From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43305) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZmHyM-0006L4-Ox for qemu-devel@nongnu.org; Wed, 14 Oct 2015 05:03:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZmHyH-0004hP-NO for qemu-devel@nongnu.org; Wed, 14 Oct 2015 05:03:46 -0400 Received: from mail-wi0-f177.google.com ([209.85.212.177]:33231) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZmHyH-0004hB-Ep for qemu-devel@nongnu.org; Wed, 14 Oct 2015 05:03:41 -0400 Received: by wicge5 with SMTP id ge5so91302064wic.0 for ; Wed, 14 Oct 2015 02:03:40 -0700 (PDT) Date: Wed, 14 Oct 2015 11:03:37 +0200 From: Eduardo Otubo Message-ID: <20151014090337.GA13329@vader> References: <1435756353-4150-1-git-send-email-drjones@redhat.com> <20150924093119.GA11859@vader> <20150924135004.GC3486@hawk.localdomain> <20150929093946.GA30238@vader> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="OgqxwSJOaUobr8KG" Content-Disposition: inline In-Reply-To: <20150929093946.GA30238@vader> Subject: Re: [Qemu-devel] [PATCH] libseccomp: add cacheflush to whitelist List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Andrew Jones , qemu-devel@nongnu.org, peter.maydell@linaro.org, pmoore@redhat.com --OgqxwSJOaUobr8KG Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Sep 29, 2015 at 11=3D39=3D46AM +0200, Eduardo Otubo wrote: > On Thu, Sep 24, 2015 at 03=3D50=3D04PM +0200, Andrew Jones wrote: > > On Thu, Sep 24, 2015 at 11:31:19AM +0200, Eduardo Otubo wrote: > > > On Wed, Jul 01, 2015 at 09=3D12=3D33AM -0400, Andrew Jones wrote: > > > > cacheflush is an arm-specific syscall that qemu built for arm > > > > uses. Add it to the whitelist. > > > >=20 > > > > Signed-off-by: Andrew Jones > > > >=20 > > > > --- > > > >=20 > > > > I'm not sure about the priority selection. Maybe cacheflush gets > > > > used frequently enough that it deserves a higher one? > > >=20 > > > The frequency is measured using strace and comparing the frequency th= ey > > > appear among other syscalls. Can you run this analysis and double che= ck > > > if the lowest priority is still accurate? > >=20 > > Hi Eduardo, > >=20 > > Short answer: The lowest priority is definitely correct. > >=20 > > Long answer: > >=20 > > I ran strace while installing a new guest, of 3.6 million syscalls, > > only 5 were cacheflush. Of course the syscalls used (and their frequenc= y) > > is host-type, qemu machine-type, config (qemu command line), and guest > > workload specific. So, ideally, qemu machine-types would register their > > own whitelists, possibly modified by host-type. For example, I ran the > > mach-virt machine-type on both a midway and a mustang. In both cases it > > was a basic guest config and an install-type workload. For the mustang, > > over 55% of the syscalls were ioctl, but, for the midway, ioctls were > > 16% and 43% were clock_gettime. I generated a most-used-first list for > > each. Neither list really matched up well with seccomp_whitelist (except > > for futex). > >=20 > > Besides allowing machine types to help set priorities, it may also be > > nice if both compile-time and run-time configs could further reduce the > > whitelist. For example, mlockall is only necessary if '-realtime mlock= =3Don' > > is passed on the command line. > >=20 > > Thanks, > > drew > >=20 > > >=20 > > > Thanks for the patch. > > >=20 > > > >=20 > > > > This patch isn't really necessary yet due to ae6e8ef11e6c: "Revert > > > > seccomp tests that allow it to be used on non-x86 architectures", > > > > which we can't revert until libseccomp has released a fix for > > > > arm-specific syscall symbol naming, but when linking to a patched > > > > libseccomp and reverting ae6e8ef11e6c, then this patch allows > > > > guests to boot with '-sandbox on'. > > > >=20 > > > > Signed-off-by: Andrew Jones > > > > --- > > > > qemu-seccomp.c | 3 ++- > > > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > >=20 > > > > diff --git a/qemu-seccomp.c b/qemu-seccomp.c > > > > index f9de0d3390feb..33644a4e3c3d3 100644 > > > > --- a/qemu-seccomp.c > > > > +++ b/qemu-seccomp.c > > > > @@ -237,7 +237,8 @@ static const struct QemuSeccompSyscall seccomp_= whitelist[] =3D { > > > > { SCMP_SYS(fadvise64), 240 }, > > > > { SCMP_SYS(inotify_init1), 240 }, > > > > { SCMP_SYS(inotify_add_watch), 240 }, > > > > - { SCMP_SYS(mbind), 240 } > > > > + { SCMP_SYS(mbind), 240 }, > > > > + { SCMP_SYS(cacheflush), 240 }, FYI: I had to fixed this minor mistake (using comma at the end of the list) before applying your patch. --=20 Eduardo Otubo ProfitBricks GmbH --OgqxwSJOaUobr8KG Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJWHhppAAoJEP0M/1sS+L0v2icH/i9MeNLYmud8Mo7Iq/v1LUzm Dl8Z3UTe3CVD2cQtn4GTmQGKB5vhh1lGXdt9JKAcnM5Hp9wK0TcBX4pAnlP/+QLL mGL3YEmfFWrjv6v4MPM32xo3Rvzpf2TFZTmuzMQqU9JRhyqyoDdR+PhCA5VDXlSJ 6fWNpH94vYDMr1SlXersz5C1mnC/1Az37Y8DMNpCVU3pdMKC6M+aE8tNIPmHUlS3 8s3BV6NkNYdUFz86w3tyNMMlzNlHl45zbSLlt8zQbiWKcDIcdmxuNdhyfGZcyiD5 t2wVM85lmacmwMF+0o8lXaxyFcQ2Vxnf/vah6Xt0gALkk3gUuCsCRTKz5lccPK4= =89tv -----END PGP SIGNATURE----- --OgqxwSJOaUobr8KG--