From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55909) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dNgDP-0005JP-5M for qemu-devel@nongnu.org; Wed, 21 Jun 2017 10:02:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dNgDJ-0004Yt-6t for qemu-devel@nongnu.org; Wed, 21 Jun 2017 10:02:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43778) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dNgDI-0004Yk-VB for qemu-devel@nongnu.org; Wed, 21 Jun 2017 10:02:33 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id F0CDD61B8F for ; Wed, 21 Jun 2017 14:02:31 +0000 (UTC) From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= Date: Wed, 21 Jun 2017 16:02:18 +0200 Message-Id: <20170621140219.4568-3-marcandre.lureau@redhat.com> In-Reply-To: <20170621140219.4568-1-marcandre.lureau@redhat.com> References: <20170621140219.4568-1-marcandre.lureau@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] [PATCH v4 2/3] Add memfd based hostmem List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: imammedo@redhat.com, ehabkost@redhat.com, =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= 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. Usage: -object memory-backend-memfd,id=3Dmem1,size=3D1G Signed-off-by: Marc-Andr=C3=A9 Lureau --- backends/hostmem-memfd.c | 67 ++++++++++++++++++++++++++++++++++++++++++= ++++++ backends/Makefile.objs | 2 ++ qemu-options.hx | 11 ++++++++ 3 files changed, 80 insertions(+) create mode 100644 backends/hostmem-memfd.c diff --git a/backends/hostmem-memfd.c b/backends/hostmem-memfd.c new file mode 100644 index 0000000000..13d300d9ad --- /dev/null +++ b/backends/hostmem-memfd.c @@ -0,0 +1,67 @@ +/* + * QEMU host memfd memory backend + * + * Copyright (C) 2016 Red Hat Inc + * + * Authors: + * Marc-Andr=C3=A9 Lureau + * + * This work is licensed under the terms of the GNU GPL, version 2 or la= ter. + * See the COPYING file in the top-level directory. + */ +#include "qemu/osdep.h" +#include "qemu-common.h" +#include "sysemu/hostmem.h" +#include "sysemu/sysemu.h" +#include "qom/object_interfaces.h" +#include "qemu/memfd.h" +#include "qapi/error.h" + +#define TYPE_MEMORY_BACKEND_MEMFD "memory-backend-memfd" + +static void +memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) +{ + int fd; + + if (!backend->size) { + error_setg(errp, "can't create backend with size 0"); + return; + } + + if (!memory_region_size(&backend->mr)) { + backend->force_prealloc =3D mem_prealloc; + fd =3D qemu_memfd_create(TYPE_MEMORY_BACKEND_MEMFD, + backend->size, + F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL= , + true); + if (fd =3D=3D -1) { + error_setg(errp, "can't allocate memfd backend"); + return; + } + memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend), + object_get_canonical_path(OBJECT(backend)), + backend->size, true, fd, errp); + } +} + +static void +memfd_backend_class_init(ObjectClass *oc, void *data) +{ + HostMemoryBackendClass *bc =3D MEMORY_BACKEND_CLASS(oc); + + bc->alloc =3D memfd_backend_memory_alloc; +} + +static const TypeInfo memfd_backend_info =3D { + .name =3D TYPE_MEMORY_BACKEND_MEMFD, + .parent =3D TYPE_MEMORY_BACKEND, + .class_init =3D memfd_backend_class_init, +}; + +static void register_types(void) +{ + type_register_static(&memfd_backend_info); +} + +type_init(register_types); diff --git a/backends/Makefile.objs b/backends/Makefile.objs index 0400799efd..67eeeba5fc 100644 --- a/backends/Makefile.objs +++ b/backends/Makefile.objs @@ -8,3 +8,5 @@ common-obj-$(CONFIG_LINUX) +=3D hostmem-file.o =20 common-obj-y +=3D cryptodev.o common-obj-y +=3D cryptodev-builtin.o + +common-obj-$(CONFIG_LINUX) +=3D hostmem-memfd.o diff --git a/qemu-options.hx b/qemu-options.hx index 30c4f9850f..6db76cf54f 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -3974,6 +3974,17 @@ The @option{share} boolean option determines wheth= er the memory region is marked as private to QEMU, or shared. The latter allows a co-operating external process to access the QEMU memory region. =20 +@item -object memory-backend-memfd,id=3D@var{id},size=3D@var{size} + +Creates an anonymous memory file backend object, which can be used to +share the memory with a co-operating external process. The memory is +allocated with memfd and sealing. (Linux only) + +The @option{id} parameter is a unique ID that will be used to +reference this memory region when configuring the @option{-numa} +argument. The @option{size} option provides the size of the memory +region, and accepts common suffixes, eg @option{500M}. + @item -object rng-random,id=3D@var{id},filename=3D@var{/dev/random} =20 Creates a random number generator backend which obtains entropy from --=20 2.13.1.395.gf7b71de06