From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Gibson <david@gibson.dropbear.id.au>
Date: Wed, 15 Feb 2017 03:45:25 +0000
Subject: Re: [bug report] KVM: PPC: Book3S HV: Outline of KVM-HV HPT resizing implementation
Message-Id: <20170215034525.GG12369@umbus.fritz.box>
MIME-Version: 1
Content-Type: multipart/mixed; boundary="oOB74oR0WcNeq9Zb"
List-Id: <kvm-ppc.vger.kernel.org>
References: <20170211051425.GA16625@mwanda>
In-Reply-To: <20170211051425.GA16625@mwanda>
To: kvm-ppc@vger.kernel.org


--oOB74oR0WcNeq9Zb
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Sat, Feb 11, 2017 at 08:14:25AM +0300, Dan Carpenter wrote:
> Hello David Gibson,
>=20
> The patch 5e9859699aba: "KVM: PPC: Book3S HV: Outline of KVM-HV HPT
> resizing implementation" from Dec 20, 2016, leads to the following
> static checker warning:
>=20
> 	arch/powerpc/kvm/book3s_64_mmu_hv.c:1554 kvm_vm_ioctl_resize_hpt_commit()
> 	error: we previously assumed 'resize' could be null (see line
> 	1532)

Nice catch, thanks.  I've sent a patch for this.

>=20
> arch/powerpc/kvm/book3s_64_mmu_hv.c
>   1514          mutex_lock(&kvm->lock);
>   1515 =20
>   1516          resize =3D kvm->arch.resize_hpt;
>   1517 =20
>   1518          /* This shouldn't be possible */
>   1519          ret =3D -EIO;
>   1520          if (WARN_ON(!kvm->arch.hpte_setup_done))
>   1521                  goto out_no_hpt;
>   1522 =20
>   1523          /* Stop VCPUs from running while we mess with the HPT */
>   1524          kvm->arch.hpte_setup_done =3D 0;
>   1525          smp_mb();
>   1526 =20
>   1527          /* Boot all CPUs out of the guest so they re-read
>   1528           * hpte_setup_done */
>   1529          on_each_cpu(resize_hpt_boot_vcpu, NULL, 1);
>   1530 =20
>   1531          ret =3D -ENXIO;
>   1532          if (!resize || (resize->order !=3D shift))
>                      ^^^^^^
> Check.
>=20
>   1533                  goto out;
>   1534 =20
>   1535          ret =3D -EBUSY;
>   1536          if (!resize->prepare_done)
>   1537                  goto out;
>   1538 =20
>   1539          ret =3D resize->error;
>   1540          if (ret !=3D 0)
>   1541                  goto out;
>   1542 =20
>   1543          ret =3D resize_hpt_rehash(resize);
>   1544          if (ret !=3D 0)
>   1545                  goto out;
>   1546 =20
>   1547          resize_hpt_pivot(resize);
>   1548 =20
>   1549  out:
>   1550          /* Let VCPUs run again */
>   1551          kvm->arch.hpte_setup_done =3D 1;
>   1552          smp_mb();
>   1553  out_no_hpt:
>   1554          resize_hpt_release(kvm, resize);
>                                         ^^^^^^
> Oops.
>=20
>   1555          mutex_unlock(&kvm->lock);
>   1556          return ret;
>   1557  }
>=20
> regards,
> dan carpenter
>=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

--oOB74oR0WcNeq9Zb
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2
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=CxFx
-----END PGP SIGNATURE-----

--oOB74oR0WcNeq9Zb--