From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45069) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b68uz-0001P8-Kv for qemu-devel@nongnu.org; Thu, 26 May 2016 23:58:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1b68uy-0004HJ-CM for qemu-devel@nongnu.org; Thu, 26 May 2016 23:58:37 -0400 Date: Fri, 27 May 2016 13:58:16 +1000 From: David Gibson Message-ID: <20160527035816.GU17226@voom.fritz.box> References: <146424972400.5666.10324293617984893259.stgit@bahia.huguette.org> <146424973033.5666.486850661983708617.stgit@bahia.huguette.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="uWKIjLx9zRJNHvcs" Content-Disposition: inline In-Reply-To: <146424973033.5666.486850661983708617.stgit@bahia.huguette.org> Subject: Re: [Qemu-devel] [PATCH 1/3] PPC/KVM: early validation of vcpu id List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Greg Kurz Cc: qemu-devel@nongnu.org, Paolo Bonzini , qemu-ppc@nongnu.org, Alexander Graf --uWKIjLx9zRJNHvcs Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, May 26, 2016 at 10:02:10AM +0200, Greg Kurz wrote: > The KVM API restricts vcpu ids to be < KVM_CAP_MAX_VCPUS. On PowerPC > targets, depending on the number of threads per core in the host and > in the guest, some topologies do generate higher vcpu ids actually. > When this happens, QEMU bails out with the following error: >=20 > kvm_init_vcpu failed: Invalid argument >=20 > The KVM_CREATE_VCPU ioctl has several EINVAL return paths, so it is > not possible to fully disambiguate. >=20 > This patch adds a check in the code that computes vcpu ids, so that > we can detect the error earlier, and print a friendlier message instead > of calling KVM_CREATE_VCPU with an obviously bogus vcpu id. >=20 > Signed-off-by: Greg Kurz Reviewed-by: David Gibson > --- > include/sysemu/kvm.h | 2 ++ > kvm-all.c | 6 ++++++ > target-ppc/translate_init.c | 8 ++++++++ > 3 files changed, 16 insertions(+) >=20 > diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h > index f9f00e2e56cb..f357ccde9122 100644 > --- a/include/sysemu/kvm.h > +++ b/include/sysemu/kvm.h > @@ -345,6 +345,8 @@ int kvm_arch_init(MachineState *ms, KVMState *s); > =20 > int kvm_arch_init_vcpu(CPUState *cpu); > =20 > +bool kvm_vcpu_id_is_valid(int vcpu_id); > + > /* Returns VCPU ID to be used on KVM_CREATE_VCPU ioctl() */ > unsigned long kvm_arch_vcpu_id(CPUState *cpu); > =20 > diff --git a/kvm-all.c b/kvm-all.c > index f9ae8f9bf809..e56f38527815 100644 > --- a/kvm-all.c > +++ b/kvm-all.c > @@ -1459,6 +1459,12 @@ static int kvm_max_vcpus(KVMState *s) > return (ret) ? ret : kvm_recommended_vcpus(s); > } > =20 > +bool kvm_vcpu_id_is_valid(int vcpu_id) > +{ > + KVMState *s =3D KVM_STATE(current_machine->accelerator); > + return vcpu_id >=3D 0 && vcpu_id < kvm_max_vcpus(s); > +} > + > static int kvm_init(MachineState *ms) > { > MachineClass *mc =3D MACHINE_GET_CLASS(ms); > diff --git a/target-ppc/translate_init.c b/target-ppc/translate_init.c > index 954195f5e494..a003c1029d31 100644 > --- a/target-ppc/translate_init.c > +++ b/target-ppc/translate_init.c > @@ -9231,6 +9231,14 @@ static void ppc_cpu_realizefn(DeviceState *dev, Er= ror **errp) > #if !defined(CONFIG_USER_ONLY) > cpu->cpu_dt_id =3D (cs->cpu_index / smp_threads) * max_smt > + (cs->cpu_index % smp_threads); > + > + if (kvm_enabled() && !kvm_vcpu_id_is_valid(cpu->cpu_dt_id)) { > + error_setg(errp, "Can't create CPU with id %d in KVM", cpu->cpu_= dt_id); > + error_append_hint(errp, "Adjust the number of cpus to %d " > + "or try to raise the number of threads per cor= e\n", > + cpu->cpu_dt_id * smp_threads / max_smt); > + return; > + } > #endif > =20 > if (tcg_enabled()) { >=20 --=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 --uWKIjLx9zRJNHvcs Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJXR8XYAAoJEGw4ysog2bOSd6cP/AssZgY5SkNI7sK8K4WUjNwC wEyWGohC8ZhtmdZOM6jmvDOJFHwQueNSre+rvo1kUejIfVxSU24W0EIFnL/F5P09 eSyPd+5mFyVzl+OpoZK2n+qhzXzN1bMpuLyHVbA02a1GkS72h+d77WFyhRPWqHPo 57sLIDk+WyU7Cme6r1+YPOxed+sJBHV1/c7j99/FRsL/Egu03oEphKF8HS4PvCDg eroicqmE9iEFMcqV9+cFsCaswm01umi/RKQPX83lxf/ar3ZAIB1pesUJCun4iE9s 1/yoz5UMsrgtwXNr+mujJ6/3VejjdLqbW6XzVKjypEBEoaJLHXqaxlVAQaMr/frJ x0BMjKaDSqco5NxLw23WUIbB/NawsAlucb6izsoXUWMGGZZY2XufvjHNjBUnROJf +Vd/M9CcGm8gCboxYeIgUKBp2bYG/w28LUk8o5IhmoEWH0jhG0epcY+UVmgTeUel lXpU3L/rRCWSmN5cvGCXsEatJsxFr3U2sNmFvvKmqNsiKwvze5pWm8+zuQ9lBqfd u2pdqpDGMipjEVbB7St6aNvZeSGRT2SPx2zxXu9PqaaJktuvDHupggB1fyw2pFMU KRSYYlogpq7+q9AFbV/Fa/OHj97OTFDnM9V82K65IJ3PPCEefwMlHlB3ehSiO3xK LH/Bn+1wbyUY2yxo45te =K9HJ -----END PGP SIGNATURE----- --uWKIjLx9zRJNHvcs--