From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33483) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fTnuQ-0006yU-GE for qemu-devel@nongnu.org; Fri, 15 Jun 2018 08:32:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fTnuP-0006c4-4g for qemu-devel@nongnu.org; Fri, 15 Jun 2018 08:32:54 -0400 Date: Fri, 15 Jun 2018 22:32:44 +1000 From: David Gibson Message-ID: <20180615123244.GB2363@umbus.fritz.box> References: <152901299450.252222.14219708016930421485.stgit@bahia.lan> <152901304242.252222.9947658955703347553.stgit@bahia.lan> <20180615000225.GC4129@umbus.fritz.box> <20180615001431.GF4129@umbus.fritz.box> <20180615075805.1213ed06@bahia.lan> <20180615062915.GU4129@umbus.fritz.box> <20180615090724.6755df6f@bahia.lan> <20180615100147.0acfa6f2@bahia.lan> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="aM3YZ0Iwxop3KEKx" Content-Disposition: inline In-Reply-To: <20180615100147.0acfa6f2@bahia.lan> Subject: Re: [Qemu-devel] [PATCH 3/5] spapr_cpu_core: add missing rollback on realization path List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Greg Kurz Cc: qemu-devel@nongnu.org, qemu-ppc@nongnu.org, =?iso-8859-1?Q?C=E9dric?= Le Goater --aM3YZ0Iwxop3KEKx Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Jun 15, 2018 at 10:01:47AM +0200, Greg Kurz wrote: > On Fri, 15 Jun 2018 09:07:24 +0200 > Greg Kurz wrote: >=20 > > On Fri, 15 Jun 2018 16:29:15 +1000 > > David Gibson wrote: > >=20 > > > On Fri, Jun 15, 2018 at 07:58:05AM +0200, Greg Kurz wrote: =20 > > > > On Fri, 15 Jun 2018 10:14:31 +1000 > > > > David Gibson wrote: > > > > =20 > > > > > On Fri, Jun 15, 2018 at 10:02:25AM +1000, David Gibson wrote: = =20 > > > > > > On Thu, Jun 14, 2018 at 11:50:42PM +0200, Greg Kurz wrote: = =20 > > > > > > > The spapr_realize_vcpu() function doesn't rollback in case of= error. > > > > > > > This isn't a problem with coldplugged CPUs because the machin= e won't > > > > > > > start and QEMU will exit. Hotplug is a different story though= : the > > > > > > > CPU thread is started under object_property_set_bool() and it= assumes > > > > > > > it can access the CPU object. > > > > > > >=20 > > > > > > > If icp_create() fails, we return an error without unregisteri= ng the > > > > > > > reset handler for this CPU, and we let the underlying QEMU th= read for > > > > > > > this CPU alive. Since spapr_cpu_core_realize() doesn't care t= o unrealize > > > > > > > already realized CPUs either, but happily frees all of them a= nyway, the > > > > > > > CPU thread crashes instantly: > > > > > > >=20 > > > > > > > (qemu) device_add host-spapr-cpu-core,core-id=3D1,id=3Dgku > > > > > > > GKU: failing icp_create (cpu 0x11497fd0) > > > > > > > ^^^^^^^^^^ > > > > > > > Program received signal SIGSEGV, Segmentation fault. > > > > > > > [Switching to Thread 0x7fffee3feaa0 (LWP 24725)] > > > > > > > 0x00000000104c8374 in object_dynamic_cast_assert (obj=3D0x114= 97fd0, > > > > > > > ^^^^^^^^^^^= ^^^ > > > > > > > pointer to the C= PU object > > > > > > > 623 trace_object_dynamic_cast_assert(obj ? obj->class= ->type->name > > > > > > > (gdb) p obj->class->type > > > > > > > $1 =3D (Type) 0x0 > > > > > > > (gdb) p * obj > > > > > > > $2 =3D {class =3D 0x10ea9c10, free =3D 0x11244620, > > > > > > > ^^^^^^^^^^ > > > > > > > should be g_free > > > > > > > (gdb) p g_free > > > > > > > $3 =3D {} 0x7ffff282bef0 > > > > > > >=20 > > > > > > > obj is a dangling pointer to the CPU that was just destroyed = in > > > > > > > spapr_cpu_core_realize(). > > > > > > >=20 > > > > > > > This patch adds proper rollback to both spapr_realize_vcpu() = and > > > > > > > spapr_cpu_core_realize(). > > > > > > >=20 > > > > > > > Signed-off-by: Greg Kurz =20 > > > > > >=20 > > > > > > Applied to ppc-for-3.0, since it definitely looks to fix some > > > > > > problems. =20 > > > > >=20 > > > > > Uh.. actually it has a definite bug - the first exit point will c= all > > > > > g_free() on an uninitialized spapr_cpu. I fixed it up with a NULL > > > > > initialization in my tree. =20 > > > >=20 > > > > Ah... as said in the cover letter, all the series is based on machi= ne_data > > > > being set before the call to object_property_set_bool()... Maybe I = should > > > > have made that explicit with a preparatory patch... Sorry. =20 > > >=20 > > > Ah, that makes sense. > > >=20 > > > So, I ended up having to rework a little differently, after I yanked > > > by intc -> machine_data patch because it broke things for clg. I > > > think I've fixed it up correctly now - if you can check the latest > > > ppc-for-3.0 I pushed out, that would be great. > > > =20 > >=20 > > I'll do this ASAP. >=20 > Oops, I've just spotted a nit in my original patch, that causes > QEMU to crash if threads > 1... but I had only tested with single > threaded cores :) >=20 > > +err_unrealize: > > + while (--j >=3D 0) { > > + spapr_unrealize_vcpu(sc->threads[i]); > ^^^ > should be j Ah, yes. I've fixed that up in my tree. >=20 > Appart from that, it looks good. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --aM3YZ0Iwxop3KEKx Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEdfRlhq5hpmzETofcbDjKyiDZs5IFAlsjsewACgkQbDjKyiDZ s5Jfww//ayayULloWKYH73diCX5yXZlxKfNFBwO1kTaKrYnJDuxSynZPJgMtoD75 8ear6+KFs2p7vWP4AUGts6nEXxQjwlRNMpDRGLvJA9U/XIu9yXESi/U+OmY4YO1D f1Le1k5/XZE6ThZ9Wt6Snz9hwrqYePypW68lDzxFIMZJeaMT2E7FE/ebQI8QME0j pvl0T/w3BRYNAUhv13blx2T7sPAixstxwmVTcrCWRKLxlea6A2N2q2gpFbxgREUc N9ELElnH9SmbygkXaHruN7cBZTbDKkfNkbNqvnODGbzj1ELfVKOAC2uycSEWL0MC p2FC4dPdh02rgqwjf51YxfSN7sp7H2LLwolsGsDdBu3WIK3Bd1YZgaS/3U+E9vKW Qjk0Ca6NPUvoo0Z1TRAjEI0Z6FnMSx9dQx4SA7Zu40HvmhG8lwxezrfhaNth2Qc4 vSSy9jxWNwk+OIeC/zhc+zT0pHASX7NMuGVWepBsJNYrv79c/PuzgVRZ+K+PaK/4 FDK6GBdh4xkzdQsxlSa08sNqorSZODWf/ZuaX96ud0FX5xI2T08mfwPQ7wYi1Bzk LUmHCj/kd0DIOUvT9p94z5CmiQAWIcH9TDSWokoj2CKukbdmiJA/6ilSbLYot88V lSivvIRlWpNsCTQ+dN9/0V5q0Uulnhz1WLyCMC0JJm1ujXyWHNY= =nJHd -----END PGP SIGNATURE----- --aM3YZ0Iwxop3KEKx--