  
>  Creates a random number generator backend which obtains entropy from

Reviewed-by: Igor Mammedov <imammedo@redhat.com>