From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50798) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZhCyc-0006z9-9U for qemu-devel@nongnu.org; Wed, 30 Sep 2015 04:43:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZhCyZ-0003bp-0n for qemu-devel@nongnu.org; Wed, 30 Sep 2015 04:43:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53868) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZhCyY-0003bW-Pu for qemu-devel@nongnu.org; Wed, 30 Sep 2015 04:42:58 -0400 Date: Wed, 30 Sep 2015 11:42:52 +0300 From: "Michael S. Tsirkin" Message-ID: <20150930114107-mutt-send-email-mst@redhat.com> References: <1443544494-28737-1-git-send-email-marcandre.lureau@redhat.com> <1443544494-28737-5-git-send-email-marcandre.lureau@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1443544494-28737-5-git-send-email-marcandre.lureau@redhat.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v6 04/24] util: add linux-only memfd fallback List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: marcandre.lureau@redhat.com Cc: haifeng.lin@huawei.com, thibaut.collet@6wind.com, jasowang@redhat.com, qemu-devel@nongnu.org, pbonzini@redhat.com On Tue, Sep 29, 2015 at 06:34:34PM +0200, marcandre.lureau@redhat.com wro= te: > From: Marc-Andr=E9 Lureau >=20 > Implement memfd_create() fallback if not available in system libc. > memfd_create() is still not included in glibc today, atlhough it's been > available since Linux 3.17 in Oct 2014. >=20 > memfd has numerous advantages over traditional shm/mmap for ipc memory > sharing with fd handler, which we are going to make use of for > vhost-user logging memory in following patches. >=20 > Signed-off-by: Marc-Andr=E9 Lureau > --- > include/qemu/memfd.h | 20 +++++++++++++++++++ > util/Makefile.objs | 2 +- > util/memfd.c | 56 ++++++++++++++++++++++++++++++++++++++++++++= ++++++++ > 3 files changed, 77 insertions(+), 1 deletion(-) > create mode 100644 include/qemu/memfd.h > create mode 100644 util/memfd.c >=20 > diff --git a/include/qemu/memfd.h b/include/qemu/memfd.h > new file mode 100644 > index 0000000..8b1fe6a > --- /dev/null > +++ b/include/qemu/memfd.h > @@ -0,0 +1,20 @@ > +#ifndef QEMU_MEMFD_H > +#define QEMU_MEMFD_H > + > +#include "config-host.h" > + > +#ifndef F_LINUX_SPECIFIC_BASE > +#define F_LINUX_SPECIFIC_BASE 1024 > +#endif > + > +#ifndef F_ADD_SEALS > +#define F_ADD_SEALS (F_LINUX_SPECIFIC_BASE + 9) > +#define F_GET_SEALS (F_LINUX_SPECIFIC_BASE + 10) > + > +#define F_SEAL_SEAL 0x0001 /* prevent further seals from being se= t */ > +#define F_SEAL_SHRINK 0x0002 /* prevent file from shrinking */ > +#define F_SEAL_GROW 0x0004 /* prevent file from growing */ > +#define F_SEAL_WRITE 0x0008 /* prevent writes */ > +#endif > + > +#endif /* QEMU_MEMFD_H */ > diff --git a/util/Makefile.objs b/util/Makefile.objs > index 114d657..84c5485 100644 > --- a/util/Makefile.objs > +++ b/util/Makefile.objs > @@ -1,6 +1,6 @@ > util-obj-y =3D osdep.o cutils.o unicode.o qemu-timer-common.o > util-obj-$(CONFIG_WIN32) +=3D oslib-win32.o qemu-thread-win32.o event_= notifier-win32.o > -util-obj-$(CONFIG_POSIX) +=3D oslib-posix.o qemu-thread-posix.o event_= notifier-posix.o qemu-openpty.o > +util-obj-$(CONFIG_POSIX) +=3D oslib-posix.o qemu-thread-posix.o event_= notifier-posix.o qemu-openpty.o memfd.o > util-obj-y +=3D envlist.o path.o module.o > util-obj-$(call lnot,$(CONFIG_INT128)) +=3D host-utils.o > util-obj-y +=3D bitmap.o bitops.o hbitmap.o > diff --git a/util/memfd.c b/util/memfd.c > new file mode 100644 > index 0000000..a98d57e > --- /dev/null > +++ b/util/memfd.c > @@ -0,0 +1,56 @@ > +/* > + * memfd.c > + * > + * Copyright (c) 2015 Red Hat, Inc. > + * > + * QEMU library functions on POSIX which are shared between QEMU and > + * the QEMU tools. > + * > + * Permission is hereby granted, free of charge, to any person obtaini= ng a copy > + * of this software and associated documentation files (the "Software"= ), to deal > + * in the Software without restriction, including without limitation t= he rights > + * to use, copy, modify, merge, publish, distribute, sublicense, and/o= r sell > + * copies of the Software, and to permit persons to whom the Software = is > + * furnished to do so, subject to the following conditions: > + * > + * The above copyright notice and this permission notice shall be incl= uded in > + * all copies or substantial portions of the Software. > + * > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXP= RESS OR > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABI= LITY, > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT S= HALL > + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES O= R OTHER > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARI= SING FROM, > + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALI= NGS IN > + * THE SOFTWARE. > + */ > + > +#include "config-host.h" > + > +#include "qemu/memfd.h" > + > +#ifdef CONFIG_MEMFD > +#include So the file is empty if CONFIG_MEMFD is set? It would be more elegant to avoid linking it in. Can be a patch on top. > +#elif defined CONFIG_LINUX > +#include > +#include > +#include > + > +#ifndef MFD_CLOEXEC > +#define MFD_CLOEXEC 0x0001U > +#endif > + > +#ifndef MFD_ALLOW_SEALING > +#define MFD_ALLOW_SEALING 0x0002U > +#endif > + > +static inline int memfd_create(const char *name, unsigned int flags) > +{ > + return syscall(__NR_memfd_create, name, flags); > +} > +#else /* !LINUX */ > +static inline int memfd_create(const char *name, unsigned int flags) > +{ > + return -1; > +} > +#endif > --=20 > 2.4.3